Plasticity-inducing TMS protocols to investigate somatosensory control of hand function.

Hand function depends on sensory feedback to direct an appropriate motor response. There is clear evidence that somatosensory cortices modulate motor behaviour and physiology within primary motor cortex. However, this information is mainly from research in animals and the bridge to human hand control is needed. Emerging evidence in humans supports the notion that somatosensory cortices modulate motor behaviour, physiology and sensory perception. Transcranial magnetic stimulation (TMS) allows for the investigation of primary and higher-order somatosensory cortices and their role in control of hand movement in humans. This review provides a summary of several TMS protocols in the investigation of hand control via the somatosensory cortices. TMS plasticity inducing protocols reviewed include paired associative stimulation, repetitive TMS, theta-burst stimulation as well as other techniques that aim to modulate cortical excitability in sensorimotor cortices. Although the discussed techniques may modulate cortical excitability, careful consideration of experimental design is needed to isolate factors that may interfere with desired results of the plasticity-inducing protocol, specifically events that may lead to metaplasticity within the targeted cortex.

Is there a role for physician involvement in introducing research to surrogate decision makers in the intensive care unit? (The Approach trial: a pilot mixed methods study).

PURPOSE: To assess the feasibility of conducting a randomized trial comparing two strategies [physician (MD) vs. non-physician (non-MD)] for approaching substitute decision makers (SDMs) for research and to evaluate SDMs' experiences in being approached for consent. METHODS: A pilot mixed methods study of first encounters with SDMs. RESULTS: Of 137 SDMs (162 eligibility events), 67 and 70 were randomized to MD and non-MD introductions, respectively. Eighty SDMs (98 events) provided consent and 21 SDMs (24 events) declined consent for studies, including 2 SDMs who provided and declined consent. We identified few missed introductions [4/52 (7.7 %)] and protocol violations [6/117 (5.1 %)], high comfort, satisfaction and acceptance scores and similar consent rates in both arms. SDMs provided consent significantly more often when a patient update was provided in the MD arm. Most SDMs (85.7 %) felt that physician involvement was inconsequential and preferred physician time to be dedicated to patient care; however, SDM experiences were closely related to their recall of being approached and recall was poor. SDMs highlighted 7 themes of importance to them in research surrogate decision-making. CONCLUSION: SDMs prioritized the personal attributes of the person approaching them over professional designation and preferred physician time to be dedicated to patient care. A mixed methods design evaluated intervention fidelity and provided the rationale for not proceeding to a larger trial, despite achieving all feasibility metrics in the pilot trial. TRIAL REGISTRATION NUMBER: NCT01232621.

Continuous theta-burst rTMS over primary somatosensory cortex modulates tactile perception on the hand.

OBJECTIVE: Theta-burst stimulation (TBS) over the primary somatosensory cortex (SI) alters cortical excitability, and in its intermittent form (iTBS) improves tactile spatial acuity. The effects of continuous TBS (cTBS) on tactile acuity remain unknown. The present study examined the influence of cTBS over SI on temporal and spatial tactile acuity on the contralateral hand. METHODS: In separate experiments, temporal discrimination threshold (TDT) and spatial amplitude discrimination threshold (SDT) were obtained from the right hand before and for up to 34 min following real and sham cTBS (600 pulses) over left-hemisphere SI. RESULTS: CTBS reduced temporal and spatial tactile acuity for up to 18 min following real cTBS. Tactile acuity was unaltered in the groups receiving sham cTBS. CONCLUSIONS: CTBS over SI impairs both temporal and spatial domains of tactile acuity for a similar duration. SIGNIFICANCE: CTBS over SI appears to decrease neural activity within targeted cortex and has potential utility in reducing excessive sensory processing.