a Schematic drawing of the behavioral apparatus and the cue–target associative relationships in the two-alternative forced-choice task. b Schematic of the task timeline. c Raster plot and peri-event time histogram showing the response of a representative neuron. Trial types are classified according to the cue modality and target choice as follows: blue, left target choices; red, right target choices; solid line, visual trials; dashed line, olfactory trials. Neural responses in the correct trials were independently aligned to the cue, withdrawal, and target-choice onset and then reconstructed because of variable time between them. Lines and shaded areas indicate mean and s.e.m., respectively. d Firing patterns across all the neurons (n = 207) for the different trial conditions. In each trial type, the mean firing rate of each neuron was normalized to its peak. For all the trial types, the neurons were sorted by their peak firing time in the visually cued left choice trials (upper left). e Comparison of temporal firing patterns of individual neurons between the different cue modalities and choice directions. For comparison between the different modalities, for each neuron, a correlation coefficient was computed between peak-normalized firing rates in the visual left (upper left in d) and olfactory left trials (bottom left in d). For comparison between the different choices, a correlation coefficient was computed between peak-normalized firing rates in the visual left (upper left in d) and visual right trials (upper right in d). Nearly identical results were achieved when correlation coefficients were computed between the visual right and olfactory right trials and between the olfactory left and olfactory right trials (two-sided Wilcoxon signed-rank test; mean correlation for different modalities = 0.872 ± 0.13, mean correlation for different choice directions = 0.62 ± 0.358, P = 1.515 × 10−23).
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