Spatial working memory in Progressive Supranuclear Palsy

Abstract

The neural and cognitive mechanisms of spatial working memory are tightly coupled with the systems that control eye-movements but the precise nature of this coupling is not well understood. In particular, there are very few neuropsychological studies that explicitly examine how deficits of oculomotor control affect visuospatial working memory. Here, we examined the link between spatial working memory and the oculomotor system in a sample of patients with Progressive Supranuclear Palsy, a degenerative neurological disease characterised by defective vertical eye-movements but relatively preserved horizontal eye-movements. Consistent with the idea that the oculomotor system plays a critical role in spatial working memory performance, people with PSP had significantly shorter spatial spans when stimuli were presented along the vertical axis compared to the horizontal axis. This effect was not observed in age matched controls. We hypothesise that PSP disrupts a colliculo-parietal feedback loop that contributes to the maintenance of activation in a parietal priority map during the delay period. This result is the first direct neuropsychological evidence for an association between oculomotor function and spatial working memory and is broadly consistent with idea that rehearsal in visuospatial working memory is mediated by an 'oculomotor loop', as proposed by Baddeley (1986). We conclude that optimal spatial working memory performance depends on an intact oculomotor system.

Keywords: Basal ganglia; Neuropsychology; Oculomotor; Ophthalmoplegia; Rehearsal; Saccade; Working memory.