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R R Fay

Publications and source records attributed to R R Fay.

At least 19 recordsLinked to original sources
PubMed1992

The effects of temperature change and transient hypoxia on auditory nerve fiber response in the goldfish (Carassius auratus).

Temperature change and hypoxia produce consistent, reversible effects on the response of single auditory nerve fibers in the goldfish. Cooling and hypoxia produce reductions of a cell's spontaneous activity, sensitivity, most excitatory or best frequency (BF) at a given signal level, and overall responsiveness to acoustic stimulation. Warming above ambient temperatures increases a cell's spontaneous activity, sensitivity, BF, and responsiveness. Adaptation, or the tendency for responsiveness to decline with time during a stimulus, increases during hypoxia and cooling, and decreases during warming. The effects of temperature change and hypoxia on a fiber's BF are similar to the effects of overall sound level. Since BF normally increases with sound level, the BF-shift with temperature change and hypoxia can be understood as a change in sensitivity or the overall effectiveness of a stimulus at a given sound level. The effects on neural response of temperature change and hypoxia are probably due in part to changes in the release and replenishment of neurotransmitter at the synapses between hair cells and auditory nerve fibers.

Acoustic Stimulation↗
PubMed1992

Analytic listening by the goldfish.

A stimulus generalization paradigm was used with classical respiratory conditioning to study analytic listening in the goldfish. Animals were first conditioned to suppress respiration upon the presentation of a long-duration complex sound comprised of two sinusoidal components, 166 and 724 Hz. Conditioned animals were then presented with a set of eight novel test tones with frequencies between 95 and 1514 Hz, and including 166 and 724 Hz. Response magnitudes were greatest at the frequencies of the components making up the complex to which the animals were initially conditioned. This is a demonstration that the goldfish had acquired independent information about the frequencies of the individual sinusoidal components making up a complex sound, and thus had listened to the complex analytically. To my knowledge, this is the first demonstration of simultaneous frequency analysis and analytic listening by a nonhuman animal, and suggests that this fundamental aspect of human hearing may be a primitive character shared with the fishes and perhaps with all living vertebrates.

Acoustic Stimulation↗
PubMed1992

Psychometric functions for level discrimination and the effects of signal duration in the goldfish (Carassius auratus): psychophysics and neurophysiology.

Classical conditioning of respiration was used to obtain psychometric functions for pulsed tone level discrimination in the goldfish (Carassius auratus). Conditioned respiratory suppression is a graded response that has some properties of a confidence rating measure. These properties were used to obtain receiver operating characteristics (ROC) and psychometric functions using a blocked method of constant stimuli. Empirical ROCs and neurometric functions were also obtained for single auditory-nerve fibers using spike count as the decision variable in order to evaluate a simple rate code for level discrimination. Psychometric and neurometric functions for level discrimination are similar in showing the same general form (summarized by Weibull functions) that is independent of signal duration. The lower slope of neurometric functions compared with behavioral functions for level discrimination is in accord with similar data on sound detection and vision in nonhuman mammals. Both neural and psychophysical level discrimination thresholds decline with increasing duration (20 to 320 ms), with similar slopes except at short signal durations (20 to 50 ms). At these durations, the animal's use of a channel-selection strategy and neural information following stimulus offset could reduce the difference between neural and psychophysical thresholds. The slopes of the neural and psychophysical duration functions are similar to those for human observers, but the majority of auditory-nerve fibers sampled have lower level discrimination thresholds than the behaving animal. Since human observers perform better than the majority of neurons in level discrimination, well-trained human listeners may be able to select channels with superior information, or to combine information across channels in ways that the goldfish and other animals do not. In general, one is encouraged to believe that neural mechanisms need not be more complex or sensitive than those considered here to account for pure-tone level discrimination in fishes, humans, and other vertebrates.

Animals↗
PubMed1991

Masking and suppression in auditory nerve fibers of the goldfish, Carassius auratus.

The responses of single fibers of the auditory nerve of the goldfish (Carassius auratus) were recorded in response to two tones of different duration (20 ms 'signals' and 200 ms 'maskers') presented simultaneously or non-simultaneously. A single tone may produce excitation, adaptation, and suppression in auditory nerve fibers. For fibers with characteristic frequencies (CF) in the 200 to 400 Hz range, frequencies well above CF tend to produce suppression. If the net response to the masker tone is excitation, an added excitatory signal tone tends to increment the response in a way predictable from the rate-level function for the masker. A masker can attenuate the response to a signal as a result of a compressive and saturating response to the masker, and as a result of a low signal-to-masker ratio. If the net response to a masker tone is suppression, it effectively subtracts from signal excitation, causing 'suppressive masking.' In non-spontaneous fibers, suppression, additive excitatory effects, and adaptation can be revealed by responses to the signal in the absence of spike responses to the masker. In general, the ability of one tone (the masker) to reduce the response to a second tone (the signal) is greater in non-spontaneous fibers than in spontaneous fibers. These results also show that estimates of the frequency selectivity of many goldfish auditory nerve fibers will depend on whether the response of the fiber is defined by excitation, suppression, or both. The response of many fibers with CF in the 200-400 Hz region, as defined by excitation, can be masked or suppressed by a broad range of frequencies covering the effective hearing range of the goldfish.

Acoustic Stimulation↗
PubMed1990

Suppression and excitation in auditory nerve fibers of the goldfish, Carassius auratus.

The suppression of background spike activity in the absence of deliberate acoustic stimulation occurs in fibers of the goldfish saccular nerve tuned in the region of 250 Hz. Suppression is most robust in the frequency range between 450 and 1050 Hz, the range of CF for the mid- and high-frequency saccular fibers. Suppression of background activity tends to occur following the suppressor tone offset ('off-suppression'), even though the spike response during the suppressor is below the background rate. This suggests that the suppressor tone is excitatory at the level of the hair cells and their synapses onto saccular afferents. Tones at the low- frequency edge of the suppression region may show net excitation at low intensity levels, and net suppression at higher levels. This suggests that the spike response observed is the result of the relative strengths of excitatory and suppressive effects which operate simultaneously. The magnitude and frequency of best suppression tends to increase with stimulus intensity. A suppressing tone produces transient excitation at onset. In fibers with high levels of spontaneous activity, a spike response 'rebound' often occurs 20 to 50 ms following the suppressing tone offset. These 'on' and 'off' effects are not due to energy 'splatter' in the stimulus domain. Suppression by tones can also be observed in non-spontaneous fibers when the background spike activity is evoked by noise. In these cases, however, off-suppression following a suppressed response and the 'rebound' seldom occurs. Possible sites of suppression are the hair cells and their synapses, the spike-initiation zones of the saccular afferents, and efferent inhibition. The most likely site seems to be the spike-initiation zones of saccular afferents. An important consequence of suppression for hearing is the sharpening of frequency response areas for low frequency fibers, and the partial preservation of frequency analysis in saccular fibers stimulated well above threshold.

Acoustic Stimulation↗
PubMed1989

Intensity discrimination of pulsed tones by the goldfish (Carassius auratus).

Intensity discrimination thresholds for 500-ms pure-tone bursts were measured as a function of frequency in the goldfish (Carassius auratus) using classical respiratory conditioning. At 55-dB sensation level (SL), thresholds range from 1.44-2.2 dB between 100 and 1600 Hz. There is not important effect of frequency on intensity discrimination. Thresholds at 35-dB SL average 0.7 dB higher than at 55-dB SL. This is a small difference in the context of the threshold variability. In intensity discrimination acuity, the goldfish is quantitatively similar to other vertebrates, including birds and mammals.

Acoustic Stimulation↗
PubMed1989

Frequency discrimination in the goldfish (Carassius auratus): effects of roving intensity, sensation level, and the direction of frequency change.

The ability of goldfish to detect a change in the frequency of 400-Hz pure-tone bursts was studied using classical respiratory conditioning. The frequency discrimination threshold was measured at 15-, 35-, and 55-dB sensation level (SL), under conditions of (1) constant intensity, (2) roving intensity (plus and minus 6-dB burst-to-burst variation in intensity), (3) upward frequency change, and (4) downward frequency change. There was no overall effect of SL on frequency discrimination, but roving the intensity elevated thresholds by about 6 Hz (33%) and increased variability. Upward shifts in frequency elevated thresholds slightly (by 2 Hz or 10%) relative to downward shifts. These relatively small and statistically insignificant effects suggest that earlier measures of frequency discrimination in the goldfish are not due to the detection of simple changes in spike rate within individual peripheral channels.

Acoustic Stimulation↗
PubMed1989

Hot-film anemometry for measuring lateral line stimuli.

A hot-film anemometer system has been calibrated and evaluated for the measurement of sinusoidal water motions used in stimulating the mechanosensory lateral line system of a teleost fish. The response of the anemometer system to water motions created by a vibrating sphere was measured over a wide range of frequencies, intensities, and distances from the sphere. The amplitude response of the system to signals along the axis of sphere vibration was found to be linear over a 50-dB range for frequencies from 10-200 Hz, with the lowest end of the dynamic range (between 10(-8) and 10(-9) m) corresponding to physiological measures of best sensitivity in the lateral line system of the mottled sculpin, Cottus bairdi. The measured attenuation of the signal with distance was also linear over this frequency range out to distances of six times the radius ( = 3 mm) of the sphere and followed the predicted falloff rate for a dipolar source. The linear response of the anemometer system over a wide dynamic range encompassing the detection range of the lateral line system, and the match between predicted and measured motions at varying distances from a dipolar source, indicates that hot-film anemometry is a useful technique for measuring low-level, low-frequency signals likely to stimulate the lateral line system and other hydrodynamic detectors.

Animals↗
PubMed1989

The temporal evolution of masking and frequency selectivity in the goldfish (Carassius auratus).

The temporal evolution of masking and frequency selectivity was studied in the goldfish using classical respiratory conditioning and a tracking psychophysical procedure. The temporal position of a brief tonal signal within a longer duration, tonal masker has little or no effect on signal detectability when the frequency of the masker is less than or equal to that of the signal. For masker frequencies above that of the signal, signal detectability improves as the signal onset is delayed relative to that of the masker. These patterns of tone-on-tone masking are quite similar to those observed for humans. These temporal masking patterns are qualitatively similar in shape to the peristimulus-time histogram profiles of the low-frequency saccular fibers thought to be used in this task. Frequency- and time-dependent changes in signal detectability result in specific changes in the sharpness of psychophysical tuning curves (PTC). In general, PTCs determined for signals occurring at masker onset are the most broadly tuned, and PTCs determined in forward masking are the most sharply tuned. The PTCs for signals temporally centered in the masker are intermediate. These results suggest that temporal tone-on-tone masking patterns and the temporal evolution of psychophysical tuning curves result from the response properties of peripheral auditory-nerve fibers.

Acoustic Stimulation↗
PubMed1988

Comparative psychoacoustics.

Psychophysical data on unspecialized mammals commonly used in auditory research were compiled from the literature, and an attempt was made to compare the hearing capacities of these species with man. Binaural hearing and sound localization were not considered. The most complete psychoacoustic data exist for chinchilla, cat, various primates, and the mouse. The existing data include audiograms, frequency and intensity discrimination thresholds, critical masking ratios, critical bandwidths, temporal summation functions at threshold, psychophysical tuning curves, gap detection thresholds, temporal modulation transfer functions, temporal discriminations, and auditory filter shapes. In general, the qualitative forms of most all psychoacoustic functions for these mammals are similar to those for man, and there is little reason to believe that the mechanisms underlying these capacities are different across mammals. Although the discriminative capacities of humans are generally more acute than those of non-humans, the database on the capacities of non-humans is not yet sufficient for systematic comparisons across species to be made with confidence.

Animals↗
PubMed1987

Response dynamics of goldfish saccular fibers: effects of stimulus frequency and intensity on fibers with different tuning, sensitivity, and spontaneous activity.

The effects of stimulus frequency and intensity on response patterns (PST histograms) to tone burst stimulation were examined in differently tuned saccular fibers of the goldfish. In addition, the sensitivity of these fibers to amplitude-modulated (AM) signals of different carrier frequencies was measured. The response patterns evoked by unmodulated signals were a complex function of tuning, spontaneous activity and sensitivity of the fiber, and the frequency and intensity of the signal. Frequency-dependent response patterns were found in low-frequency fibers with best frequencies (BF) below 200 Hz. Responses in these fibers ranged from tonic to phasic in nonspontaneous fibers and included more complex patterns in spontaneously active fibers, such as suppression of evoked activity below spontaneous levels. Midfrequency fibers (BF = 500-600 Hz) showed responses similar to those in low-frequency fibers, but with less dependence on frequency. In contrast, both high-frequency (BF = 800-1000 Hz) and wideband, untuned fibers showed frequency-invariant patterns of adaptation. High-frequency fibers were equally sensitive to AM signals at all frequencies tested. The sensitivity of low-frequency fibers to AM, however, increased as a function of carrier frequency and corresponded to the degree of adaptation in response to unmodulated tones. In general, the AM sensitivity of a fiber could be predicted more by its pattern of response to unmodulated signals than by its tuning characteristics.

Acoustic Stimulation↗
PubMed1986

Acoustic response and tuning in saccular nerve fibers of the goldfish (Carassius auratus).

The acoustic frequency selectivity of over 500 saccular nerve fibers of the goldfish was studied using automated threshold tracking based on spike rate increments defined statistically. Saccular fibers of the goldfish show great variation in (1) best sensitivity (-26 to + 35 dB re: 1 dyn/cm2), (2) best frequency (below 100 to 1770 Hz), (3) spontaneous rate (0 to over 200 spikes/s), (4) spontaneous type (silent, regular, irregular, burst), and (5) degree of tuning (Q 10 dB from less than 0.1 to 2). Saccular fibers may be grouped into four nonoverlapping categories based on tuning and best frequency: (1) untuned (less than 10-dB variation in sensitivity between 100 and 1000 Hz), (2) low frequency (BF from below 120 to 290 Hz), (3) midfrequency (BF between 330 and 670 Hz), and (4) high frequency (BF between 790 and 1770 Hz). Within each category, all spontaneous rates and types, and all degrees of tuning can be observed. The least sensitive fibers within each group have zero spontaneous rates. The goldfish is like all other vertebrates studied in that the peripheral auditory system is adapted for frequency selectivity throughout the animal's entire frequency range of hearing. Peripheral tuning most likely accounts for behavioral determinations of the "auditory filter" and for the detectability of signals masked by noise. The signal-to-noise ratio enhancement provided by these peripheral filters is likely to be of primary biological significance. A "place principle" of sound quality analysis based on lines "labeled" according to best frequency in the brain cannot be ruled out on the basis of the peripheral physiology.

Acoustic Stimulation↗
PubMed1985

Adaptation effects on amplitude modulation detection: behavioral and neurophysiological assessment in the goldfish auditory system.

The ability of goldfish to detect the presence of amplitude modulations (AM) impressed on 200, 570 and 800 Hz tones was measured under stimulus conditions producing intermittent, short-term adaptation and continuous, long-term adaptation. Sensitivity to AM under intermittent conditions increased as a function of modulation rate, with thresholds of AM detection occurring between 10 and 25% modulation at 10 Hz and around 2% modulation at 100 Hz. AM sensitivity was independent of carrier frequency and did not change under randomly varying intensity changes. Under long-term adaptation, thresholds of AM detection ranged from 1.3% at 100 Hz to 2.1% at 10 Hz, showing increased sensitivity and less dependence on modulation rate. The effects of overall intensity on AM sensitivity were the same for both conditions, with sensitivity being relatively independent of overall signal level at 10 Hz modulation and dependent on level at 100 Hz. The responses of goldfish auditory neurons to modulated and unmodulated signals were measured under stimulus conditions similar to those for behavioral studies. Single saccular neurons responded to modulated signals with both an increase in average rate above that evoked by the unmodulated signal and with phase-locking to the AM envelope. Rate increments and phase-locking responses were observed in neurons showing significant short-term adaptation to the unmodulated signal, whereas neurons showing no increase in rate or synchronization to the AM envelope showed little or no adaptation to the unmodulated signal. The effects of overall intensity, modulation rate and adaptation duration on neural responses were similar to behaviorally measured effects. These results show that adaptation affects AM detection and that phase-locking to the AM envelope is the most likely basis for behavioral detection.

Acoustic Stimulation↗
PubMed1985

Sound intensity processing by the goldfish.

Capacities of the goldfish for intensity discrimination were studied using classical respiratory conditioning and a staircase psychophysical procedure. Physiological studies on single saccular (auditory) nerve fibers under similar stimulus conditions helped characterize the dimensions of neural activity used in intensity discrimination. Incremental intensity difference limens (IDLs in dB) for 160-ms increments in continuous noise, 500-ms noise bursts, and 500-ms, 800-Hz tone bursts are 2 to 3 dB, are independent of overall level, and vary with signal duration according to a power function with a slope averaging - 0.33. Noise decrements are relatively poorly detected and the silent gap detection threshold is about 35 ms. The IDLs for increments and decrements in an 800-Hz continuous tone are about 0.13 dB, are independent of duration, and are level dependent. Unlike mammalian auditory nerve fibers, some goldfish saccular fibers show variation in recovery time to tonal increments and decrements, and adaptation to a zero rate. Unit responses to tone increments and decrements show rate effects generally in accord with previous observations on intracellular epsp's in goldfish saccular fibers. Neurophysiological correlates of psychophysical intensity discrimination data suggest the following: (1) noise gap detection may be based on spike rate increments which follow gap offset; (2) detection of increments and decrements in continuous tones may be determined by steep low-pass filtering in peripheral neural channels which enhance the effects of spectral "splatter" toward the lower frequencies; (3) IDLs for pulsed signals of different duration can be predicted from the slopes of rate-intensity functions and spike rate variability in individual auditory nerve fibers; and (4) at different sound pressure levels, different populations of peripheral fibers provide the information used in intensity discrimination.

Acoustic Stimulation↗
PubMed1978

Coding of information in single auditory-nerve fibers of the goldfish.

Patterns of activity in single fibers of the saccular branch of the auditory nerve of goldfish were analyzed in response to acoustic stimulation. Neurons were categorized on the basis of differences in spontaneous activity patterns, rates of adaptation, and frequency response areas. The sensitivity and responsiveness of neurons are presented both in terms of impulse rate and synchronization (phase locking). Nonspontaneous neurons fall into two clear frequency response area categories based upon impulse rate criteria. Spontaneously active neurons have continuously distributed frequency response characteristics based upon synchronization criteria. Functions relating impulse rate responsiveness to frequency indicate that frequency is coded only crudely as an across-fiber pattern of impulse rates. Synchronization responsiveness functions show that frequency is coded temporally with the same precision in the goldfish auditory nerve that it is in mammals, at 1000 Hz and below.

Action Potentials↗
PubMed1978

Auditory masking patterns in the goldfish (Carassius auratus): psychophysical tuning curves.

The masking effects of tones on the detection auditory signals were studied in goldfish using the psychophysical tuning-curve paradigm. For signals below 350 Hz, masking is an inverse function of the frequency separation between masker and signal; a finding consistent with previous masking studies on fishes, birds and mammals. For signals above 350 Hz, masking peaks occur both in the 350 Hz region and at the frequency of the signal. Quantitative comparisons with recent neural tuning curves for goldfish saccular neurones suggest that the filtering observed may be determined by mechanical frequency selectivity below 350 Hz, but by a neural analysis of temporal patterns above this range.

Animals↗
PubMed1978

Psychophysical tuning curves in vibrotaction.

The frequency-response characteristics of channels used in human vibrotaction were studied by using a psychophysical tuning-curve paradigm derived from auditory research. Sinusodial 200-msec vibratory bursts delivered to the thenar eminence of the hand were detected in the presence of sinusodial maskers delivered to the same skin area either continuously or pulsed in forward masking. Psychophysical tuning curves were obtained by determining the intensity of maskers of varied frequency necessary to mask a 10-dB SL test stimulus of fixed frequency. The results support the notion that at least two independent channels operate in human vibrotaction. There was no evidence for frequency selective mechanisms other than those at the periphery. Psychophysical tuning curves were similar to neural tuning curves for individual cutaneous mechanoreceptors.

Adult↗