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Tuesday, October 28, 2014

Cognitive neurocomputation

Cognitive brain functions including sensory processing and control of behavior are understood as “neurocomputation” in axonal–dendritic synaptic networks of “integrate-and-fire” neurons. Cognitive neurocomputation with consciousness is accompanied by 30- to 90-Hz gamma synchrony electroencephalography (EEG), and non-conscious neurocomputation is not. Gamma synchrony EEG derives largely from neuronal groups linked by dendritic–dendritic gap junctions, forming transient syncytia (“dendritic webs”) in input/integration layers oriented sideways to axonal–dendritic neurocomputational flow.
As gap junctions open and close, a gamma-synchronized dendritic web can rapidly change topology and move through the brain as a spatiotemporal envelope performing collective integration and volitional choices correlating with consciousness. The “conscious pilot” is a metaphorical description for a mobile gamma-synchronized dendritic web as vehicle for a conscious agent/pilot which experiences and assumes control of otherwise non-conscious auto-pilot neurocomputation.
"At the neuronal level, dendritic/somatic integration of synaptic inputs is not passive, involving complex logic functions and signal processing in dendritic spines, local dendritic regions , and intra-dendritic and somatic cytoskeletal processes Anesthetics act almost exclusively on dendritic and cell body/somatic proteins to erase consciousness, with little or no effects on axonal firing capabilities. And coherent spike volleys/firing explosions are preceded and caused by synchronized dendritic/somatic integrations. Arguably, dendritic/somatic integration is the sub-neuronal correlate of consciousness. And dendritic/somatic integration is the origin of gamma synchrony."
"Groups of neurons linked by dendritic–dendritic gap junctions form extensive gamma-synchronized syncytia or “dendritic webs” extending through brain regions.
Within neurocomputational networks, dendritic webs are laterally connected input/integration layers which can enable collective integration among synchronized neurons. As gap junctions open and close, spatiotemporal envelopes of synchronized neurons (dendritic webs) move and distribute rapidly around the brain as mobile integrators, vehicles for a conscious agent able to experience and control—tune into and take over—otherwise non-conscious auto-pilot neurocomputation. The conscious agent itself may be some finer-scale process extending within neuronal interiors through the dendritic web.
As a metaphor, an airplane flies on auto-pilot while the conscious pilot is sleeping or out of the cockpit engaged in other activities. If turbulence occurs, or an alarm sounds, the conscious pilot immediately returns to the cockpit and assumes conscious perception and control of the plane. When the problem resolves, the conscious pilot may again wander off as the auto-pilot computer takes over. In the brain, the auto-pilot is neurocomputation mediated by axonal firings and synaptic transmissions in feed-forward and feedback neuronal networks. The conscious pilot is synchronized collective integration (dendritic webs) moving and evolving sideways through input/integration layers of the same neuronal network architecture."
In the brain, the auto-pilot is neurocomputation mediated by axonal firings and synaptic transmissions in feed-forward and feedback neuronal networks. The conscious pilot is synchronized collective integration (dendritic webs) moving and evolving sideways through input/integration layers of the same neuronal network architecture.