期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：2
页码：E214-E219
DOI：10.1073/pnas.1410130112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceNeural activity was recorded from the dorsolateral prefrontal cortex (DLPFC) when a monkey performed visuo-haptic crossmodal and haptic-haptic unimodal delayed matching-to-sample (cue) tasks. Results indicate that neural networks in the DLPFC function sequentially in the crossmodal task from visual stimulus encoding and crossmodal information transferring between visual and tactile stimuli to the behavioral action. Our findings may clarify the neural mechanisms by which the cerebral cortex stores information in working memory, a cognitive function of prime importance in the coordination of behavior, speech, and reasoning. Previous studies have shown that neurons of monkey dorsolateral prefrontal cortex (DLPFC) integrate information across modalities and maintain it throughout the delay period of working-memory (WM) tasks. However, the mechanisms of this temporal integration in the DLPFC are still poorly understood. In the present study, to further elucidate the role of the DLPFC in crossmodal WM, we trained monkeys to perform visuo-haptic (VH) crossmodal and haptic-haptic (HH) unimodal WM tasks. The neuronal activity recorded in the DLPFC in the delay period of both tasks indicates that the early-delay differential activity probably is related to the encoding of sample information with different strengths depending on task modality, that the late-delay differential activity reflects the associated (modality-independent) action component of haptic choice in both tasks (that is, the anticipation of the behavioral choice and/or active recall and maintenance of sample information for subsequent action), and that the sustained whole-delay differential activity likely bridges and integrates the sensory and action components. In addition, the VH late-delay differential activity was significantly diminished when the haptic choice was not required. Taken together, the results show that, in addition to the whole-delay differential activity, DLPFC neurons also show early- and late-delay differential activities. These previously unidentified findings indicate that DLPFC is capable of (i) holding the coded sample information (e.g., visual or tactile information) in the early-delay activity, (ii) retrieving the abstract information (orientations) of the sample (whether the sample has been haptic or visual) and holding it in the late-delay activity, and (iii) preparing for behavioral choice acting on that abstract information.
关键词：prefrontal ; cross-modal working memory ; monkey ; delay activity ; single unit
