Funds are requested to continue our studies of how the shape is represented and processed in the somatosensory system and to determine how those representations are modulated by selective attention. In this proposal we concentrate on determining how information from multiple digits are integrated to form central representations of object shape. These studies build on our previous studies showing that many neurons in somatosensory cortex show feature selective responses to oriented bars, the selectivity is in skin centered coordinates, and the sensitivity is modulated by changes in hand conformation. From those findings we hypothesize that shape perception is based on populations of neurons integrating points of contact with the positions of the fingers. There are two (2) specific aims. The first is to investigate how the points of contact are integrated during the processing of two-dimensional (2D) shapes. In these experiments, shapes that contact multiple digits are decomposed into features that will be presented to the hand either alone or in combination with other features while the animal performs a tactile-visual matching task. This study will determine how independent views of objects are integrated across digits to form neural representations of two-dimensional (2D) objects. The study will also determine the role that attention plays in the binding of tactile features.
The second aim i s to determine how feature selectivity is modulated by hand conformation. In these experiments, animals will be trained to grasp three-dimensional (3D) objects with one (1) or more digits. The objects are chosen such that they span the conformational space that animals and humans use when grasping objects. These experiments will test the hypothesis that shape perception is encoded by populations of neurons with feature selective responses tuned to specific hand conformations. Experiments will be performed in primary (SI) and secondary (SII) somatosensory cortex.
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