Figure 3.

Neural responses in the pre-motion epoch are larger on the 2-choice task, (a) Average firing rate from a single neuron during the pre-motion epoch when 2 or 4 choice-targets were displayed. Vertical black line indicates the onset of the choice targets. Insets are a schematic of the target configurations used in this experiment. One target is in the neuron’s RF (shading). (b) Population average response. Same conventions as in (a) except that traces are average firing rates from 70 neurons. All trials contribute to these averages. Insets illustrate that one target is in the RF of the neuron; the location of this RF varies from neuron to neuron, (c) Comparison of firing rates from individual neurons on the 2- and 4-choice tasks. Responses were measured from 200 to 300 ms after choice target onset. The green circle marks the neuron shown in (a). Points for three neurons with high background firing rates are omitted from the plot to facilitate an appropriate scale for the remaining points (^{{227,174}, {132,99}, {144,127}}) Error bars are s.e.m. and are occasionally obscured by the points. Histogram displays the firing rate differences for all 70 neurons. Shading indicates significance (p<0.05). (d) Comparison of firing rates from individual neurons on the 2-choice and the 90° control tasks. Same conventions as in (c). Two neurons were omitted from the scatter plot ({131,138}, {227,226}).