Lateral geniculate body evoked potentials elicited by visual and electrical stimulation

Area of Science:

• Neuroscience
• Biomedical Engineering
• Ophthalmology

Background:

• Individuals with photoreceptor loss can perceive phosphenes via electrical stimulation of retinal ganglion cells.
• Implantable lateral geniculate body (LGB) stimulus electrode arrays are proposed for generating phosphene vision.

Purpose of the Study:

• To refine the reference of electrical evoked potentials (EEPs) elicited by microelectrical stimulation of the optic nerve, optic tract, and LGB in a domestic pig.
• To compare EEPs with visual evoked potentials (VEPs) elicited by short-flash stimuli.

Main Methods:

• VEPs were measured in response to short-flash stimuli on the left eye of a domestic pig.
• Platinum wire electrodes were inserted into the optic nerve, optic tract, and LGB under anesthesia.
• EEPs were recorded while varying stimulus current, pulse duration, and power to determine optimal parameters; threshold current and charge density for EEPs were established.

Main Results:

• Stimulation of the optic nerve, optic tract, and LGB effectively evoked visual cortex activity.
• Stimulation closer to the LGB resulted in shorter P1 latency.
• LGB-stimulated EEPs showed a pattern similar to simultaneously generated VEPs, despite differences in implicit time.

Conclusions:

• A comparison of EEPs and VEPs derived from visual system stimulation was performed.
• The LGB-stimulated EEP waveform closely resembled the VEP waveform, differing mainly in implicit time.
• Prosthetic-based electrical stimulation of the LGB holds potential for enabling blind individuals to perceive phosphene vision.