A test for modulation of synaptic efficacy by induced membrane potential variance.

A modification of Klopf's heterostatic adaptive neuron hypothesis is proposed, in which membrane potential variance, rather than depolarization, has adaptive influence on individual nerve cells. Recordings from each of two configurations of three-cell networks of Aplysia buccal ganglia test for either nonspecific or associative effects of excess membrane potential and current variance, in the form of noise injection into voltage-clamped postsynaptic neurons. No effects of noise are reported, suggesting either that the hypothesis is incorrect, or else that the frequency spectrum or duration of recording were inappropriate to produce the adaptive modulation.