Figure 6. Rats plan their response during the delay period on memory trials.
(A) Movement times (MT) are faster for memory trials than non-memory trials. Movement times are measured as median Response time - Response Onset time for each physiology session. The mean difference between memory and non-memory trials is 47 ms (t-test,t141=3.58, p<10−5 from the 5 electrode implanted rats). The dot above the histogram indicates the mean ± s.e. of the distribution. (B) Average head-angle data from 84 recording sessions. Thin lines are 200 example trials randomly sub-sampled from all 84 sessions. The thick lines are the average across all trials across all sessions. In our coordinate system, φ = zero degrees points directly towards the center port, positive φ corresponds to rightward orientations, and negative φ to left-ward orientations. On memory trials one can observe a subtle but clear change in the head angle in the direction of the response during the delay period, starting around 500 ms before the end of the fixation period. (See also Figure S6 for head-direction related neural activity)