Figure 2.

Po stimulation modulates subsequent responses in M1wk and S1BF to passive multi-whisker stimulation. (A) Diagram of the experimental protocol. Tactile stimulation (air puffs) was applied to the contralateral whiskers (four trains of 100 stimuli, 1 Hz). A single train of electrical pulses (50 Hz, 1 s, 20–100 μA) was applied to Po immediately after the first train of air puffs (“control train”). SEPs were recorded in the S1BF and M1wk cortices. In each area, separate recordings were made in the superficial and deep layers (shaded in different color hues, respectively). (B) Representative image of a coronal brain section counterstained with cytochrome oxidase showing the location of the bipolar electrode tip in Po. Bar = 500 μm. (C) Effect of Po electrical stimulation on tactile responses in M1wk cortex. Left: changes in SEP1 area are shown as the percentage of differences to control values. Right: representative individual SEPs recorded during control (black line), first (colored line) and second (gray dashed line) train. Arrowheads indicate whisker stimuli application. (D) Effect of Po stimulation on tactile responses in S1BF cortex. Conventions as in (C).