Figure 12.
Response of the network to external inputs in the high DA depletion condition, D = 20%. Black, Circuit 1; gray, circuit 2. In A–C, from top to bottom, the input to the cortical populations and the average population activities (20 neurons) in the GPi, the thalamus, and the cortex are shown. The input to striatal neurons is always the same as in Figure 8. A, The external input is slightly selective as in Figure 8A. Oscillatory activities occur in the three populations represented. During input, activity in both cortical populations increases only slightly. B, The external input to the cortex, which is three time larger than in A, is plotted in the top panel. The thalamus is strongly inhibited during input. The oscillatory activity in the network is suppressed. C, Response to the large and strongly selective input to the cortex (ϵ = 0.6) plotted in the top panel. Oscillations are stopped and selectivity is trivially restored. D, Effective input–output transfer function of neurons in the thalamus in presence of noise (black, SD of the noise given in Table 1). For comparison, the function without noise is plotted in gray.