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. 2010 Jun 2;588(Pt 14):2633–2641. doi: 10.1113/jphysiol.2010.189548

Figure 4. Interactions between LIHI and LICI in one representative subject.

Figure 4

Traces represent averaged MEPs from 10 trials. A, the test stimulus (TS) alone. TS was set to produce MEP of about 1 mV (state 3A in Table 2). B, TS1mVCS100 alone. TS was adjusted to produce test MEP of 1 mV in the presence of CS100 (cortical stimulation that precedes the TS by 100 ms) (state 3D). C, LICI induced by CS100 preceding the TS1mVCS100 by 100 ms (state 3E). D, long interhemispheric inhibition (LIHI) induced by contralateral cortical stimulation (CCS40) preceding TS1mVCS100 by 40 ms (state 3F). The test MEP amplitude matched was similar to the test MEP amplitude in condition 3A. E, combined LIHI and LICI (CS100–CCS40–TS1mVCS100 combination, state 3G). The combined effects of LICI and LIHI are less than the individual inhibitory effects showing that these two inhibitory circuits have inhibitory interactions. Addition of the CCS40 (E, state 3G) pulse to the CS100–TS1mVCS100 combination (C, state 3F) resulted in MEP facilitation.