implantation-recording-wireless-electroretinogram-visual-evoked

Implantation and Recording of Wireless Electroretinogram and Visual Evoked Potential in Conscious Rats

The full-field electroretinogram (ERG) and visual evoked potential (VEP) are useful tools to assess retinal and visual pathway integrity in both ...

University of Melbourne

To investigate the effect of old age (3 vs. 18 months) on the retinal function of albino (Sprague-Dawley [SD]) and pigmented (Long-Evans [LE]) rats.

Age-related retinal function changes in albino and pigmented rats.

To determine whether there is an age-dependent susceptibility in retinal function in response to repeated anterior chamber cannulation with or without intraocular pressure (IOP) elevation.

Increased susceptibility to injury in older eyes.

The electroretinogram (ERG, retina) and visual evoked potential (VEP, brain) are widely used in vivo tools assaying the integrity of the visual pathway. Current recordings in preclinical models are conducted under anesthesia, which alters neural physiology and contaminates responses. We describe a conscious wireless ERG and VEP recording platform in rats. Using a novel surgical technique to chronically implant electrodes subconjunctivally on the eye and epidurally over the visual cortex, we are able to record stable and repeatable conscious ERG and VEP signals over at least 1 month. We show that the use of anaesthetics, necessary for conventional ERG and VEP measurements, alters electrophysiology recordings. Conscious visual electrophysiology improves the viability of longitudinal studies by eliminating complications associated with repeated anaesthesia. It will also enable uncontaminated assessment of drug effects, allowing the eye to be used as an effective biomarker of the central nervous system.

Conscious wireless electroretinogram and visual evoked potentials in rats.

Objective. To examine whether retinal electrophysiology is a useful surrogate marker of drug penetrance into the central nervous system (CNS). Materials and Methods. Brain and retinal electrophysiology were assessed with full-field visually evoked potentials and electroretinograms in conscious and anaesthetised rats following systemic or local administrations of centrally penetrant (muscimol) or nonpenetrant (isoguvacine) compounds. Results. Local injections into the eye/brain bypassed the blood neural barriers and produced changes in retinal/brain responses for both drugs. In conscious animals, systemic administration of muscimol resulted in retinal and brain biopotential changes, whereas systemic delivery of isoguvacine did not. General anaesthesia confounded these outcomes. Conclusions. Retinal electrophysiology, when recorded in conscious animals, shows promise as a viable biomarker of drug penetration into the CNS. In contrast, when conducted under anaesthetised conditions confounds can be induced in both cortical and retinal electrophysiological recordings.

Retinal Electrophysiology Is a Viable Preclinical Biomarker for Drug Penetrance into the Central Nervous System.

To present stimuli with varied sizes, colors, and patterns over a large range of luminance.

Article	Year
Age-related retinal function changes in albino and pigmented rats. Investigative ophthalmology & visual science\| PubMed ID: 22003116	2011
Increased susceptibility to injury in older eyes. Optometry and vision science : official publication of the American Academy of Optometry\| PubMed ID: 23422944	2013
Conscious wireless electroretinogram and visual evoked potentials in rats. PloS one\| PubMed ID: 24069276	2013
Retinal Electrophysiology Is a Viable Preclinical Biomarker for Drug Penetrance into the Central Nervous System. Journal of ophthalmology\| PubMed ID: 27239335	2016
Developing an Outcome Measure With High Luminance for Optogenetics Treatment of Severe Retinal Degenerations and for Gene Therapy of Cone Diseases. Investigative ophthalmology & visual science\| PubMed ID: 27309625	2016

Jason Charng

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