'Reassurance and healthcare seeking in people with persistent musculoskeletal low back pain consulting orthopaedic spine practitioners: A prospective cohort study'.

BACKGROUND: Guidelines recommend self-management for most people living with persistent musculoskeletal low back pain (PMLBP) when surgery is ruled out. Conveying this message to patients can be challenging. This study examined patients' perceptions of reassuring communications from surgical spine team practitioners attempting to deliver this message in a single consultation. METHODS: Pre-consultation baseline measures included levels of pain, disability and previous consultation history. Patients' perceptions of reassuring communications were measured within 1-week post-consultation. The outcome variables, measured at 3-month follow-up, included patients' report of subsequent GP visits for back pain, the number of other healthcare providers consulted for back pain and distress. RESULTS: Data from 296 patients (9.8% loss to follow-up) were analysed using hierarchical regression models, controlling for demographic, clinical and study-related factors. In each model, perceived reassurance accounted for a small but significant variance, above and beyond other predictors. Further GP visits were predicted by disability at baseline and perceived reassurance (adjusted R2 of 14.6%). Subsequent consultations with any healthcare professionals were predicted by a shorter duration of back pain, disability at baseline and perceived reassurance (adj. R2  = 10.6%). Distress was predicted by older age, disability and reassurance (adj. R2  = 59.5%). CONCLUSION: Findings suggest that better communication in consultations with orthopaedic spine clinicians might help reduce unnecessary subsequent healthcare utilization and distress. SIGNIFICANCE: Low back pain patients' perceptions of their communication with orthopaedic spine practitioners are associated with subsequent healthcare seeking and distress at follow-up. This study examines the intersection of two important but fairly neglected areas in the pain research: provider communication and patient healthcare utilization.

GABA, noise and gain in human visual cortex.

High levels of GABA (gamma-aminobutyric acid, the brain's primary inhibitory neurotransmitter) are associated with enhanced cognitive and perceptual performance. It has been proposed that these effects result from GABA reducing neural noise or variability, but the precise mechanisms remain unknown. We have measured how individual differences in GABA concentration in the visual cortex are related to performance on a visual contrast discrimination task. Our results reveal that the facilitatory strength of the typical "dipper" function elicited by this task is strongly correlated with GABA concentration. A simple, biologically plausible, network model comprising excitatory and suppressive neural populations accounts for the data well and indicates that the strength of suppression increases as GABA concentration increases. Inter-individual variations in GABA were correlated both with the inhibition strength of the model (mimicking the effect of GABA) and, inversely, with the magnitude of the response criterion. This enhanced suppression has the dual effect of suppressing noise and reducing the gain of the neural response. Our findings thus suggest that the changes in performance conferred by high GABA concentration are mediated by both a reduction of noise and, paradoxically, a reduction in neural, but not perceptual, sensitivity.