Fig. 1.

Responses of single neurons in primary auditory cortex (A1) of rhesus monkeys to band-passed noise (BPN) bursts centered at particular frequencies. (A and B) Peristimulus time histograms (PSTHs) and raster displays for two different A1 neurons. Center frequency of the BPN burst increases in each row from left to right in steps of ¹/₃ octave, as displayed above each PSTH. The bandwidth of the BPN burst was also ¹/₃ octave, and its duration was 250 ms. Two vertical dashed lines indicate onset and offset times of the BPN burst at t = 0 and t = 250 ms, following a pretrial interval starting at −500 ms. ON and OFF responses were quantified by measuring peak firing rate (minus baseline rate during the pretrial interval) within a 40-ms sliding window after stimulus onset or offset, respectively. Statistical significance of the responses was determined with the Wilcoxon Signed Rank test. Spike times were recorded at a resolution of 1 ms but displayed at a binwidth of 10 ms. Two different response types were noted, and typical examples for each type are displayed here. (A) Type-S (simple-like) cell responds either to the onset or the offset of the BPN burst depending on center frequency. Only occasionally both significant ON and OFF responses are seen. (B) Type-C (complex-like) cell regularly responds to both onset and offset of BPN burst (or not at all) regardless of center frequency.