Fig. 4: The onset of late activity is delayed in MST mice.
From: Multisensory task demands temporally extend the causal requirement for visual cortex in perception
a The Venn diagrams show for each training cohort the percentage of neurons encoding orientation (grating after stimulus change), occurrence (presence of a visual change or not), or hit/miss (visual hits versus visual misses, with no lick response) as established with ROC analysis. Only maximum visual change trials were used. Shown are percentages out of all coding neurons; percentage of non-coding neurons per cohort: NE: 15.5%; UST: 13.3%, MST: 35.6%. b Fraction of neurons (summed over all recordings) coding for task-relevant variables over time. Each coding fraction is baseline-subtracted and normalized by its maximum. Visual hit/miss coding (hits vs misses) was only present in UST and MST mice (as expected) and started earlier in UST than MST mice (highlighted with black arrows). c Heatmaps of the fraction of coding neurons across time and cortical depth, with neurons binned based on their recorded depth relative to the granular layer (400–550 μm from dura). Only UST and MST cohorts were included to compare sensory and hit/miss coding in the same datasets. SG = supragranular, G = granular, IG = infragranular. Occurrence coding, 0–200 ms, ANOVA, SG versus IG, F(1,16) = 7.21, p = 0.016. Hit/miss coding, Thr, 200–1000 ms, G vs IG, F(1,15) = 5.21, p = 0.037; Max, G vs IG, F(1,15) = 4.96, p = 0.042. Significance (sidebars): *p < 0.05. d Earliest increase in the fraction of significantly coding neurons. Mean ± 95% CI (bootstrap). The apparent fast onset of visual occurrence coding is likely due to temporal smoothing of firing rates. (Bootstrap test, two-sided, UST n = 128, MST n = 306 neurons, p = 0.012) e Reaction time correlated with the onset of hit/miss coding in population-averaged activity (ANOVA, n = 26 sessions, F(1,24) = 5.15, p = 0.03). Gray dotted line shows linear regression fit. Each dot is one session. Error bars show mean ± SEM. f Same as e, but now for the bootstrapped average for each visually trained condition using single-neuron AUC (as in d). Reaction time correlated with the earliest moment of significant hit/miss coding (ANOVA, F(1,2) = 102.33, p = 0.0096). Error bars show bootstrapped mean and 95% CI. Blue dotted line at 200 ms marks the time point where late photostimulation was applied (see Fig. 5d). At this point, unisensory trained mice already showed hit/miss- coding in V1, while multisensory trained mice did not.
