Richard R. Fay - US grants

No Abstract Provided

This proposal is for funds to help support an international, interdisciplinary conference entitled The Evolutionary Biology of Hearing: Comparative Hearing in Vertebrates, to be held in Sarasota, Florida, May 20-24, 1990. Expected are 44 participants presenting at the meeting, and about 50 additional registrants who will come as attendees to the conference. All presenters and other attendees will be scientists with a particular interest in the evolution of hearing. The conferences's major goals are: 1. To present an integrated understanding of peripheral and central auditory mechanisms in an evolutionary context; 2. To provide a structured forum for the development and exchange of ideas and research findings on hearing adaptation and evolution; 3. To integrate recent anatomical, physiological, and psychophysical findings into an understanding of the evolution of hearing; 4. To synthesize the data, methods, emergent principles, and future trends in the study of the evolutionary biology of hearing in a tightly-edited and integrated volume. The conference will bring together 45 international scientists who are leaders in studies of animal hearing and of the evolution of hearing and the auditory system in both vertebrates and invertebrates. Approximately thirty-five presentations, from the viewpoints of comparative anatomy, physiology, biophysics, acoustic behavior, psychophysics, evolutionary biology, ontogeny, and paleontology, will synthesize past and current research.

biomedical equipment purchase;

This project aims to determine how a simple vertebrate auditory system (Carassius auratus) identifies and locates sound sources. We focus on the perception of sound sources rather than on the processing of sounds per se. We hypothesize that vertebrates share essential hearing functions to determine sound sources so as to behave appropriately in relation to them. Perceiving one source among many requires that the frequency components of the source be grouped for common processing. Identifying a sound source requires information about the individual components belonging to the source. Thus, listening is both synthetic and analytic. This is the essential problem for hearing in general, and it seems likely that all vertebrate auditory systems function, to some degree, to both group and analyze the components of complex sounds. Goldfish hearing shares characteristics with all vertebrates investigated. At the same time, fishes represent an extreme position among vertebrates with respect to inner ear structure and are thus an "anchor point", so that our conclusions will help define the important dimensions of variation and similarity among vertebrates. This work will help establish a biological context among vertebrates within which human hearing can be more completely understood. Complementary behavioral and neurophysiological studies will help identify the neural codes and mechanisms underlying these fundamental aspects of hearing. We will use classical conditioning in a stimulus generalization paradigm with rippled noise and sine tone complexes as stimuli. To study synthetic listening, animals will be conditioned to respond to a complex sound producing perceptions of pitch in humans, and then tested for generalization to various pure tones, including that equal to the pitch of the complex, and others making up the complex sound's spectrum. Analytic listening will be studied similarly by asking whether individual components making up a complex are perceived independently. We will also determine how the pitch and other features of complex sounds are represented among cells of the midbrain and medulla, and the extent to which cells are selective for the pitch of the complex as well as for its individual frequency components. These studies will help identify the fundamental mechanisms underlying pitch perception and synthetic listening in a simply organized vertebrate auditory system. In studies on sound source location, we will measure the ability to detect and segregate components from two spatially-separated, simultaneous sources using a unique stimulator system capable of controlling the axis of particle motion as well as the pressure waveform. Complementary neurophysiological experiments at the levels of the midbrain and medulla will determine the fat of peripherally coded directional information and some of the fundamental mechanisms by which sound source location is represented in the brain.

The overall goals of this proposal are to study the mechanisms of hearing and sound communication in a simply organized vertebrate, the oyster toadfish (Opsanus tau). The toadfish is a vocal species whose acoustic vocalization behavior, vestibular organs, and brainstem nuclei are well studied. In fishes, sound is transduced by hair cells of one or more otolith organs that are adapted as acoustic receivers operating in a frequency range up to several kHz. The otolith organs of fishes have been important preparations for the study of hair cell synaptic physiology, efferent mechanisms, hair cell biophysics, and neurophysiology-behavior relations in hearing. However, wide gaps in our understanding of hearing and sound communication mediated by otolith organs has been due to the difficulties in specifying the adequate stimulus (pressure, displacement, velocity or acceleration), and the identify of the endorgans normally responsive to these quantities. New methods for controlling these variables now make it possible to advance our knowledge about the mechanisms of the ears, hearing, and sound communication in these simply organized vertebrates. Sounds, including sinusoids and model toadfish vocalizations will be synthesized in the laboratory using a 3-dimensional motion system and a sound pressure source. Recording from primary afferents of the utricle, lagena, and saccule will characterize their spatial directionality, acceleration and pressure sensitivity, and tuning. Comparisons with the vocalization sounds toadfish normally experience in the natural environment will permit an identification of the adequate stimulus in the field, and the role of each endorgan in hearing. Intracellular recording of primary afferents from the otolith organs will physiologically characterize their response to communication sounds, and injections of biocytin or other tracers molecules will allow visualization of their peripheral terminations and central projections. New knowledge will be obtained on the morphological substrates that distinguish acoustic and vestibular functions peripherally and centrally, and the projection and convergence from the various endorgans of auditory signals of known biological significance in the brainstem will be described and analyzed. Studies of hearing in animals are not only necessary for the development of specific model systems for normal and pathological hearing functions in humans, but are also important for providing a general biological and evolutionary context within which new data from any species, including humans, may be better interpreted and applied. This research will help determine the distinctions and commonalities between vestibular and auditory functions and structures so that we may better understand how vestibular organs may function in hearing.

DESCRIPTION: The overall goals of this research program are to determine how simple vertebrate auditory systems function to give rise to the sense of hearing defined in a comparative and evolutionary context. We argue that the sense of hearing functions in species of all vertebrate classes primarily in the detection, identification, classification, and the location of both animate and inanimate sound sources. In addition, we hypothesize that the neural mechanisms underlying sound source determination consist of primitive components and strategies that are widely shared among vertebrate species, including human beings. This view motivates and guides the proposed experiments.Preliminary work has demonstrated that in spite of wide differences in the inner ears of fishes compared with tetrapods, the sense of hearing revealed in psychophysical and neurophysiological studies on goldfish appears to be indistinguishable in fundamental aspects from that of terrestrial animals, including mammals. The present proposed behavioral, neurophysiological, and neuroanatomical experiments are designed to help evaluate the hypothesis that the sense of hearing and its underlying neural mechanisms are widely shared among the most numerous and successful vertebrates, the fishes. Comparisons of these results with those for goldfish and tetrapods will help reveal the dimensions on which variation occurs among vertebrate ears. Two fundamental aspects of sound source determination will be studied: sound source localization and sound source identification and classification. These studies will be carried out at three levels of analysis: behavior (psychophysics and scaling type of studies), single-cell neurophysiology at various levels of the auditory system, and comparative neuroanatomy. The goals are to compare fishes with humans and other tetrapods with respect to the neural mechanisms underlying sound source determination. These results will help in the development and evaluation of animal models for human hearing and help establish the comparative and evolutionary contexts within which the human sense of hearing can be better understood.

This proposal requests support for a meeting on basic and applied aspects of fish bioacoustics to be held in mid-2001 in Chicago. There are investigators interested in basic issues of fish bioacoustics ( hearing, sound production, etc.), others interested in use of sound to assay fish populations, and still others are interested in the effects of intense sound on fish behavior and the potential use of sound to control fish behavior. However, there has been very little interaction or collaboration among these investigators. Each of these groups has unique knowledge and approaches to questions, and these investigators and their fields would benefit from interactions. Thus, the purpose of the proposed meeting is to bring together investigators interested in all basic and applied aspects of fish biocacoustics to present material, share ideas, and most importantly, learn from, and develop an understanding of, the questions and approaches taken by one another. The conference is designed to foster these interactions and help investigators with widely different research interests get to know one another. Long-term goals of the conference are to educate those in the field who don't normally interact professionally, and to help establish collaborations among investigators across disciplines and research fields

[unreadable] DESCRIPTION (provided by applicant): The most important features of the human sense of hearing are those that promote the segregation and integration of acoustic features in a way that results in the determination of actual sound sources. Since environments often include multiple and simultaneous objects, the auditory system must function fundamentally as a "separation machine" whose job it is to determine individual sources from the complex mixture of source sounds reaching the ears. This sort of auditory scene analysis is now well appreciated as an important function of human hearing. We suggest here that these functions are also primitive features of a general vertebrate sense of hearing, and that these are the functions that have defined success and fitness most importantly throughout the evolution of the vertebrate auditory system. The overall goals are to determine how these primitive functions of the vertebrate sense of hearing operate in a relatively simple vertebrate species. One goal is to help establish a biological and evolutionary context within which human hearing can be more fully understood. Aim 1: We will investigate the capacities of a simple vertebrate species to determine source characteristics when there are multiple, simultaneous sound sources present (i.e., auditory scene analysis and source segregation). We will investigate other acoustic features that promote auditory perceptual segregation in human listeners for their effects on fish listeners. These features include onset asynchrony, amplitude modulation, duration, harmonic structure, (and spatial origin: Aim 2). These features will be investigated for their effects on perception using behavioral conditioning methods using stimulus generalization paradigms. Aim 2: We will investigate auditory source segregation using multiple, discrete local sources. We will analyze the effects of the spatial origin of sources independently of the non-spatial acoustic features (Aim 1) that may play a role in sound source sesegregation. Aim 3: We will determine the nature of the neural codes and representations underlying source segregation by recording from peripheral and central auditory neurons in response to the same signals and sources used in the above behavioral experiments. We will focus on understanding the dimensions of neural activity that the brain could use in segregating and integrating simultaneous acoustic components from one or more sources. [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Terrestrial animals use binaural processing to help them detect, discriminate, locate, and segregate sounds sources. All regions of the central auditory system participate in the computations used for these general tasks of hearing, but several nuclei of the mammalian and avian brainstem have been most intensively studied with respect to binaural processing. Recent observations on fishes, including behavior, central auditory system morphology and peripheral and central neurophysiology converge in suggesting not only that the flow of information from the periphery to the epencephalon follows the same general pattern in all classes of jawed vertebrates, but that the sense of hearing itself may be homologous within these taxa, having first developed among early fishes. This, in turn, suggests that binaural processing may have first developed in early fishes, too. In this proposal, we aim to systematically investigate, for the first time, the strategies and mechanisms of binaural hearing in a fish (oyster toadfish - Opsanus tau). These studies using combinations of natural acoustic and bilateral mechanical otolith manipulation, in vivo, will provide the first systematic description and analysis of binaural processing in a fish, and will help determine what binaural mechanisms observed in terrestrial animals are primitive, or shared among vertebrates, and what mechanisms are likely to have been more recently derived. We hypothesize that several fundamental structural and functional aspects of binaural processing are primitive vertebrate characters and we expect them to be primitively revealed in the auditory brainstem of fishes. This work will contribute to our understanding of the evolution of auditory systems and the sense of hearing, and thereby help establish a biological and evolutionary context within which human hearing and animal models for human hearing can be better understood and applied.

This research will investigate sound source localization by fishes to ascertain how fish integrate the various sound cues available to them to behave appropriately in complex acoustic environments. Evidence suggests that the capacity for sound source localization is common to mammals, amphibians, birds and reptiles, but surprisingly it is not known whether fishes locate sound sources in the same manner. Therefore, sound source localization by fishes remains an important topic in biology and in the hearing sciences. This study will test the major assumptions of several related theories, including the leading theory of sound source localization by fishes. The plainfin midshipman fish (Porichthys notatus), in which females locate males by sounds that the males produce, will be used as a general model to investigate how fishes localize underwater sound sources. Two hypotheses will be tested: 1) fish orient to the direction of acoustic particle motion to localize sound sources (a major assumption of several, related theories including the leading theory of sound source localization), and 2) both particle motion and sound pressure detection (via the swimbladder) are necessary for sound source localization, but neither alone is sufficient. As an integral part of this research program, both graduate and undergraduate students will receive training and mentoring. In addition, annual public lectures regarding this research will be presented at the University of California Bodega Marine Laboratory.