Fig. 1: Temporal pattern discrimination task (TPDT) and activity of single neurons in S2. | Nature Communications

Fig. 1: Temporal pattern discrimination task (TPDT) and activity of single neurons in S2.

From: A continuum of invariant sensory and behavioral-context perceptual coding in secondary somatosensory cortex

Fig. 1

a Trials’ sequence of events. The mechanical probe is lowered (pd), indenting the glabrous skin of one fingertip of the right, restrained hand (500 µm); in response, the monkey places its free hand on an immovable key (kd). After a variable prestimulus period (from 2 to 4 s), the probe vibrates for 1 s, generating one of two possible stimulus patterns [P1, either grouped (G) or extended (E); mean frequency of 5 Hz]. Note that in extended pattern (E), pulses are delivered periodically. After a first delay (2 s length, from 1 to 3 s) between P1 and P2, the second stimulus (P2) is delivered, again either of the two possible patterns [P2, either G or E; 1 s duration]; this is also called the comparison period. After a second 2 s delay (from 4 to 6 s) between the end of P2 and the probe up (pu), the monkey releases the key (ku) and presses, with its free hand, either the lateral or the medial push button (pb) to indicate whether P1 and P2 were the same (P1 = P2) or different (P1 ≠ P2). b Performance for the whole TPDT (gray, n = 423 sessions), for each class [G-G (red), G-E (orange), E-G (green), E-E (blue)] and for the whole LCT (yellow, n = 76 sessions). See legend of Supplementary Fig. 5 for box-plot statistics and Supplementary Fig. 5a, b for box-plots and statistics for the individual monkeys. c Top of the brain (left figurine) for approaching the secondary somatosensory cortex (S2) and coronal section of the brain (right) for locations of recordings in S2 (red spots). Recordings were made contralateral and ipsilateral to the stimulated fingertip. d–f Raster plots of three S2 neurons sorted according to the four possible classes (stimulus pairs). Each row is a single trial, and each tick is an action potential. Trials were interleaved randomly, although the rows were sorted by class afterward (only 10 out of 20 trials per class are shown). Correct and incorrect trials are indicated by black and dark red ticks, respectively. Average firing rates (PSTHs), per class, demonstrated in traces below each raster. Color traces indicate the four possible classes: G-G (red); G-E (orange); E-G (green); and E-E (blue). One neuron exhibits a sensory response (d) while the other two exhibit categorical activity (e–f).

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