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This Article Full Text Full Text (PDF) All Versions of this Article: 98/6/3548    most recent 00310.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kim, Y. B. Articles by Jung, M. W. Search for Related Content PubMed PubMed Citation Articles by Kim, Y. B. Articles by Jung, M. W.

Encoding of Action History in the Rat Ventral Striatum

¹Neuroscience Laboratory, Institute for Medical Sciences, Ajou University School of Medicine, Suwon, Korea; and ²Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut

Submitted 20 March 2007; accepted in final form 14 October 2007

In a dynamic environment, animals need to update information about the rewards expected from their alternative actions continually to make optimal choices for its survival. Because the reward resulting from a given action can be substantially delayed, the process of linking a reward to its causative action would be facilitated by memory signals related to the animal's previous actions. Although the ventral striatum has been proposed to play a key role in updating the information about the rewards expected from specific actions, it is not known whether the signals related to previous actions exist in the ventral striatum. In the present study, we recorded neuronal ensemble activity in the rat ventral striatum during a visual discrimination task and investigated whether neuronal activity in the ventral striatum encoded signals related to animal's previous actions. The results show that many neurons modulated their activity according to the animal's goal choice in the previous trial, indicating that memory signals for previous actions are available in the ventral striatum. In contrast, few neurons conveyed signals on impending goal choice of the animal, suggesting the absence of decision signals in the ventral striatum. Memory signals for previous actions might contribute to the process of updating the estimates of rewards expected from alternative actions in the ventral striatum.