Figure 2. Evidence for top-down thalamic modulation in divided attention.

(a) Disrupting PFC activity by delivering blue laser pulses (50Hz, 18msec; 90% duty cycle) impaired task performance at 100% stimulus intensity on both modalities equally only when manipulation was performed during stimulus anticipation (n = 4 VGAT-ChR2 mice, * p < 0.05, Wilcoxon rank-sum test). (b) Effect was related to the cross-modal nature of the task, not its difficulty, as PFC inhibition did not impact performance on a visual-only task. (c) Disruption of primary visual cortex during stimulus presentation impaired performance on visual trials (n = 4 mice). (d) Effect in c was related to task difficulty, as it increased visual detection threshold in a visual-only task. (e) The data in a and c do not support a causal role for PFC interactions with primary visual cortex in performance. (f) Perturbing visual thalamic function in a manner similar to cortical perturbations in VGAT-ChR2 mice preferentially diminished performance on visual trials both during anticipation and presentation of target stimuli (n = 12 sessions from 3 mice, * p < 0.05, ** p < 0.01, *** p < 0.001, Wilcoxon rank-sum test). (g) Finding in f supports a model in which PFC activity influences thalamic sensory processing. Bar graphs represent mean ± s.e.m. Error bars for psychometric curves are 95% confidence intervals.