Transformation of binomial input by the postsynaptic membrane at a central synapse.

Although a binomial model gives an adequate description of the release properties of central afferent synapses, slight differences between experimental and predicted probability density functions are observed, with an excess number of responses recorded around the means. These discrepancies can be quantified by comparing experimental and theoretical entropies, which could relate to information transfer at these junctions. A model, based on the experimentally supported assumption that the postsynaptic membrane functions as a nonlinear processor, minimizes the differences between the distributions of the recorded and predicted potentials. According to this model, the nonlinearity is due to a localized interaction between the effects of simultaneously activated adjacent synapses.