ChatGPT on Action Potentials and Consciousness

What percentage of time does an action potential take up in an average neuron? 

The duration of an action potential in an average neuron is typically between 1 and 2 milliseconds (ms).

The percentage of time that an action potential takes up in an average neuron depends on the firing rate of that neuron. Neurons can fire at different rates depending on their type and location in the nervous system, and the level of activity in the network of neurons they are connected to.

For example, if an average neuron is firing at a rate of 10 spikes per second, each action potential will take up approximately 0.01 seconds (10 ms) out of a second, which is equivalent to 1% of the time. If the neuron is firing at a higher rate, say 100 spikes per second, each action potential will take up approximately 0.001 seconds (1 ms) out of a second, which is equivalent to 0.1% of the time.

Therefore, the percentage of time that an action potential takes up in an average neuron depends on the firing rate of that neuron, and can range from less than 1% to several percent of the time.

Do human says that consciousness feels continuous?

Yes, humans generally describe their experience of consciousness as feeling continuous, without any gaps or interruptions. Consciousness is often described as an ongoing stream of thoughts, feelings, perceptions, and experiences that seamlessly flow from one moment to the next, creating a sense of unity and coherence in our subjective experience.

This subjective experience of continuity in consciousness is supported by the functioning of the brain, which is constantly processing and integrating incoming sensory information, memories, and other cognitive processes in real time. While there may be brief lapses in attention or gaps in awareness, such as when we fall asleep or lose consciousness briefly, the overall experience of consciousness is typically described as a continuous and uninterrupted flow of experience.

However, it is worth noting that the nature and mechanisms of consciousness are still not fully understood, and there is ongoing scientific research and philosophical debate on this topic.

You just said action potentials take up less than 1% of the time and humans say consciousness feels continuous then does this imply that consciousness cannot only come from action potentials because they are not continuous ?

It is true that action potentials are not continuous, and that the experience of consciousness is typically described as feeling continuous. However, this does not necessarily mean that consciousness cannot arise solely from neural activity, including action potentials.

Therefore, while the brief and discontinuous nature of action potentials may seem at odds with the continuous experience of consciousness, it is important to consider the larger context of neural activity in the brain, as well as the many other factors that contribute to the complex and multifaceted phenomenon of consciousness.

Are subthreshhold near fields produced inside neurons between action potentials firing? 

Yes, subthreshold near fields can be produced inside neurons between action potentials firing. These fields arise from the movement of charged ions across the neuronal membrane in response to subthreshold membrane depolarizations, which are depolarizations that are below the threshold required to generate an action potential. These subthreshold depolarizations can result from the summation of small excitatory and inhibitory inputs from other neurons, or from intrinsic membrane properties such as membrane resistance and capacitance.

Overall, the study of subthreshold near fields and their relationship to neuronal processing is an active area of research in neuroscience, with important implications for understanding the mechanisms underlying perception, thought, and behavior.

Do subthreshold near fields between action potentials last longer than the action potentials? 

Yes, subthreshold near fields can last longer than action potentials. Action potentials are brief, all-or-nothing electrical signals that typically last only a few milliseconds, while subthreshold near fields can persist for much longer periods of time.

The duration of subthreshold near fields can vary depending on the specific properties of the neuron and the pattern of inputs it is receiving, but they can persist for several hundred milliseconds or even longer in some cases. This is because subthreshold near fields are generated by the movement of charged ions across the neuronal membrane in response to subthreshold depolarizations, which can persist for longer periods of time than the brief depolarization that occurs during an action potential.

The persistence of subthreshold near fields is one of the factors that contributes to their functional significance for neuronal processing. By summing the effects of multiple inputs over a longer period of time, subthreshold near fields can act as integrative signals that help the neuron respond selectively to specific patterns of inputs and modulate its output in a flexible and dynamic manner.

During which types of processing are subthreshold near fields continuous in neurons ? 

Subthreshold near fields can be involved in many types of neuronal processing, and their continuity across neurons can be important for the integration and modulation of multiple inputs. Some examples of types of processing that may involve continuous subthreshold near fields include:

1. Sensory processing: Sensory information is typically processed in a hierarchical fashion, with early sensory areas providing feedforward input to higher-order areas. Subthreshold near fields can be propagated across these areas, allowing for the integration of multiple sensory inputs and the generation of more complex representations of sensory information.
2. Working memory: Working memory is the ability to hold and manipulate information over short periods of time. Subthreshold near fields can be involved in the maintenance of information during working memory tasks, and their continuity across neurons can help to ensure the stability and accuracy of the representation.
3. Attention: Attention is the process by which the brain selects and prioritizes sensory inputs for further processing. Subthreshold near fields can be involved in the modulation of neuronal responses to attentional cues, and their continuity across neurons can help to ensure that the selected inputs are integrated and processed effectively.
4. Decision-making: Decision-making involves the integration of multiple inputs and the generation of a behavioral response. Subthreshold near fields can be involved in the integration of sensory and contextual information during decision-making tasks, and their continuity across neurons can help to ensure that the response is appropriate and adaptive.

In general, the continuity of subthreshold near fields across neurons is an important mechanism for integrating and modulating multiple inputs, and can be involved in many different types of neuronal processing.

A Model of Western Society

A Model of Western Society 

This is a second post on consciousness as the mechanism for calibrating Western society. The first post can be found here

I’d like to present a simple model of Western Society. You have probably spoken about it many, many times, but have probably never put the big picture together. Understanding the bigger picture will help you to analyse, argue and communicate benefits and problems in society. 

Western society is composed from six major self-calibrating systems. Each of these systems is based on the self-calibration of small changes and feedback from individual’s consciousness. We are all familiar with this feedback, which takes the form of choosing to spend money, choosing who to vote for, choosing not to commit a crime, choosing a partner etc. These six systems have evolved together so that an improvement in one system has helped to create an improvement in another system. These systems are so precious we write them into our constitutions and are willing to go to war to fight for them. 

Diagram showing the relationship between the six major self calibrating systems. 

Each of the five systems (Life, Capitalism, Science, Justice and Democracy) that make up Western Society manifest themselves in institutions (Family, Markets, Research, Legal and Government) and improve through small changes (DNA, Products, Knowledge, Laws and Policies), whilst calibration is driven by conscious feedback (Emotions, Money, Facts, Order, Votes). 

Diagram showing the name, institution, changes and feedback in the six systems. 

Each system can only maintain its calibration through feedback from individuals. This feedback (mostly) takes the form of conscious deliberation.  The exception is the relationship between Life and the Individual, which emerges into consciousness as emotions rather than deliberation.  

Each system has five relationships with the other five other systems. Whilst the diagram above shows consciousness at the centre, the centre could be swapped with any other system to show other relationships. This diagram can represent many different possible societies, but the systems, institutions, types of changes and types of feedback remain constant.

Historically these systems have evolved through a complex set of dependencies. For example families, markets, education, law and government have all evolved over time. Over time this evolution has created a vertical aspect to this model and this requires stability to be built into the system as it evolves. Undermining stability undermines the whole system.

Regulation and Protection

Each system can be broken down into consumers and producers. For example in Government the consumers of the system are voters and the producers are politicians.

Diagram showing consumers (white-half) and producers (black-half) and regulators (small black-dot) and protectors (small white-dot).

Regulators have been given special power to control producers and Protectors have been given special powers to protect consumers. These two control mechanisms keep the power of producers in check.

Diagram showing protectors (small black rectangle) and regulators (small white rectangle).

Over time regulation of producers and protectors for consumers has waxed and wained rather than evolved with the system as their functions are not immediately necessary and are open to corruption. 

For the betterment of society it is recommended that a consumer champion and producer watchdog be elected for each of the five systems. These 10 independent “judges” would need to reform the current ad-hoc system of support and regulation, provide transparency, and hold the new and existing regulators to account. Providing a feedback mechanism into the regulators through voting is a necessary step to improve the functioning of society.

Fractalization

The simple model of six systems can get very complex, very quickly because of the fractal geometry. The diagram below shows society only from the perspective of individual consciousness. There are five other diagrams that place each system in the centre. 

Diagram showing the six systems with consumers, producers, regulators and protectors.  

Hybridisation

There are many real-world organisations that are hybridised because they belong to two or more systems. For example Universities whose students are funded by students or commercial research grants. Another example is Government funded television and radio stations that complete with commercial stations. 

The key to understanding the fundamental nature of an organisation is to identify its existential feedback mechanism. 

For example, the BBC is funded by a Government tax whilst Twitter is funded by advertisers. The BBC is a Government organisation because it is funded by a tax whilst Twitter or CNN are commercial organisations because they are funded by adverts even though all compete for viewership.

An analysis by this model shows helps to understand the functioning of these organisations. The BBC avoids any feedback whatsoever because it is independent of politicians, it is not effected by implicitly voting of viewership numbers, its directors are not voted in and its regulation and consumer protection is all in-house. In other words the BBC is pretty immune to any feedback. The BBC model needs to be reformed by enabling feedback and removing its in-house regulation. 

Twitter’s business model is to act as a kind of global information journal with individuals reviewing its content and advertisers paying for the footfall. In other words twitter is a commercial organisation driven by advertisers feedback. It’s dependency on advertisers creates a deep weakness in that it is open to commercial influence. Elon has made the correct decision to improve Twitter’s free-speech, increase individual monetisation and then to trust in human consciousness to be its judge. 

Another example is political activism. Political activism demands legal and/or policy changes else it is just griping. Before policies or laws are introduced they should require a political mandate in the form of votes. Often political activists accuse those who do not share their views of criminal-like activities, which is slander or ridicule which should be addressed by both parties through the courts. Any accusations should assume innocence before guilt so social or individual costs should not be incurred where no law exists.

Corruption

Everything has an upside and a downside and if you can’t see both you’re not looking hard enough. The system described relies on regulators and protectors to maintain the positive evolution of these systems. The stability of Western society relies on the strength and transparency of it’s regulation and protection, but these controls are most open to corruption because the instability it creates is not immediately apparent. 

Governments and large organisations involve themselves in directly influencing and undermining our conscious decisions using propaganda, narratives, coercion. This behaviour by producers from the five systems is corrupt. There is no such thing as virtuous manipulation.

All of these systems have, can and will be open to corruption. Markets, Science. Law and Governments are all corrupted to a degree. It is important that the regulators and protectors are completely open and transparent with their selection and activities. It is important that all producers in all systems reveal their activity and relationships with other systems. The relationships between larger organisations are particularly open to corruption. Big business, big science, big law and big Government, especially, need to be open and open to calibration by individual conscious deliberation.

Expulsion of Ions from Ion Channels

The purpose of this post is to briefly describe the explusion of ions from ion channels. Ion expulsion is very important because ions are the source of electric and magnetic quasi static fields in the brain.

Background

A previous post has briefly looked at Ionophores (ion channels and ion pumps) and includes a paragraph on the expulsion of ions from ion channels.  

Much of the discussion and research on ion channels has been about activation, gating and filtering of ions through ion channels. However it is of great importance to understand the expulsion of ions from ion channels because this is the source of the quasi static fields in the brain. The nature of ion expulsion has the same importance as the nature of transmitting electromagnetic fields from transmitting antennas when understanding electromagnetic waves.

This post will briefly describe:-

• Steps in Knock on Model
• Hard or Soft Knock on Model
• Energetics of ion Expulsion
• Differences between Ion Channels

There are three aspects of ion expulsion which are not dealt with in this post.

• Ion entanglement
• Spin-polarisation
• Ion-wavelengths

Previous posts have looked, hypothetically, at electromagnetic fields in water and neurons. However, It is not well understood how quasi-static fields evolve, but it is important to remember that even if fields do not produce a transmitting field their entanglement, spin-polarisation and ion-wavelength properties are carried through the near and quasi-static field in order to become a transmitting field.

Ion Expulsion Models

There have been a number of models put forward to explain the the expulsion of ions from ion channels:-

• Pull model
• One-step knock-on model
• Two-step knock-on model
• Soft knock on model 
• Hard knock-on model 

Pull Model

The first the model of ion expulsion was that ions were pulled through the ion channel due to a difference in the electrical potential between the inside and the outside of cell (Hodgkin 1952). This model is still taught in many school text books. 

One-step knock-on Model

Early evidence showed the potassium movement across the membrane were dependent of the number of potassium ions outside the channel and not the voltage (Hodgkin 1955). A tenfold rise in external potassium altered the ion throughput by a factor of about 80.  The conclusion was that K+ ions moved in single file through potassium-selective sites which stretched through the membrane, and that all the sites were occupied by potassium ions. This created a ‘knock-on’ type of transfer, similar to that in the mechanical model 

This one-step “knock-on model” was proposed by Hodgkin and Keynes (1955). This model stated that the ion permeation proceeded in a three step process where the outermost ion in the channel is pushed in by an incoming ion.

Diagram showing Hodgkin and Keynes knock on model (Nelson 2011)

The energetics of this “knock-on” model was calculated by Nelson (2011) and showed the highest energy was inside the ion channel, with the energy falling to zero when the ion was emitted.

Diagram showing the energetics for Hodgkin and Keynes knock on model (Nelson 2011)

Two-step knock on Model

A more complex model was proposed by Nelson (2003, 2011). In this model permeation is a two-step process where all three ions move together in a concerted manner as the entering ion shunts-on the two helper ions to form the triply occupied state. There is then an independent dissociation step of the outermost ion to the extracellular fluid. This two-step association/dissociation (A/D) model (Nelson 2003, 2011) correctly predicted permeation behaviour at high voltages

Diagram showing Nelson two-step knock-on model (Nelson 2011).

The energetics of this two-step “knock-on” model was calculated by Nelson (2011) and showed the highest energy was when the ion was emitted.

Diagram showing the Energetics of the two step knock-on model for positive membrane voltage V.

Soft and Hard knock-on Model

It was assumed for a long time that the ions being pushed through ion channels did so through a “soft” knock-on model, which meant the ions were mediated by water molecules. The first soft knock-on model was originally proposed by crystallographers (Furina 2009). Electrophysiologists had estimated that 1.0–1.5 water molecules per K+ ion crossed the cell membrane (Fuinia 2009).

This water-mediated “soft” knock-on mechanism was the generally accepted model in the field until 2014, when a new study suggesting that the ions are in pushed through in a “hard” knock-on model where ions were in direct contact with each other, and that no water molecules are involved in the conduction process (Köpfer 2014).

Diagram (Fuinia 2009) showing KWK (soft knock-on model).

The hard knock-on model assumed that ions are expelled by direct coulomb repulsion (Bernsteiner 2019).

Diagram (Fuinia 2009) showing KK (hard knock-on model).

Berneche (2019) modelled the expulsion of potassium ions and found a complex set of forces were absolutely essential for rapid conduction. It was found that ions are as little as 0.4 nm apart. The ion at the exit site was held by the carbonyl molecules inside the ion channel until the energy from the incoming ions built up and the ion at exit site was finally pushed across the energy barrier and exited. This model predicted the expulsion of the ion carried a relatively high energy, in line with the two step knock-on model (Nelson 2011).

There is a general lack of consensus concerning “direct” knock-on versus “soft” knock- on (Bernsteiner 2019). These discrepancies mainly stem from the use of different force fields in ion models, which seem to favor different conductance mechanisms. 

Potassium Ion Expulsion

In a detailed study of the ion pore of a voltage gated channel Kasahara (2016) found that potassium ions were moved by both a push and pull mechanism. There was a pull into the cell, dependent on the ion concentration and voltage difference. When the ion concentration was high in the extracellular fluid (top of diagram), the pore was filled by 3,4 or 5 ions. Ions temporary stopped at at the second narrowing before the static charge of a preceding ion pushed the ion into the intracellular fluid (top of diagram) . When the ion concentration did not fill the pore then the ion was pulled out by the voltage difference, rather than being pushed out by the preceding ion.

Diagram from Kasahara 2016.

The diagram below showing detailed simulation (Kasahara 2016) of the speed of different ions (each ion has a different colour) being pulled (slowly) or pushed (quickly) through the pore.

Diagram from Kasahara 2016.

However, Kopec (2018) found rapid permeation of potassium ions was due to direct knock-on of completely desolvated (naked) ions in the channels’ selectivity filter, which also gave rise to a natural exclusion of any competing ions.

Sodium Ion Expulsion

How sodium ions permeate through ionic channels has remained “obscure and ambiguous” (Lianga 2021).

It was found (Peng 2016) that each sodium ion is hydrated with three water molecules which diffuses orders of magnitude more quickly than other ion hydrates. These water water molecules “attach” to the inside surfaces of ion channels and act like rollers that move the ions.

Diagram (Peng 2016) showing how sodium ions are carried by (red) oxygen on rotating water molecules whilst the (white) hydrogen is bound to the interface. 

More recently, a soft knock-on ion permeation mediated by water molecules was observed in a sodium ion channel (Lianga 2021).

Calcium Ion Expulsion

Calcium channels come from the same family of ion channels as potassium channels. The idea of a hard-knock through the Calcium ion channel was first proposed by Hess (1984) who found movement through the Ca channel was mediated by electrostatic repulsion. 

Internal Calcium Ion Channels

Internal calcium channels have been found to be fully hydrated. Ryanodine receptors (RyR) are ion channels responsible for the release of calcium ions from the sarco/endoplasmic reticulum and play a crucial role in the precise control of Ca2+ concentration in the cytosol. (Zhang 2020). Found The Ca2+ ions are fully hydrated during permeation.

Diagram (Zhang 2020) showing calcium ions are fully hydrated during permeation.

Conclusion

The verdict is currently open on both when and which ion channels process ions through hard and soft knock on models. 

Based on the available evidence for both potassium and calcium ion channels there is a soft knock-on model when the processing starts. There is also a soft knock-on for internal calcium ion channels. Otherwise, once processing starts there is a hard knock-on model potassium and calcium ion channels with the expulsion involving a relatively high energy. Sodium ion channels are been found to process using a soft knock-on model. However, the evidence is still incomplete and this investigation is not exhaustive.

Importantly, the nature of the fields produced by a hard or soft knock-on ion expulsion process can create different field properties. Ion expulsion is driven by a static coulomb force known as the “Pauli Repulsion” force, which could create a stream of entangled ions during the time the ion channels is streaming ions. This stream of entangled ions would create a long lived field with “connected” properties.

Conscious Self-Calibration in Society

The purpose of this post is to briefly describe consciousness as a self-calibrating system within the functioning of other self-calibrating systems. The hypothesis is that consciousness is a real-time, self-calibrating system and the other self-calibrating systems ultimately rely on consciousness to maintain their function.

Self Calibration Systems

A number of systems have an emergent property that allows them to improve themselves through a process, I shall call, self-calibration. These systems have often been identified as “natural” or “bottom up” and are counter to “managed” or “top down” systems. This framework is not prescriptive but acts as a model to view the structure of the actual situation. This post follows on from an earlier post on the same theory.

The six major self-calibrating systems are:-

• Life  
• Markets
• Science
• Politics
• Justice
• Consciousness

Diagram showing the major calibrating systems and their interactions (note: some not showing).

Life includes the individual and the family. The markets includes products and wealth. Politics includes democracy and government. Justice includes law-making and crimes. Science includes the peer-review and journals.

Each of these systems can interact within each other or between each other. The solid lines are personal interactions. The dotted lines are either intra-system interactions or inter-system interactions. When interactions reciprocate they create feedback.  The process of feedback is called calibration. Calibration is where small changes lead to improvements. The process of self-calibration is when a system can calibrate itself. 

These systems are often called “natural”. However they are not natural, in the sense that only they are uniquely “part” of nature, but in fact they have certain inherent properties that allow the property of self-calibration to emerge. Looking at each of these systems there is nothing uniquely “natural” about them, rather they are the “winners” amongst systems because they have feedback loops and they can improve through self-calibration. There are other “natural” systems that do not have positive self-calibration and cease to exist because they are short lived.   

Aspects

All the systems of self-calibration have similar aspects, but different properties:-

• System (life, markets, politics, justice,science)
• Atoms (genes, products, policies, laws, hypothesis) 
• Model (phenotypes, markets, government, courts, journals)
• Conscious Interaction (emotions, price, votes, order, theory)
• System Interaction (feelings, consumption, policies, laws, research)
• Underlying (lineage, resources, power, ethics, truth)

The building blocks of self-calibration systems are “atoms” these are the smallest units that are able to change and reconfigure themselves based on feedback. Atoms are built into a model. For example DNA is formed into a phenotype. Feedback from the model also affects the atoms. 

This is not a prescriptive theory of systems. Different systems in different contexts will operate differently. However for each system there are be different forms configurations that work better that will brought about by calibration. 

Systems Life Cycle

All the systems of self-calibration have similar life cycles:-

• Assembly
• Operation
• Assessment
• Interaction
• Feedback

Rights and Responsibilities

Rights are often criticised as having no natural basis. However rights drop-out of this natural framework. These are not an exhaustive list of rights, but just to a flavour of the compulsion of these rights from this framework:-

• Right to Life (and family)
• Right to Justice
• Right to Democracy
• Right to Markets (and jobs)
• Right to Science (theory and experiment)

Individual rights also drop out of this natural framework, on the basis that individuals have the right to observe, monitor and change the other 4 systems. This means individuals have the following rights related to these systems:-

• Right to transparency
• Right to speak
• Right to change

Responsibilities also drop out of this system, as laws. However there is the special case that those running the four systems and individuals interacting with the four systems as having a responsibility to ensure and uphold the constitutional integrity and rights of the individuals.

Bad Systems

There are a number of behaviours that can become over controlling and reduce the ability of a system to calibrate itself:-

• Opaqueness
• Corruption 
• Damage
• Regulation

Consciousness

At some point in evolution consciousness evolved and it is the hypothesis that consciousness evolved the ability to self calibrate. This means it was able to recalibrate the brain to reality, which then led to recalibrating the organisms behaviour to the environment. Later consciousness evolved to produce social groups and finally consciousness evolved to produce civilisations.  

Consciousness, or rather the emergence of judgment into consciousness provides the strongest feedback into these systems. Of all the systems consciousness is the only one that can understand the other systems, but more importantly individual consciousness is the only one that can provide feedback to the other systems to recalibrate them. 

Are Myelin Sheaths Magnetic Wormholes ?

The purpose of this post is to describe how myelin sheaths may act as a neural magnetic hose, and in combination with a neural magnetic cloak may function as a neural magnetic wormhole. This combination could create a “consciousness shielding” or “conscious cloaking” from inspection or interference. 

This post is part three of a three part series describing the possible function of magnetic fields formed by myelin sheaths.  The previous post looked at the magnetic properties of myelin sheaths.

Magnetic Waveguides

This discussion does not include the field “magnonic waveguides”, which is based on high-frequency spin waves running along one-dimensional ferromagnetic material (Lenk 2011). 

A magnetic waveguide is a material structure that acts as a channel for magnetic fields, but it allows magnetic fields to travel outside its boundaries. 

Magnetic Hoses

The functional properties of a magnetic hose are stricter that of a magnetic waveguide because a magnetic waveguide allows the magnetic field to exit outside the bounds of the channel whilst a magnetic hose confines the magnetic field within the channel.  

Navau (2014) created a magnetic hose consisting of alternating concentric cylinders of a high-permeability material (a ferromagnet) and a low-permeability material (a superconductor). The material created a channel that was able to direct magnetic fields over long distances (Anlage 2014). These layers formed a anisotropic meta-material, this mirrors the anisotropic layers in myelin sheaths. It is possible myelin sheaths mirror this functionality

Navau (2014) found a magnetic hose with 6 layers could transfer 80% of the magnetic field. This graph shows a similar number of layers as myelin sheaths.

Diagram (Navau 2014) showing a cylindrical magnetic insulators.

The inclusion of a soft-and-hard surface lining was found to considerably improve magnetic cloaking and wormholes (Greenleaf 2007a). This mirrors the compaction, lipid and aqueous layers in myelin sheaths. 

Magnetic hoses have been used to create a confined magnetic waveguide where the magnetic flux from multiple static magnets are superimposed in a location away from the static magnets (Sun 2015). This magnetic hose is made of an anisotropic material with very high permeability along its axis with very low permeability perpendicularly.  

Magnetic Wormholes

The idea of an electromagnetic wormhole was first proposed by Greenleaf (2007b). Electromagnetic wormholes “allow the passage of waves between possibly distant regions while most of the region of propagation remains invisible.” … “the wormhole device has the effect of changing the topology of space.” (Greenleaf 2007b).

Prat-Camps (2015) created an electromagnetic wormhole composed of a outer “magnetic cloak” at one end and a magnetic hose that projected from the magnetic cloak. The magnetic wormhole enabled a magnetic field to travel between two places and the field of propagation remained magnetically invisible. The device produced a magnetic monopole at one end of the field. It has been proposed that circular arrays of astrocytes could create a magnetic cloak.

In the design by Prat-Camps (2015) the outer magnetic cloak was a spherical bi-layer in order to shield magnetic fields from all directions. However a cylindrical cloak, instead of a spherical cloak, would still function as a cloak if the fields were from a perpendicular direction. The magnetic hose was composed of a spiral sheet composed of a thin bi-layer of ferromagnetic and superconducting material very much like Navau (2014) above. 

Diagram (Prat-Camps 2015) showing the “magnetic wormhole”. 

Previous posts have described how a magnetic cloak could be formed by a cylindrical array of astrocytes. This post describes how a magnetic hose could be formed by a myelin sheath around an axon. The containment relationship between the cylindrical array of astrocytes and myelin sheath parallels the containment relationship of the magnetic cloak and magnetic hose in the magnetic worm hole design. 

A combination of glia and neurons could create a quasi static  electro or magnetic worm hole that stretches across the neocortex. An additional part of the hypothesis predicts that the field created by Ca+2 would be need to be the main carrier of a quasi static field because it lasts for several seconds underlying spikelets. Further Na+ and K+ would undertake the role of producing short controlling, reset signals between these signs, in the form of action potentials. 

Conclusions

The current hypothesis is that magnetic shielding is created in the brain in the from perpendicular astrocytes and myelin sheaths.  The hypotheses that glial cells shield consciousness from external access or inspection bears out in the lack progress trying to find the neural correlates of consciousness. 

The current hypothesis sketches out a conscious mechanism vaguely along the lines of a “global workspace” (e.g Baars 1997) whereby continuous fields spread across the brain via axons within  myelin sheaths. A magnetic wormhole could produce a distribution mechanism for space-like fields across the neo-cortex, and possibly cerebellum, suggested in previous posts.

Magnetic Properties of Myelin Sheaths

The purpose of this post is to briefly describe some of the magnetic properties of myelin. 

This post is part two of a three part series describing the possible function of magnetic fields in myelin sheaths. The previous post looked at the structure and distribution of myelin. The next post looks at whether myelin sheaths form magnetic hoses.

Background

Myelin is the part of non-neuronal glial cell that wraps around a neuron’s axon to form a layered sheath. Myelin from different cells forms a series of sheaths separated by a 1um gap call the Node de Ranvier. When the myelin wraps around an exon its different layers have different electric and magnetic properties that interact to form a composite “meta-material” that has functions beyond each individual layer. 

Myelin as an Insulator of Action Potentials

The traditional view of myelin is that it functions as an insulator. The insulation of the axon by the non-conducting myelin sheath increases the transverse resistance and reduces the transverse capacitance of the adjacent internodal membrane. This blocks current leakage through myelin sheath and speeds up the charging of the myelin sheath (2007). 

Magnetic Induction of Action Potentials

As well as acting as an insulator the coiled myelin sheath can convert magnetic fields to an electric potential thereby inducing an the action potential from magnetic stimulation (Wang 2021, Tomassy 2014). Unmyelinated nerves cannot to be stimulated by the magnetic field as they do not have the coil structure to convert the magnetic field to electric potentials. 

In the peripheral nervous system (PNS) the myelin sheaths random or alternating direction of their winding means magnetic induction will cancel each other out. In the central nervous system magnetic stimulation was found to initiate a forward and reverse action potential. In addition the position of soma in the central nervous systems is much easier to be stimulated by the magnetic field (Wang 2021). The PNS nerves can only be stimulated at the soma using electrical thresholds, in the traditional manner.  In the CNS trans magnetic stimulation was found to directly depolarize the soma, leading to initiation of an action potential (A.P.) in the initial segment of the axon. 

Magnetic Susceptibility of Myelin

The frequency response of myelin sheaths to an external magnetic field is called magnetic susceptibility and reflects degree of magnetisation of the material.  Magnetic resonance imaging (MRI) give insights into the magnetic susceptibility myelin. 

MRI imposes a very strong external magnetic field into the brain which causes some of the molecular dipoles, particularly or water, to orientate along the magnetic field. When molecular dipoles change their axis of rotation, it is called a precession. The strength of the magnetic field, is measured in Tesla and is called the Larmor frequency. Once the tissue has been “magnetised” it then disturbed using  90° radiofrequency (RF) pulses which cause the oriented molecular dipoles to return a radio signal, which can be measured. TR measures the time to repeat, or the repetition of the pulses and TE measures the “time to echo”, or time between the pulse being sent and echoed back. R1 measures how long it takes for the magnetised tissue to orientate to the external magnetic field and R2 measures long it takes for the tissue to relax back when the magnetic field is switched off (Möller 2019). T1 relaxation imaging shows the recovery of the longitudinal magnetisation,  measured by time it takes for the nuclei to return to 63% of their original magnetisation. T2 relaxation is the recovery of transverse magnetisation after the RF pulse, measured the time it takes for the signal to decay to 37% of its excited state.

Phase contrast MRI is a specific type of MRI that is used to determine the atoms velocity in response to an external magnetic field. 

Magnetic Anisotropic Properties of Myelin

Myelin sheaths are composed of layers of cell membrane and water. Myelin in white matter fibres (axons) exhibits an anisotropic frequency and susceptibility response to the orientation of magnetic resonance imaging (Li 2011, Duyn 2014). There is a complete loss of anisotropy in the demylenated mouse brain implying myelin is the cause of the ansitrophy (Li 2011). White matter is the most paramagnetic in the fiber direction while equally diamagnetic in the other two perpendicular directions.

The anisotropic properties of the myelin layers and water creates a magnetic return signal that is dependent on the orientation of the external magnetic field with respect to the direction of axons (Yablonskiy 2014). The myelin sheath is anisotropic because the spiral of the myelin sheath can only sense the magnetic field when it is perpendicular to the phospholipids in the myelin (Xu 2018). 

Predictions of the molecular magnetic properties of lipid molecules in the myelin sheath agree with the anisotropic magnetic susceptibility of mouse brain ex vivo and human brain in vivo (Li 2011b). In addition lipid layers have been shown to orient in the direction of a magnetic field (Rosenblatt 1987) meaning there is a possible feedback mechanism making the magnetic response more complex. 

Myelin Water

The theory based phospholipid molecules underestimates the frequency response by an order of magnitude (Duyn 2014). Duyn (2014) points to the “exotic” possibility that water has a net orientation preference as well. 

Previous posts have examined how structured and oscillated water in a confined space of hydrolipds and phospholipids can drastically reduce the permittivity and permeability of water towards two orders of magnitude. 

The water trapped between the myelin bilayers is called Myelin Water (MW). The ratio of myelin water to the total water content is called the myelin water fraction (MWF). When myelin and water is subjected to a magnetic field the exchange of magnetization between water and tissue is called the magnetization transfer ratio (MTR) (Laule 2007). There is a strong association shown between MTR and myelin content, (Laule 2007)

Myelin water shows a different T2 response to intracellular water. 

Diagram (Laule 2007) showing the MRI T2 relaxation reaction signal. 

Myelin Water Fraction is between 23 and 58% higher in adults then children (Morris 2020).

Diagram (Morris 2020) showing the Myelin Water Fraction in adults an children.

Myelin Iron

Myelin is composed of diamagnetic layers containing lipids and the paramagnetic layers containing iron. Lipids and iron have sufficient concentration and susceptibilities, relative to water, to play a significant role in the magnetic properties of myelin. Heavily myelinated white matter is generally the most diamagnetic tissue in healthy brain. (Duyn 2017).

The magnetic action of water molecules between adjacent myelin layers is accelerated by ferritin and myelin (Möller 2019). Iron in myelin sheaths contains unpaired valence electrons, creating an open shell and a magnetizability roughly a thousand times stronger than that of closed shell (Duyn 2017).

In multiple sclerosis the degeneration of the myelin sheath leads to decrease in iron in the oligodendrocyte’s myelin sheaths and high iron deposits in oligodendrocytes blood vessels, in grey matter and white matter (Möller 2019). Multiple sclerosis has been found in experiment to reduce the ability to localize body parts in space and reduce bodily self consciousness (Nava 2018), and consciousness processing of visual signals (Reuter 2009). Complex seizures have been reported of partial and general seizures in late stage multiple sclerosis. A pathological balance of magnetism in the brain is also evident with the observation that Parkinson’s disease has a doubling of iron in the forebrain (Möller 2019). 

Grey vs White Matter

Post-mortem transverse relaxation rates R2 yielded only moderate differences between cortical gray matter and white matter (Langkammer 2011). 

From histological studies, it is known that iron concentration in the white matter is similar to that in the gray matter (Li 2011a). 

In gray matter the phase shift was positive indicating that overall paramagnetic contributions to susceptibility are larger than their diamagnetic contributions. However in white matter phase shifts were negative indicating the diamagnetic contributions are greater than the paramagnetic contributions. (Langkammer 2011).

These results suggest that phase contrast between gray and white matter can be mainly attributed to differences in myelin content (Langkammer 2011).

The magnetic susceptibility of the hippocampus grey matter in mice in vitro is -0.19 for control and -.023 for demyelinated mice but for white matter for the control is -1.32 and +0.04 demyelinated mice (Li 2011a). This implies gray matter is not anisotropic in vitro. A possible contribution to this is that grey matter is populated with many other types of cells, and differs between regions.  

The fraction of myelin water to the total water (MWF) of grey matter is approximately 20% of white matter. This means that there is relatively much more water in myelin in white matter than grey matter. The transfer of magnetism from water to non-aqueous matter (MTR) of grey matter is approximately 53% of white matter. This suggests that water in grey matter involves over double the transfer of magnetism per molecule, but half the transfer overall. 

Graph (Laule 2007) showing the amount of MWF (circles) and MTR (squares) in grey and white matter. 

Spikelets In Axon’s Myelin Sheaths

Spikelets are small spike like depolorizations that only cause an action potential along the axon, but not a full depolarisation of the soma (2017a). Spikelets occur across and between larger spike generation and are called complex spikes. During the period of spikelets there are raised intracelluar Ca+2 transient. Spikelets (current evidence) come from dendrosomatic origin (Michalikova 2017) . Spikelets can also possibly be of axonaxonal origin through extra-cellular waves (Michalikova 2017b) and drive small orthodromic (reverse) depolorizations. It was also found that Ca+2 transients drove spikelet timing within complex spikes, as well as larger spike generation (Bender 2009).

Spikelets can be found in both pyramidal (layer 5) and purkinje cells. 

Diagram (Bender 2009) showing how Pyramidal (left) and Purjinke (right) cells both mirror the behaviour of fast spikes (top) and Ca+2 transients (below).

Ca2+ (and Na+) transients in the proximal axon were found in the axon initial segment (AIS) and were as large as those Ca+2 transients observed in boutons and dendrites (where there were no Na+ transients) and appeared to be strictly confined to the axon initial segment (Bender 2009). 

Diagram (Bender 2009) showing how spikelets in the bouton (dendrite spines) continues though to the action initial segment.

It was found (Grundemann  2015) that repolorization (downslope during full scale action potential from +30mV to -70mV) is driven by calcium influx, to about 4x resting, at the nodes of Ranvier via the calcium-activated potassium channels (KCa3.1) during high (100hz) firing rates. 

It was also found that Ca+2 drove at the axon initial segment drove long lasting depolarisations with high firing rates (Bender 2009). 

Diagram (Grundeman 2015) showing higher density of Ca+2 at Node de Ranvier. 

Diagram (Grundeman 2015) showing how Ca+2 increases around (<10um) either side of the node de ranvier on the depolorization (downward) phase of the action potential. 

The current hypothesis is that consciousness happens between action potentials and that the field formed by Ca+2 transients during spikelets, and Ca+2 transients in dendrites, forms a carrier field for consciousness. The source of the magnetic fields could be orthogonally aligned ion channels where Flemming’s left hand rule means magnetic fields could be produced along the axon.

Myelin Sheath Structure and Distribution

The purpose of this post is to briefly describe some aspects of myelin sheaths structure and distribution. 

This post is part one of a three part series describing the possible function of magnetic fields formed in myelin sheaths. The next post looks at the magnetic properties of myelin sheaths.

Background 

Myelin is the part of a glial cell that wraps around a neuron’s axon to form a layered sheath. In the central nervous system these glial cells are called oligodendrocytes, and in the peripheral nervous system these glial cells are called Schwann cells.

Diagram (Poliak 2003) showing the myelin sheath (green) in the central nervous system (CNS).

Myelin Sheath Function

The traditional interpretation of myelin sheaths function is to form an insulating layer around axons of pyramidal neurons to improve the speed of action potentials, however myelin has other functions (Fields 2014). 

One view is that the myelin sheaths provide an inductive function to conduct and generate both electrical and magnetic signals during the action potential (Wang 2021).

The purpose of these posts is to discover other functions of myelin sheaths by relating its structure and distribution to nano-technology with similar structure and magentic properties. 

Myelin Sheath Structure

Early structural analysis of the central nervous system found the myelin sheath was composed of cylindrical layers. Cross sectional photos of myelin shows it wrapping around axons. 

Photo (Hirano 1967) showing 6 layers in the myelin sheath in white matter. 

Most myelinated axons have a ratio between the external and internal diameter of mylenation of 0.5 and 0.7 with a modal average of 0.6 (Rushton 1951). It was also found that speed of action potentials in mylenated axons to be 4 times quicker than unmylenated axons. Given the cost of forming myelin sheaths is more expensive than the energy it saves transmitting signals it is widely that speed of action potential transmission is the main function of myelin sheaths. 

Diagram (Rushton 1951) showing the difference in condition speed between medulated (myelinated) and non-medulated axons. 

Myelin sheaths are up to 1,500um in length and are separated by gaps, called the node de Ranvier, which are 1um in length, or 100 times the axonal diameter (Poliak 2003).  Historically myelin sheaths have been seen the perspective of the node de Ranvier. For this reason the myelin sheath is called the internode and the start and end of the myelin sheath is called the paranode. The nodes of Ranvier contain Na+/Ca2+ exchangers and high density of voltage-gated Na+ channels that generate action potentials. Potassium channels are concentrated in the paranodal region.

Myelin contains a different lipid composition than other cells and contain 30% of the dry weight of the brain (Schmitt 2015).

In the peripheral nervous system cytoplasm forms within myelin in the inner and outer layers of myelin , whilst in the central nervous system there is no cytoplasm in the outer myelin (Peters 1960). 

Diagram (Peters 1960) showing myelin sheath and cytoplasm (C0/C1) around peripheral nervous system (1A) and central nervous system (1B)

Myelin Water

The myelin sheath is formed of rolled up sheets of phospholipid molecules with a water filling called myelin water. Water forms about 40% of myelin. Water between the cylindrical layers is 3-4nm thick with 0.5nm in some pockets (Duyn 2014). Individual water molecules area about 0.275nm in diameter.

Diagram (Duyn 2014) showing the myelin sheath and myelin water.

The area between the outer- and inner-membrane layers is composed mainly of hydrocarbon chains (long chain fatty acids). Over half of these hydrocarbons contain one or more double bonds, which result in bends and kinks, allowing them to remain in a fluid state and less stable. (Barkovich 1999)

The lipids in myelin are composed of 30% Cholesterol, 40% Phospholipids and 30% Glycosphingolipids. Less than 1% of myelin is composed of proteins, of this 30% are Myelin Basic proteins at the cytoplasmic surface of compact myelin, 50% Proteolipid proteins which are a hydrophobic protein in the membrane-spanning domains, and 4% Cyclic Nucleotide Phosphodiesterase next to the water layers (Laule 2007).

In the peripheral nervous system it was discovered that adjacent myelin sheaths wrap in clockwise and counter-clockwise direction (Uzman 1957). Richards (1983) found it was random but found adjacent fibers in contact with the same glial process tend to be wrapped in the same direction, which could still result in adjacent sheaths having different windings. In the central nervous system myelin was found to wrap in the same direction 

Myelin Iron

The main iron-containing cells in the brain are oligodendrocytes. Approximately two thirds of the iron in the brain is found in oligonucleotides. The ferritin protein makes up two thirds of the iron in the brain and contains up to 4500 Fe3+ ions (Möller 2019). The myelin sheath has the highest amount of iron of an cell in the body (Moller 2019). 

Iron, in the form of the ferritin protein, occurs in both white matter myelin, and grey matter myelin (Fukunaga 2010). Iron in grey matter is concentrated into the layer 5 of grey matter. For example in the layer of Gennari is a layer of myelinated axons that forms the input from the thalamus. Relative Iron concentrations in the frontal grey and white matter measured 25 and 44, whilst in the occipital cortex was 40 and 34 (Langkammer 2011)

Photos showing the colocation of myelin, iron and MRI R2 (Fukunaga 2010).

Myelin Compaction

A process known as myelin compaction occurs in white matter where myelin layers connect so tightly that most of the water is remove,  leaving the electron-dense hydrocarbon chains (Stadelmann 2019).

Photo (Levesque 2014) showing compacted layers of myelin.

Compacted myelin has an unusual composition, lipids form 78% of compacted myelin dry weight, almost all the proteins are removed from the lips and the lipids have a disordered polypeptide chain (Aggarwal 2013).

Diagram (Hartline 2007) Showing compaction of the myelin sheath near a Node De Ranvier. 

The myelin basic protein (MBP) is an essential protein to  compact of the two adjacent cytoplasmic membrane surfaces into a dense line of myelin (Stadelmann 2019). One of the major functions of MBP is to bring the opposing cytoplasmic surfaces of the myelin membrane closely together (Aggarwal 2013). It has been speculated that MBP can trigger a phase translation from a sol-gel state to a state of compaction by removing an electrostatic repulsion (Aggarwal 2013).

Diagram (Stadelmann 2019) showing myelin compaction in white matter.

In the neocortex remyelination occurs more frequently and compaction happens less often. Re-myelination is strongly correlated with learning. Once compacted it is difficult to see how compacted myelin sheaths can retract and remyelinate (Stadelmann 2019). 

Recently, evidence has been provided that disordered protein domains play a role in phase transitions of proteins into cohesive hydrogels. (Agwarall 2013).

Myelin in Grey Matter

In the neocortex half the myelin in layer 2/3 covers axons of inhibitory (GABA) neurons most likely cortical basket cells. The other half covers excitatory (non-GABA) neurons, most likely pyramidal cells (Micheva 2016). Inhibitory axons have 20% higher myelin basic protein content than neighbouring excitatory axons (Micheva 2016), indicating slightly more compaction in inhibitory neurons. 

Inhibitory basket neurons are fast spiking neurons with short partially myelinated neurons (Dubey 2021). The loss of myelin in inhibitory (GABA) neurons results in a decrease in inhibitory synapses, and  increase in theta oscillation power during quiet wakefulness promoting epileptic activity (Dubey 2021). 

Diagram (Micheva 2016) showing the distribution of GABA and non GABA myelinated axons in the cortex.

A map of the human neocortex showing the estimated overall myelin content, within the grey matter of the neocortex. The more sensory areas have higher myelin whilst the more evolved higher order cognitive functions in the forebrain have less myelin. (Nieuwenhuys 2017). 

Diagram (Nieuwenhuys 2017) showing the distribution of myelin in the neo-cortex.

There appears to be a correlation between the location of myelin and the location of micro-columns in the grey matter in the neo-cortex, with both being raised in the sensory and parietal cortex. This also correlates with observations that conscious correlates with rear and mid rather than frontal areas of the cortex (Boly 2017)

Are Cylindrical Arrays of Perpendicular Astrocytes Magnetic Cloaks?

The purpose of this post is to briefly describe quasi static magnetic fields formed by cylindrical arrays of perpendicular astrocytes and how they may form magnetic shields or magnetic cloaks.

This post is part three of a three part series describing the possible function of quasi static magnetic fields formed by cylindrical arrays of astrocyte and glia. The previous post looked at calcium charges moving through perpendicular arrays of astrocytes.

Background 

There are two commonly described physical mechanisms that can form cylindrical magnetic fields. In one a cylindrical magnetic is composed of a magnetostatic material, and is called a static (Halbach) magnetic field. In the other the a magnetic field is induced by an electrical current (electrons or ions) moving down wires in a cylindrical arrangement, and is called an active magnetic field. Both types of magnetic cylinders are often used for magnetic shielding. 

The two types of cylinders have a lot in common and can be combined in a hybrid design. However there are subtle differences. For example magnetostatic field shielding is more effective to reduce tangential fields whilst active magnetic field shielding is more effective to reduce perpendicular fields. 

Diagram showing magnetostatic field shielding. 

Diagram showing active magnetic field shielding 

Passive Shielding

Cylindrical static magnets can be composed of a number of different static magnets to manipulate the magnetic field in and around the magnet in a number of different ways. These arrangements are called Halbach magnets. For example the magnetic field can be confined entirely within the cylinder or entirely outside the cylinder. Unlike dynamic induction magnets, these magnetics are formed of static fields whose direction can be controlled.

Diagram showing the different arrangements of magnets and their effect on the magnetic field (Hilton 2012 wiki)

This form of magnet can also be used to redirect external magnetic fields around the cylinder and thereby keeping the external field from entering the cylinder. In practice complete exclusion using a static magnet is not possible and the magnetic field is either aligned, weakened or heavily disrupted inside the cylinder. 

Diagram (Vogel 2016), showing magnetic fields (a) Halbach, (b) reverse Halbach, (c) tangential (d) radial for different magnetostatic patterns. 

Another feature of Halbach cylindrical magnetic shields is that they require the diameter of the magnet to be large (4x) compared with the diameter of the internal shielded space (Bjørk 2016).

Diagram (Bjørk 2016) showing the ideal diameter of a Halbach magnet.  

Active Magnetic Shielding

Active magnetic cylindrical arrays were originally invented by early pioneers, such as Tesla, and commonly seen in applications such as squirrel cage motors (e.g brushless power tools). Active magnetic shields have also been designed for use as electromagnetic shielding in space vehicles (Westover 2014).

Shielding does not have to be cylindrical in shape and it can be formed from nanowires. Mirzaei (2015) showed a nanophotonic cage of non-cylindrical nanowires can both stop fields from escape and entering a closed shape. Note: Cage like functionality is different to Shield like functionality.

Diagram (Mirzaei 2015) showing light failed to enter or exit a cage of nanowires in the shape of Australia.  

Magnetic Cloak

Cloaking is a more complex function than shielding. Whilst shielding stops external magnetic fields from (1) entering a space, cloaking also (2) stops internal magnetic fields from exiting that space AND (3) maintains external magnetic fields paths to continue as-if an object was not there. In terms of the current context a cylindrical form can shield or cloak fields coming from 2 dimensions whilst in a spherical form they can work in 3 dimensions.   

Redirecting fields around cylindrical shapes using active cylindrical arrays has also been investigated for use as an electromagnetic cloak over predetermined (cylindrical) shapes from a point source (Selvanayagam 2013).

Diagram (Selvanayagam 2013) showing active shielding forming a cloak around an object.  

Efficient shielding has been used to create cloaking, where fields are bent around the cylinder and resume their path as if the cylinder was not there. Cloaking is difficult to achieve for electromagnetic fields but has proven easier for static and quasi static magnetic fields (Anlage 2014).

Quasi-static magnetic cloaks have been developed which used super conductors ran at very low temperatures and narrow high frequencies. Quasi-static cloaks have since been developed and optimised to operate at room temperature, across a broadband of frequencies and did not use super conductors (Jiang 2017, 2018) and uses  thin structures (Steckiewicz 2019, 2021).

Quasi-static magnetic cloaks have been developed (Souc 2013) that operated at room temperature and consisted of a superconducting and ferromagnetic bi-layer that cancelled out the distortion by the external field. The cloak was effective for quasi static field oscillations between 18 and 144Hz. This is of a very similar range to quasi static fields oscillations by ions in the brain.

For example a device developed to run at room temperature consists of an array of wires running along a metallic cylinder whose current can be varied (Jiang 2018). It can deflect static magnetic fields up to 20 times the earths magnetic field. This device bears a structural resemblance to cylindrical arrays of astrocytes. 

Diagram (Jiang 2018) showing a cylindrical cloaking device. 

Diagram (Jiang 2018) showing a cylindrical device shielding a magnetic field. 

It has also been shown then when the cylinder is “capped” by a continuous “growth” structure of the same material that it enhances the magnetic shielding (Laurent 2019).

Diagram (Laurent  2019) showing magnetic flux around a cylinder subject to an axial field, with an open and closed caps. With top increasing having current density (J), bottom increasing top thickness (e).  

Astrocytes as Magnetic Shields or Cloaks 

Astrocytes form arrays from layer 1 to 3a and from layer 6-3.  Calcium flows within these cells could create extra cellular magnetic fields that shield columns of neurons.

In the engineering literature circular arrays of current carrying wires shows they are able to form quasi static magnetic shielding of magnetic fields much stronger than gravity at room temperature (Jiang 2017). 

Astrocytes and glia may form magnetic shielding of neurons and astrocytes in layer 1-3 and 3-6. The engineering science shows the function of astrocytes producing magnetic fields is not to ephaptically couple columns, but to shield columns from each other. 

The interaction between adjacent shielded columns could occur using direct excitatory spiny stellate neurons and inhibitory double-bouquet neurons.  

The shielding around columns of neurons creates a more magnetically neutral environment that would provide a more stable environment for the quasi static electric and magnetic fields to function. The “escape’ of magnetic fields through the top and bottom of the micro-column may be limited or controlled by the “capping” of astrocytes.

Cylindrical Arrays of Perpendicular Astrocytes

The purpose of this post is to very briefly describe how  interlaminar astrocytes and Bergman glia form perpendicular cylindrical arrays around columns of neurons.

This post is part two of a three part series describing the possible function of quasi static magnetic fields formed by cylindrical arrays of perpendicular astrocytes. The next post looks at how cylindrical arrays of perpendicular astrocytes might form a magnetic shield or magnetic cloak.

Background

Micro-columns are columnar groupings of neurons and astrocytes that form repeating structures in some parts of the neocortex.

Micro-columns were first described by Mountcastle (1957) as “neurons of the somatic cortex [that] are organized into vertical columns or cylinders which extend perpendicular: through the cortical layers.” 

Diagram (DeFelipe, J. 2015) representing a neocortical micro column, based mainly around the layer 5 pyramidal neurons. 

Micro-columns are assumed to commonly map between an internal topology and an external topology (Tommerdahl 2005). In that sense cortical columns are semantic structures much like cortical maps have a semantic basis. In some cortical maps they confirm an evolutionary or functional advantage and may have evolved or develop. 

Diagram (Tommerdahl 2005) showing how the micro columns in the somatosensory cortex map to sensory finger nerves.  

Micro-columns are often based on pyramidal neurons whilst, excitatory spiny stellate cells and inhibitory double-bouquet cells, excite and inhibit micro-columns in adjacent micro-columns (Tommerdahl 2005). 

Diagram (Tommerdahl 2005) showing how the micro columns excite and inhibit adjacent micro-columns.

Only some parts of the cortex contain repeating micro-column structures and their detailed structure and function varies between mammalian species and even individuals (Jones 2000). Micro-columns are more prevalent in the sensory cortex, such as visual, temporal and striate cortex. These regions correlate with the more laminated areas in cortex proposed by (John 2021).

There is a continuous debate about the function of micro-columns (Buxhoeveden 2005). A canonical microcircuit that corresponds to cortical columns has not been found across the cortex and the size of their structure could be the result of a common evolutionary journey (Horton 2005). 

The size and existence of micro-columns is dependent on the individual function of the map in which they occur. There is a spectrum in the literature between larger columnar arrays such as the barrel and ocular dominance columns and smaller micro-columns and cortical maps with no micro-columns. Some columns are 600um to 900um across whilst others are 30um-80um across (Jones 2000). These varying sizes of columns have columns have been given names such as macro, mini or micro columns.

Distribution of Astrocytes in Micro-columns

Astrocyte morphology is strongly confined within cortical micro-column boundaries in mammals, ranging from mice to human, as measured by the lower density of astrocytes at boundaries of micro-columns (Eilam 2016). This distribution was found for cytoplasmic astrocytes in the mouse barrel cortex and rat auditory rat cortex and for the interlaminar astrocytes in the human colour-blobs cortex and human striate cortex and V1 of the human visual cortex. 

Picture (Eilam 2016) showing the distribution of astrocytes in the layer 5 of the mouse barrel cortex. 

Astrocytic Calcium

The protoplasmic (not interlaminar) astrocytic calcium response to visual stimulus was found to vary between mammalian species and was dependent on having cortical micro columns. It was found (López-Hidalgo 2017) that a species with cortical V1 orientation micro-columns (ferrets) has sustained calcium response to visual stimulus, whereas species with no cortical V1 orientation micro-columns (mice) had weak calcium response to visual stimulus. In ferrets astrocytes are twice as big as mice, and overlap 50% of its territory with 6-8 neighboring astrocytes unlike mice. 

Diagram showing neural and astrocytic calcium response to ferret (left) and mouse (right).

In contrast, the mouse cortical A1 auditory (tonal) micro-columns were found to have a large sustained calcium response to stimulation (Tischbirek 2019). The mouse barrel cortex is also known to have a micro-column structure and also has sustained calcium response. 

Magnetic Fields in Astrocytes

Magnetic fields can travel through tissue similarly to free space as tissue has the same magnetic permeability (magnetic) as free space (Caruso 2017). However electric fields are limited in their ability to pass through cellular tissue and bulk water. Previous posts have shown that confined water inside neurons can orientate water so that the permittivity (electric) is greatly reduced along the line of the cell, but not directly through the cell wall. 

It was hypothesised that owing to the long, thin, geometry of intralaminar astrocytes (and possibly Bergman glia) they can produce bio-electric and and bio-magnetic fields, which can “coherently integrate external and internal signals between neurons and astrocytes by ephaptic interaction”. (Martinez-Banaclocha M. 2018).

Martinez-Banaclocha (2018) speculated that the magnetic fields produced by astrocytes creates ephaptic coupling. Ephaptic coupling refers to interaction between neurons and astrocytes through the electric and magnetic fields in the extra cellular field. Ephaptic coupling has generally been used to refer to coupling between action potentials along axons, but it also has a small effect on dendrites where it effects post synaptic potentials. 

Diagram (Martinez-Banaclocha 2018) showing how a moving Ca+2 charge induces a magnetic field inside an astrocyte. 

Ca+2 moves continuously inside astrocytes during cycles of action potentials.

Diagram (Gai 2020) showing a continuous movement of Ca+2 during cycles of action potentials. 

Magnetic Fields in Micro-columns

Martinez-Banaclocha (2020) further hypothesised that astrocytes surrounding cortical micro-columns produce magnetic fields which ephaptic couple with astrocytes and neurons in adjacent micro-columns. This hypothesis suggests there is a ephaptic coupling between microcolumns. 

Diagram (Martinez-Banaclocha M. 2020) showing magnetic and electric fields in microcolumns. 

However the previous study (Eilam 2016) showed that astrocytes do not form a boundary around micro-columns (see image above). In fact astrocytes are spread evenly within the micro-column and are reduced at the boundary. This means the micro-column structure surrounded by astrocytes suggested Martinez-Banaclocha M. (2020) may not be correct. 

An alternatively biologically realistic model, that retains the concept of vertical cylindrical arrays of astrocytes and the movement of Ca+2 molecules, has been suggested by Colombo (2002). In this model  cylindrical arrays of astrocytes containing moving Ca+2 ions expands outwards concentrically. 

It was found that the “sphere of influence” of diffusing Ca+2 molecules may control a radial arrangement of interlaminar processes (Colombo 2002). This model suggests that interlaminar astrocytes trigger adjacent astrocytes through electrical synapses, to form an efficient, radial cylindrical structure containing moving Ca+2.  This moving Ca+2 creates magnetic fields.

Diagram (Colombo 2002) showing the model of a cross section of the expansion of a Ca+2 wave across interlaminar astrocytes in the horizontal axis, where each hexagon is a micro-column.

A similar radial spread of Ca+2 though vertical Bergman glia (astrocytes) has also been found in the cerebellum (Hooglanda 2009). This suggests that both interlaminar astrocytes and Bergman glia form vertical arrays of moving Ca+2 in both the cortex and cerebellum. 

Diagram (Hooglanda 2009) showing the cross section of the expansion of a Ca+2 wave across cerebellum, in the horizontal axis.  

Next Step 

The next post will show the possible function of cylindrical magnetic fields produced by astrocytes in the cortex and glia in the cerebellum.  

Perpendicular Astrocytes

The purpose of this post is to very briefly describe the structure and location of interlaminar astrocytes, polarised astrocytes and Bergman glia.

This post is part one of a three part series describing the possible function of quasi static magnetic fields formed by cylindrical arrays of perpendicular astrocytes. The next post looks at how perpendicular astrocytes form cylindrical arrays. 

Background

Neurons and astrocytes (including glia) are the two main types of electrically active cells in the brain. Both are approximately co-located but have different forms and functions. Astrocytes generally function as neuronal support cells and thereby influence the function of neurons.  

The close relationship between neurons and astrocytes has been known since the very early studies of neurons (Schleich 1894) when they were called neuroglia. 

Diagram (Verkhratsky 2018) showing relationships between pyramidal neurons (black) and neuroglia (red) in the neocrtical layers from Schleich 1894. 

There are three main types of astrocytes related to neurons in the neocortex. Interlaminar astrocytes, which descend from layer I of the neocortex in straight projections. Protoplasmic astrocytes, which form dense spherical branches which contact chemical synapses in a structure known as the tripartite synapse (Araque 1999). Fibrous astrocytes, which contact axons that descend from the neo-cortex to the white matter.   

Oberheim (2003) showing the location of interlaminar and protoplasmic astrocytes in the neocortex.

The “traditional” model of astrocytes is that they are a neural analogue without electrically excitable action potentials, that act as a caretaker for signalling molecules and ions. Most research has focused on protoplasmic astrocytes forming the “tripartite synapse” (Araque 1999) that support and influence chemical synapses and synaptogenesis. The latest view is that protoplasmic astrocytes are functionally integrated with synapses and are formed of nodes and shafts that are active not only at the site of synaptic integration but also along the length of the branches (Arizono 2020). 

Parallel Astrocytes

Differences between interlaminar and protoplasmic astrocytes were understood in early studies (Andriezen 1893, Verkhratsky 2018). Since then interlaminar astrocytes have never received as much research as neurons or protoplasmic astrocytes. 

Picture (Andriezen 1893) showing “caudate cells”.

Interlaminar astrocytes, in humans, descend from layer 1 to layer 3 in straight projections and run parallel with pyramidal neuron’s trunks but perpendicular to the apical dendritic branches of pyramidal neurons. Long projections of interlaminar astrocytes frequently end on large blood vesicles (Sosunov 2014). 

Polarised are another form of perpendicular astrocyte that are found sparsely in layer 6 and their processes cover layer 6 to 3. Polarised astrocytes cover the basal dendrites of the layer 5 pyramidal neurons (Oberheim 2006, 2012).

Diagram Verkhratsky (2018) showing the location of interlaminar and polarised astrocytes in the cortex.

Human Phenotype

A significant evolutionary difference has been found between the length of interlaminar astrocytes amongst mammals. Interlaminar astrocytes descend to the layer 1/2 boundary in mammals but descend to the layer 3a in primates and humans.

Diagram showing the length of the interlaminar astrocytes across different mammalian species (Falcone 2019)

Picture showing interlaminar astrocytes in a rat, where the line represents the layer 1/2 boundary (Colombo 2016).

Picture showing interlaminar astrocytes of human intracellular astrocytes, where the dotted line represents the layer 1/2 boundary (Colombo 2016).

Another major difference between primates (including humans) and mammalian astrocytes is that speed of the calcium signals in human astrocytes are four times the speed of mammals (Oberheim 2009). This has an important effect on the electric and magnetic field created by these astrocytes. 

Both extended interlaminar astrocytes and polarised astrocytes are perpendicular to the cortical surface and are only found in primates and humans (Oberheim 2012).

Cerebella Glia

Another for of perpendicular astrocyte in the brain are Bergman glia which form descending projections parallel with the Purkinje neurons in the cerebellum.

Diagram showing Bergman glia running parallel with the Purkinje neurons in the cerebellum (Hooglanda 2009)

Diagram showing the close relationship between Bergman glia (green) and Purkinje neurons (red) in the cerebellum (Tanaka 2008). 

Extracellular Fields

Astrocytes are known to create calcium waves (Scenes 2006) both within individual astrocytes and between adjacent astrocytes, through electrical and chemical junctions. Calcium waves in protoplasmic astrocytes were found to be much more active (50-100x) in small micro-domains next to synapses rather than their soma (Lia 2021).

Calcium waves appear to play two main functions in the cortex (Guerra-Gomes 2018). First a focal response to support synaptic activity and plasticity in the fine astrocytic processes leading to the tripartite synapse (Araque 1999). Second a global response to support neural synchronisation of global rhythms and behaviour (Lyon 2021), including sensori-motor, fear-anxiety, feeding, cognitive processes and reward and addiction. 

Extracellular electric fields can be produced along the length of cells by ions moving in and out of cells, which change voltages along the length of the cell. Extra cellular magnetic fields can be created by charges moving along cells, like electrons moving along wires. 

Extra cellular electric fields have been shown to have a modest effect during normal physiological conditions (Jefferys 1995). The extra-cellular field was 0.5mv, which was substantially less than the -70 to +25mv action potential. They do rarely play a role in synchronising, or coupling, action potentials. For example they were found to synchronise slow moving (< 8hz) spikes among adjacent neurons (Anastassiou 2010). 

Extra cellular coupling has also been found between cerebellar purkinje axons (not soma or dendrites) where the synchronisation of the rising phase of action potentials (Han 2018) is caused by the opening sodium (Na) channels between nearby axons, but not extra cellular fields. 

If extra cellular electrical coupling becomes too strong it produces pathological conditions, such as in multiple sclerosis where a reduction in myelin enables undesirable axonal interactions (Han 2018) or in epilepsy (Jefferys 1995).

However, unlike electric fields, magnetic fields can pass through brain tissue and water easily. Magnetic fields that are created by Ca+2 moving within astrocytes will create extra cellular magnetic fields coupled. It has been speculated that extra cellular magnetic fields synchronise oscillations (Martinez-Banaclocha 2018). 

Diagram showing possible production of magnetic fields by moving Ca+2 in astrocytes (Martinez-Banaclocha 2018).

Next Step 

The next post will show how perpendicular astrocytes and glia form perpendicular cylindrical arrays around columns of neurons.