Figure 4.

PPC disruption has a larger effect on visual, compared with auditory, decisions. A, Visual psychometric functions from stimulation in a single location within PPC (Rat 1, 1624 trials). Smooth lines are fits to the data (logistic regression). Error bars reflect the Wilson binomial confidence interval. B, Outcome of a probabilistic model that measures the effect of sensitivity to stimulus rate on decisions. The fitted parameter is plotted for stimulation (laser-on, vertical axis) versus control (laser-off, horizontal axis) trials. All values are positive, indicating that increasing stimulus rate led to more high rate decisions. Error bars indicate SEs. Dashed line, y = x. Colors: individual rats; multiple points for each animal indicate data collected from different optical fibers/depths (sites) within PPC. Black circle indicates the animal shown in A. C, Same as B but for the “success history” parameter. Positive values indicate that the rat tended to repeat rewarded decisions. D, Weighting of visual sensory evidence during 100 ms windows. Vertical axis indicates the weight for the time indicated by the corresponding value on the horizontal axis. Weights were computed via logistic regression (see Materials and Methods). Values would approximate dashed line (y = 0) for times during which sensory evidence failed to influence the choice. Black line indicates control (15,267 trials). Cyan line: stimulation (6046 trials). E, Same as B but for the “failure history” parameter. Negative values indicate the rat tended to switch after unrewarded decisions. F, Same as B but for the “bias” parameter. Zero indicates unbiased decisions; negative values indicate an ipsilateral bias. G, Auditory psychometric functions from the same rat/site as in (A) (1655 trials). H, I, K, L, Same as B, C, E, F, respectively, but for auditory trials. J, Same as D but for auditory trials. Black line indicates control (10,148 trials). Cyan line indicates stimulation (4665 trials).