Decoding accuracy in supplementary motor cortex correlates with perceptual sensitivity to tactile roughness

Perceptual sensitivity to tactile roughness varies across individuals for the same degree of roughness. A number of neurophysiological studies have investigated the neural substrates of tactile roughness perception, but the neural processing underlying the strong individual differences in perceptual roughness sensitivity remains unknown. In this study, we explored the human brain activation patterns associated with the behavioral discriminability of surface texture roughness using functional magnetic resonance imaging (fMRI). First, a wholebrain searchlight multi-voxel pattern analysis (MVPA) was used to find brain regions from which we could decode roughness information. The searchlight MVPA revealed four brain regions showing significant decoding results: the supplementary motor area (SMA), contralateral postcentral gyrus (S1), and superior portion of the bilateral temporal pole (STP). Next, we evaluated the behavioral roughness discrimination sensitivity of each individual using the just-noticeable difference (JND) and correlated this with the decoding accuracy in each of the four regions. We found that only the SMA showed a significant correlation between neuronal decoding accuracy and JND across individuals; Participants with a smaller JND (i.e., better discrimination ability) exhibited higher decoding accuracy from their voxel response patterns in the SMA. Our findings suggest that multivariate voxel response patterns presented in the SMA represent individual perceptual sensitivity to tactile roughness and people with greater perceptual sensitivity to tactile roughness are likely to have more distinct neural representations of different roughness levels in their SMA. © 2015 Kim et al.close0

Effect of splint on pain, function and quality of life in trapeziometacarpal osteoarthritis patients?

Trapeziometacarpal (TM) Osteoarthritis is one of the most common osteoarthritis. It causes pain, loss of mobility and strength and affected function in daily life. Splint is one of the conservative treatments proposed to patients. The purpose of this study was to assess the effect of this conservative treatment on pain, function and quality of life at long-term. We sent 193 questionnaires to patients who received a CMC splint for their TM osteoarthritis. The CMC splint immobilizes only the TM joint and leaves free the interphalangeal joint of the thumb and the wrist. First, we comptuted how many patients had finally undergone surgical treatment. On the non-operated patients, we analyzed the pain (VAS), the function (QuickDASH score) and the quality of life (SF-12). We compared the results to literature and norms. Finally, 186 people could be included in the study ,115 we answered and 28 were operated on (24%). After 4 years (3.8±1.7 yrs) of conservative treatment, The VAS and QuickDASH scores were significantly worse comparatively to a cohort of healthy patients, trapezectomy and arthrodesis patients. The SF-12 scores were reduced from 20% comparative to norms. In conclusion, few patients had surgery after splinting as a conservative treatment. However, these non- operated patients do not provide good results

Difficult to treat osteoarticulars infections : Focus on Mycobacterial and Fungal infection.

Bone and joint infections are rare but often devastating. While bacteria are most commonly encountered organisms, mycobacteria and fungi are less frequent. Management of the latter is often more complex, especially in the presence of foreign material. We will increasingly be faced with mycobacterial and fungal bone infections, as medical conditions and newer therapeutics lead to more immunosuppression. In this article, we will review osteomyelitis, septic arthritis and peri-prosthetic joint infections related to mycobacteria and fungi

Atypical influence of biomechanical knowledge in Complex Regional Pain Syndrome-towards a different perspective on body representation

Abstract Part of the multifaceted pathophysiology of Complex Regional Pain Syndrome (CRPS) is ascribed to lateralized maladaptive neuroplasticity in sensorimotor cortices, corroborated by behavioral studies indicating that patients present difficulties in mentally representing their painful limb. Such difficulties are widely measured with hand laterality judgment tasks (HLT), which are also used in the rehabilitation of CRPS to activate motor imagery and restore the cortical representation of the painful limb. The potential of these tasks to elicit motor imagery is critical to their use in therapy, yet, the influence of the body’s biomechanical constraints (BMC) on HLT reaction time, supposed to index motor imagery activation, is rarely verified. Here we investigated the influence of BMC on the perception of hand postures and movements in upper-limb CRPS. Patients were slower than controls in judging hand laterality, whether or not stimuli corresponded to their painful hand. Reaction time patterns reflecting BMC were mostly absent in CRPS and controls. A second experiment therefore directly investigated the influence of implicit knowledge of BMC on hand movement judgments. Participants judged the perceived path of movement between two depicted hand positions, with only one of two proposed paths that was biomechanically plausible. While the controls mostly chose the biomechanically plausible path, patients did not. These findings show non-lateralized body representation impairments in CRPS, possibly related to difficulties in using correct knowledge of the body’s biomechanics. Importantly, they demonstrate the challenge of reliably measuring motor imagery with the HLT, which has important implications for the rehabilitation with these tasks