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Prior reports have described a transient and focal decline in transcranial magnetic stimulation (TMS)-induced motor evoked potential (MEP) amplitude following fatiguing motor tasks. However, the neurophysiological causes of this change in MEP amplitude are unknown. The aim of this study was to determine whether post-task depression of MEPs is associated with repetitive central motor initiation. We hypothesized that MEP depression is related to repeated central initiation of motor commands in task-related cortex independent of motor fatigue. Twenty healthy adults had MEPs measured from the dominant first dorsal interosseous (FDI) muscle before and after six different tasks: rest (no activity), contralateral fatiguing hand-grip, ipsilateral fatiguing hand-grip, contralateral finger tapping, ipsilateral finger tapping, and imagined hand-grip (motor imagery). Changes in MEPs from baseline were assessed for each task immediately following the task and at 2-min intervals until MEPs returned to a stable baseline. Measures of subjective effort and FDI maximum voluntary contractions (MVC) were also recorded following each task. A statistically significant drop in MEP amplitude was noted only with contralateral finger tapping and imagined grip. Changes in MEP amplitude did not correlate with subjective fatigue or effort. There was no significant change in FDI MVCs following hand-grip or finger-tapping tasks. This study extends our knowledge of the observed decline in MEP amplitude following certain tasks. Our results suggest that central initiation of motor programs may induce a change in MEP amplitude, even in the absence of objective fatigue.

OBJECTIVE: To measure the effect of behavior management training on restraint use and prn medication delivery on an acute inpatient brain injury unit. SETTING/PARTICIPANTS: Interdisciplinary staff and hospitalized brain injury patients on a 20-bed unit within a freestanding rehabilitation hospital. INTERVENTION: Staff participated in the Nonviolent Crisis Intervention (NCI) program from the Crisis Prevention Institute. MAIN OUTCOME MEASURES: Applied physical restraints and delivered prn medications. RESULTS: Despite comparable patient levels of agitation severity across the duration of the study, the use of physical restraints initially declined and then increased after training. Data collected on prn medication delivery also indicated a trend for an increase in the delivery of select medication categories across time. CONCLUSION: NCI training resulted in a temporary, short-lived reduction in physical restraint use, but had an inverse effect on prn medication delivery for select categories of medication. Medication delivery significantly increased over time and restraint use eventually exceeded baseline level. Ramifications of these results are discussed. Language: en