OPTICAL IMAGING OF BIPOLAR CORTICAL STIMULATION

In order to better understand the degree of cortical activation that o ccurs during bipolar surface stimulation, the authors stimulated monke y visual cortex while monitoring the degree of activation with optical imaging. Optical imaging of intrinsic signals in monkey visual cortex during visual stimulation resulted in functional maps of ocular domin ance and orientation selectivity. After functional maps of ocular domi nance and orientation preference were obtained, bipolar surface stimul ation was applied to activate just the cortical areas around the bipol ar electrodes. Graded responses to changes in the stimulation intensit y and duration were found. These findings demonstrate the reliability of bipolar cortical surface stimulation in localizing functional regio ns of cortex. The area of activation, at least in the region around th e bipolar stimulating electrodes, did not appear to activate nearby oc ular dominance columns or orientation patches. Intraoperative bipolar surface stimulation continues to be a consistently reliable technique for localizing rolandic cortex and essential language sites.