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. 2017 Feb 15;37(7):1721–1732. doi: 10.1523/JNEUROSCI.1091-16.2016

Figure 2.

Figure 2.

Motor cortical activity reflects recent visuomotor gain experience even before the target appears. A, Six example neurons' PSTHs during the center target hold and subsequent reaching movement. Mean firing rates during CG 0.5, 1, and 2 are shown in bright violet, blue, and green, respectively. RG trials were grouped by the visuomotor gain applied on the previous trial, which is shown with a darker shade of this gain's color. Horizontal black bars show the mean ±1 SD of reaction times across all analyzed trials. Datasets were J.2014.09.12 and R.2014.08.24. B, Trial-averaged population firing rate differences between trials after low and high gain trials for monkeys J (gray) and R (red). Lighter hues show the differences during CG conditions and darker hues show the differences between RG trials grouped based on the previous trial's gain. Differences were calculated as the vector norm of all electrodes' firing rate differences with chance-level differences subtracted and were normalized by the number of electrodes (see Materials and Methods). Traces are thickened when the firing rate difference is significantly larger than expected by chance (p < 0.001, shuffle test). Almost all RG and CG time points during the pretarget hold period show significant differences. The horizontal gray and red bars show each monkey's 100 ms pretarget time window chosen for more detailed subsequent analysis. Data are averaged across all five of each monkey's datasets. C, Histograms of electrodes' firing rate differences between CG 0.5 and CG 2 during the pretarget analysis windows shown in B. Each monkey's distribution median and mean are shown as dotted and solid vertical lines, respectively. Black shading within the histograms denotes the number of electrodes showing statistically significant differences (p < 0.01, rank-sum test). Data aggregated across all five of monkey J's (left) and monkey R's (right) datasets. D, Similar to C, but showing the pretarget firing rate differences between RG trials with a previous gain that was 0.5 versus 2.