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MECHANISMS UNDERLYING SOMATOSENSORY CORTICAL DYNAMICS: II. IN VITRO STUDIES
Citation:
Lee, C., B. Whitesel, AND M. Tommerdahl. MECHANISMS UNDERLYING SOMATOSENSORY CORTICAL DYNAMICS: II. IN VITRO STUDIES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-92/376.
Description:
The response of the sensorimotor cortical slice to repetitive, single site afferent drive is mapped using both evoked potential and metabolic mapping (2DG) methods. ystematic changes (increases or decreases) in the evoked potential occur during repetitive 3-5 Hz stimulation. hese resemble the changes in S1 neuron response observed in the in-vivo studies of the preceding paper: i.e., they occur rapidly, recover within 1 minute and are reproducible if stimulus parameters remain unchanged. lace, timing, and intensity of repetitive stimulation influence the amplitude and form of the response alterations observed at a given cortical locus. he neuron populations which exhibit different response modifications to the same repetitive stimulus are distributed non-randomly in the slice: eurons occupying column-shaped aggregates undergo a common response alteration (either an increase or decrease) during repetitive stimulation, with sharp boundaries separating neighboring aggregates distinguishable on the basis of their dynamic behaviors. he distribution of stimulu-evoked 2DG uptake in the slice is "columnar", the dimensions of the 2DG columns corresponding to those mapped with neurophysiological methods. aken together, the findings support the concept (Whitsel et al., 1991) that repetitive stimulation causes the intrinsic network of somatosensory cortex to dynamically modify the network's response to extrinsic excitatory drive so that the local differences inthe pattern of extrinsic excitatory drive to neighboring cortical columns are enhanced.