Figure 8.

In contrast to their counterparts in primary somatosensory cortex, neurons in secondary somatosensory cortex exhibit task- dependent modulation in their responses to identical vibratory stimuli. (A) Spiking responses recorded from one neuron in APC and one in LPC (adapted, with permission, from (152) and from (311), respectively). Each row shows the response to a pair of stimuli: 10 or 26 Hz in the first stimulus period (f1) and 18 Hz in the second (f2). In APC, the response to f2 is independent of f1, while in LPC, the response to f2 is greater when f2 > f1. (B) LPC firing rates as a function of the frequency of vibration in the tactile stimulus. During the first stimulation period (f1), rates decrease monotonically as stimulus frequency increases. During the comparison period (f2), neurons respond preferentially when f2 > f1 (shown here) or vice versa (black points show trials on which f2 > f1; green traces denote trials on which f2 < f1).