81 ALTERED VISUOMOTOR PROCESSING IN NA 4 those same movements. Behaviour did not correlate with brain activity in either region in healthy participants (parieto-occipital sulcus: r =-0.12, p = 0.56; right extrastriate: r = -0.02, p = 0.93). Symptom severity did not correlate significantly with brain activity in the parieto-occipital sulcus (r < ± 0.17, p > 0.31) or with overall RT (r < ± 0.29, p ≥ 0.07). Discussion In this fMRI study, we show that patients with a lateralized peripheral nervous system disorder (i.e. NA of the brachial plexus, affecting the right upper extremity) have altered cerebral and behavioural responses during hand laterality judgement. Specifically, compared to healthy participants, NA patients were overall slower, and had decreased cerebral activity when mentally rotating their affected limb in two brain regions: right extrastriate cortex and bilateral parieto-occipital sulcus.. This indicates that NA patients have altered sensorimotor representations of their affected upper extremity. It also suggests that this maladaptive cerebral neuroplasticity arises from visuomotor rather than primary somatomotor regions. Exploratory analyses revealed that patients with greater symptom severity were relatively slower and had decreased cerebral activity when imagining movements with their affected limb, which may suggest a link between altered sensorimotor representations and clinical outcome in NA. Figure 5 Brain-Behaviour-Symptom correlations Shows the significant correlations between brain-behaviour-symptom within NA patients A. BrainSymptom correlation. negative correlation (r = -0.45, p = 0.004) showing that NA patients with more pain had significantly less activity in the right extrastriate cortex when imagining complex movements with the affected limb (Rightcomplex > Leftcomplex). B. Brain-Behaviour correlation negative correlation (r = -0.42, p = 0.008) showing that NA patients with relatively more difficulty with complex movements of the affected limb (i.e. higher Δ reaction time Rightcomplex - Leftcomplex), had less activity along the bilateral parieto-occipital sulcus when imagining those same movements (Rightcomplex > Leftcomplex) C. Behaviour-Symptom correlation significant positive correlation (r = 0.33, p = 0.04) showing that NA patients with more pain had relatively more difficulty with complex trials of the affected limb (i.e. higher Δ reaction time Rightcomplex - Leftcomplex). L = left; ms = milliseconds; POS = parieto-occipital sulcus; R = right; VAS = Visual Analogue Scale; Δ = delta
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