Figure 3.
Units fail to respond to nonspeech sounds. (A) PSTHs for unit 6a to 100 ms pure tones at 18 different frequencies demonstrate no changes in the firing rate. (B) Unit 6a demonstrates a large response to auditory words but a much reduced response to word-matched noise. LFP waveforms are superimposed on the raster plot. (C) PSTHs to each of the 10 repeated words for the SA task played forward (black) or time-reversed (gray) demonstrate shifted latencies and relatively reduced responses in most of the cases. (D) Only unit 6a (black) and unit 36a (gray) demonstrated statistically significant responses to any of the presented environmental sounds (Monte-Carlo permutation test, P < 0.05). Unit 6a only responded to laughter, while unit 36a only responded to a baby crying, both human vocal sounds. Magnitude of responses was significantly lower than the response to spoken words.