Fig. 5.

Emergence of the cortical population response.A, Onset latencies are mapped onto corresponding electrode positions (rat r28, stimulus site B₁). Nonresponding electrodes areblack. The electrode yielding the shortest latency response (6 msec) is indicated by the bullet.B, Distribution of latencies. The procedure ofA was repeated for 33 whisker stimuli across three rats; a histogram of all latencies is shown. C, Thesolid line shows the expansion of activated cortical territory, averaged over all 33 stimuli. For this analysis an electrode was considered active at all times after its response onset, and cortical territory was derived from the number of electrodes. Error bars denote ±1 SD. The points indicate the rate of expansion of the active territory. D, The distribution of all response offsets for 33 stimuli.