Fig. 2.

Stimulus-driven and task-dependent components of V1 responses. (A–C) Averaged PSTHs of neuronal responses from both monkeys in the pretraining fixation task. Only V1 sites with RFs covering the target location (Materials and Methods) contributed to the average. They were separated into three groups according to the deviations of their preferred orientations from the background orientation: within 22.5° (A; n = 10 sites, 5/5 from MA/MD), between 22.5° and 67.5° (B; n = 20, 15/5 from MA/MD), or larger than 67.5° (C; n = 8, 6/2 from MA/MD). The top Inset schematizes the relationship between a contributing RF (dashed cyan circle), its preferred orientation (within the cyan sectors), and the six nearest background bars. Each PSTH corresponding to an orientation contrast (0° to 90° in multiples of 15°, blue to red) is the average of n PSTHs; each in turn is the average of the corresponding PSTHs from a single electrode across the pretraining days (5 and 3 d for MA and MD, respectively). The preferred orientation associated with an electrode was the average of the preferred orientations measured across the days. Each orientation contrast involves pooling two target orientations, clockwise and anticlockwise tilted from the background. Two small panels on the right show the relative mean neuronal responses within 0–80 and 80–200 ms, as a function of the orientation contrast. Linear regression results are shown in each panel. (D–F) Same as A–C but during the singleton detection task across the training days [11 and 10 d for MA and MD, respectively; (D) n = 8, 4/4 from MA/MD; (E) n = 34, 19/15 from MA/MD; and (F) n = 7, 5/2 from MA/MD].