TEMPORAL-MODULATION OF SPATIAL BORDERS IN RAT BARREL CORTEX

Temporal modulation of spatial borders in rat barrel cortex. J. Neurop hysiol. 79: 464-470, 1998. We examined the effects of varying vibrissa stimulation frequency on intrinsic signal and neu ronal responses in rat barrel cortex, Optical imaging of intrinsic signals demonstrated t hat the region of cortex activated by deflection of a single vibrissa at I Hz is more diffuse and more widespread than;he territory activate d at 5 or 10 Hz. With the use of two different paradigms, constant tim e of stimulation and constant number of vibrissa deflections, we showe d that the optically imaged spread of activity is more discrete at hig her stimulation frequencies. We combined optical imaging with multiple electrode recording and confirmed that the neuronal response to indiv idual vibrissa stimulation at the optically imaged center of activity is greater than the response away from the imaged center. Consistent w ith the imaging data, these recordings also showed no response to a se cond vibrissa def-lection at 5 Hz at a peripheral recording site, thou gh there was a significant response to a second vibrissa deflection at 1 Hz at the same peripheral site. These findings demonstrate that vib rissa stimulation at higher frequencies leads to more focused physiolo gical responses in cortex. Thus the spread of activation In rat barrel cortex is modulated in a dynamic fashion by the frequency of vibrissa stimulation.