SOMATOSENSORY CORTEX & THALAMUS OF PRIMATES

点击翻译按钮获取中文摘要

Significance To determine the anatomical substrate for higher level functions such a manual dexterity and bilateral coordination of the hands. Objectives Using electrophysiological recording techniques, areas of the lateral sulcus and posterior parietal cortex will be explored so that the functional organization of distinct areas can be ascertained. The connections of these regions with the thalamus, ipsilateral areas of the cortex, and with the contralateral hemisphere will be determined by injecting small amounts of anatomical tracers into electrophysiologically defined areas. After the tracers have transported, the regions that are connected to the area injected will be explored electrophysiologically so that the exact nature of topographic and non-topographic connections can be better understood. One would expect that these higher order fields would integrate information across the hand, and thus non-topographic connections should be present. In addition, we expect dense connections with areas in the contralateral hemisphere, since information from both hands must be integrated to coordinate movements across the body. Finally, connections with motor cortex, needed to subserve sensorimotor integration and direct future movements would also be expected. Results Preliminary results demonstrate that areas of the lateral sulcus do have strong connections with the opposite hemisphere, particularly hand representations in the second somatosensory area, SII, and parietal ventral area, PV. Another important finding is that there are relatively dense connections between posterior parietal cortex and motor cortex. Finally, we have found that connections from the thalamus are both topographically matched and mismatched. This finding is particularly important for studies of cortical plasticity, in which the anatomical substrate for functional changes in the cortex has yet to be determined. Future Directions Goals are to compare the present results with studies in humans utilizing functional imaging techniques, such as fMRI and MEG in both humans and non-human primates. KEYWORDS second somatosensory area, parietal ventral area, posterior parietal cortex, sensorimotor integration