Skip to main content
. Author manuscript; available in PMC: 2009 Dec 26.
Published in final edited form as: Neuron. 2008 Dec 26;60(6):1153–1168. doi: 10.1016/j.neuron.2008.12.003

Figure 3.

Figure 3

Simulated neural activity during sample trials with 4 choices and 0% coherence level. (A) Spiking activity of the pyramidal (black) and inhibitory (red) neurons in the model. Pyramidal neurons are arranged along the ordinate according to their preferred direction. The directions of the targets are 45°, 135°, 225° and 315°. (B) Color-coded activity of the pyramidal neurons in (A) after smoothing (see Experimental Procedures). (C-F) Activity time course of neurons located around the targets in four sample trials. The colors of the traces correspond to the targets in the schematic illustration of target locations (left). Similar to neural data from LIP, neurons located around the targets respond vigorously to the presence of the targets even before the onset of the motion stimulus. When the motion stimulus is presented, firing activity shows an initial dip, which in the model is assumed to arise from divided attention between the target and the motion stimuli. During the decision process the network displays competitive dynamics, and eventually, the activity of a group of neurons ramps up and reaches the preset decision threshold (solid vertical line). Due to stochastic firing within the network, both the winning neural pool (hence the choice) and the response time vary from trial to trial even when the stimulus condition remains unchanged.