On the possible role of protein vibrations in information processing in the brain: three Russian dolls.

John Smythies

doi:10.3389/fnmol.2015.00038

Abstract

Until recently it was held that the neurocomputations conducted by the brain involved only whole neurons as the operating units. This may however represent only a part of the mechanism. This theoretical and academic position article reviews the considerable evidence that allosteric interactions between proteins (as extensively described by Fuxe et al., 2014), and in particular protein vibrations in neurons, form small scale codes that are involved as parts of the complex information processing systems of the brain. The argument is then developed to suggest that the protein allosteric and vibration codes (that operate at the molecular level) are nested within a medium scale coding system whose computational units are organelles (such as microtubules). This medium scale code is nested in turn inside a large scale coding system, whose computational units are individual neurons. The hypothesis suggests that these three levels interact vertically in both directions thus materially increasing the computational capacity of the brain. The whole hierarchy is thus similar to three nested Russian dolls. This theoretical development may be of use in the design of experiments to test it.

Highlights

Fuxe et al (2014) have recently proposed that information essential to the laying down of permanent memories in the brain is carried by allosteric waves between the various protein molecules that make up the post-synaptic density and presynaptic regions
In the ‘‘bar-code’’ model of the synapse proposed in previous communications by Fuxe et al (2014), the bar-code mechanism was formed by ‘‘lock-and-key,’’ allosteric interactions between the various proteins that make up the hetero-receptor complexes
Further experimental work is needed to tease out the contributions of each level of this hierarchy to the function of the neuron

Summary

Introduction

Fuxe et al (2014) have recently proposed that information essential to the laying down of permanent memories in the brain is carried by allosteric waves between the various protein molecules (receptors, ion channels and scaffolding proteins) that make up the post-synaptic density and presynaptic regions (hypothesis A). They propose that binding of a neurotransmitter to its receptor induces a conformational change in the receptor molecule that is transmitted by an allosteric wave to induce conformational changes in the other protein molecules that make up the heteroreceptor complex This pattern is learned through the resulting reorganization of the various homo- and hetero-receptor protein complexes in the post-perisynaptic membrane into the formation of novel ‘‘bar-codes’’ represented anatomically by the novel heteroreceptor complexes formed, and physiologically by their new balance with the corresponding homoreceptor complexes. In this way a molecular engram for short-term memory is created. For further comprehensive information on protein allosterics and bar-codes see Fuxe et al (2014) and Smythies (2015)

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Conclusion