Neurons’ “antennae” are unexpectedly active in neural computation

There is no need to invoke a purely electromagnetic effect at the synapse - the electro-chemical mechanism is already well understood and documented. This is a point mechanism and does not involve any sort of antenna effects due to the shape of the dendrite tree. Where the “antenna” part comes in is the overall interaction between the rising axons and the dendrite arbor. The axons tend to be spatially coherent and the trained synapse pattern forms the “receptive field” of the antenna metaphor.

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“This is point mechanism” because you chose to view it that way. There is nothing intrinsically point-like in any synapse. The axon is an extended object, the action potential as well; so is the dendritic spine, the dendrite, the postsynaptic density, neurotransmitters, etc. There are very few point-like objects in this process. (I think have identified a truly point-like process, but this is a discussion for another topic)

What concerns the synaptic transmission, the extendetness of the biological hardware might very well play a crucial role, as it has the ability to combine time and space in a very powerful way. Take a look at this figure from my paper:

It is often assumed that the action-potential is a regenerative phenomenon. This means that as it advances, the coupling between the voltage-gated ion-channels and the electrical potential elicits currents with a similar magnitude and time-course at different places along the axon. These currents “recreate” the pulse at different positions.

From the perspective of a stationary spine, with which the AP-carrying axon synapses, the fact that currents with similar magnitude and time-course are elicited in a chained, directed fashion, will alter in a predictive way the electromagnetic field that the postsynaptic neuron is experiencing along its boundaries due to this phenomenon. Given that at a synapse, the axon and the spine come in close proximity, the AP will at one point have reached this position. Thus, from the time that the AP was elicited, to the moment that the AP is right above the spine, the distance from the boundary of the spine to the AP’s current sources has continually decreased, and thus the magnitude of the magnetic field elicited by the regenerating currents and falling upon the spine’s boundary, has continually increased.

Considering that the ion-channels in the postsynaptic neuron are closed during this period, the conductive fraction of the intracellular volume of this neuron will oppose the change of the magnetic field, caused by the advancing AP, eliciting an electrical circulation of its own that gives rise to a magnetic field, pointing in the opposite direction, as required by Lenz’s Law. The approaching AP thus induces an in-time-increasing amount of energy in the postsynaptic neuron; the amount of energy that the postsynaptic neuron is able to absorb depends on the topology of the conductor. The more current loops a conductive volume is able to sustain, the higher will be the magnitude of the generated magnetic field, and thus the higher will be magnitude of the absorbed energy, at equal absolute magnitudes in the change of the magnetic flux (e.g. simplistically, a coil with more turns will absorb a greater amount of energy than a coil with fewer turns if presented with equal fluxes, as the inductance depends (quadratically?) on the number of turns).

Considering the topology of the intracellular conductor of a biological spine, as macromolecular structures such as the cytoskeletal elements do not conduct ionic currents, any such compartment will have a literally astronomical genus. Take again a look at the same reconstruction that I posted earlier.

At this scale, however, we can no longer talk about inductor, capacitors and resistances. If one would seriously model such a phenomenon, and solve coupled 3D+1 EM with real materials-properties (via something like finite-differences in the time-domain (FDTD) or some other time-domain fully coupled EM numerical method), then the architectural elements within these volumes might give rise to all sorts of exotic behaviors, since material patterning that are well below the spatial frequency of the incoming wave are classified as metamaterials.

You might want to think that synaptic processes are by now well understood, but I can tell from my 10-year long experience of modelling and studying dendritic spines, that these processes are from being satisfactory handled by any classical biophysical formalism.

Using molecules might not be that easy with a purely classical EM-formalism. The quantizations that involve modelling molecular surfaces surpass any Maxwellian formalism, and this is why quantum-biology is becoming increasingly popular. However, because brains and living beings in general are highly patterned objects, with rigorous architectural/dynamic patterns showing up on every scale, scale-free couplings might be present while an individual is alive, and thus models with a lower-than-molecular resolution might still provide highly interesting insights.

Because the material architecture stays remarkably constant for long periods of time, the way in which a stereotypical electromagnetic wave is distorted by the material interposed between the source and a static receiver will be quasi identical each time the stereotypic wave is elicited. Thus, receivers with geometries tuned to listen to any event within such a system can be imagined.

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ok… forget about selectivity.

Let’s talk about metabotropic receptors. (Most of the cortex connections are those no ionotropic receptors, and are critically important for feedback, thalamocortical loop, etc…). The interaction triggered by the metabotropic receptors mostly occurs inside the cell not outside. The effects might stay for seconds. I can’t see how EM can affect inner cell state.

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If electricity can influence the intracellular domain, then surely electromagnetism is able to do so as well. Electricity is only one axis of the inextricable electromagnetic field. A fundamental aspect of electromagnetism, which is not captured by electrostatics, is its ability to deal with with circuital flows. Thinking that all flows are linear, you will end up with “Penrose-stairs” models, where you arrive in the same place by going always down.

Metabotropic receptors are specialized molecules that release “messengers” into the intracellular domain. These messengers are chemicals which, like all other molecules have a charged surface and polar momentum. Timely releasing such objects into the intracellular environment may alter the resonant modes that that volume is able to sustain. Thinking that they whizz around randomly in a hopeless search for a fitting interaction, without affecting by their presence the way all other material constituents that share the same space interact, is a simplistic perspective.

You go into all that physics, which is very cool but seems unnecessary. If the brain did rely on magnetism to any extent, wouldn’t MRI totally mess it up?

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Probably because the magnetic field generated by an MRI-machine has a rather constant field-strength and direction. Like the constant magnetic filed of the earth, such offsets should be easily compensated by the brain. Endogenous magnetism is extremely specific, both what the direction and the time-dependent magnitude of these fields concern, as magnetism is always associated with electric currents, which are forced to flow onto very specific routes by the material architecture of living beings.