FIG. 5.

The effects of IT microstimulation during visual classification learning when microstimulation is informative, but not required, for classification. A: in this task, 4 new images of stamps were selected before each test session. Random colored noise was added to each stimulus to introduce initial variability during the discrimination task. Two stimuli were shown upright, and 2 were rotated 45°. Microstimulation was included on all trials containing 1 of the 2 upright stimuli (randomly assigned to either the left or right in each session). Thus during learning, 1 of 4 patterns was always experienced with the microstimulation present. Inset: the recorded analog return signal from the stimulating electrode, which verified the timing and amplitude of the microstimulation. The rotated stamps served as control stimuli in each experiment. B: performance plotted as a function of number of stimulus repetitions shows that for this task, the additional microstimulation (filled circles) did not significantly affect learning rates of the patterns assigned to the stimulation condition compared with performance for unstimulated stimuli (open circles). By 100 stimulus repetitions per stimulus, performance was between 90 and 100% for both trial types.