Epileptic and normal neurons in monkey neocortex: a quantitative study of degree of operant control.

The object of this study was to quantify and compare the degree of control monkeys may assert over firing patterns of normal and epileptic neurons. Thirty-seven epileptic and 70 normal neurons were studied in detail. The operant task was for the monkey to generate specified consecutive interspike intervals (ISI). The monkeys demonstrated far greater accuracy in controlling consecutive ISIs of normal neurons and were only able to control the intervals between bursts from epileptic neurons. The data implies that high frequency bursts of action potentials from epileptic neurons are all-or-nothing events initiated by synaptic mechanisms. In addition, some data are from a monkey with epilepsia partialis continua; in comparison to less active foci, this focus was comprised of a higher percentage of 'pacemaker' epileptic neurons.