Firstly describes how synaptic mechanism can't explain the very fast and complex changes of functional neuronal connectivity necessary for cognition and show that the intraneuronal matrix modulates neurotransmission and memory consolidation. They describe how the neuronal cytoskeleton supports highly cooperative energy transport and information processing based on molecular coherence, existing long-range coherent dynamics within the intracellular and extracellular filamentous matrices. Then coherence operate at multiple levels of neuronal organisation and cognition emerges from it. There are numerous interesting commentaries of the authors, for example they say that coherent oscillatory dynamics sum the output of individual elements, enabling a powerful response to a weak external input, an efficient communication between different systems and the encoding information in terms of the phase, frequency, or amplitude of the oscillating system. But the most important thing of the paper is their integrative approach combining neuroscientific and biophysical disciplines, and apart from a review of the importance of synchronization and coherent oscillation of brain neuronal electric potential and spikes, they also speculate on how neuronal and molecular coherent oscillations could functionally interact by taking into account the electrodynamic properties of the intra- and extracellular filamentous matrices, for example there is a strong indication that coherent calcium waves are frequency and amplitude modulated (which implies their capability of encoding information) and the authors hypothesize that those modulatory signals is utilized for the integration of neuronal long-range activity using wave interference patterns and that for such complex integration are required ephaptic signals from endogenous EM fields. They say that EM field-mediated interactions between juxtaposed neurons have been demonstrated in the cortex even at very weak naturalistic EM stimulation, affecting the APs, PSPs and spike field correlations only indirectly, because electric fields caused very small (below stochastic fluctuation) changes in the membrane potential of individual neurons. And that investigations point to the concept that EM fields can modulate macroscopic oscillations at the network level, and may thus influence oscillations that generated them in the first place, giving rise to emergent properties of synchronous oscillations that could not be simply deconstructed to the contributions of single components, so endogenous electromagnetic fields could contribute to information processing, and that for some authors this can be a substrate for consciousness. A large part of the text is a review of different synchronous oscillations that take place between brain regions combining all type of frequencies (in the gamma, beta, alpha, theta or delta bands) and their relation to different cognitive experiences, mental states, memory access, etc. The authors also say that although it is unknown why cognitive functions could emerge from synchronized firing this is a fact, and the "hard problem" of subjective awareness is open to discussion (in this web it's proposed an electromagnetic nature of consciousness). They also mention microtubules and describe a theory in which those serve as electrical wires, where conductivity is mediated by counterionic propagation along the filaments in the form of nonlinear, soliton-like propagation and where ionic waves electrostatic perturbations of counterions between adjacent MTs could couple via the MAP2, thus potentially integrating the whole matrix into an electrically coupled network. There is a section [1] in this web where MT function in biophotonic signaling it considered as well. They review molecular coherence proposed by Fröhlich (and also there is a section [2] about this topic) where thermally distributed excitation energies are funneled into a single (coherent) oscillation mode, resulting from the phase synchronization of electromechanical oscillations. Below, the authors dedicated a section specifically to coherent electromagnetic fields (pag 33) where retaking microtubules, they expose their potential to electrodynamic interactions (because their ferroelectric and piezoelectric properties) and that EM field produced by the longitudinal dipole oscillations in the MTs could exert biological effects (more about Microtubules and endogenous electromagnetic field in [3]) one of them a resonant interaction of the field with condensed counterions surrounding the filaments, suggesting a modulatory effect of the coherent field on voltage-dependent ion channels. And the authors extend with an interesting description of MT's possible functions including a possible role as a quantum optical cavity (for biophotons) where water dipole interactions inside MT are ordered allowing highly synchronized interactions with the quantized electromagnetic field entering the filament, and a consequent propagation of coherent excitations along the cavity without energy dissipation. Together it can be said that microtubules support coherent transport of energy and information at various layers (as the various layers working in [4]) remaining to be determined which of these layers could interact with the synaptic (or non-synaptic) input and contribute to signal integration and neuronal response. [1] EMMIND › Endogenous Fields & Mind › Biophotons › Biophotons in Neurons and Brain |
Last modified on 20-Mar-16 |