# Developing a rational strategy for visual rehabilitation after cortical lesions

> **NIH VA I01** · VA BOSTON HEALTH CARE SYSTEM · 2020 · —

## Abstract

Visual field loss is a common corollary of stroke (Pollock et al,The Cochrane Library:John Wiley & Sons; 2011,p
p. 1-83) that is prevalent in the VA population. Posterior and middle cerebral artery infarcts often injure visual
cortical networks resulting in partial or complete homonymous hemianopia or quadrantanopia. The most
common clinically significant visual cortical injury involves the primary visual cortex and adjacent regions (area
V1+). Area V1 is the chief relay of visual input to higher (extrastriate) cortical areas, and V1 lesions result in a
dense contralateral scotoma within which visual perception is severely impaired. The resulting visual deficit is
long thought to be resistant to rehabilitation, i.e. to be essentially irreversible, and impairs quality of life
significantly. Visual field loss impairs many activities of daily living, including the ability to ambulate safely, drive,
read, cook, supervise minors, and others, markedly reducing the independence of the patient (Veterans Health
Initiative 2002: Visual Impairment and Blindness). Loss of visual motion perception is particularly problematic for
navigating the environment and for avoiding collision with moving objects. Here we focus on studying
rehabilitation of visual motion perception.
Several studies demonstrated that visual cortex can be driven from the interior of the scotoma, i.e. from areas of
the visual field where there is no visual perception. One such area that can be visually modulated in the
absence of V1 input is hV5/MT+, an area important for visual motion perception. Although this modulation is
weak and does not generally confer useful vision (“blindsight”), it raises the hope that appropriately designed
new rehabilitative strategies may be able to strengthen these partially functioning pathways promoting recovery.
Recent work (Huxlin et al. J Neuroscience 29(13):3981-91, 2009) has shown that intensive training in a visual
motion discrimination task can improve visual motion perception in some subjects with cortical V1 lesions (see
fig 5-6). However, this work is still at the preliminary stage. Specifically, not all subjects appear to benefit
(section C2), it is not clear which parts of the visual field are amenable to visual rehabilitation, and the
mechanism of recovery remains unclear. Our goal here is twofold: 1) To pilot functional magnetic resonance
imaging (fMRI) population receptive field mapping methods for identifying regions of the visual field that are
more amenable to visual rehabilitation after lesions of the primary visual cortex (area V1+). 2) To probe the
mechanisms underlying the recently reported rehabilitation-induced improvement in visual performance that
occurs in some subjects (preliminary data fig. 5-7). We will address the following specific aims:
Aim 1: We will show that functional magnetic resonance imaging (fMRI) population receptive field mapping
methods can identify regions of the visual field that are more amenable to visual motio...

## Key facts

- **NIH application ID:** 9952832
- **Project number:** 1I01RX002981-01A1
- **Recipient organization:** VA BOSTON HEALTH CARE SYSTEM
- **Principal Investigator:** Stelios Manolis Smirnakis
- **Activity code:** I01 (R01, R21, SBIR, etc.)
- **Funding institute:** VA
- **Fiscal year:** 2020
- **Award amount:** —
- **Award type:** 1
- **Project period:** 2020-02-01 → 2024-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9952832

## Citation

> US National Institutes of Health, RePORTER application 9952832, Developing a rational strategy for visual rehabilitation after cortical lesions (1I01RX002981-01A1). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9952832. Licensed CC0.

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