PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 12726834

Synaptic energy efficiency in retinal processing.

Benjamin T Vincent·Roland J Baddeley
View original source ↗Export metadata ↓

Abstract

Recent work suggests that the visual system may represent early visual information in an energy efficient manner [Nature 381 (1996); Nature, 381 (1996) 607; Neural Comput. 3 (2001) 799; Curr. Opin. Neurobiol. 11 (2001) 475]. This paper applies the idea of energy efficient representations to understand retinal processing, and provides evidence that centre surround processing observed is efficient in terms of minimizing synaptic activity. In particular, it is shown that receptive fields at different retinal eccentricities and at different levels of noise, can be understood in terms of maximizing the transmission of visual information given a constraint on total synaptic strengths and hence energy consumption.

Explore related subjects

Contrast SensitivityEnergy MetabolismHumansRetinaSynapsesSynaptic TransmissionJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Benjamin T Vincent, Roland J Baddeley. 2003. Synaptic energy efficiency in retinal processing.. https://doi.org/10.1016/s0042-6989(03)00096-8

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2003

Response suppression in v1 agrees with psychophysics of surround masking.

When a target stimulus is embedded in a high contrast surround, the target appears reduced in contrast and is harder to detect, and neural responses in visual cortex are suppressed. We used functional magnetic resonance imaging (fMRI) and psychophysics to quantitatively compare these physiological and perceptual effects. Observers performed a contrast discrimination task on a contrast-reversing sinusoidal target grating. The target was either presented in isolation or embedded in a high-contrast surround. While observers performed the task, we also measured fMRI responses as a function of target contrast, both with and without a surround. We found that the surround substantially increased the psychophysical thresholds while reducing fMRI responses. The two data sets were compared, on the basis of the assumption that a fixed response difference is required for correct discrimination, and we found that the psychophysics accounted for 96.5% of the variance in the measured V1 responses. The suppression in visual areas V2 and V3 was stronger, too strong to agree with psychophysics. The good quantitative agreement between psychophysical thresholds and V1 responses suggests V1 as a plausible candidate for mediating surround masking.

Contrast Sensitivity↗
PubMed2003

Perceptual consequences of centre-surround antagonism in visual motion processing.

Centre-surround receptive field organization is a ubiquitous property in mammalian visual systems, presumably tailored for extracting image features that are differentially distributed over space. In visual motion, this is evident as antagonistic interactions between centre and surround regions of the receptive fields of many direction-selective neurons in visual cortex. In a series of psychophysical experiments we make the counterintuitive observation that increasing the size of a high-contrast moving pattern renders its direction of motion more difficult to perceive and reduces its effectiveness as an adaptation stimulus. We propose that this is a perceptual correlate of centre-surround antagonism, possibly within a population of neurons in the middle temporal visual area. The spatial antagonism of motion signals observed at high contrast gives way to spatial summation as contrast decreases. Evidently, integration of motion signals over space depends crucially on the visibility of those signals, thereby allowing the visual system to register motion information efficiently and adaptively.

Contrast Sensitivity↗