Figure 1.

Experimental procedures. A, Extracellular voltage measured by a single microelectrode yields several signals. MSPs are detected and sorted into SUs (different colors). LFPs and MUA are obtained by low- and high-pass filtering, respectively. Spikes are fast (∼1 ms) high amplitude (∼100 μV) events, LFPs capture slow fluctuations (<100 Hz), and MUA recordings reflect energy in high frequencies (300–6000 Hz). B, MUA is estimated by bandpass filtering and taking the RMS. For details, see Materials and Methods. C, Prehension task. The time sequence of a single trial is illustrated. Gray bar, Extent of analysis period (see Materials and Methods). In each trial, an object was briefly presented in one of six locations arranged in a virtual circle around the central button of a touch pad. Grasps were drawn from video recordings of monkeys performing the task. D, Tracing task. In each trial, a path was shown in gray. As the monkey moved the yellow cursor along the path, the green marker was advanced indicating the immediate path the monkey had to follow. This task yielded a rich sampling of movement parameters; histograms show data from one session.