The Section on Neurophysiology uses the methods of behavioral neurophysiology and neuropsychology in primates to study two major, related problems in neurobiology: the specialized functions of the frontal cortex and the neural network underlying symbolic visuomotor mapping. Most of our research involves role of the frontal cortex in visually guided actions, including the mapping of symbols to actions. The selection and control of action is not always recognized as an important issue in psychiatry or in psychiatric research. However, what a person does and the basis on which actions are selected comprise fundamental features of human life. There is increasing recognition that diseases such as schizophrenia, attention deficit-hyperactivity disorder, obsessive-compulsive disorder, and others may result from inappropriate selection and control of actions. The work on this project has shown that accurate and appropriate action depends upon the proper function of specific parts of the frontal lobes and other parts of the telencephalon. Our research has thus been dedicated to understanding the functions of these areas of the cerebral cortex so that, eventually, physicians, therapists, and other health care specialists can develop improved treatments for people suffering those and other mental health disorders. An important aspect of our work focuses on symbolic mapping behavior. In symbolic mapping, the choice of an action to be made depends on the behavioral context provided by a symbol. This is the basis for learning the meaning of most words, for learning to associate that meaning with the motor programs necessary to generate speech and language, and for the wide variety of symbol- and signal-guided behavior that underlies much of our behavioral flexibility and higher-order behavior generally. In the past year, the highlights of our research include: (1) the first physiological distinction between neurons involved in vision-for-perception versus those involved in vision-for-action (Lebedev, Moody, Douglass and Wise, 2001); (2) demonstrating, for the first time, that neurons in the dorsal premotor cortex have activity that reflects the orientation of selective spatial attention in addition to neurons reflecting the planned direction of reach (Lebedev and Wise, 2001); (3) the invention of a novel automatic food-pellet dispenser that allows food to be visible, without physical barriers between a subject and the food, yet with the experimenters retaining control of food availability (Mitz, Boring, Wise and Lebedev, 2001); (4) demonstrating an important physiological distinction between premotor cortex and prefrontal cortex, which is that cells in prefrontal cortex (and the frontal eye field) reflect whether the monkey is fixating the leftmost or rightmost of two objects whereas cells in dorsal premotor cortex do not reflect that information, but instead encode the leftmost or rightmost target of future reaching movements or attention; (5) demonstrating that cells in dorsolateral prefrontal cortex encode spatial memory in much smaller numbers than those encoding spatial attention (Lebedev and Wise, 2002); (6) showing that the orbital and ventral parts of prefrontal cortex are necessary for fast learning of symbolically guided actions (Bussey, Wise and Murray, 2001, 2002); and (7) demonstrating that the hippocampal system functions in symbolically guided actions even when neither the symbol nor the action involve spatial or idiothetic information processing (Brasted, Bussey, Murray and Wise, 2002 and submitted). The past year has seen the completion or publication of thirteen reports, reviews and other academic works, including six peer-reviewed research articles in archival journals, as well as several refereed reviews and encyclopedia articles.
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