Boosting Reward-based Attention Through VEstibular STimulation

Not Applicable

Suspended

Conditions: Unilateral Spatial Neglect for Half of Them
Brain Lesion of the Right Hemisphere

Interventions: Procedure: Non-invasive brain stimulation of the vestibular system through caloric vestibular stimulation.

Brief Summary: The exploration of space is more effective when intrinsically rewarding elements are located in the visual scene. Thus, rewards could be exploited as a novel rehabilitation approach to various attentional disorders. The first part of the project aims to characterize these effects at the behavioural level. The interventional part consists then in the administration of Caloric Vestibular Stimulation (CVS), which by means of injection of a small quantity of water in the external ear activates the vestibular organs and subsequently vestibular-related brain areas. Among the observed brain activations, the possibility to reach cingulate areas appears particularly interesting because it foreshadows the possibility to further enhance attentional capture by rewards.

CVS will be delivered to patients with brain lesion of the right hemisphere, engaged in cancellation tasks requiring the processing of targets of different nature (e.g. monetary or neutral). The main prediction is that CVS administration would enhance spatial exploration in terms of center of gravity of the cancellation and improved accuracy as a function of the type of target processed (e.g. its value).

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Arm && Interventions

Group	Intervention	Description
Caloric Vestibular Stimulation, SHAM	Non-invasive brain stimulation of the vestibular system through caloric vestibular stimulation.	The SHAM condition uses water with a temperature of 37°. It does not induce nystagmus
Caloric Vestibular Stimulation, Left-Warm	Non-invasive brain stimulation of the vestibular system through caloric vestibular stimulation.	Caloric Vestibular Stimulation (CVS) stimulates the vestibular system through thermic currents applied through small quantity of water injected in the external ear. The Left-Warm condition uses water with a temperature of 44°. It induces a nystagmus with its slow phase towards the right.
Caloric Vestibular Stimulation, Left-Cold	Non-invasive brain stimulation of the vestibular system through caloric vestibular stimulation.	Caloric Vestibular Stimulation (CVS) stimulates the vestibular system through thermic currents applied through small quantity of water injected in the external ear. The Left-Cold condition uses water with a temperature of 30°. It induces a nystagmus with its slow phase towards the left.

Primary Outcome Measures

Name	Time	Method
Center of Gravity (pixels).	Days 1, 2, and 3	For line bisection defined as the difference between participants' mark and the objective center of the line. For cancellation tasks it is calculated as the grand average of horizontal and vertical coordinates of all the marks. In both cases smaller indices indicate a leftward exploration bias, whereas larger indices indicate rightward bias.

Secondary Outcome Measures

Name	Time	Method
Reaction times (ms).	Days 1, 2, and 3.	The speed of response is a traditional indicator of the amount of cognitive processing underneath provided responses. It is measured by professional programs (e.g. Presentation) running on standard PCs
Response accuracy (%)	Days 1, 2, and 3.	The proportion of correct responses provided, automatically computed by professional programs (e.g. Presentation) running on standard PCs.

Locations (2): CRNL, équipe IMPACT (CNRS UMR5292, INSERM U1028)
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Bron, France
Service de médecine et réadaptation neurologique, Hôpital Henry Gabrielle
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Saint-Genis-Laval, France