Brain Stimulation and Visually-guided Navigation

Study Overview
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Brief Summary
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This study investigates the neural mechanisms causally involved in how people navigate through their immediately visible environment (e.g., walking around one's bedroom flawlessly and effortlessly, not bumping into the walls or furniture). To investigate whether particular neural mechanisms are causally involved in visually-guided navigation, repetitive transcranial magnetic stimulation (rTMS) is used to temporarily disrupt the functioning of particular brain regions in healthy adults while they are shown simple visual stimuli of places (e.g., bedrooms, kitchens, and living rooms) and asked to perform simple computer tasks or to complete simple behavioral tasks.

Detailed Description
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Human ability to navigate through the immediately visible environment is crucial for survival. However, the representations and computations underlying this remarkable ability are not well understood, and current computer vision algorithms (robots) still lag far behind human performance. One promising strategy for attempting to understand visually-guided navigation is to characterize the neural systems that accomplish it. The results from functional magnetic resonance (fMRI) on adult humans have begun to elucidate the cortical regions involved in visually-guided navigation, with the central finding that there is at least one visual cortical region - called the occipital place area (OPA) that may play a central role in the ability to navigate through currently visible places (e.g., walking around our bedroom flawlessly and effortlessly, not bumping into the walls or furniture our bedroom). However, fMRI is a correlational method, and research still needs to determine if this functionally specific brain region is causally involved in visually-guided navigation. Understanding the causal involvement of this region will provide important clues about how humans navigate their world, and also perhaps someday be harnessed to help those individuals who devastatingly lose the ability to navigate, as a result of eye diseases, brain surgery, stroke, neurodegenerative diseases, or developmental disorders. The use of rTMS to investigate the causal involvement of particular brain regions in particular human abilities is not novel, having been used to investigate face recognition, scene recognition, and object recognition. The general question for this research is to determine, using rTMS, the causal involvement of OPA in visually-guided navigation.

Official Title
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Brain Stimulation Study of Human Visually-guided Navigation Using Repetitive Transcranial Magnetic Stimulation (rTMS)

Conditions
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Healthy Participants

Intervention / Treatment
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* Device: Repetitive Transcranial Magnetic Stimulation (rTMS)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Normal or corrected-to-normal vision Exclusion Criteria: Metal in the body Personal or first-degree family history of epileptic seizure A known brain injury Claustrophobia Taking certain medications that may increase the risk of seizures (e.g., bupropion, varenicline, chlorpromazine, theophylline) or reduce the effects of rTMS, such as benzodiazepines Adults who are unable to consent, pregnant women, and prisoners

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Repetitive Transcranial Magnetic Stimulation (rTMS)<br>Participants will have two study visits. During the first visit, participants will have an fMRI scan to identify the OPA location in each individual participant. During the second visit, participants will receive rTMS. Each visit lasts approximately 90 minutes. | Device: Repetitive Transcranial Magnetic Stimulation (rTMS)<br>* TMS is a safe and noninvasive method for affecting brain function relying on the properties of electromagnetic induction. Action potentials are triggered in neurons, along with a subsequent period of deactivation. Normal ongoing brain activity is disrupted providing a way for investigators to produce a transient and reversible period of brain disruption. Participants will be seated comfortably in a chair and asked to complete either a simple computer-based task or a simple behavioral task that will require them to walk around in a small room. During or just before each of these tasks, participants will receive rTMS. In rTMS, a small plastic coil is placed next to the participant's head. The coil will be placed over the relevant brain region identified during the participant's fMRI scan. The coil will then generate a magnetic pulse, and stimulation will occur. The entire visit will last about one and a half hours.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Performance During Visually-guided Navigation Computer Task | To determine baseline performance, rTMS is applied to to the control vertex site, which is not implicated in visually-guided navigation. Then rTMS is applied to the OPA site. While participants are shown simple visual stimuli of places (e.g., bedrooms, kitchens, and living rooms) they are asked to perform simple computer tasks (e.g., imagine they are walking through the room, and respond via button press whether they can leave through a door on the left, center, or right wall, as indicated by a continuous path on the floor). Performance is measured as the time (in milliseconds) that it takes to complete the task correctly. A decrease in performance on the visually-guided navigation task only after rTMS is applied to OPA (but not vertex) indicates causal involvement of OPA in visually-guided navigation. | Baseline (rTMS of control site) and during rTMS of OPA, on Day 1 | 
| Change in Performance During Visually-guided Navigation Behavioral Task | To determine baseline performance, rTMS is applied to to the control vertex site, which is not implicated in visually-guided navigation. Then rTMS is applied to the OPA site. Participants are asked to complete simple behavioral tasks (e.g., actually walk around a small room and search for hidden objects). Performance is measured as the time (in milliseconds) that it takes to complete the task correctly. A decrease in performance on the visually-guided navigation task only after rTMS is applied to OPA (but not vertex) indicates causal involvement of OPA in visually-guided navigation. | Baseline (rTMS of control site) and during rTMS of OPA, on Day 1 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Visually-guided navigation