Vanderbilt Addiction Center

Optical Imaging of Tactile Information in SI Cortex

This proposal aims to study the stability of cortical representation by examining cortical maps under different states of anesthesia and alertness (pentothal and isofluane anesthesia, and awake state). Previous studies have hypothesized that different parts of single thalamocortical arbors have different degrees of dominance in Area 3b and that the effects of these secondary arbor inputs may be masked under some conditions and revealed under others. Using optical imaging and electrophysiological methods, we will probe this hypothesis by examining three aspects of finger pad representation in Area 3b and Area 1 of the squirrel monkey: topography, vibrotactile information (pressure SA, flutter RA, and vibration PC), and spatial integration (two digit). We will examine whether digit representation can, in contrast to the standard somatotopic maps, take on non-topographic organizations that are characterized by hotspots and secondary activation zones. We will examine whether SA, RA, and PC inputs can map in both overlapping and segregated manners in the superficial layers. To examine spatial integration in Area 3b and 1, we will examine whether mapping with simultaneous two-finger stimulation paradigm will result in an apparent shift in topography, and whether such a shift is more pronounced in Area 1 and more pronounced in the awake state. These examinations of alternative and shifting topographies are likely to modify the definition of topographic organization in SI and what shifting topographies are likely to modify the definition of topographic organization in SI and what topographic organization is used for in the awake animal. Furthermore, these studies may reveal that the establishment of topography is area-specific and is based on a stimulus-driven or behavior-driven integration of features rather than a simple representation of the sensory epithelium.

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