The Coding and Processing of Temporal Information in the Electrosensory System of Fish
Electric fish generate and perceive weak electric signals which are generated by an electric organ in their tail. They evaluate modulations in the amplitude as well as in the timing, or “phase”, of such signals to detect moving objects and to communicate with conspecifics. Electric fish are able to discriminate phase differences of less than 1 microsecond although their electroreceptors code the timing of signals with a standard deviation as large as 10 to 40 microseconds. The central nervous system of electric fish, therefore, is able to enhance tem poral resolution by approximately two orders of magnitude. This temporal “hyperacuity” is achieved by averaging messages from local populations of receptors and relaying this information along neurons that are “designed” to transmit the timing of action potentials with minimal jitter. At a higher level, phase differences are coded by modulating the firing rate of small neurons, and phase differences as small as 1 microsecond appear to affect the firing rate of these neurons to an extent that is at least statistically detectable. The pooling of information from these small neurons at a still higher level should achieve temporal resolution in the sub-microsecond range.
KeywordsSpherical Cell Electric Organ Discharge Electric Fish Differential Phase Torus Semicircularis
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- Amagai S (1993) The neural representations of temporal information. PhD Thesis, Cornell University, Ithaca, NYGoogle Scholar
- Heiligenberg W (1991) Neural nets in electric fish. MIT Press, Cambridge, MassGoogle Scholar
- Heiligenberg W, Rose GJ (1985) Phase and amplitude computations in the midbrain of an electric fish: intracellular studies of neurons participating in the jamming avoidance response of Eigenmannia. J Neurosci 2:515–531Google Scholar
- Lytton W (1991) Simulations of a phase-comparing neuron of the electric fish Eigen mannia. J Comp Physiol 1169:117–125Google Scholar