Cortical Visual Mapping following Ocular Gene Augmentation Therapy for Achromatopsia

Area of Science:

• Neuroscience
• Ophthalmology
• Genetics

Background:

• Congenital achromatopsia (CNGA3) causes severe visual impairment due to cone photoreceptor dysfunction.
• Adult brain plasticity following correction of congenital deafferentation is poorly understood, especially in visual deficits.

Observation:

• Two adults with CNGA3-achromatopsia underwent gene therapy, with pre- and post-treatment assessments using behavioral tests and fMRI.
• Functional magnetic resonance imaging (fMRI) revealed untypically large population-receptive fields in early visual areas before treatment.

Findings:

• Minor behavioral improvements included reduced photoaversion and improved acuity, with limited color detection. fMRI showed a decrease in receptive field sizes in treated eyes post-therapy.
• Cortical changes suggest the adult brain can encode new visual input, but color perception did not recover, possibly due to retinal or cortical processing limitations.

Implications:

• This study provides evidence for adult cortical plasticity and the potential for visual function recovery after gene therapy.
• Findings highlight the complex interplay between retinal restoration and cortical adaptation in treating congenital visual disorders.