Fig. 9.

The effect of general anesthetic on SCEPs recorded from an epidural electrode at Th8 after TCMS. When the subject was awake and at rest, the SCEP had a D wave followed by four I waves (I₁,I₂,I₃, andI₄) (top traces). After the subject was anesthetized (0.5% isoflurane, 66% N₂O, and 33% O₂), theI₁ wave was delayed and diminished, and theI₂,I₃, and I₄waves were absent (bottom traces) when compared with that obtained during the awake state. In contrast, the Dwave was relatively unaffected by anesthesia. TCMSintensity (SCEP T + 40% of the maximum output of the stimulator) and stimulus coil position were the same in the awake and anesthetized conditions.