Analysis for dependence between sequential responses evoked in visual cortex

The chi-square method has revealed dependence at a high level of significance between the amplitudes of successive responses elicited in secondary visual cortex by repetitive electrical stimulation of the visual radiation fibers. Dependence has been demonstrated to exist between responses as far apart as 6 sec. In many sequences dependence at a high level of significance was found between responses at the longer intervals of separation when absent 1 sec earlier. In three cases the sequences behaved like stationary, first-order Markov chains, insofar as all observed transition matrices for intervals of 2–5 sec could be generated by probability matrices estimated from the observed transition matrices for immediately consecutive responses. In four cases there was agreement between observed and predicted transition matrices only for intervals up to 2 or 3 sec, and it is suggested that these represented chains of some order higher than one.