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Visual cortical simple cells: who inhibits whom.
1Department of Neurobiology, University of Pittsburgh School of Medicine, PA 15261, USA. saul+@pitt.edu
Visual Neuroscience
|August 4, 1999
Summary
Simple cells show delayed responses after adaptation, affecting stimulus onset but not offset. These visual adaptation aftereffects, observed with moving and stationary stimuli, suggest a model of mutually inhibitory simple cells.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Visual Perception
Background:
- Simple cells in the visual cortex exhibit adaptation aftereffects.
- These aftereffects specifically impact the onset of responses to drifting gratings.
Purpose of the Study:
- To investigate the spatiotemporal characteristics of adaptation aftereffects in simple cells.
- To propose a computational model explaining these observed aftereffects.
Main Methods:
- Adaptation experiments using drifting gratings and time-modulated stationary bars.
- Analysis of response onset and offset timing.
- Development of a computational model based on spatiotemporal quadrature and mutual inhibition.
Main Results:
- Adaptation aftereffects were observed, characterized by a delayed response onset but unaffected offset.
- Aftereffects were spatially and temporally specific.
- Stimuli with modulated luminance revealed aftereffects at particular spatiotemporal points.
- Aftereffects with moving stimuli were predictable from stationary stimulus data.
Conclusions:
- A model of mutually inhibitory simple cells in spatiotemporal quadrature explains the observed aftereffects.
- Inhibition is localized in space and time to produce the specific aftereffect patterns.
- Direction-selective simple cells receive inhibition from cells with the same preferred direction.