Figure 1. A somatosensory decision-making task that depends on the cerebellum.

(A) In each trial, two streams of random, temporally Poisson-distributed air puffs were delivered to the left and right whiskers. After a delay, mice licked one of two lick ports indicating the side with more cumulative puffs to receive a water reward. Gray-shaded regions from left to right: cue period, delay, intertrial interval. Decision lick: first detected lick after the delay. (B) Psychometric performance data on the evidence accumulation task. Gray lines, individual mice; black points, average across all trials from all animals (n = 38,615 trials, 12 mice). (C) Logistic regression analysis correlating animal choice with cues delivered at different time bins of evidence presentation, demonstrating that the entire cue period was used to guide decisions. Each point indicates the magnitude of that time bin’s influence on decisions (all points significantly greater than zero, Wald test, p<0.0001). For comparison, bins (gray points) or choices (shaded 1 s.d. gray zone) were shuffled. Error bars: 95% confidence interval. (D) Behavioral effect of bilateral injections of muscimol or saline into crus I, compared to baseline performance with no injections. Each set of joined points represents one mouse. Error bars: 95% confidence interval. *p<0.05, n.s.: not significant (two-tailed paired t-test). (E) Movie-based licking measurements from mice over the duration of trials. Bar heights show mean ±s.e.m. across animals of trial-averaged licking signals. (F) Example cranial window over the left posterior hemispheric cerebellum, indicating the site of imaging and inactivation.

Figure 1—figure supplement 1. Behavioral performance in the decision-making task.

(A) Psychometric data for individual subjects in individual behavioral sessions. For each subject, data from the session at the 75th percentile of performance is displayed. (B) Histogram of percent correct performance over all mice and sessions in the accumulation stages of the task.

Figure 1—figure supplement 2. Behavior in inactivation experiments.

(A) Left: Psychometric curves for all trials from the baseline, saline, and muscimol conditions. Only L/R: trials from earlier in the shaping procedure were delivered, in which puffs were presented exclusively on the correct side, guide puffs were delivered following the cue period, and free rewards were delivered on the correct side. Performance was measured according to the side that the mice licked first, just as they do to indicate their decision in the main task. Right: Regression analysis as in Figure 1C for all trials in the indicated conditions. Error bars: 95% confidence interval. (B) Quantification of lick rate and decision latency (time from port arrival to decision lick) for all mice in all conditions. Boxes: lower and upper quartiles, line: median, whiskers: 5th to 95th percentile. Within-subject differences of rate and latency across control (baseline/saline) and muscimol conditions, and across left (L) and right (R) choices, were not significant (p>0.05, two-tailed paired t-test). As in all analyses, trials with no decision lick were excluded; this accounted for 2.0 ± 2.7% of trials in the baseline condition, and 2.6 ± 5.1% of trials in the muscimol condition (mean ±std over sessions), and was not significantly different across the baseline and muscimol conditions (p=0.54, two-tailed t-test). (C) Best-fit coefficients from the behavioral regression model. Each data point corresponds to one pair of sessions (colored by animal identity), corresponding to a muscimol inactivation session and the control session directly preceding it. Error bars indicate standard error of the fit coefficients. The evidence sensitivity parameter was significantly reduced in the muscimol condition relative to control, and the success history and failure history fit parameters were significantly increased relative to control (p<0.05, bootstrap). For the latter three parameters, one data point is omitted from display because the best-fit standard error was uninterpretably large (>8 standard deviations from others). (D) Psychometric curves for all trials from the five individual subjects in the control and muscimol conditions (one panel per subject). Curves show fits to a four-parameter logistic function (see Methods). In top-left panel, L and R indicate additional sessions in which muscimol was delivered only to the left (L) or right (R) cerebellum, to determine whether vertical shifts in the psychometric curve can be explained by left-right asymmetry of injections. Error bars: 95% confidence interval.

Figure 1—figure supplement 3. Muscimol injection sites.

For three mice in the muscimol inactivation experiment, coronal view demonstrating the sites of injection of muscimol, as marked by fluorescein delivered by injection of identical protocol after completion of the experiments. Lesions near or encompassing injections sites may be due to bone growth or damage from implant removal.