, 1994). The learned change in firing rate, when present, had several important features. First, it appeared in temporal register with the learned Entinostat solubility dmso change in eye velocity in the interval preceding the visual input caused by the instructive target motion. Second, it was present in the probe trials in the learning block (Figure 2A, blue trace) and had a transient time course that peaked near the instruction time. Third, it appeared during target

motion in a direction that did not evoke much neural activity before learning, as seen by comparison of the blue and black traces in Figure 2A. Therefore, the learned firing rate is related to the acquisition of a vertical response to the horizontal target motion and not to the horizontal eye movement itself, which changed very little as a consequence of learning (Figure 1F, top). Figure 2 shows an important feature of the data that motivated our analysis procedures. The averages of both eye velocity and firing rate selleck followed the same trajectory during learning trials and the interleaved probe trials, up to about 70 ms after the instruction time (Figure 2). Thereafter, the mean eye velocity and firing rate in the learning trials, but not the probe trials, showed large visually-driven reactions to the instructive change in target direction. The sequence of identical responses followed by divergence due to the visual stimulus is expected because

the learning and probe trials were interleaved randomly. It allowed us to assess neural changes related purely to learning from the more frequent learning trials in the 220 ms interval from 100 ms after the onset of target motion to 70 ms after the instruction time. We showed in Figure 2 that the size of the learned response could be very different across FEFSEM neurons even when the concomitant behavioral changes were similar. Only 35% of neurons (15/55 in Monkey G, 20/45 in Monkey S) exhibited a significant learned change in firing rate (Mann-Whitney

U test: p < 0.001). All neurons with statistically significant changes in firing rate showed increases in activity as a result of learning. Because the firing rate in the preceding fixation period ALOX15 almost always remained stable in spite of learning, we argue that the neural changes in the analysis interval probably are due to learning and not to fatigue, decreases in motivation, or recording instabilities. Finally, learning did not affect eye velocity during control trials and only five neurons showed significant changes in firing rate during the control trials from the baseline and learning blocks: 4/55 in Monkey G, 1/45 in Monkey S. Excluding neurons with significant changes in response amplitude during pursuit in the control direction did not alter any of our conclusions. Each neuron’s response during pursuit of a ramp target motion at constant velocity showed a distinct and repeatable trajectory as a function of time (e.g.