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Identification of Specific Sensory Neuron Populations for Study of Expressed Ion Channels
Published on: December 24, 2013
Stimulus selectivity is enhanced by voltage-dependent conductances in combination-sensitive neurons
Bruce A Carlson1, Masashi Kawasaki
1University of Virginia, Department of Biology, 277 Gilmer Hall, P.O. Box 400328, Charlottesville, VA 22904-4328, USA. bc6s@virginia.edu
Journal of Neurophysiology
|September 29, 2006
Summary
Weakly electric fish use neural circuits to detect frequency differences. Voltage-dependent conductances in neurons enhance selectivity for specific stimulus combinations, revealing nonlinear mechanisms in sensory processing.
Area of Science:
- Neuroscience
- Sensory Biology
- Computational Neuroscience
Background:
- Central sensory neurons exhibit attribute selectivity, but underlying mechanisms are unclear.
- Weakly electric fish (Gymnarchus) discriminate electric organ discharge (EOD) frequency differences (Df).
- Sign-selective midbrain neurons respond to Df >0 or Df <0 by processing amplitude modulation (AM) and phase modulation (PM).
Purpose of the Study:
- Investigate the cellular mechanisms of combination sensitivity in sign-selective midbrain neurons.
- Determine how neurons achieve selectivity for specific combinations of stimulus attributes.
Main Methods:
- Whole-cell intracellular recordings from midbrain neurons in vivo.
- Recorded postsynaptic potential (PSP) responses to AM, PM, Df >0, and Df <0.
- Utilized current clamp and compared results to synaptic integration models.
Main Results:
- Responses to AM and PM showed alternating excitatory and inhibitory PSPs, in phase or offset depending on Df sign.
- Responses to the nonpreferred Df sign were weaker than linear predictions.
- This reduced response to the nonpreferred Df was attributed to decreased voltage-dependent excitatory conductances.
Conclusions:
- Nonlinear decoders, specifically voltage-dependent conductances, enhance single-neuron selectivity for stimulus combinations.
- This mechanism explains how Gymnarchus discriminates EOD frequency differences.
- Provides insight into neural computation and sensory information processing.
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