Understanding Visual Processing After Occipital Stroke

University of Rochester

Status: Withdrawn

Conditions: Peripheral Visual Field Defect of Both Eyes; Vision; Loss, Both Eyes; Hemianopia; Hemianopia, Homonymous; Vision Loss Partial; Cortical Blindness; Quadrantanopia; Stroke - Occipital Infarction; Stroke, Ischemic; Occipital Lobe Infarct

Study type: Observational

Funder types: Other

Identifiers

NCT06352086

STUDY00009227

Details and patient eligibility

About

The purpose of this study is to investigate how visual orientation discrimination and metacognition (i.e., perceptual confidence) are affected by occipital stroke that causes hemianopia and quadrantanopia in adults. This research will provide insight as to how the residual visual system, which not directly damaged by the occipital stroke, processes orientation (assayed in terms of orientation discrimination) and metacognition (by measuring perceptual confidence for orientation discrimination). These measures will be used to refine computational models that attempt to explain how the brain copes with loss of primary visual cortex (V1) as a result of stroke. This knowledge is essential to devise more effective visual rehabilitation therapies for patients suffering from occipital strokes.

Sex: All

Ages: 21 to 75 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Residents of the United States or Canada
• MRI and/or CT scans showing unilateral stroke or stroke-like damage to primary visual cortex or its immediate afferent white matter sustained 1-year or more prior to enrollment
• Reliable visual field defects in both eyes as measured by Humphrey, Macular Integrity Assessment (MAIA), Goldmann, and/or equivalent perimetry. This deficit must be large enough to enclose a 5-deg diameter visual stimulus.
• Ability to fixate on visual targets reliably for 1000ms (as demonstrated by visual fields, and verified in study participation)
• Willing, able, and competent to provide informed consent
• Cognitively able to understand and respond to written and oral instructions in English

Exclusion criteria

• Past or present ocular disease interfering with visual acuity
• Corrected vision worse than 20/40 in either eye
• Presence of damage to the dorsal Lateral Geniculate Nucleus
• Diffuse, whole brain degenerative processes
• Brain damage deemed by study staff to potentially interfere with testing ability or outcome measures
• Documented history of traumatic brain injury
• Documented history of drug/alcohol abuse
• Current use neuroactive
• Cognitive or seizure disorders
• Subjects with one-sided attentional neglect