DETERMINATION OF THE PRECISION OF SPIKE TIMING IN THE VISUAL-CORTEX OF ANESTHETIZED CATS

Neuronal cortical spike trains contain precisely replicating patterns whose presence cannot be accounted for by chance production. A compari son of the number of triplets of spikes present two times with the num ber of doublets replicated three times in the same window duration giv es a frequency-insensitive measure of this type of fine temporal organ isation. By varying the tolerance with which such precisely replicatin g patterns are detected, one can evaluate the accuracy of spike timing in spike trains. In the sample of data here analysed, it was found th at replicating patterns were best seen in the precision range 0.4-1.4 ms (a result evidently at variance with a simple 'integrate and fire' model of neurons). Surprisingly, the fine temporal structure of spike trains thus evidenced was stronger at relatively low firing rate disch arges and was present in both the 'spontaneous' and 'evoked' responses .