significance has been studied in natural conditions (e.g., prey capture, food
storage, vocal recognition) as the functional output of the central nervous
system and then attempts to determine the underlying neural mechanisms.
The neurobiological analysis may follow either a top-down approach (e.g.,
Moiseff and Konishi 1981) or a bottom-up approach (e.g., Heiligenberg
1991), but in either case the general methodology is predicated on prior
knowledge about adaptive behavior.
Traditionally, neuroethologists interested in acoustic communication
have investigated species with well-developed vocal systems and have
focused on neuronal selectivity and specificity within the vocal repertoire.
Given this focus, the extent to which the neural mechanisms of vocal communication in specialized animals can yield insight into more general mechanisms of audition should be considered. Historically, such consideration
has led to criticisms that mimic those leveled against early ethology in that
generalization is hampered by concentration on a limited component of the
acoustic biotope (i.e., vocalizations) and by the choice of animals highly
specialized for acoustic communication.
These criticisms fail at both the theoretical and empirical levels. Foremost, such criticisms are inconsistent with an evolutionary perspective
maintaining that the perceptual world of each species is a unique consequence of its evolutionary history. As with morphological traits, similarities
in behavioral phenotypes across species may result from either common
origins or convergent evolution and so do not ensure a corresponding similarity in the underlying neural mechanisms. Comprehensive theories of
behavior must therefore embrace, not ignore, evolution (e.g., Gallistel 1990;
cf. Dickinson 1980) and must be allowed to emerge from comparative
studies of many different species engaged in natural behaviors. A similar
reasoning applies to the derivation of general neural mechanisms and their
emergence through comparative studies. Moreover, as a matter of practical
experience, the foregoing criticisms of the neuroethological approach to
acoustic communication are not substantiated by the experimental literature. For example, among the most extreme cases of acoustic specialization
is autocommunication in the contexts of echolocation and vocal learning.
Yet many organizational features common to the vertebrate auditory (or
octavolateralis) system have been usefully described—in many cases first
elucidated—in relation to processing of vocalizations in echolocating bats,
weakly electric fish, other fishes specialized for vocal communication, frogs,
songbirds, and related systems. These principles include the forms and
actions of parallel and hierarchical systems (including distorted tonotopic
maps, feedforward, feedback, and lateral dynamic connections), distributed
representations, single neurons with complex receptive field properties,
temporal coding in single neurons and populations of neurons, sensorimotor interactions, state-dependent and dynamic receptive field properties,
and sexual dimorphisms. Current studies of these systems continue to be
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storage, vocal recognition) as the functional output of the central nervous
system and then attempts to determine the underlying neural mechanisms.
The neurobiological analysis may follow either a top-down approach (e.g.,
Moiseff and Konishi 1981) or a bottom-up approach (e.g., Heiligenberg
1991), but in either case the general methodology is predicated on prior
knowledge about adaptive behavior.
Traditionally, neuroethologists interested in acoustic communication
have investigated species with well-developed vocal systems and have
focused on neuronal selectivity and specificity within the vocal repertoire.
Given this focus, the extent to which the neural mechanisms of vocal communication in specialized animals can yield insight into more general mechanisms of audition should be considered. Historically, such consideration
has led to criticisms that mimic those leveled against early ethology in that
generalization is hampered by concentration on a limited component of the
acoustic biotope (i.e., vocalizations) and by the choice of animals highly
specialized for acoustic communication.
These criticisms fail at both the theoretical and empirical levels. Foremost, such criticisms are inconsistent with an evolutionary perspective
maintaining that the perceptual world of each species is a unique consequence of its evolutionary history. As with morphological traits, similarities
in behavioral phenotypes across species may result from either common
origins or convergent evolution and so do not ensure a corresponding similarity in the underlying neural mechanisms. Comprehensive theories of
behavior must therefore embrace, not ignore, evolution (e.g., Gallistel 1990;
cf. Dickinson 1980) and must be allowed to emerge from comparative
studies of many different species engaged in natural behaviors. A similar
reasoning applies to the derivation of general neural mechanisms and their
emergence through comparative studies. Moreover, as a matter of practical
experience, the foregoing criticisms of the neuroethological approach to
acoustic communication are not substantiated by the experimental literature. For example, among the most extreme cases of acoustic specialization
is autocommunication in the contexts of echolocation and vocal learning.
Yet many organizational features common to the vertebrate auditory (or
octavolateralis) system have been usefully described—in many cases first
elucidated—in relation to processing of vocalizations in echolocating bats,
weakly electric fish, other fishes specialized for vocal communication, frogs,
songbirds, and related systems. These principles include the forms and
actions of parallel and hierarchical systems (including distorted tonotopic
maps, feedforward, feedback, and lateral dynamic connections), distributed
representations, single neurons with complex receptive field properties,
temporal coding in single neurons and populations of neurons, sensorimotor interactions, state-dependent and dynamic receptive field properties,
and sexual dimorphisms. Current studies of these systems continue to be
326
T.Q. Gentner and D. Margoliash