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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

Electrically-evoked potential (EEP) of optic nerve, optic track and lateral geniculate body (LGB). (A) Visual evoked potentials (VEPs) in response to short flash stimuli on a right eye of the pig after optic nerve was severed (control). (B) EEPs to electrical stimulations on optic nerve (right eye side). (C) EEPs to electrical stimulations on optic track before optic chiasm (right eye side). (D) EEPs to electrical stimulations on optic track after optic chiasm (right eye side). (E) EEPs to electrical stimulations on LGB (right eye side).
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Figure 4: Electrically-evoked potential (EEP) of optic nerve, optic track and lateral geniculate body (LGB). (A) Visual evoked potentials (VEPs) in response to short flash stimuli on a right eye of the pig after optic nerve was severed (control). (B) EEPs to electrical stimulations on optic nerve (right eye side). (C) EEPs to electrical stimulations on optic track before optic chiasm (right eye side). (D) EEPs to electrical stimulations on optic track after optic chiasm (right eye side). (E) EEPs to electrical stimulations on LGB (right eye side).

Mentions: In the domestic pig, the locations of the optic nerve, optic tract and LGB are analogous to those of human. Data were collected from the animal and consistent positive potentials were obtained for VEP (P75) and for EEPs of the intraorbital optic nerve (P70), optic tract (P37), and LGB (P36). For a control, we performed VEP in a normal left eye (Fig. 3A). An anesthesia effect was observed on VEPs after anesthesia in the right eye (Fig. 3B). The administration of anesthesia may modify the response to flash stimuli in comparison with a sedated animal. Characteristic peaks appeared in the early part of the waves N1 (40 msec) and P1 (70 msec) and with VEP on the optic nerve (Fig. 3). VEP of the right eye was observed as flat (Fig. 4A) after the optic nerve was severed. Overall peaks of EEP resembled those of VEP. However, when the optic nerve was stimulated with two electrodes (about 1.0 mm apart) the characteristic EEP patterns of each were different (Fig. 4B). EEPs on the optic tract and LGB were measured, and each showed short latency (P39 and P33, respectively) compared with P70 of VEP (Fig. 4C-4E). Finally, the skull of the animal was opened from the right frontal lobe to part of the temporal lobe, while VEP to flash stimuli on the left eye were recorded to compare with the preoperative VEP (Fig. 5).


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)

Electrically-evoked potential (EEP) of optic nerve, optic track and lateral geniculate body (LGB). (A) Visual evoked potentials (VEPs) in response to short flash stimuli on a right eye of the pig after optic nerve was severed (control). (B) EEPs to electrical stimulations on optic nerve (right eye side). (C) EEPs to electrical stimulations on optic track before optic chiasm (right eye side). (D) EEPs to electrical stimulations on optic track after optic chiasm (right eye side). (E) EEPs to electrical stimulations on LGB (right eye side).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Electrically-evoked potential (EEP) of optic nerve, optic track and lateral geniculate body (LGB). (A) Visual evoked potentials (VEPs) in response to short flash stimuli on a right eye of the pig after optic nerve was severed (control). (B) EEPs to electrical stimulations on optic nerve (right eye side). (C) EEPs to electrical stimulations on optic track before optic chiasm (right eye side). (D) EEPs to electrical stimulations on optic track after optic chiasm (right eye side). (E) EEPs to electrical stimulations on LGB (right eye side).
Mentions: In the domestic pig, the locations of the optic nerve, optic tract and LGB are analogous to those of human. Data were collected from the animal and consistent positive potentials were obtained for VEP (P75) and for EEPs of the intraorbital optic nerve (P70), optic tract (P37), and LGB (P36). For a control, we performed VEP in a normal left eye (Fig. 3A). An anesthesia effect was observed on VEPs after anesthesia in the right eye (Fig. 3B). The administration of anesthesia may modify the response to flash stimuli in comparison with a sedated animal. Characteristic peaks appeared in the early part of the waves N1 (40 msec) and P1 (70 msec) and with VEP on the optic nerve (Fig. 3). VEP of the right eye was observed as flat (Fig. 4A) after the optic nerve was severed. Overall peaks of EEP resembled those of VEP. However, when the optic nerve was stimulated with two electrodes (about 1.0 mm apart) the characteristic EEP patterns of each were different (Fig. 4B). EEPs on the optic tract and LGB were measured, and each showed short latency (P39 and P33, respectively) compared with P70 of VEP (Fig. 4C-4E). Finally, the skull of the animal was opened from the right frontal lobe to part of the temporal lobe, while VEP to flash stimuli on the left eye were recorded to compare with the preoperative VEP (Fig. 5).

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