attention modulation of local and global inhibition mechanisms

Conditions: Optical Phenomena

Summary: human behavior is both flexible and adapted to the environmental context through inhibition capabilities; the investigator control the subject's behavior by repressing inappropriate responses and selecting, among several possibilities, those that are appropriate. these mechanisms are not independent of attentional control. attention acts as a selection filter for the investigator's behavior. this leads us to hypothesize that attention modulates the mechanisms of inhibition. nevertheless, the different brain structures involved, as well as mechanisms underlying the interaction between inhibition and attention remain largely unknown. previous research has suggested that inhibition requires selective attention and, conversely, attentional mechanisms would result in the "deselection", or inhibition, of objects in space or irrelevant actions. reconciling the literature on attention with the one on inhibition appears fundamental for the understanding of the instance to which the mechanisms of inhibition and the cognitive processes interact. therefore, the goal of this research project will be to investigate how inhibition mechanisms are implemented in the brain and, in more detail, what determines the type of resulting inhibitory control: spatially localized or global. the investigator will test 3 different patient groups (optic ataxia, hemispatial neglect and attention-deficit hyperactivity disorder) compared to control. in conclusion, this research project will aim to develop a theoretical model of the interaction between attentional control and inhibition mechanisms in order to improve diagnostic and rehabilitation tools in the future.


Eligibility criteria:
all patients and healthy subjects: inclusion criteria: * male and female, age from 18 to 75 years included * normal vision or corrected vision * covered by social security * signed written informed consent exclusion criteria: * unable to comply with requirements of the study (neurological, psychiatric, sensory or motor troubles) * adults under legal protection patient with hemispatial neglect: inclusion criteria: * after a stroke (\> 1 month ago), presence of a neurological impairment documented by brain imaging (standard of care) and by clinical symptoms. * the diagnosis will be dissociated from hemianopia by perimetry. the hemispatial neglect consists of a lack of perception and responsiveness concerning the controlesional visual hemifield. patient with optic ataxia: * after a stroke (\> 1 month ago), presence of neurological injury in parietal cortex only, supported by a standard of care cerebral mri * present optic ataxia symptoms (the oa consists of pointing errors with the hand contralateral to the lesion (hand effect) and / or to visual targets presented in the field contralateral to the lesion (field effect)). patient (adult and children) with attention-deficit hyperactivity disorder: * present a diagnosis of adhd subtype inattention or impulse / hyperactivity as established by a neuropsychologist. * children will be between 8 and 18 years old * adults will be between 18 and 75 years old. * participants will not report any comorbid learning disabilities to adhd. for minors: - having obtained the written consent of the legal representative(s) healthy subjects inclusion criteria: - no known neurological injury

Keywords: attention-deficit hyperactivity disorder (adhd) attention deficit disorder with hyperactivity attention inhibition healthy volunteers perceptual disorders