Thu, 24 Jul 2008 20:29:06 BST CiteULike: oamg cev http://www.citeulike.org/user/oamg/tag/cev CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/oamg/article/2285145 <i>Neuron, Vol. 57, No. 2. (24 January 2008), pp. 314-325.</i><br /><br />Summary Rapid optimization of behavior requires decisions about when to explore and when to exploit discovered resources. The mechanisms that lead to fast adaptations and their interaction with action valuation are a central issue. We show here that the anterior cingulate cortex (ACC) encodes multiple feedbacks devoted to exploration and its immediate termination. In a task that alternates exploration and exploitation periods, the ACC monitored negative and positive outcomes relevant for different adaptations. In particular, it produced signals specific of the first reward, i.e., the end of exploration. Those signals disappeared in exploitation periods but immediately transferred to the initiation of trials--a transfer comparable to learning phenomena observed for dopaminergic neurons. Importantly, these were also observed for high gamma oscillations of local field potentials shown to correlate with brain imaging signal. Thus, mechanisms of action valuation and monitoring of events/actions are combined for rapid behavioral regulation. Behavioral Shifts and Action Valuation in the Anterior Cingulate Cortex Rene Quilodran Marie Rothe Emmanuel Procyk doi:10.1016/j.neuron.2007.11.031 Neuron, Vol. 57, No. 2. (24 January 2008), pp. 314-325. 2008-01-24T15:58:11-00:00 2008 Neuron 57 2 314 325 acc action_value behavioral_shifts cev http://www.citeulike.org/user/oamg/article/1856179 <i>J. Cogn. Neurosci., Vol. 19, No. 6. (1 June 2007), pp. 1004-1012.</i><br /><br />Impaired retrieval of conceptual knowledge for actions has been associated with lesions of left premotor, left parietal, and left middle temporal areas [Tranel, D., Kemmerer, D., Adolphs, R., Damasio, H., & Damasio, A. R. Neural correlates of conceptual knowledge for actions. Cognitive Neuropsychology, 409-432, 2003]. Here we aimed at characterizing the differential contribution of these areas to the retrieval of conceptual knowledge about actions. During functional magnetic resonance imaging (fMRI), different categories of pictograms (whole-body actions, manipulable and nonmanipulable objects) were presented to healthy subjects. fMRI data were analyzed using SPM2. A conjunction analysis of the neural activations elicited by all pictograms revealed (p < .05, corrected) a bilateral inferior occipito-temporal neural network with strong activations in the right and left fusiform gyri. Action pictograms contrasted to object pictograms showed differential activation of area MT+, the inferior and superior parietal cortex, and the premotor cortex bilaterally. An analysis of psycho-physiological interactions identified contribution-dependent changes in the neural responses when pictograms triggered the retrieval of conceptual action knowledge: Processing of action pictograms specifically enhanced the neural interaction between the right and left fusiform gyri, the right and left middle temporal cortices (MT+), and the left superior and inferior parietal cortex. These results complement and extend previous neuropsychological and neuroimaging studies by showing that knowledge about action concepts results from an increased coupling between areas concerned with semantic processing (fusiform gyrus), movement perception (MT+), and temporo-spatial movement control (left parietal cortex). Functional Interactions during the Retrieval of Conceptual Action Knowledge: An fMRI Study Ann Assmus Carsten Giessing Peter Weiss Gereon Fink J. Cogn. Neurosci., Vol. 19, No. 6. (1 June 2007), pp. 1004-1012. 2007-11-02T12:54:34-00:00 2007 J. Cogn. Neurosci. 19 6 1004 1012 cev concepts fmri objects