Figure 8.

Illustration of fine discrimination in a two-choice task with 0% coherence using a simplified model. A, In the decision state (e.g., when 2 targets are separated by 40°), the network has two stable steady states with peak activity (represented by s_NMDA) at the direction of either target and an unstable steady state. In the merging state (e.g., when 2 targets are separated by 30°), the merging of bumps at the direction of two targets constitutes the only stable steady state. B, Maximum eigenvalue of the Jacobian matrix for the steady state with its peak activity located between the directions of two targets versus the angular distance between the two targets. A merging state occurs when the maximum eigenvalue is positive. The curve shifts leftward with increasing J_sim. J_opp is fixed at 1.05. C, Schematics of neural firing activity. The activity of pyramidal cells induced by two targets further elicits a bump of activity profile in interneurons, which peaks between the directions of two targets. The similar-feature inhibition exerts stronger inhibition to pyramidal cells located between the directions of the two targets, preventing the two bumps from merging.