Exploring Animal Behavior Through Sound: Volume 1

This open-access book empowers its readers to explore the acoustic world of animals. By listening to the sounds of nature, we can study animal behavior, distribution, and demographics; their habitat characteristics and needs; and the effects of noise. Sound recording is an efficient and affordable tool, independent of daylight and weather; and recorders may be left in place for many months at a time, continuously collecting data on animals and their environment. This book builds the skills and knowledge necessary to collect and interpret acoustic data from terrestrial and marine environments. Beginning with a history of sound recording, the chapters provide an overview of off-the-shelf recording equipment and analysis tools (including automated signal detectors and statistical methods); audiometric methods; acoustic terminology, quantities, and units; sound propagation in air and under water; soundscapes of terrestrial and marine habitats; animal acoustic and vibrational communication; echolocation; and the effects of noise. This book will be useful to students and researchers of animal ecology who wish to add acoustics to their toolbox, as well as to environmental managers in industry and government

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 128, May 1974

This special bibliography lists 282 reports, articles, and other documents introduced into the NASA scientific and technical information system in April 1974

Scale dependent processing of conspecific signals in the gray treefrog Hyla versicolor

Acoustic communication is both widespread and often essential for successful mate selection, territorial defense, and many social behaviors in many taxa. Laboratory studies often use ‘simplified’, artificial stimuli which have high signal-to-noise rations and are easy to manipulate, but often do not capture the true range and variation of sounds experienced by organisms in the field. In nature, acoustic signals from socially aggregating animals are often emitted together, clustered in space and time. As these signals come from conspecifics they tend to be self-similar in many parameters, providing a challenge for the auditory system to detect, localize, and discriminate between target signals amongst the background. Additionally, signal-environment interactions during transmission further increase the difficulty. In this dissertation, I explore the processing of natural signals in the eastern grey treefrog, Hyla versicolor. During the mating season, numerous males gather near water sources and form choruses, emitting a stereotyped advertisement calls, creating a challenging auditory environment. Females later approach the chorus from daytime resting sites, often up to several hundred meters distant. Females must first detect and orient to the chorus, and subsequently detect, localize, and discriminate among individual male calls embedded in the chorus background. In chapter 2, I quantify the attraction of the chorus using recordings made at increasing distances from a single calling male. In the field, females oriented to the chorus at distances up to 100 m. In laboratory playback experiments, females were only attracted to chorus recordings made up to 32 m from a male. Chapter 3 explores whether sound amplitude or temporal structure degradation, dynamic acoustic features that changes with distance to a calling male, has a greater impact on chorus attractiveness and orientation. Through playback experiments we found that distance-dependent changes in call temporal structure had a larger effect on signal attractiveness than sound level, and that localization accuracy was proportional to sound level, signal attraction was not. This supported the necessity of perceptible fine temporal structure (pulse rise/fall time, pulse duration, etc.) in calls for female localization and discrimination, and that this information is probably not present at distances greater than 32 m. Finally, chapter 4 describes the representation of synthetic calls and natural chorus sounds in the central auditory system of H. versicolor. Single midbrain neurons had diverse response properties, including rapid, slow, and intermediate firing rate adaptation in response to stimuli, which resemble phasic, tonic, and phasi-tonic responses found in other anuran studies, respectively. The slowly-adapting cells had the least attenuation with recording distance from a calling male, and for an approaching female would likely be the first cells to respond to the chorus itself, or individual male calls embedded within. Rapidly-adapting cells, which demonstrate strong attenuation with distance and strong on/offset properties to call pulses are well positioned to aid in the detection of nearby individual male calls and the discrimination of temporal features essential for mate selection, which most likely take place at distances of no more than 4-8 m from a male calling in a dense chorus. Overall, we have just begun to explore auditory behavior and physiology with significant attention to the real-world context of the animal. The results of these studies demonstrate both the strict limits nature places on sensory systems, and their adaptability to the needs of the organism

Exploring Animal Behavior Through Sound: Volume 1

This open-access book empowers its readers to explore the acoustic world of animals. By listening to the sounds of nature, we can study animal behavior, distribution, and demographics; their habitat characteristics and needs; and the effects of noise. Sound recording is an efficient and affordable tool, independent of daylight and weather; and recorders may be left in place for many months at a time, continuously collecting data on animals and their environment. This book builds the skills and knowledge necessary to collect and interpret acoustic data from terrestrial and marine environments. Beginning with a history of sound recording, the chapters provide an overview of off-the-shelf recording equipment and analysis tools (including automated signal detectors and statistical methods); audiometric methods; acoustic terminology, quantities, and units; sound propagation in air and under water; soundscapes of terrestrial and marine habitats; animal acoustic and vibrational communication; echolocation; and the effects of noise. This book will be useful to students and researchers of animal ecology who wish to add acoustics to their toolbox, as well as to environmental managers in industry and government

How Do Adult Songbirds Learn New Sounds? Using Neuromodulators to Probe the Function of the Auditory Association Cortex

The ability to associate sounds and outcomes is vital in the life history of many species. Animals constantly assess the soundscape for cues associated with threats, competitors, allies, mates or prey, and experience is crucial for those associations. For vocal learning species such as humans and songbirds, learning sounds (i.e. perception and association learning) is also the first step in the process of vocal learning. Auditory learning is thought to depend on high-order cortical brain structures, where sounds and meaning are bound. In songbirds, the caudomedial nidopallium (NCM) is part of the auditory association cortex and is known to be involved in sound learning and perception. During songbird development, NCM plays a role in song learning, but in adulthood, NCM’s role is less clear and a matter of controversy in the literature. Furthermore, NCM is a site of action of neuromodulators including neuroestradiol (E2) and dopamine (DA). E2 is known to be produced by NCM neurons that contain the enzyme aromatase, which converts testosterone into E2. E2 production is also known to increase in the NCM during social interactions, and exogenous E2 modulates neuronal firing, but its effects on auditory behavior have not been pinpointed. Effects of E2 within the mammalian and avian hippocampus had been previously reported to support spatial learning. My main goal in this dissertation was to clarify the role of NCM in adult zebra finches (Taeniopygia guttata). Towards this end, I developed experiments in which I manipulated and thus documented the effects of two neuromodulatory systems, E2 and DA. I first examined the role of E2 in auditory-dependent behavior. For this, I developed a novel operant conditioning task with social reinforcement. Using this task, I showed that inhibiting E2 production within NCM during learning impairs acquisition of auditory associations. However, after the learning process was completed, I found that E2 production and even NCM activity were no longer required for maintaining high auditory performance, suggesting that NCM does not play a role in memory retrieval or auditory discrimination in adults. These findings led me to develop the hypothesis that E2 in NCM modulates online associative learning signals. In mammals, plasticity in virtually all learning-related brain regions is dependent on dopamine (DA) regulation and E2-DA interactions have been reported in several of these regions. Much is known about DA signaling in brain areas involved in decision-making and reinforcement learning. I here review the literature on motor and, especially, sensory cortical regions and provide a comprehensive review of the current knowledge of DA’s roles in cortical regions involved in sensory and motor learning, paying especial attention to non-mammalian vertebrates. I found that this literature is surprisingly limited in mammals, and often non-existent in non-mammalian vertebrates. Then, I hypothesized that E2 could be operating on dopaminergic (DAergic) signaling in NCM, in which D1 receptor (D1R) mRNA had been reported. Since there were no data on the anatomical and functional effects of these receptors, I investigated whether D1R protein could be detected and D1R-mediated signaling modulated synaptic plasticity in NCM. Specifically, I found that D1R protein is prevalent in NCM neurons, especially in aromatase-, GABA-, and parvalbumin-positive neurons. Activating D1R in vitro reduced the amplitude of spontaneous GABAergic and glutamatergic currents and increased the frequency of the latter. Similarly, activating D1R in vivo reduced firing of putative-inhibitory interneurons, but increased firing of putative-excitatory projection neurons. Finally, I showed that D1R activation disrupted stimulus-specific adaptation of NCM neurons, a phenomenon reflective of active auditory memory formation. In conclusion, this dissertation advances the literature by providing direct evidence that E2 production within the auditory cortex affects sensory learning, potentially by tapping into the DAergic system, which itself modulates plasticity mechanisms associated with learning and memory. I propose that these findings could apply to other vertebrates that contain aromatase and DA receptors in their auditory cortex, including humans

Transfer Properties of the Hair Cell-Afferent Fiber Synapse

The perception of sound is initiated in the inner ear by the conversion of vibrational energy into a neural code, a transduction process achieved by the chemical synapses of hair cells in the auditory periphery. Thus, the operation of the hair cell’s presynaptic active zone is key to understanding auditory transduction. However, the lack of suitable experimental systems in which to investigate both the presynaptic and postsynaptic aspects of this synapse with high resolution has limited our understanding of its functional characteristics. This work describes the development of a novel in vitro preparation of the amphibian papilla from Rana catesbeiana that provides electrical access to the pre- and postsynaptic elements of the hair cell’s afferent synapse. The transfer properties of this ribbon-type synapse have been explored with a variety of electrophysiological techniques, including whole-cell recordings, capacitance measurements, and iontophoresis. Glutamate is released from hair cells in response to Ca2+ influx through L-type Ca2+ channels and is detected by AMPA receptors in postsynaptic fibers. Gradations in the extent of presynaptic stimulation are encoded by a linear increase in the postsynaptic response with respect to the presynaptic Ca2+ current, a relation imparted primarily by an increase in the frequency of release events. Both spontaneous and evoked postsynaptic signals are stereotyped in waveform but highly variable in amplitude. Determination of the size of the quantal response provides compelling evidence that the majority of these events are multiquantal. Multiquantal events may originate from individual active zones and do not typically saturate postsynaptic receptors, thus suggesting that they may have functional significance. The results presented in this study are most consistent with compound exocytosis as the dominant form of transmitter release at individual hair-cell active zones