Achromatopsia-Visual Cortex Stability and Plasticity in the Absence of Functional Cones.

Area of Science:

• Neuroscience
• Ophthalmology
• Genetics

Background:

• Achromatopsia (ACHM) is an inherited retinal disorder causing nonfunctional cone photoreceptors.
• The central visual field's cortical representation is deprived of input in ACHM patients.
• This raises questions about potential cortical remapping and its impact on gene therapy.

Purpose of the Study:

• To investigate the nature and plasticity of vision in achromatopsia.
• To test the hypothesis of foveal remapping in the primary visual cortex of ACHM patients.
• To determine if cortical representations shift to process paracentral inputs in the absence of central cone function.

Main Methods:

• A multicenter study involving 17 individuals with autosomal recessive achromatopsia (CNGA3/CNGB3 mutations).
• Utilized two functional magnetic resonance imaging (fMRI) approaches: phase-encoded eccentricity mapping and population receptive field mapping.
• Compared fMRI data between ACHM patients and healthy controls.

Main Results:

• Both fMRI methods yielded consistent results.
• No significant remapping of the central visual field representation was observed in the primary visual cortex of ACHM patients compared to controls.
• Sizable cortical remapping was not apparent in the group comparison.

Conclusions:

• Cortical remapping of the central visual field is not a general characteristic of achromatopsia.
• Human primary visual cortex plasticity appears less pronounced than previously thought.
• Pre-therapeutic imaging is recommended to optimize gene therapy interventions for achromatopsia.