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Lateral geniculate body evoked potentials elicited by visual and electrical stimulation.

Choi CW, Kim PS, Shin SA, Yang JY, Yang YS - Korean J Ophthalmol (2014)

Bottom Line: Our experimental results showed that visual cortex activity can be effectively evoked by stimulation of the optic nerve, optic tract and LGB using penetrating electrodes.The EEPs of two-channel in the visual cortex demonstrated a similar pattern with stimulation of different spots of the stimulating electrodes.We found that the LGB-stimulated EEP pattern was very similar to the simultaneously generated VEP on the control side, although implicit time deferred.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Wonkwang University Hospital, Wonkwang University School of Medicine, Iksan, Korea.

ABSTRACT

Purpose: Blind individuals who have photoreceptor loss are known to perceive phosphenes with electrical stimulation of their remaining retinal ganglion cells. We proposed that implantable lateral geniculate body (LGB) stimulus electrode arrays could be used to generate phosphene vision. We attempted to refine the basic reference of the electrical evoked potentials (EEPs) elicited by microelectrical stimulations of the optic nerve, optic tract and LGB of a domestic pig, and then compared it to visual evoked potentials (VEPs) elicited by short-flash stimuli.

Methods: For visual function measurement, VEPs in response to short-flash stimuli on the left eye of the domestic pig were assessed over the visual cortex at position Oz with the reference electrode at Fz. After anesthesia, linearly configured platinum wire electrodes were inserted into the optic nerve, optic track and LGB. To determine the optimal stimulus current, EEPs were recorded repeatedly with controlling the pulse and power. The threshold of current and charge density to elicit EEPs at 0.3 ms pulse duration was about ±10 µA.

Results: Our experimental results showed that visual cortex activity can be effectively evoked by stimulation of the optic nerve, optic tract and LGB using penetrating electrodes. The latency of P1 was more shortened as the electrical stimulation was closer to LGB. The EEPs of two-channel in the visual cortex demonstrated a similar pattern with stimulation of different spots of the stimulating electrodes. We found that the LGB-stimulated EEP pattern was very similar to the simultaneously generated VEP on the control side, although implicit time deferred.

Conclusions: EEPs and VEPs derived from visual-system stimulation were compared. The LGB-stimulated EEP wave demonstrated a similar pattern to the VEP waveform except implicit time, indicating prosthetic-based electrical stimulation of the LGB could be utilized for the blind to perceive vision of phosphenes.

No MeSH data available.


Related in: MedlinePlus

Diagram of the procedure and taking the visual evoked potential (VEP) and electrical evoked potential (EEP) in this study. LGB = lateral geniculate body.
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Figure 1: Diagram of the procedure and taking the visual evoked potential (VEP) and electrical evoked potential (EEP) in this study. LGB = lateral geniculate body.

Mentions: We used a domestic pig as the experiment model, and the feasibility of visual prostheses based on penetrating electrical stimulations were investigated (Fig. 1). Firstly, VEP was performed on both eyes after sedation. The right side served as the experiment side and the left as the control. After anesthesia with endotracheal intubation, VEP was performed on the right eye. The globe was removed for exposure, a platinum wire electrode was implanted, and optic nerve EEP was done (Fig. 2). The frontal skull including right orbital wall was removed to visualize the right side intracranial optic nerve and optic chiasm. VEP was performed by implantation of the platinum wire electrode to the optic tract near the optic chiasm. Subsequently, the right frontal lobe and part of the temporal lobe were removed, and deep optic tract and LGB responses were recorded after direct electrical stimulation. Left eye VEP was done to compare with the right-side EEP.


Lateral geniculate body evoked potentials elicited by visual and electrical stimulation.

Choi CW, Kim PS, Shin SA, Yang JY, Yang YS - Korean J Ophthalmol (2014)

Diagram of the procedure and taking the visual evoked potential (VEP) and electrical evoked potential (EEP) in this study. LGB = lateral geniculate body.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4120355&req=5

Figure 1: Diagram of the procedure and taking the visual evoked potential (VEP) and electrical evoked potential (EEP) in this study. LGB = lateral geniculate body.
Mentions: We used a domestic pig as the experiment model, and the feasibility of visual prostheses based on penetrating electrical stimulations were investigated (Fig. 1). Firstly, VEP was performed on both eyes after sedation. The right side served as the experiment side and the left as the control. After anesthesia with endotracheal intubation, VEP was performed on the right eye. The globe was removed for exposure, a platinum wire electrode was implanted, and optic nerve EEP was done (Fig. 2). The frontal skull including right orbital wall was removed to visualize the right side intracranial optic nerve and optic chiasm. VEP was performed by implantation of the platinum wire electrode to the optic tract near the optic chiasm. Subsequently, the right frontal lobe and part of the temporal lobe were removed, and deep optic tract and LGB responses were recorded after direct electrical stimulation. Left eye VEP was done to compare with the right-side EEP.

Bottom Line: Our experimental results showed that visual cortex activity can be effectively evoked by stimulation of the optic nerve, optic tract and LGB using penetrating electrodes.The EEPs of two-channel in the visual cortex demonstrated a similar pattern with stimulation of different spots of the stimulating electrodes.We found that the LGB-stimulated EEP pattern was very similar to the simultaneously generated VEP on the control side, although implicit time deferred.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Wonkwang University Hospital, Wonkwang University School of Medicine, Iksan, Korea.

ABSTRACT

Purpose: Blind individuals who have photoreceptor loss are known to perceive phosphenes with electrical stimulation of their remaining retinal ganglion cells. We proposed that implantable lateral geniculate body (LGB) stimulus electrode arrays could be used to generate phosphene vision. We attempted to refine the basic reference of the electrical evoked potentials (EEPs) elicited by microelectrical stimulations of the optic nerve, optic tract and LGB of a domestic pig, and then compared it to visual evoked potentials (VEPs) elicited by short-flash stimuli.

Methods: For visual function measurement, VEPs in response to short-flash stimuli on the left eye of the domestic pig were assessed over the visual cortex at position Oz with the reference electrode at Fz. After anesthesia, linearly configured platinum wire electrodes were inserted into the optic nerve, optic track and LGB. To determine the optimal stimulus current, EEPs were recorded repeatedly with controlling the pulse and power. The threshold of current and charge density to elicit EEPs at 0.3 ms pulse duration was about ±10 µA.

Results: Our experimental results showed that visual cortex activity can be effectively evoked by stimulation of the optic nerve, optic tract and LGB using penetrating electrodes. The latency of P1 was more shortened as the electrical stimulation was closer to LGB. The EEPs of two-channel in the visual cortex demonstrated a similar pattern with stimulation of different spots of the stimulating electrodes. We found that the LGB-stimulated EEP pattern was very similar to the simultaneously generated VEP on the control side, although implicit time deferred.

Conclusions: EEPs and VEPs derived from visual-system stimulation were compared. The LGB-stimulated EEP wave demonstrated a similar pattern to the VEP waveform except implicit time, indicating prosthetic-based electrical stimulation of the LGB could be utilized for the blind to perceive vision of phosphenes.

No MeSH data available.


Related in: MedlinePlus