Computerised Assessment of Visual Neglect Symptoms in Peripersonal Space

Study Overview
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Brief Summary
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Healthy subjects will undergo cathodal stimulation of the right posterior parietal Cortex (PPC) and assessment of neglect-like symptoms in the encircling monitor system (EMS) as well as in a standard clinical test (Test Battery for Attention Performance, TAP, Zimmermann & Fimm, 1993). The aim of this study is to investigate whether cathodal stimulation leads to poorer test performance.

Official Title
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Computerised Assessment of Visual Neglect Symptoms in Peripersonal Space

Conditions
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Visual Neglect

Intervention / Treatment
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* Other: Cathodal tDCS
* Other: Sham tDCS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Younger subjects aged between 18 and 35 years ability to provide written informed consent right-handedness Elderly subjects aged between 50 and 85 years ability to provide written informed consent right-handedness Exclusion Criteria: - Exclusion criteria for both groups: serious psychiatric disorders (including depression, psychosis) in the past severe neurological disorders (such as epilepsy, dementia, stroke) in the past current severe medical disorder drugs, medication or alcohol abuse at the time of the study severe traumatic brain injury or tumor in the past operations on the brain, trepanations metallic implants in the head / neck area (except in the mouth), such as screws, splinter, artificial cochlea, electrodes severe skin diseases (like eczema) or very sensitive skin in the head region in the past epilepsy in the family current use of neuroleptics, antiepileptics, antidepressants, L-dopa, benzo-diazepines current pregnancy or lactation current claustrophobia

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 85 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: Diagnostic
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Cathodal tDCS in young study participants<br>Cathodal tDCS in young study participants | Other: Cathodal tDCS<br>* Cathodal tDCS applied over the right PPC<br>|
| Experimental: Cathodal tDCS in elderly study participants<br>Cathodal tDCS in elderly study participants | Other: Cathodal tDCS<br>* Cathodal tDCS applied over the right PPC<br>|
| Sham Comparator: Sham tDCS in young study participants<br>Sham tDCS in young study participants | Other: Sham tDCS<br>* Sham tDCS applied over the right PPC<br>|
| Sham Comparator: Sham tDCS in elderly study participants<br>Sham tDCS in elderly study participants | Other: Sham tDCS<br>* Sham tDCS applied over the right PPC<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Test performance of young study participants in the encircling monitor system with/without cathodal stimulation | Comparison of the young subjects' performance with vs. without transcranial direct current stimulation (tDCS) in the following computerised tests: Star Cancellation (number of omissions, latency & crossing index; based on Rabufetti, 2012), Landmark (reaction times, accuracy; based on Giglia et al., 2011), Visual Detection (reaction times, omissions; based on Sparing et al., 2009), Extinction (number of correct responses; based on Niedeggen & Hoffmann, 2011) |  | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Test performance of elderly study participants in the encircling monitor system with/without cathodal stimulation | Comparison of the performance with vs. without transcranial direct current stimulation (tDCS) in the following tests: Star Cancellation, Landmark, Visual Detection, Extinction (see above) |  | 
| Test performance of study participants in the Test Battery for Attention Performance (TAP) with/without cathodal stimulation | Comparison of reaction times and number of omissions in the left and right visual field in the TAP subtest Neglect with vs. without tDCS. |  | 
| Comparison of visual search patterns between neglect patients and healthy subjects with cathodal stimulation | Comparison of visual search direction, structuredness (crossing index), and omissions in the Star Cancellation Test |  |