Visuotopic mapping through a multichannel stimulating implant in primate V1

Area of Science:

• Neuroscience
• Biomedical Engineering
• Ophthalmology

Background:

• Cortical visual prostheses aim to restore vision by directly stimulating the visual cortex.
• Establishing reliable animal models is crucial for developing and testing these neuroprosthetic devices.
• Previous models have limitations in accurately assessing the functional capabilities of visual prostheses.

Purpose of the Study:

• To establish and validate a rhesus monkey model for the development and behavioral testing of cortical visual prostheses.
• To assess the precision and learning capabilities of a primate subject responding to direct cortical stimulation.
• To provide a platform for rigorous evaluation of visual prosthesis efficacy.

Main Methods:

• Implantation of 152 iridium electrodes with activated iridium oxide film in the primary visual cortex of a rhesus monkey.
• Recording neuronal cluster activity to map visually responsive regions corresponding to each electrode.
• Training the monkey in a delayed saccade task using visual targets and then targets defined by direct cortical stimulation.

Main Results:

• 114 out of 152 implanted electrodes were functional.
• Saccade endpoint standard deviation was 2.5 times larger with electrical stimulation compared to visual targets.
• High correlation (approaching unity) was achieved between saccade endpoints and receptive field locations after training.
• Newly introduced electrodes showed high initial correlation, suggesting rapid adaptation and learning.

Conclusions:

• The developed rhesus monkey model is suitable for rigorous behavioral testing of cortical visual prostheses.
• Direct cortical stimulation can elicit visually guided saccadic eye movements with significant accuracy.
• This model offers a promising avenue for advancing the development of artificial vision technologies.