Journal: Brain Stimulation

Article Title: Two forms of short-interval intracortical inhibition in human motor cortex

doi: 10.1016/j.brs.2021.08.022

Figure Lengend Snippet: TMS Coil Set-up (A, B) and protocol of simple reaction time task (C). The figure-of-eight coil connecting by current reversing cable was applied to induce anterior-posterior direction conditioning current in paired-pulse stimulation (A) and triple-pulse stimulation (B). There were three triple-pulse stimulation protocols here: triple pulse stimulation with two cortical conditioning, with cerebellar conditioning, and with peripheral sensory afferent input. The direction and colour of arrows indicate the orientation and coil selected to induce currents over the cortex. The images on the left side depict scenarios in which both coils (conditioning stimulus: figure-of-eight coil in red; test stimulus: oval-coil in yellow) delivered posterior-anterior (PA) currents. In triple-pulse stimulation, another conditioning stimulus was applied with the oval-coil (green), cerebellar conditioning stimulus (violet), or peripheral sensory afferent input (brown). On the right, the figure-of-eight coil produces an anterior-posterior ( AP ) current (blue). The bottom figure illustrated the timing giving SICI during a simple reaction time task (C).

Article Snippet: To investigate how somatosensory input interacts with SICI, we applied a conditioning peripheral nerve stimulation (DS7A; Digitimer Ltd, Welwyn Garden City, Hers, UK) to the ulnar nerve prior to M1 TMS (CS UNS ).

Techniques:

Journal: Brain Stimulation

Article Title: Two forms of short-interval intracortical inhibition in human motor cortex

doi: 10.1016/j.brs.2021.08.022

Figure Lengend Snippet: Interaction between SICI and CBI. The left panel depicts the effect of cerebellar stimulation alone (CBI: ISI = 5 ms) compared to the responses elicited when combined with CS AP3 (middle-panel) or CS PA3 (right-panel). The combination of CBI and CS AP3 produced more inhibition than either conditioning stimulus alone, whereas the combination of CBI and CS PA3 produced approximately the same amount of inhibition as either conditioning stimulus alone. Double asterisks indicate p < 0.05 in post hoc pairwise comparison. CS1 indicates the earlier CS, and CS2 means the later CS.

Article Snippet: To investigate how somatosensory input interacts with SICI, we applied a conditioning peripheral nerve stimulation (DS7A; Digitimer Ltd, Welwyn Garden City, Hers, UK) to the ulnar nerve prior to M1 TMS (CS UNS ).

Techniques: Produced, Inhibition, Comparison

Journal: Brain Stimulation

Article Title: Two forms of short-interval intracortical inhibition in human motor cortex

doi: 10.1016/j.brs.2021.08.022

Figure Lengend Snippet: SICI at 2 and 3 ms ISI: effect of different conditioning stimulus intensities for CS AP and CS PA . The left column (A, C, E) depicts SICI at ISI = 2 ms and in the right column (B, D, F) SICI at ISI = 3 ms. Panels in the top row (A, B) plot the CS intensity in percent MSO; panels in the middle row (C, D) plot CS intensity in percent of AMT PA ; panels (E, F) in the bottom raw plot CS intensity in percent of direction-appropriate AMT (i.e. AMT AP for CS AP , AMT PA for CA PA ). When intensities of conditioning stimulation were given based on AMT PA , panel D shows that at ISI = 3 ms, both CS AP (light blue) and CS PA (red) have approximately the same threshold (i.e. 90% AMT PA ). In contrast, at ISI = 2 ms (panel C), inhibition is evident only with CS PA but not with CS AP . Because of the lack of SICI over these intensities with CS AP , an additional run was performed in which the intensity of CS AP was expressed in percent AMT AP . When intensities of conditioning stimulation were giving based on the AMT of the direction of conditioning stimulation (i.e. CS AP by AMT AP ), panel F reveals that SICI CSAP3 by AMT AP (deep blue) is significantly different from SICI CSPA3 by AMT PA (red). In contrast, panel E shows that SICI CSAP2 by AMT AP (deep blue) is not different from SICI CSPA2 by AMT PA (red). The data from both these runs are combined in panels A and B, in which the intensity of the conditioning stimuli is expressed in %MSO in order to plot all data on the same x-axis. Because AMT varies (in terms of %MSO) across individuals, the data are plotted with x-error bars. In each graph, the data points in red and light blue replot the data in panels C and D; the dark blue points and line plot data from the additional runs at higher intensities of CS AP . Green points are data from points in the two runs of CS AP in which the absolute intensities of CS were the same, and thus the data was combined. The graphs show that at ISI = 3 ms, the threshold for producing SICI is approximately the same for both directions of CS. However, at ISI = 2 ms, SICI was evident only with high intensities of CS AP . The single asterisk indicates the significant (p < 0.05) “Orientation” X “Intensity” interaction in a two-way RM-ANOVA; double asterisks indicate intensities with a significant difference (post hoc pairwise comparison) in the amount of inhibition produced by CS PA and CS AP . (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article).

Article Snippet: To investigate how somatosensory input interacts with SICI, we applied a conditioning peripheral nerve stimulation (DS7A; Digitimer Ltd, Welwyn Garden City, Hers, UK) to the ulnar nerve prior to M1 TMS (CS UNS ).

Techniques: Inhibition, Comparison, Produced

Journal: Brain Stimulation

Article Title: Two forms of short-interval intracortical inhibition in human motor cortex

doi: 10.1016/j.brs.2021.08.022

Figure Lengend Snippet: Interaction of SICI with SAI. The left panel shows the MEP conditioned by ulnar nerve stimulation input (SAI; ISI = 22 ms). The middle panel represents SICI obtained with CS AP3 , either alone or combined with ulnar nerve stimulation (SAI-CS AP3 ). The right panel plots SICI induced by CS PA3 alone and combined with ulnar nerve stimulation (SAI-CS PA3 ). The combination SAI-CS AP3 produced more inhibition than either conditioning stimulus alone, whereas SAI-CS PA3 produced approximately the same amount of inhibition as each conditioning stimulus alone. Double asterisks indicate p < 0.05 in post hoc pairwise comparison. CS1 indicates the earlier CS, and CS2 means the later CS.

Article Snippet: To investigate how somatosensory input interacts with SICI, we applied a conditioning peripheral nerve stimulation (DS7A; Digitimer Ltd, Welwyn Garden City, Hers, UK) to the ulnar nerve prior to M1 TMS (CS UNS ).

Techniques: Produced, Inhibition, Comparison