Cross-modal integration in a dart-poison frog
- *Department of Physiological Science, University of California, Los Angeles, CA 90095-1606; ‡Institute of Zoology, University of Vienna, Althanstrasse 14, A 1090 Vienna, Austria; and ¶Mission pour la Création du Parc de la Guyane, 81 Rue Christophe Colomb, 97300 Cayenne, Guyane, France
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Edited by Eric I. Knudsen, Stanford University School of Medicine, Stanford, CA (received for review August 31, 2004)
Abstract
The mechanisms by which the brain binds together inputs from separate sensory modalities to effect a unified percept of events are poorly understood. This phenomenon was studied in males of the dart-poison frog Epipedobates femoralis. These animals physically and vigorously defend their territories against conspecific calling intruders. In prior field studies with an electromechanical model frog, we were able to experimentally evoke this aggressive behavior only when an auditory cue (advertisement call) was presented simultaneously with a visual cue (vocal-sac pulsations). In the present field experiments, we used a modified version of the electromechanical model frog to present territorial males with visual and auditory cues separated by experimentally introduced temporal delays or spatial disparities to probe temporal and spatial integration in this animal. In temporal integration experiments, bimodal stimuli with temporal overlap during calling bouts consistently evoked aggressive behavior; stimuli lacking bimodal temporal overlap were relatively ineffective at the same task. In spatial integration studies, despite presenting the components of the bimodal stimulus with an initial spatial disparity of up to 12 cm, fighting behavior persisted. These results demonstrate that temporal and spatial integration may be reliably estimated in a freely behaving animal in its natural habitat and that we can use aggressive behavior in this species as an index of cross-modal integration in the field.
Footnotes
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↵ † To whom correspondence should be addressed. E-mail: pnarins{at}ucla.edu.
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↵ § Present address: Department of Psychology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
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Author contributions: P.M.N. designed research; P.M.N., D.S.G., K.K.S., P.G., and W.H. performed research; P.M.N. and D.S.G. analyzed data; and P.M.N. wrote the paper.
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This paper was submitted directly (Track II) to the PNAS office.
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Abbreviations: EMF, electromechanical model frog; IS, in sync; OL, overlap; IL, interleave; GA, gross alternate; SI, spatial integration; EL, external loudspeaker.
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See Commentary on page 2267.
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↵ ∥ Grant, K. W. & Van Wassenhove, V. (2004) J. Acoust. Soc. Am. 115, 2402 (abstr.).
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↵ ** The importance of the visual component of the anuran advertisement call generally has been downplayed because most anuran amphibians are nocturnally active. Nevertheless, some evidence exists that visual signals may play an important role in diurnal species (7–9) and in nocturnal species under limited light regimes (10, 11).
- Copyright © 2005, The National Academy of Sciences
