| L- and M-cone input to 12Hz and 30Hz flicker ERGs across the human retina. | |
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MedLine Citation:
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PMID: 20883333 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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We recorded L- and M-cone isolating ERGs from human subjects using a silent substitution technique at temporal rates of 12 and 30 Hz. These frequencies isolate the activity of cone-opponent and non-opponent post-receptoral mechanisms, respectively. ERGs were obtained using a sequence of stimuli with different spatial configurations comprising; (1) circular stimuli of different sizes which increased in 10° steps up to 70°diameter, or (2) annular stimuli with a 70° outer diameter but with different sized central ablations from 10° up to 60°. L- and M-cone isolating ERGs were obtained from five colour normal subjects using a DTL fibre electrode. Fourier analysis of the ERGs was performed and we measured the amplitude of the first harmonic of the response. For 12 Hz ERGs the L:M cone response amplitude ratio (L:M(ERG)) was close to unity and remained stable irrespective of the spatial configuration of the stimulus. The maintenance of this balanced ratio points to the existence of cone selective input across the human retina for the L-M cone opponent mechanism. For 30 Hz the L:M(ERG) ratio was greater than unity but varied depending upon which region of the retina was being stimulated. This variation we consider to be a consequence of the global response properties of M-cone ERGs rather than representing a real variation in L:M cone ratios across the retina. |
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Authors:
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N K Challa; D McKeefry; N R A Parry; J Kremers; I J Murray; A Panorgias |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists) Volume: 30 ISSN: 1475-1313 ISO Abbreviation: Ophthalmic Physiol Opt Publication Date: 2010 Sep |
Date Detail:
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Created Date: 2010-10-04 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8208839 Medline TA: Ophthalmic Physiol Opt Country: England |
Other Details:
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Languages: eng Pagination: 503-10 Citation Subset: IM |
Copyright Information:
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© 2010 The Authors, Ophthalmic and Physiological Optics © 2010 The College of Optometrists. |
Affiliation:
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Bradford School of Optometry and Vision Sciences, University of Bradford, UK. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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