Pairing Transcranial Magnetic Stimulation and Loud Sounds Produces Plastic Changes in Motor Output.

Most current methods for neuromodulation target the cortex. Approaches for inducing plasticity in subcortical motor pathways, such as the reticulospinal tract, could help to boost recovery after damage (e.g., stroke). In this study, we paired loud acoustic stimulation (LAS) with transcranial magnetic stimulation (TMS) over the motor cortex in male and female healthy humans. LAS activates the reticular formation; TMS activates descending systems, including corticoreticular fibers. Two hundred paired stimuli were used, with 50 ms interstimulus interval at which LAS suppresses TMS responses. Before and after stimulus pairing, responses in the contralateral biceps muscle to TMS alone were measured. Ten, 20, and 30 min after stimulus pairing ended, TMS responses were enhanced, indicating the induction of LTP. No long-term changes were seen in control experiments which used 200 unpaired TMS or LAS, indicating the importance of associative stimulation. Following paired stimulation, no changes were seen in responses to direct corticospinal stimulation at the level of the medulla, or in the extent of reaction time shortening by a loud sound (StartReact effect), suggesting that plasticity did not occur in corticospinal or reticulospinal synapses. Direct measurements in female monkeys undergoing a similar paired protocol revealed no enhancement of corticospinal volleys after paired stimulation, suggesting no changes occurred in intracortical connections. The most likely substrate for the plastic changes, consistent with all our measurements, is an increase in the efficacy of corticoreticular connections. This new protocol may find utility, as it seems to target different motor circuits compared with other available paradigms.SIGNIFICANCE STATEMENT Induction of plasticity by neurostimulation protocols may be promising to enhance functional recovery after damage such as following stroke, but current protocols mainly target cortical circuits. In this study, we developed a novel paradigm which may generate long-term changes in connections between cortex and brainstem. This could provide an additional tool to modulate and improve recovery.

Relationship between burnout and physical activity level among pre-clinical medical students.

OBJECTIVE: To identify the relationship between burnout stress and physical activity, specifically in pre-clinical medical students at Universitas Indonesia. METHODS: This cross-sectional study included 318 students selected by stratified random sampling. The Maslach Burnout Inventory General Survey was used to measure burnout stress, and the International Physical Activity Questionnaire Short Form was used for physical activity. Correlation and multiple regression tests were performed to evaluate the relationship between all variables. RESULTS: Overall, most students had a moderate burnout stress and moderate physical activity level. Spearman's correlation showed a statistically significant association for personal achievement with moderate intensity (r = 0.127, p = 0.024) and overall physical activity (r = 0.113, p = 0.045). Meanwhile, the correlation between depersonalisation and emotional exhaustion was non-significant. A statistically significant association was found for depersonalisation with both gender (r = -2.411, p = 0.016) and study programme (r = 1.007, p = 0.001). Additionally, at least 40% of students suffered from at least one aspect of severe burnout, while 25.7% had low levels of physical activity. Both conditions were the most severe among Grade III students. CONCLUSIONS: An association was found between physical activity and the personal performance component of burnout stress, indicating how low levels of physical activity will lower students' sense of satisfaction with their own personal accomplishments. This will lead to higher levels of stress when doing school-related tasks as they see their efforts as a student in vain.