Figure 4. Striatal U+ neurons' responses are object-dependent.

(a) Responses of a single U+ neuron to 100 and 50% reward predictions without a trace period (CS objects remained until the outcome) (black and red), and with a trace period (CS objects disappeared after 1 s) (green and blue). (b) In all, 22/32 neurons displayed significant differences in reward-uncertainty responses across the no-trace and trace conditions (red; rank-sum test; P<0.01; 26/32 were significant with a 0.05 threshold). All significant changes were reductions of uncertainty responses. Here normalization was performed by subtracting 100% CS responses from 50% CS responses (for trace and no-trace conditions, separately). (c) Single neuron (insets above) and population reward-uncertainty discriminability was greatly diminished in the trace condition. AUC, area under receiver-operating characteristic curve.