Modulation of somatosensation by transcranial magnetic stimulation over somatosensory cortex: a systematic review

Features of virtual reality impact effectiveness of VR pain alleviation therapeutics in pediatric burn patients: A randomized clinical trial

Key features of virtual reality (VR) that impact the effectiveness of pain reduction remain unknown. We hypothesized that specific features of the VR experience significantly impact VR's effectiveness in reducing pain during pediatric burn dressing care. Our randomized controlled trial included children 6 to 17 years (inclusive) who were treated in the outpatient clinic of an American Burn Association-verified pediatric burn center. Participants were randomly assigned (1:1:1) to active VR (playing the VR), passive VR (immersed in the same VR environment without interactions), or standard-of-care. On a scale from 0 to 100, participants rated overall pain (primary outcome) and features of the VR experience (game realism, fun, and engagement). Path analysis assessed the interrelationships among these VR key features and their impact on self-reported pain scores. From December 2016 to January 2019, a total of 412 patients were screened for eligibility, and 90 were randomly assigned (31 in the active VR group, 30 in the passive VR group, and 29 in the standard-of-care group). The current study only included those in the VR groups. The difference in median scores of VR features was not statistically significant between the active (realism, 77.5 [IQR: 50-100]; fun, 100 [IQR: 81-100]; engagement, 90 [IQR: 70-100]) and passive (realism, 72 [IQR: 29-99]; fun, 93.5 [IQR: 68-100]; engagement, 95 [IQR: 50-100]) VR distraction types. VR engagement had a significant direct (-0.39) and total (-0.44) effect on self-reported pain score (p<0.05). Key VR features significantly impact its effectiveness in pain reduction. The path model suggested an analgesic mechanism beyond distraction. Differences in VR feature scores partly explain active VR's more significant analgesic effect than passive VR. Trial Registration: ClinicalTrials.gov Identifier: NCT04544631.

The acute effects of repetitive transcranial magnetic stimulation on laminar diffusion anisotropy of neocortical gray matter

Repetitive transcranial magnetic stimulation (rTMS) is increasingly used to treat neuropsychiatric disorders. Inhibitory and excitatory regimens have been both adopted but the exact mechanism of action remains unclear, and investigating their differential effects on laminar diffusion profiles of neocortex may add important evidence. Twenty healthy participants were randomly assigned to receive a low-frequency/inhibitory or high-frequency/excitatory rTMS targeting the left dorsolateral prefrontal cortex (DLPFC). With the brand-new submillimeter diffusion tensor imaging of whole brain and specialized surface-based laminar analysis, fractional anisotropy (FA) and mean diffusion (MD) profiles of cortical layers at different cortical depths were characterized before/after rTMS. Inhibitory and excitatory rTMS both showed impacts on diffusion metrics of somatosensory, limbic, and sensory regions, but different patterns of changes were observed-increased FA with inhibitory rTMS, whereas decreased FA with excitatory rTMS. More importantly, laminar analysis indicated laminar specificity of changes in somatosensory regions during different rTMS patterns-inhibitory rTMS affected the superficial layers contralateral to the DLPFC, while excitatory rTMS led to changes in the intermediate/deep layers bilateral to the DLPFC. These findings provide novel insights into acute neurobiological effects on diffusion profiles of rTMS that may add critical evidence relevant to different protocols of rTMS on neocortex.