Shaping of motor responses by incentive values through the basal ganglia.
Journal of Neuroscience. 2007-01-31; 27(5): 1176-1183
DOI: 10.1523/jneurosci.3745-06.2007
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The striatum is a key neural interface for cognitive and motor information
processing in which associations between reward value and visual stimulus can be
used to modify motor commands. It can guide action-selection processes that occur
farther downstream in the basal ganglia (BG) circuit, by encoding the reward
value of an action. Here, we report on the study of simultaneously recorded
neurons in the dorsal striatum (input stage of the BG) and the internal pallidum
(output stage of the BG) in two monkeys performing a center-out motor task in
which the visual targets were associated with different reward probabilities. We
show that the tuning curves of motor-related neurons in both structures are
modulated by the value of the action before movement initiation and during its
execution. The representations of values associated with different actions change
dynamically during the task in the internal globus pallidus, with a significant
increase in the number of encoding neurons for the chosen target at the onset of
movement. This report sheds additional light on the functional differences
between the input and output structures of the BG and supports the assertion that
the dorsal basal ganglia are involved in movement-related decision-making
processes based on incentive values.