Optimal processing of photoreceptor signals is required to maximize behavioural sensitivity.
Abstract
The sensitivity of receptor cells places a fundamental limit upon the sensitivity
of sensory systems. For example, the signal-to-noise ratio of sensory receptors has
been suggested to limit absolute thresholds in the visual and auditory systems. However,
the necessity of optimally processing sensory receptor signals for behaviour to approach
this limit has received less attention. We investigated the behavioural consequences
of increasing the signal-to-noise ratio of the rod photoreceptor single-photon response
in a transgenic mouse, the GCAPs-/- knockout. The loss of fast Ca2+ feedback to cGMP
synthesis in phototransduction for GCAPs-/- mice increases the magnitude of the rod
single-photon response and dark noise, with the increase in size of the single-photon
response outweighing the increase in noise. Surprisingly, despite the increased rod
signal-to-noise ratio, behavioural performance for GCAPs-/- mice was diminished near
absolute visual threshold. We demonstrate in electrophysiological recordings that
the diminished performance compared to wild-type mice is explained by poorly tuned
postsynaptic processing of the rod single-photon response at the rod bipolar cell.
In particular, the level of postsynaptic saturation in GCAPs-/- rod bipolar cells
is not sufficient to eliminate rod noise, and degrades the single-photon response
signal-to-noise ratio. Thus, it is critical for retinal processing to be optimally
tuned near absolute threshold; otherwise the visual system fails to utilize fully
the signals present in the rods.
Type
Journal articleSubject
AnimalsMice, Knockout
Mice
Calibration
Behavior, Animal
Electrophysiology
Excitatory Postsynaptic Potentials
Light
Retinal Bipolar Cells
Guanylate Cyclase-Activating Proteins
Retinal Rod Photoreceptor Cells
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https://hdl.handle.net/10161/17858Published Version (Please cite this version)
10.1113/jphysiol.2010.188573Publication Info
Okawa, Haruhisa; Miyagishima, K Joshua; Arman, A Cyrus; Hurley, James B; Field, Greg
D; & Sampath, Alapakkam P (2010). Optimal processing of photoreceptor signals is required to maximize behavioural sensitivity.
The Journal of physiology, 588(Pt 11). pp. 1947-1960. 10.1113/jphysiol.2010.188573. Retrieved from https://hdl.handle.net/10161/17858.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Greg D. Field
Adjunct Associate Professor of Neurobiology
My laboratory studies how the retina processes visual scenes and transmits this information
to the brain. We use multi-electrode arrays to record the activity of hundreds of
retina neurons simultaneously in conjunction with transgenic mouse lines and chemogenetics
to manipulate neural circuit function. We are interested in three major areas. First,
we work to understand how neurons in the retina are functionally connected. Second
we are studying how light-adaptation and circadian rhythms a

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