Neural readaptation to earth’s gravity following return from space. J Neurophysiol 86: 2118–2122,... more Neural readaptation to earth’s gravity following return from space. J Neurophysiol 86: 2118–2122, 2001. The consequence of exposure to microgravity on the otolith organs was studied by recording the responses of vestibular nerve afferents supplying the utricular otolith organ to inertial accelerations in four toadfish, Opsanus tau, sequen-tially for 5 days following two National Aeronautics and Space Administration shuttle orbital flights. Within the first day postflight, the magnitude of response to an applied translation was on average three times greater than for controls. The reduced gravitational accel-eration in orbit apparently resulted in an upregulation of the sensitivity of utricular afferents. By 30 h postflight, responses were statistically similar to control. The time course of return to normal afferent sensitivity parallels the reported decrease in vestibular disorientation in astronauts following return from space.
... Haley, Joy Hiramoto, Mark Hixon, Tom Hourigan, John R. Hunter, Chris Kelley, George Losey, Ma... more ... Haley, Joy Hiramoto, Mark Hixon, Tom Hourigan, John R. Hunter, Chris Kelley, George Losey, Marv Lutnesky, Beverley Macewicz, Steve Ralston, Ernst Reese, John Stimson, and Bill Tyler greatly improved the dissertation and its derived manuscripts. Sue Nakamura critically ...
Sharks, skates, and rays exploit a marine environment rich in bioelectric and motional electric f... more Sharks, skates, and rays exploit a marine environment rich in bioelectric and motional electric fields, which are very weak but nevertheless very useful for prey capture, predator avoidance, social interactions, and orientation in the sea. The elasmobranchs’ appreciation of these fields is made possible by two distinct specializations. The first of these is an array of extraordinarily sensitive receptors, the ampullae of Lorenzini, which derive much of their sensitivity from positive feedback mechanisms held delicately balanced at threshold. The second specialization is a sophisticated set of filter mechanisms in the brain for extracting the weak electrosensory signals from much stronger background noise. A large portion of this background noise is created by the fish’s own movements. Recent experiments show that a remarkable adaptive filter mechanism implemented by the cerebellar-like circuitry of the medullary electrosensory nucleus accounts for much of the noise suppression. The specializations of receptors and CNS so well developed in these fishes allow us to recognize important general principles operating in other sensory systems and in other vertebrates.
Fish produce context-specific sounds during social communication but it is not known how acoustic... more Fish produce context-specific sounds during social communication but it is not known how acoustic behaviors have evolved in relation to specializations of the auditory system. Butterflyfishes (family Chaetodontidae) have a well-defined phylogeny and produce pulsed communication sounds during social interactions on coral reefs. Recent work indicates two sound production mechanisms exist in the bannerfish clade and others for one species in the Chaetodon clade which is distinguished by an auditory specialization, the laterophysic connection (LC). We determine the kinematic action patterns associated with sound production during social interactions in four Chaetodon subgenera and the non-laterophysic Forcipiger. Some Chaetodon species share the head bob acoustic behavior with Forcipiger which along with other sounds in the 100-1000 Hz spectrum are likely adequate to stimulate the ear, swim bladder or LC of a receiver fish. In contrast, only Chaetodon produced the tail slap sound which ...
Butterflyfishes are conspicuous members of coral reefs that communicate with acoustic signals dur... more Butterflyfishes are conspicuous members of coral reefs that communicate with acoustic signals during social interactions with mates and other conspecifics. Members of the genus Chaetodon have a laterophysic connection (LC), a unique association of anterior swim bladder horns and the cranial lateral line, but the action of the LC system on auditory sensitivity was previously unexplored. Baseline auditory evoked potential threshold experiments show that Forcipiger flavissimus (which lacks swim bladder horns and LC) is sensitive to sound tones from 100 Hz up to 1000 Hz, and that thresholds for three species of Chaetodon were 10-15 dB lower with extended hearing ranges up to 1700-2000 Hz. The relatively high thresholds to sound pressure and low pass response near 500 Hz for all four species is consistent with a primary sensitivity to hydrodynamic particle acceleration rather than sound pressure. Deflation of the swim bladder in Forcipiger had no measurable effect on auditory sensitivity...
Detailed neuroanatomical studies of model species are necessary to facilitate comparative experim... more Detailed neuroanatomical studies of model species are necessary to facilitate comparative experiments which test hypotheses relevant to brain evolution and function. Butterflyfishes (Chaetodontidae) boast numerous sympatric species that differ in social behavior, aggression and feeding ecology. However, the ability to test hypotheses relevant to brain function in this family is hindered by the lack of detailed neural descriptions. The cytoarchitecture of the telencephalon in the monogamous and territorial multiband butterflyfish, Chaetodon multicinctus, was determined with Nissl-stained serial sections and an immunohistochemical analysis of arginine vasotocin (AVT), serotonin, substance P and tyrosine hydroxylase. The ventral telencephalon was similar to that of other perciform fishes studied, with one major difference. A previously undescribed postcommissural region, the cuneate nucleus, was identified and putatively assigned to the ventral telencephalon. While the function of this...
Sounds provide important signals for inter- and intraspecific communication in fishes, but few st... more Sounds provide important signals for inter- and intraspecific communication in fishes, but few studies examine fish acoustic behavior in the context of coevolution of sound production and hearing ability within a species. This study characterizes the acoustic behavior in a reproductive population of the Hawaiian sergeant fish, Abudefduf abdominalis, and compares acoustic features to hearing ability, measured by the auditory evoked potential (AEP) technique. Sergeant fish produce sounds at close distances to the intended receiver (<or=1-2 body lengths), with different pulse characteristics that are associated primarily with aggression, nest preparation and courtship-female-visit behaviors. Energy peaks of all sounds were between 90 and 380 Hz, whereas courtship-visit sounds had a pulse repetition rate of 125 Hz with harmonic intervals up to 1 kHz. AEP threshold, which is probably higher than the behavioral threshold, indicates best sensitivity at low frequencies (95-240 Hz), with ...
The consequence of exposure to microgravity on the otolith organs was studied by recording the re... more The consequence of exposure to microgravity on the otolith organs was studied by recording the responses of vestibular nerve afferents supplying the utricular otolith organ to inertial accelerations in four toadfish, Opsanus tau, sequentially for 5 days following two National Aeronautics and Space Administration shuttle orbital flights. Within the first day postflight, the magnitude of response to an applied translation was on average three times greater than for controls. The reduced gravitational acceleration in orbit apparently resulted in an upregulation of the sensitivity of utricular afferents. By 30 h postflight, responses were statistically similar to control. The time course of return to normal afferent sensitivity parallels the reported decrease in vestibular disorientation in astronauts following return from space.
Cartilaginous fishes continuously replace their teeth throughout their life (polyphyodonty) and o... more Cartilaginous fishes continuously replace their teeth throughout their life (polyphyodonty) and often show a sexually dimorphic dentition that was previously thought to be an invariant sex character. Radial vector analysis of tooth shape in the polyphyodontic stingray Dasyatis sabina across a consecutive 24 month period shows a stable molariform morphology for females but a periodic shift in male dentition from a female-like molariform to a recurved cuspidate form during the reproductive season. The grip tenacity of the male dentition is greater for the cuspidate form that occurs during the mating season than for the molariform dentition that occurs during the non-mating season. Dental sexual dimorphism and its sex-dependent temporal plasticity probably evolved via polyphyodontic preadaptation under selective pressures on both sexes for increased feeding efficiency and sexual selection in males to maximize mating success. These phenomena are important considerations for the identifi...
Neural readaptation to earth’s gravity following return from space. J Neurophysiol 86: 2118–2122,... more Neural readaptation to earth’s gravity following return from space. J Neurophysiol 86: 2118–2122, 2001. The consequence of exposure to microgravity on the otolith organs was studied by recording the responses of vestibular nerve afferents supplying the utricular otolith organ to inertial accelerations in four toadfish, Opsanus tau, sequen-tially for 5 days following two National Aeronautics and Space Administration shuttle orbital flights. Within the first day postflight, the magnitude of response to an applied translation was on average three times greater than for controls. The reduced gravitational accel-eration in orbit apparently resulted in an upregulation of the sensitivity of utricular afferents. By 30 h postflight, responses were statistically similar to control. The time course of return to normal afferent sensitivity parallels the reported decrease in vestibular disorientation in astronauts following return from space.
... Haley, Joy Hiramoto, Mark Hixon, Tom Hourigan, John R. Hunter, Chris Kelley, George Losey, Ma... more ... Haley, Joy Hiramoto, Mark Hixon, Tom Hourigan, John R. Hunter, Chris Kelley, George Losey, Marv Lutnesky, Beverley Macewicz, Steve Ralston, Ernst Reese, John Stimson, and Bill Tyler greatly improved the dissertation and its derived manuscripts. Sue Nakamura critically ...
Sharks, skates, and rays exploit a marine environment rich in bioelectric and motional electric f... more Sharks, skates, and rays exploit a marine environment rich in bioelectric and motional electric fields, which are very weak but nevertheless very useful for prey capture, predator avoidance, social interactions, and orientation in the sea. The elasmobranchs’ appreciation of these fields is made possible by two distinct specializations. The first of these is an array of extraordinarily sensitive receptors, the ampullae of Lorenzini, which derive much of their sensitivity from positive feedback mechanisms held delicately balanced at threshold. The second specialization is a sophisticated set of filter mechanisms in the brain for extracting the weak electrosensory signals from much stronger background noise. A large portion of this background noise is created by the fish’s own movements. Recent experiments show that a remarkable adaptive filter mechanism implemented by the cerebellar-like circuitry of the medullary electrosensory nucleus accounts for much of the noise suppression. The specializations of receptors and CNS so well developed in these fishes allow us to recognize important general principles operating in other sensory systems and in other vertebrates.
Fish produce context-specific sounds during social communication but it is not known how acoustic... more Fish produce context-specific sounds during social communication but it is not known how acoustic behaviors have evolved in relation to specializations of the auditory system. Butterflyfishes (family Chaetodontidae) have a well-defined phylogeny and produce pulsed communication sounds during social interactions on coral reefs. Recent work indicates two sound production mechanisms exist in the bannerfish clade and others for one species in the Chaetodon clade which is distinguished by an auditory specialization, the laterophysic connection (LC). We determine the kinematic action patterns associated with sound production during social interactions in four Chaetodon subgenera and the non-laterophysic Forcipiger. Some Chaetodon species share the head bob acoustic behavior with Forcipiger which along with other sounds in the 100-1000 Hz spectrum are likely adequate to stimulate the ear, swim bladder or LC of a receiver fish. In contrast, only Chaetodon produced the tail slap sound which ...
Butterflyfishes are conspicuous members of coral reefs that communicate with acoustic signals dur... more Butterflyfishes are conspicuous members of coral reefs that communicate with acoustic signals during social interactions with mates and other conspecifics. Members of the genus Chaetodon have a laterophysic connection (LC), a unique association of anterior swim bladder horns and the cranial lateral line, but the action of the LC system on auditory sensitivity was previously unexplored. Baseline auditory evoked potential threshold experiments show that Forcipiger flavissimus (which lacks swim bladder horns and LC) is sensitive to sound tones from 100 Hz up to 1000 Hz, and that thresholds for three species of Chaetodon were 10-15 dB lower with extended hearing ranges up to 1700-2000 Hz. The relatively high thresholds to sound pressure and low pass response near 500 Hz for all four species is consistent with a primary sensitivity to hydrodynamic particle acceleration rather than sound pressure. Deflation of the swim bladder in Forcipiger had no measurable effect on auditory sensitivity...
Detailed neuroanatomical studies of model species are necessary to facilitate comparative experim... more Detailed neuroanatomical studies of model species are necessary to facilitate comparative experiments which test hypotheses relevant to brain evolution and function. Butterflyfishes (Chaetodontidae) boast numerous sympatric species that differ in social behavior, aggression and feeding ecology. However, the ability to test hypotheses relevant to brain function in this family is hindered by the lack of detailed neural descriptions. The cytoarchitecture of the telencephalon in the monogamous and territorial multiband butterflyfish, Chaetodon multicinctus, was determined with Nissl-stained serial sections and an immunohistochemical analysis of arginine vasotocin (AVT), serotonin, substance P and tyrosine hydroxylase. The ventral telencephalon was similar to that of other perciform fishes studied, with one major difference. A previously undescribed postcommissural region, the cuneate nucleus, was identified and putatively assigned to the ventral telencephalon. While the function of this...
Sounds provide important signals for inter- and intraspecific communication in fishes, but few st... more Sounds provide important signals for inter- and intraspecific communication in fishes, but few studies examine fish acoustic behavior in the context of coevolution of sound production and hearing ability within a species. This study characterizes the acoustic behavior in a reproductive population of the Hawaiian sergeant fish, Abudefduf abdominalis, and compares acoustic features to hearing ability, measured by the auditory evoked potential (AEP) technique. Sergeant fish produce sounds at close distances to the intended receiver (<or=1-2 body lengths), with different pulse characteristics that are associated primarily with aggression, nest preparation and courtship-female-visit behaviors. Energy peaks of all sounds were between 90 and 380 Hz, whereas courtship-visit sounds had a pulse repetition rate of 125 Hz with harmonic intervals up to 1 kHz. AEP threshold, which is probably higher than the behavioral threshold, indicates best sensitivity at low frequencies (95-240 Hz), with ...
The consequence of exposure to microgravity on the otolith organs was studied by recording the re... more The consequence of exposure to microgravity on the otolith organs was studied by recording the responses of vestibular nerve afferents supplying the utricular otolith organ to inertial accelerations in four toadfish, Opsanus tau, sequentially for 5 days following two National Aeronautics and Space Administration shuttle orbital flights. Within the first day postflight, the magnitude of response to an applied translation was on average three times greater than for controls. The reduced gravitational acceleration in orbit apparently resulted in an upregulation of the sensitivity of utricular afferents. By 30 h postflight, responses were statistically similar to control. The time course of return to normal afferent sensitivity parallels the reported decrease in vestibular disorientation in astronauts following return from space.
Cartilaginous fishes continuously replace their teeth throughout their life (polyphyodonty) and o... more Cartilaginous fishes continuously replace their teeth throughout their life (polyphyodonty) and often show a sexually dimorphic dentition that was previously thought to be an invariant sex character. Radial vector analysis of tooth shape in the polyphyodontic stingray Dasyatis sabina across a consecutive 24 month period shows a stable molariform morphology for females but a periodic shift in male dentition from a female-like molariform to a recurved cuspidate form during the reproductive season. The grip tenacity of the male dentition is greater for the cuspidate form that occurs during the mating season than for the molariform dentition that occurs during the non-mating season. Dental sexual dimorphism and its sex-dependent temporal plasticity probably evolved via polyphyodontic preadaptation under selective pressures on both sexes for increased feeding efficiency and sexual selection in males to maximize mating success. These phenomena are important considerations for the identifi...
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