Figure 3.

Cortical M1 and SMA inputs coding the direction of an upcoming limb movement (R_A, R_B) and cortical cells coding expected reward outcome (O_A, O_B) send converging projections to striatal output cells (a, b, c, d) which, via striato-pallido-thalamo-cortical pathways promote persistence of activity in the cortical cells. If the animal initiates a behavioral response leading to a reward or reward-predicting cue, the currently active synapses (R_A/O_B to b) are strengthened by DA-mediated LTP, increasing the likelihood that the same cortical inputs will produce reverberatory activity in the circuit in the future. Once the relevant corticostriatal synapses have been strengthened by DA responses to the reward-predicting cue (e.g., a trigger stimulus associated with response-contingent reward delivery), the likelihood of future reverberatory activity through those synapses will be increased even if future inputs arrive earlier in the trial (e.g., seconds prior to the trigger stimulus).