Fig. 7.

Possible reactions of a population of neurons sensitive to referent hand directions to external central influences (2-dimensional space). A: it is assumed that each point (x, y) of the hand space is represented by a column of neurons with a uniform distribution of referent directions (arrows). B: the required task-specific referent shift (red arrows) influences the whole neuronal population. Only neurons with positive referent projections to the global referent shifts are activated, whereas other neurons are defacilitated (reciprocal pattern). The line orthogonal to the global referent shifts separates these subgroups of neurons (note that the meaning of this line is different from the lines in Figs. 2 and 3). C: the population can react to rotation of the global input. D: cofacilitation of the 2 subgroups can result in activation of neurons in a part of space (x, y).