Alexander Ya. Supin

Marine mammal sensory systems

Sensory Anatomy, Morphology, and Neurology: Morphological and Histochemical Features of Odontocete Visual Neocortex I. Glezer, et al. The Cetacean Ear D.R. Ketten. Hearing Abilities: Auditory Brainstem Responses in the Harbor Porpoise N.G. Bibikov. Detection of Tone Glides by the Beluga Whale C.S. Johnson. Echolocution Abilities: The Rate at which a Harbor Porpoise Uses Echolocution at Night T. Akamatsu, et al. Target Sonar Discrimination Cues W.W.L. Au. Acoustic Communication and Behavior: Humpback Whale Song D.A. Helwig, et al. Seismic Communication in Northern Elephant Seals C. Shipley, et al. Sensory Systems and Behavior: Multi-Scale Communication by Vertebrates D.G. Bain. Effects of Adding Sounds to Cod Traps on the Probability of Collisions by Humpback Whales J. Lein, et al. Bioacoustics W.C. Verboom. 37 additional articles. Index.

The sensory physiology of aquatic mammals

1. Intruduction.- 1.1. General.- 1.2. Aquatic Mammals as Subjects of Experimental Studies.- 1.3. The Physical Properties of Water as a Sensory Medium.- 1.3.1. Acoustics.- 1.3.2. Optics.- 1.4. Psychophysical Measurement Procedures.- 1.4.1. The Operant Conditioning Method.- 1.4.2. Conditioned Reflex.- 1.4.3. The Statistical Basis for Threshold Evaluation.- 1.4.4. Data-Collection Procedures.- 2. Hearing in Cataceans.- 2.1. Ear Morphology.- 2.1.1. Outer Ear and Middle Ear.- 2.1.2. Inner Ear and Peripheral Neurons.- 2.2. Auditory Evoked Potentials in Cetaceans.- 2.2.1. Intracranial Evoked Potentials.- 2.2.2. Auditory Brainstem Responses (ABR).- 2.2.3. Noninvasively Recorded Cortical Evoked Responses.- 2.2.4. Rhythmic Evoked Potentials.- 2.2.5. Contribution of Various Frequency Bands to ABR.- 2.3. Evoked-Potential Procedures in Hearing Measurements.- 2.3.1. ABR Threshold Measurements.- 2.3.2. EFR and RFR Threshold Measurements.- 2.4. Hearing Sensitivity and Frequency Range.- 2.4.1. Psychophysical Data.- 2.4.2. Evoked-Potential Data.- 2.5. Temporal Resolution.- 2.5.1. Psychophysical Studies.- 2.5.2. Dependence of ABR on Stimulus Duration.- 2.5.3. ABR Recovery at Double-Click Stimulation.- 2.5.4. Gap-in-Noise Detection Measurements.- 2.5.5. Derivation of the Temporal Transfer Function of the Auditory System.- 2.5.6. Rhythmic Amplitude-Modulation Test and Modulation Transfer Function.- 2.5.7. Rhythmic Click Test.- 2.6. Frequency Tuning.- 2.6.1. Critical Ratios and Critical Bands.- 2.6.2. Tuning Curves.- 2.6.3. Notch-Noise Masking.- 2.6.4. Frequency-Discrimination Limens.- 2.6.5. Frequency Resolving Power.- 2.7. Sound-Intensity Discrimination.- 2.8. Directional Sensitivity, Spatial, and Binaural Hearing.- 2.8.1. Psychophysical Studies.- 2.8.2. Directional Sensitivity: Evoked-Potential Studies.- 2.8.3. Binaural Hearing: Evoked-Potential Studies.- 2.9. Frequency-Temporal and Frequency-Spatial Interactions.- 2.9.1. Temporal Interaction of Frequency-Colored Sound Pulses.- 2.9.2. Paradoxical Lateral Suppression.- 2.9.3. Interaction of Directional and Frequency Sensitivity.- 2.10. Sound-Conduction Pathways.- 2.11. Central Representation of the Auditory System.- 2.12. Implements to Echolocation.- 2.12.1. Hearing Frequency Range.- 2.12.2. Frequency Tuning and Temporal Resolution.- 2.12.3. Recovery Functions as a Basis of Invariant Perception of Echo Signals.- 2.12.4. Rippled Spectrum Resolution and Echolocation.- 2.12.5. Frequency-Temporal Interactions.- 2.12.6. Spatial Resolution.- 2.13. Summary.- 3. Hearing in Pinnipeds and Sirenians.- 3.1. Hearing in Pinnipeds.- 3.1.1. Ear Anatomy.- 3.1.2. Hearing Sensitivity and Frequency Range.- 3.1.3. Temporal Processing.- 3.1.4. Frequency Tuning.- 3.1.5. Intensity Discrimination.- 3.1.6. Directional Hearing.- 3.1.7. Auditory Representation in the Cerebral Cortex.- 3.1.8. Hearing Adaptation to Amphibious Lifestyle.- 3.2. Hearing in Sirenians.- 3.2.1. Ear Morp1hology.- 3.2.2. Psychophysical Audiogram.- 3.2.3. Evoked-Potential Data.- 3.3. Summary.- 4. Vision in Aquatic Mammals.- 4.1. Vision in Cetaceans.- 4.1.1. Eye Morphology.- 4.1.2. Visual Abilities of Cetaceans: Psychophysical Studies.- 4.1.3. Topographic Distribution of Retinal Ganglion Cells.- 4.1.4. Visual Projections to the Cerebral Cortex.- 4.2. Vision in Pinnipeds.- 4.2.1. Eye Morphology.- 4.2.2. Visual Abilities of Pinnipeds.- 4.2.3. Topographic Distribution of Retinal Ganglion Cells and Retinal Resolution.- 4.2.4. Visual Projections to the Cerebral Cortex.- 4.3. Vision in Sirenians.- 4.3.1. Eye Anatomy and Retinal Structure.- 4.3.2. Psychophysical Studies.- 4.3.3. Topographic Distribution of Ganglion Cells and Retinal Resolution.- 4.4. Summary.- 5. Somatic Sense in Aquatic Mammals.- 5.1. Somatic Sense in Cetaceans.- 5.2. Somatic Sense in Pinnipeds.- 5.2.1. Morphological and Psychophysical Data.- 5.2.2. Somatosensory Projections to the Cerebral Cortex.- 5.2.2. Tactile Sensitivity of Vibrissae.- 5.3. Summary.- References.

Behavioral and auditory evoked potential audiograms of a false killer whale (Pseudorca crassidens)

Behavioral and auditory evoked potential (AEP) audiograms of a false killer whale were measured using the same subject and experimental conditions. The objective was to compare and assess the correspondence of auditory thresholds collected by behavioral and electrophysiological techniques. Behavioral audiograms used 3-s pure-tone stimuli from 4 to 45 kHz, and were conducted with a go/no-go modified staircase procedure. AEP audiograms used 20-ms sinusoidally amplitude-modulated tone bursts from 4 to 45 kHz, and the electrophysiological responses were received through gold disc electrodes in rubber suction cups. The behavioral data were reliable and repeatable, with the region of best sensitivity between 16 and 24 kHz and peak sensitivity at 20 kHz. The AEP audiograms produced thresholds that were also consistent over time, with range of best sensitivity from 16 to 22.5 kHz and peak sensitivity at 22.5 kHz. Behavioral thresholds were always lower than AEP thresholds. However, AEP audiograms were completed in a shorter amount of time with minimum participation from the animal. These data indicated that behavioral and AEP techniques can be used successfully and interchangeably to measure cetacean hearing sensitivity.

Envelope-following response and modulation transfer function in the dolphin's auditory system.

Potentials following the envelopes of sinusoidally amplitude-modulated tones (envelope response, EFR) were recorded from the head surface in bottle-nosed dolphins. EFR appeared at modulation rates from 300 to 3400 Hz. EFR amplitude was higher at rates from 500 to 1400 Hz with peaks at 600 and 1000 Hz and troughs at 700-850, 1200, and 2000 Hz; at rates above 1700 Hz it fell steeply. EFR dependence on modulation depth was linear except at the highest response amplitudes, which made it possible to obtain the modulation transfer function (MTF). EFR appears to be generated by several sources. One source had a latency of about 4 ms and followed modulation rates up to 1700 Hz, while another had a latency of 2 ms and followed modulation rates up to 3.4 kHz. The latencies of both sources coincided with those of waves of the auditory brainstem response (ABR). Comparison of MTF with the ABR spectrum had shown that several MTF peaks and troughs reflected the ABR spectrum. The latencies of the two sources were consistent with origins in the midbrain and auditory nerve, respectively.

Frequency resolving power measured by rippled noise

Frequency resolving power (FRP) was measured in normal humans using rippled noise with a phase-reversal test. The principle of the test was to find the highest ripple density at which an interchange of mutual peak and trough position (the phase reversal) in the rippled spectrum is detectable. In the frequency range below 0.5 kHz FRP was found to be about 21 ripples per kHz when tested by both broad-band and narrow-band rippled noise. In the frequency range above 2 kHz, FRP measured by the narrow-band rippled noise was 22 to 23 relative units (relation of the noise central frequency to the ripple frequency spacing).

Adaptive features of aquatic mammals' eye

The eye of aquatic mammals demonstrates several adaptations to both underwater and aerial vision. This study offers a review of eye anatomy in four groups of aquatic animals: cetaceans (toothed and baleen whales), pinnipeds (seals, sea lions, and walruses), sirenians (manatees and dugongs), and sea otters. Eye anatomy and optics, retinal laminar morphology, and topography of ganglion cell distribution are discussed with particular reference to aquatic specializations for underwater versus aerial vision. Aquatic mammals display emmetropia (i.e., refraction of light to focus on the retina) while submerged, and most have mechanisms to achieve emmetropia above water to counter the resulting aerial myopia. As underwater vision necessitates adjusting to wide variations in luminosity, iris muscle contractions create species‐specific pupil shapes that regulate the amount of light entering the pupil and, in pinnipeds, work in conjunction with a reflective optic tapetum. The retina of aquatic mammals is similar to that of nocturnal terrestrial mammals in containing mainly rod photoreceptors and a minor number of cones (however, residual color vision may take place). A characteristic feature of the cetacean and pinniped retina is the large size of ganglion cells separated by wide intercellular spaces. Studies of topographic distribution of ganglion cells in the retina of cetaceans revealed two areas of ganglion cell concentration (the best‐vision areas) located in the temporal and nasal quadrants; pinnipeds, sirenians, and sea otters have only one such area. In general, the visual system of marine mammals demonstrates a high degree of development and several specific features associated with adaptation for vision in both the aquatic and aerial environments. Anat Rec, 290:701–715, 2007.

Electrophysiological Studies of Hearing in Some Cetaceans and A Manatee

Auditory brain stem response (ABR) is used extensively for studies of hearing. The possibility to record activity of auditory nerve centers without any surgery makes this evoked response useful for investigation of auditory physiology and pathology, particularly, for comparative studies of hearing in various groups of animals.

Temporal resolution in the dolphin’s auditory system revealed by double‐click evoked potential study

Temporal resolution of hearing in two bottlenosed dolphins was estimated by measuring auditory brain-stem response (ABR) recovery in conditions of double-click stimuli. From these data, temporal transfer function of the supposed integrator was derived assuming nonlinear transform of the integrator output to ABR amplitude. The obtained temporal transfer function showed a nearly constant level up to 200 microseconds. then decay to approximately -3 dB at 300 microseconds (as presented in the sound intensity domain), and subsequent decay of 10-11 dB per time doubling (about 35 dB/decade).

Hearing in Cetaceans

The auditory system of cetaceans, since they are capable of underwater hearing and adapted for echo location, has attracted major interest for many years. More precisely speaking, one of the two cetacean suborders, Odontoceti (toothed whales, dolphins, and porpoises) was a subject of a particular interest. Probably all of them (at least, all species investigated to date) are capable of active echolocation. For echolocation, they use ultrasonic signals ranging to higher than 100 kHz (Kellogg, 1959; Norris et al., 1961; Norris, 1969; Au, 1993). Some information on auditory perception of odontocetes obtained in behavioral conditioning studies is presented in reviews by Popper (1980), Fobes and Smock (1981), Watkins and Wartzok (1985), and Au (1993).

The interaction of outgoing echolocation pulses and echoes in the false killer whale’s auditory system: Evoked-potential study

Brain auditory evoked potentials (AEP) associated with echolocation were recorded in a false killer whale Pseudorca crassidens trained to accept suction-cup EEG electrodes and to detect targets by echolocation. AEP collection was triggered by echolocation pulses transmitted by the animal. The target was a hollow aluminum cylinder of strength of -22 dB at a distance from 1 to 8 m. Each AEP record was obtained by averaging more than 1000 individual records. All the records contained two AEP sets: the first one of a constant latency and a second one with a delay proportional to the distance. The timing of these two AEP sets was interpreted as responses to the transmitted echolocation pulse and echo, respectively. The echo-related AEP, although slightly smaller, was comparable to the outgoing click-related AEP in amplitude, even though at a target distance as far as 8 m the echo intensity was as low as -64 dB relative to the transmitted pulse in front of the head. The amplitude of the echo-related AEP was almost independent of distance, even though variation of target distance from 1 to 8 m influenced the echo intensity by as much as 36 dB.