Figure 5.

Examples of typical delay-period responses in PMd. A, Mean ± SE firing rates for four example neurons. Three of these showed increases in firing rate after target onset, whereas one showed a decrease. Data are from experiments using a continuous range of delay periods (500–900 for monkey B and 400–800 for monkey A). For each time point, mean firing rate was computed from only those trials with a delay period at least that long. Labels give the monkey initial and cell number. Details (direction, distance, instructed speed, and trials/condition) were as follows: cell B29, 45°, 85 mm, fast, 23 trials; cell B16, 135°, 60 mm, fast, 20 trials; cell B46, 335°, 85 mm, fast, 41 trials; cell A2, 185°, 120 mm, slow, 42 trials. B, Mean ± SE firing rates of one example neuron from monkey G (cell G20, ∼23 trials per condition per delay duration), from the dataset using discrete delay-period durations. Data are shown for the 30 ms (gray) and 230 ms (black) delays for all directions and for one distance (100 mm). Dots show mean times of movement onset. Note that downwards targets were not used. This was because the monkey's arm obscured his vision at that location.