Fig. 4.

Example posterior parietal cortex (PPC) neuron (recorded at a depth of 0.85 mm) with inseparable responses that coded for the reach vector (T−H). Top: response fields (color maps) and superimposed vector fields are based on mean firing rates during the perireach epoch for the neuron shown in Fig. 3. Response fields are plotted as a function of starting hand position and target position (in degrees of visual angle). Bottom: corresponding field orientations derived from the vector fields (see methods for details). T, target position; H, hand position.