Statistical Learning as a Novel Intervention for Cortical Blindness

N/AEnrolling By InvitationNCT06578117

University of Rochester30 enrolled

Overview

This project aims to develop a novel visual training paradigm for use in visually-intact participants and those sufferings from stroke-induced visual impairments. Our task design is built upon theories of statistical learning to reduce the overall training burden while still producing profound improvements to visual abilities. Efficacy will be first established in visually-intact controls before testing in stroke survivors to assess the feasibility of this form of learning in the damaged visual system.

Study Type

INTERVENTIONAL

Allocation

NON_RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

NONE

Enrollment

Conditions

Stroke, Ischemic Hemianopia, Homonymous Hemianopsia Occipital Lobe Infarct Visual Field Defect, Peripheral

Interventions

Vision Training and Learning TaskDEVICE

Participants will be seated at a computer, and will be shown a random-noise visual stimulus drifting in one of eight directions. Participants will be instructed to indicate the direction of motion they perceive using a Sony Access Controller or a computer keyboard. Sound cues during stimulus presentation will also be used to ensure participants are aware of stimulus onset during the training task. After several repetitions of this visual training, a second set of visual cues will be presented to evaluate participant's learning of the program. Responses will be provided in the same manner by input from the controller or the keyboard.

Eligibility

Sex: ALLMin age: 21 YearsMax age: 75 YearsHealthy volunteers:

Medical Language ↔ Plain English

Cortically Blind participants Inclusion criteria: * Between 21 and 75 years of age * Residents of the United States or Canada * Have successfully completed previous enrollment in Dr. Huxlin study (IRB #5966 or #75) * Exhibit unilateral stroke or stroke-like damage to primary visual cortex or its immediate afferent white matter sustained within the specified age range of 21 - 75 years (verified by MRI and/or CT scans) * Reliable visual field defects in both eyes (homonymous defects) as measured by Humphrey visual fields. This deficit must be large enough to enclose a 5-deg diameter visual stimulus. * Able to fixate on visual targets reliably for 1000ms within 1-deg of visual angle. * Willing, able, and competent to provide their own informed consent * Normal cognitive abilities and be able to understand written and oral instructions in English Exclusion criteria: * Past or present ocular disease interfering with visual acuity * Best corrected visual acuity (BCVA) worse than 20/40 in either eye * Sustained documented or suspected damage to the dorsal Lateral Geniculate Nucleus * Presence of diffuse whole brain degenerative processes * History of traumatic brain injury * Any other brain damage deemed by study staff to potentially interfere with training ability or outcome measures * Documented history of drug/alcohol abuse * Currently taking neuroactive medications which would impact training, as determined by PI * Cognitive or seizure disorders * One-sided attentional neglect * Those who lack the competence or are otherwise unable to perform the visual training exercises as directed. Control participants Inclusion criteria: * Between 21 and 75 years of age * No history of neurological disorder. * Competent and responsible, as determined by the screening interview Exclusion criteria: * Any damage to the visual system * Those who are suffering from an active disease process involving their nervous system. * Presence of cognitive or seizure disorders * Best corrected visual acuity worse than 20/40 in either eye * Presence of visual field loss from ocular disease or disorder

Outcomes

Primary Outcomes

Explicit Learning - Response Time

Reaction time (ms) when performing motion discriminations for the final stimulus of a statistically-linked triplet will be compared against reaction times for stimuli with identical motion directions, presented with alternative placement within a triplet. Comparisons will be made only for correct responses in the final 20% of overall testing session trials.

Time frame: Baseline

Implicit Learning - Triplet Familiarity

Participant familiarity with statistically-linked triplets of motion will be assessed via a two-interval, forced-choice task. Familiarity will be measured as a percentage of comparisons in which the more prevalent triplet is selected as more familiar. Familiarity of high-probability, low-probability, and null-probability triplets will be compared following training.