Figure 7.

GABA-A receptor blockade with picrotoxin reduced the sensory-evoked increases in cortical activity and CBF. A, Representative somatosensory evoked potentials (SEP) induced by stimulation of the whiskers at 4 Hz under vehicle and picrotoxin. B, Quantification of the decreases in SEP amplitude and evoked CBF responses induced by picrotoxin compared with vehicle when all rats were included in the analysis (n = 12), including two that did not respond to picrotoxin based on no CBF reduction. C, The changes in the evoked CBF responses and SEP amplitudes induced by picrotoxin were significantly correlated (Pearson correlation, r = 0.7284, p < 0.01, n = 12). Note that 0% change in cortical activity was associated with a small reduction of CBF (9.4%, intercept of gray line on x-axis), suggesting a possible effect of picrotoxin on vascular GABA-A receptors (see text). D, When only rats that showed decreases in the evoked CBF response under picrotoxin (n = 10 of 12) were included in the analysis, the SEP amplitudes were significantly reduced compared with vehicle. *p < 0.05, **p < 0.01, ***p < 0.001, by paired Student's t test.