Saccadic latency in Parkinson's disease correlates with executive function and brain atrophy, but not motor severity

Brain regions related to saccadic control are affected by Parkinson's disease (PD) pathology and a relationship between abnormal saccades and cognitive features of PD has been suggested. We measured the latency of visually-evoked saccades, and correlated best-fit parameters in a LATER neuronal decision model μ and σ (mean and SD of the distribution of reciprocal latency, i.e. speed of response), and σE (SD of the early component) with motor function, cognition and grey matter volume in 18 patients with PD and 17 controls. There was a negative correlation between verbal fluency and σ; no correlation was found between motor function and any of the latency parameters. Higher μ (shorter latency) positively correlated with grey matter volume in the prefrontal cortex, the cerebellar vermis, and the fusiform gyrus. There was a negative correlation between σ and grey matter volume in the frontal and parietal eye fields, the premotor cortex, and the lateral prefrontal cortex. σE negatively correlated with grey matter volume in the frontal eye fields and the middle frontal gyrus. Our behavioural and imaging findings point to an association between saccade latency, executive function and the structural integrity within a well-defined oculomotor network.

Research highlights► Saccadic latency is related to brain regions affected by Parkinson's disease. ► Information on the underlying neural decision process can be derived from saccades. ► We present the grey matter volume and cognitive correlates of saccade alterations. ► Implications for the neural decision process are discussed.