To 1-st page

• A.K.Vidybida. Information processing at single neuron level. Poster presented at NATO ASI "Modulation of Neuronal Signaling: Implications for Visual Perception", Nida, Lithuania, July 12-21, 2000
  PDF
  Abstract. The understanding of mechanisms of higher brain functions expects a continuous reduction from higher activities to lower ones, eventually, to activities in individual neurons, expressed in terms of membrane potentials and ionic currents. While this approach is correct scientifically and desirable for applications, the complete range of the reduction is unavailable to a single researcher due to human brain limited capacity. In this connection, it would be helpful to abstract from the rules by which a neuron changes its membrane potentials to rules by which the information is processed in the neuron. The ``coincidence detector", and ``temporal integrator" are the examples of such an abstraction. While being useful in constructing artificial networks, the above two abstractions are neither connected with known brain functions, nor they are relevant to the biological nature of nervous cell, including justification of its survival in the natural selection. In this poster, an alternative abstraction is described, which seems to be free from these shortages. Based on the Hodgkin and Huxley set of equations, we analyze the neuronal reaction to compound stimuli, comprising large number (1000) of EPSP (Box 1). The unitary EPSPs in a compound stimulus are distributed randomly over a time window [0;W]. The probability to fire a spike as a function of W is calculated by means of Monte Carlo method. In this course, several values of proximal GABA_b-type inhibition are applied (Box 1, term with g_{iK}). The dependencies obtained (Fig.4) allow to formulate one more abstraction of neuronal functioning (Box 2). In this abstraction the temporal structure of stimulus as well as the inhibition get their information processing meaning. The formulation is expressed in terms of binding, or feature linking --- an essential ability of the brain. In this formulation a single neuron is endowed with a meaningful ability, the binding, which might be the reason for survival of excitable cells in the natural selection. The information processing scheme in a single neuron (Fig.5) could be the first step in the bottom-up reductionistic explanation of brain functioning.