A sensory brain map for each behavior?

A sensory brain map for each behavior?

W. Metzner*,† and
J. Juranek‡

^*Department of Biology, and ^‡Program in Neuroscience, Department of Psychology, University of California, Riverside, CA 92521

Edited by Masakazu Konishi, California Institute of Technology, Pasadena, CA, and approved November 3, 1997 (received for review September 9, 1997)

Abstract

Multiple brain maps are commonly found in virtually every vertebrate sensory system. Although their functional significance is generally relatively little understood, they seem to specialize in processing distinct sensory parameters. Nevertheless, to yield the stimulus features that ultimately elicit the adaptive behavior, it appears that information streams have to be combined across maps. Results from current lesion experiments in the electrosensory system, however, suggest an alternative possibility. Inactivations of different maps of the first-order electrosensory nucleus in electric fish, the electrosensory lateral line lobe, resulted in markedly different behavioral deficits. The centromedial map is both necessary and sufficient for a particular electrolocation behavior, the jamming avoidance response, whereas it does not affect the communicative response to external electric signals. Conversely, the lateral map does not affect the jamming avoidance response but is necessary and sufficient to evoke communication behavior. Because the premotor pathways controlling the two behaviors in these fish appear to be separated as well, this system illustrates that sensory–motor control of different behaviors can occur in strictly segregated channels from the sensory input of the brain all through to its motor output. This might reflect an early evolutionary stage where multiplication of brain maps can satisfy the demand on processing a wider range of sensory signals ensuing from an enlarged behavioral repertoire, and bridging across maps is not yet required.

Footnotes

↵ † To whom reprint requests should be addressed at: Department of Biology, University of California, Riverside, CA 92521-0427. e-mail: walter.metzner{at}ucr.edu.
This paper was submitted directly (Track II) to the Proceedings Office.
Abbreviations: CLS, centrolateral segment of the electrosensory lateral line lobe; CMS, centromedial segment of the electrosensory lateral line lobe; ELL, electrosensory lateral line lobe; EOD, electric organ discharge; JAR, jamming avoidance response; LS, lateral segment of the electrosensory lateral line lobe.