Stimulation of the parietal cortex affects reaching in a patient with epilepsy

Abstract

A 15-year-old girl with complex partial epilepsy had subdural electrodes implanted. She was tested on reaching tasks during electrocortical stimulation prior to neurosurgery. MRI showed left mesial parietal dysplasia. Stimulation of the superior parietal cortex (electrode pair 37-45, figure, A) during line bisection and visually guided reaching resulted in movement arrest followed by the arm drifting upward (figure, B, videos 1 and 2 on the Neurology ® Web site at www.neurology.org). Stimulation of these electrodes also resulted in reaching arrest when aiming toward proprioceptive targets (video 3). These observations are consistent with the idea that superior parietal cortex contains representations of defensive arm postures 1 or is involved in sensoryguided reaching.

Role of posterior parietal cortex in reaching movements in humans: Clinical implication for ‘optic ataxia’

“…To our knowledge, the present study is the first demonstration of misreaching similar to optic ataxia by direct cortical stimulation of the human PPC. However, there was one report that described arrest of visually-guided reaching followed by upward arm drift during cortical stimulation at the PPC (Dijkerman et al , 2009). By contrast, the present BP study of reaching employed a reaching task to the target placed in the central vision, but not in the peripheral vision.…”

Identifying peripersonal space boundaries in newborns

“…It has been suggested that it can be represented as a multisensory and sensorimotor interface mediating both social and physical interactions between the body and the environment 1–4 . In fact, peripersonal spatial representations are thought to have the dual function 1,2 of supporting goal-directed actions 5 and enabling us to defend ourselves from imminent threats 6,7 .…”