Sensori-motor and Perceptual Functions of the PPC. (PPCfonctions)

Sensori-motor and Perceptual Functions of the Posterior Parietal Cortex (PPC) in Patients With Optic Ataxia (AO) and Healthy Subjects.

To produce hand's movement directed towards a target, the investigator must combine several sensory information, such as vision or proprioception. The posterior parietal cortex (PPC) is a region of the cortex involved in this multisensory integration. A lesion of the PPC cause a visuo-motor trouble called optic ataxia but these patients also have perceptual troubles. The aim of the study is to understand the different functions of the PPC and especially how the processes of spatial coding of the sensory information influences perception and motor planning. In this study, the investigator want to explore the sensory motor and the perceptual performance of patients with optic ataxia compared with healthy subjects, using 6 behavioral tests. Objectify the consequences of PPC impairment (visual-motor and perceptual consequences) on patients' quality of life and autonomy.

In the experiences 1 and 2, the participant needs to point different visual targets (LED) in the dark.

In the experience 3, a tactile stimulation is applied to the middle finger of the 2 hands. The participant needs to indicate into a microphone when he feels the stimulation.

Target dots or visual images are presented on a computer screen. The participant is required to point to the targets or to react as soon as possible by pressing a response button when they are detected.

Inclusion Criteria: All patients and healthy subjects: male and female, age from 18 to 75 years included normal vision or corrected vision covered by social security signed written informed consent Patients: neurological injury in posterior parietal cortex supported by a cerebral MRI present optic ataxia symptoms Healthy subjects no known neurological injury Exclusion Criteria: - unable to comply with the tasks (neurological, psychiatric, sensory or motor troubles)