Dorsomedial striatum and expected return

85266_largeThe dorsomedial striatum encodes net expected return

Alice Wang, Keiji Miura, Naoshige Uchida

Decision making is argued to involve the vigour of activity fluctuating in line with the net value of options. In the event of lesions to the dorsal striatum and to a lesser extent lesions to the ventral striatum, the vigour of activity was related to preceding activity more than to immediate signals.

It is adaptive to assess the costs as well as the benefits of actions. The vigour of response is suggested to depend on the calculation of the net expected future reward. Such energising effect is spread over a range of actions. The basal ganglia is seen as having an important role in action selection and the vigour of response. Within the basal ganglia, specific areas of the striatum are seen as encoding specific values and regulating value-related behaviour. The striatum has for a long time been associated with motivation.

The response vigour of actions was seen in this study to fluctuate in line with the net value of behaviour options. Lesions in the dorsomedial striatum reduce the influence of the net value of actions in motivation. Responses then depend on the immediately preceding experience rather than the net value of options. However, the choice of action as distinct from the vigour of response was not effected by lesions to the dorsomedial striatum. The study also suggests that the dorsomedial striatum is involved in assessing the outcome values of particular actions. Lesions in this area reduce sensitivity to changes in outcome.



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