Document Detail

Frequency-dependent reduction of voltage-gated sodium current modulates retinal ganglion cell response rate to electrical stimulation.
MedLine Citation:
PMID:  22027396     Owner:  NLM     Status:  Publisher    
The ability to elicit visual percepts through electrical stimulation of the retina has prompted numerous investigations examining the feasibility of restoring sight to the blind with retinal implants. The therapeutic efficacy of these devices will be strongly influenced by their ability to elicit neural responses that approximate those of normal vision. Retinal ganglion cells (RGCs) can fire spikes at frequencies greater than 200 Hz when driven by light. However, several studies using isolated retinas have found a decline in RGC spiking response rate when these cells were stimulated at greater than 50 Hz. It is possible that the mechanism responsible for this decline also contributes to the frequency-dependent 'fading' of electrically evoked percepts recently reported in human patients. Using whole-cell patch clamp recordings of rabbit RGCs, we investigated the causes for the spiking response depression during direct subretinal stimulation of these cells at 50-200 Hz. The response depression was not caused by inhibition arising from the retinal network but, instead, by a stimulus-frequency-dependent decline of RGC voltage-gated sodium current. Under identical experimental conditions, however, RGCs were able to spike at high frequency when driven by light stimuli and intracellular depolarization. Based on these observations, we demonstrated a technique to prevent the spiking response depression.
David Tsai; John W Morley; Gregg J Suaning; Nigel H Lovell
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-10-26
Journal Detail:
Title:  Journal of neural engineering     Volume:  8     ISSN:  1741-2552     ISO Abbreviation:  -     Publication Date:  2011 Oct 
Date Detail:
Created Date:  2011-10-26     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101217933     Medline TA:  J Neural Eng     Country:  -    
Other Details:
Languages:  ENG     Pagination:  066007     Citation Subset:  -    
Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
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