Healing power in the Marian miracle books of Bavarian healing shrines, 1489-1523 A.D.
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Books↗
Biomedical subjects
D B Moody
Publications and source records attributed to D B Moody.
Formant frequency discrimination by Japanese macaques (Macaca fuscata).
These studies investigated formant frequency discrimination by Japanese macaques (Macaca fuscata) using an AX discrimination procedure and techniques of operant conditioning. Nonhuman subjects were significantly more sensitive to increments in the center frequency of either the first (F1) or second (F2) formant of single-formant complexes than to corresponding pure-tone frequency shifts. Furthermore, difference limens (DLs) for multiformant signals were not significantly different than those for single-formant stimuli. These results suggest that Japanese monkeys process formant and pure-tone frequency increments differentially and that the same mechanisms mediate formant frequency discrimination in single-formant and vowel-like complexes. The importance of two of the cues available to mediate formant frequency discrimination, changes in the phase and the amplitude spectra of the signals, was investigated by independently manipulating these two parameters. Results of the studies indicated that phase cues were not a significant feature of formant frequency discrimination by Japanese macaques. Rather, subjects attended to relative level changes in harmonics within a narrow frequency range near F1 and F2 to detect formant frequency increments. These findings are compared to human formant discrimination data and suggest that both species rely on detecting alterations in spectral shape to discriminate formant frequency shifts. Implications of the results for animal models of speech perception are discussed.
Adult↗
Low-frequency detection and discrimination following apical hair cell destruction.
This study assessed the effects of apical hair cell destruction on the detection and discrimination of low-frequency stimuli. Monauralized chinchillas were trained using operant conditioning and positive reinforcement to respond to pure-tone stimuli in the absence and the presence of a high-pass noise masker. Following the collection of the baseline absolute thresholds, psychophysical tuning curves (PTCs) also were determined at low and high frequencies. Apical hair cells in the experimental ear of each subject then were destroyed by applying a liquid-nitrogen-cooled miniature cryoprobe to the bony wall of the cochlea. Post-cryosurgery, unmasked and masked absolute thresholds and psychophysical tuning curves were re-evaluated. Following cryosurgery, low-frequency absolute thresholds increased by 30-50 dB. High-pass masking data suggested that receptors that were unaffected by the masking noise were responsible for the remaining low-frequency hearing. Low-frequency tuning, monitored by assessing changes in PTCs, was significantly altered following apical receptor cell loss, with the most effective maskers located several octaves above the test tone frequency. Following these determinations, one control and two experimental subjects then participated in a third experiment assessing low-frequency discrimination acuity. Some discrimination ability was retained after the cryosurgery; however, these post-lesion difference limens increased when a high-pass noise masker was added to the test environment. At the termination of the behavioral experiment, subjects were euthanized and their cochleae dissected to correlate behavioral and histopathological data. The data suggest that receptors located in frequency regions of the cochlea normally responsive to middle and high frequencies may be responsible for detection and discrimination of low-frequency stimuli in apically damaged cochleae. These data are consistent with other reports which indicate that redundant mechanisms are available for the detection of low-frequency stimuli, and they provide new information regarding how low-frequency stimuli are discriminated throughout the cochlea.
Acoustic Stimulation↗
Apical hair cells and hearing.
This study assessed the contribution of the apical hair cells to hearing. Guinea pigs, chinchillas and monkeys were behaviorally trained using positive reinforcement to respond to pure-tone stimuli. When a stable audiogram had been determined, each subject received one of three experimental treatments: ototoxic drug administration, low-frequency noise exposure, or the application of a cryoprobe to the bony wall of the cochlear apex. After post-treatment audiograms stabilized, subjects were euthanized and the percentage of hair cells remaining was assessed by light microscopy. Results indicate that a redundancy of encoding mechanisms exist in the mammalian cochlea for low-frequency stimuli. They also suggest that a very small percentage of apical hair cells are sufficient for some low-frequency hearing. Finally, data from this and other studies suggest that the low-frequency threshold shift caused by the loss of a certain percentage of apical hair cells is less pronounced than the high-frequency threshold shift caused by the loss of a comparable percentage of basal hair cells. These data agree with anatomical and electrophysiological evidence that functional as well as anatomical differences may exist between the apex and base of the cochlea.
Animals↗
Frequency discrimination in the monkey.
This study evaluated frequency discrimination ability in 11 monkeys over an extended period of time using a repeating-standard procedure and the method of constant stimuli. The intersubject variability of the difference limens for frequency (delta F) was large, as reported by other investigators, but similar in magnitude to the variability of the difference limens for intensity (delta I) from three of the same subjects in an intensity discrimination experiment. Continued training generally resulted in a rapid decrease in delta F's, followed by a longer-term, slower decrease. For one subject delta F's slowly decreased throughout a 190-week time period. This long-term training effect was specific to frequency discrimination; a similar effect was not observed for the same subject tested in an intensity discrimination experiment. Finally, delta F's from the well-trained monkeys of this study were larger than monkey delta F's from this laboratory reported in an earlier study, and than human delta F's. An anatomical explanation for the human/monkey delta F magnitude difference is explored.
Animals↗
Categorical perception of conspecific communication sounds by Japanese macaques, Macaca fuscata.
Field studies indicate that Japanese macaque (Macaca fuscata) communication signals vary with the social situation in which they occur [S. Green, "Variation of vocal pattern with social situation in the Japanese monkey (Macaca fuscata): A field study," in Primate Behavior, edited by L. A. Rosenblum (Academic, New York, 1975), Vol. 4]. A significant acoustic property of the contact calls produced by these primates is the temporal position of a frequency peak within the vocalization, that is, an inflection from rising to falling frequency [May et al., "Significant features of Japanese macaque communication sounds: A psychophysical study," Anim. Behav. 36, 1432-1444 (1988)]. The experiments reported here are based on the hypothesis that Japanese macaques derive meaning from this temporally graded feature by parceling the acoustic variation inherent in natural contact calls into two functional categories, and thus exhibit behavior that is analogous to the categorical perception of speech sounds by humans. To test this hypothesis, Japanese macaques were trained to classify natural contact calls by performing operant responses that signified either an early or late frequency peak position. Then, the subjects were tested in a series of experiments that required them to generalize this behavior to synthetic calls representing a continuum of peak positions. Demonstration of the classical perceptual effects noted for human listeners suggests that categorical perception reflects a principle of auditory information processing that influences the perception of sounds in the communication systems not only of humans, but of animals as well.
Animal Communication↗
Discrimination strategies in animal psychophysics and their role in understanding sensory receptor function.
Discrimination is defined in a restricted sense here as a precise and specifiable relation between stimuli and responses. Experimenter control of stimulation is one significant feature of this relation. It is suggested that there may be some important differences between discrimination of drugs and exteroceptive stimulation. However, a discussion of current strategies in animal psychophysics might uncover similarities between these two discrimination formats useful in formulating questions and designing future research. Traditionally animal psychophysics has focused on basic questions of acuity and sensitivity (threshold). Beyond their obvious value in the study of comparative sensory function and evolutionary development, these experiments have provided particularly important new insights into the understanding of peripheral sensory transduction and processing and their relation to perception. Our experiments have been carried out in animals whose hearing has been impaired by drugs and cryolesions, and relations have been sought between the subsequent hearing loss and the histopathological changes occurring in the auditory receptor cells of the inner ear. But threshold sensitivity is only one of many perceptual dimensions and tells us nothing of the discriminations that are made among stimuli which are clearly above minimum detectable levels. For example, discriminations occur along stimulus dimensions such as wavelength of light, sound pressure, acoustic frequency, and so on. Sensory systems also permit the accurate location of the source of stimulation at a distance, the selection of certain frequencies or wavelengths and the rejection of others, and finally the discrimination among very complex but biologically useful signals such as speech. Prototypical experiments are described; the results suggest significant and orderly relations with peripheral sensory processing mechanisms. The power of operant behavior to examine perception from a variety of perspectives is discussed.
Animals↗
Cryoprobe-induced apical lesions in the chinchilla. II. Effects on behavioral auditory thresholds.
Lesions of the hair cells in the cochlear apex were produced by a miniature cryoprobe and changes in behavioral auditory thresholds were measured. Monauralized adult chinchillas were behaviorally trained using operant procedures to produce pure-tone audiograms at frequencies from 63 Hz to 40 kHz. Following collection of baseline thresholds, the apical and middle turns of the experimental ear were visualized through a hole drilled in the bulla and a copper cryoprobe that had been cooled in liquid nitrogen was placed on the apical turn of the cochlea. Post-lesion threshold shifts from two subjects showed a flat loss of approximately 20 dB restricted to frequencies below either 710 Hz or 1 kHz; thresholds were normal at higher frequencies. The cytocochleograms, prepared from the ears following completion of threshold testing, show an almost complete loss of both inner and outer hair cells in the apical-most 20% of the cochlea with an abrupt transition region to areas of normal-looking hair cell populations. The relationship between the frequencies at which hearing was impaired and the location of missing hair cells along the basilar membrane is in agreement with the frequency-place map for the chinchilla of Eldredge et al. [(1981) J. Acoust. Soc. Am. 69, 1091-1095]. The magnitude of the loss, however, is less than might be expected based on comparison with threshold shifts produced by similar pathology in the basal turns.
Acoustic Stimulation↗
Effects of outer hair cell loss on the frequency selectivity of the patas monkey auditory system.
This report describes a study that took advantage of the unique reactivity of the patas monkey (Erythrocebus patas) to dihydrostreptomycin-sulfate (DHSM) to investigate the effects of selective outer hair cell (OHC) lesions on psychophysical tuning curves (PTC). Four patas monkeys were trained using operant reinforcement techniques to perform forward masking PTCs at frequencies of 500 Hz, 2, 4, and 8 kHz, at 10 dB SL. Steady and pulsed-tone thresholds were also measured from 63 Hz to 40 kHz in half-octave steps. The animals were given daily i.m. injections of DHSM at 20 mg/kg per day until shifts in absolute threshold at 16 kHz exceeded 10 dB, at which time the drug was discontinued. Initial changes in PTC shape included elevations in the tip region associated with the increase in threshold and no elevation or a hypersensitivity of the low-frequency tail region. In general, threshold and therefore PTC tip elevations of at least 40 dB were required before any increase in the low-frequency tail became evident. Following completion of psychophysical testing, animals were sacrificed and cytochochleograms were determined. At frequencies corresponding to regions of complete OHC loss and complete IHC retention a lack of selectivity was evident and PTCs closely resemble low-pass filters. This residual low-pass tuning is similar to that seen in VIIIth nerve fibers in ears devoid of OHCs and in basilar membrane transfer functions from traumatized ears. PTCs taken at frequencies corresponding to areas with no loss of receptors showed no systematic changes in sensitivity or selectivity. Because loss of normal OHC function results in greater than a 50-dB loss in sensitivity, as well as a detuned PTC, these findings strongly support the suggestion that the role of the OHC system is to increase the sensitivity and selectivity of the auditory system.
Animals↗
Effects of changes in absolute signal level on psychophysical tuning curves in quiet and noise in patas monkeys.
Forward masking psychophysical tuning curves (PTCs) were measured in patas monkeys (Erythrocebus patas) at 2, 4, and 8 kHz at signal levels of 10, 30, and 60 dB SL in quiet, and at 10 dB above masked threshold in two levels of wideband noise. Absolute signal levels with masking approximated those at 30 and 60 dB SL in quiet. Results in quiet agree with those reported in the literature, demonstrating broadening of the PTC as signal level is increased. The PTCs measured in noise also demonstrated a similar broadening, or loss of selectivity, at higher SPLs. These later findings differ from those of a previous study [D.M. Green, B.R. Shelton, M.C. Picardi, and E.R. Hafter, J. Acoust. Soc. Am. 69, 1758-1762 (1981)] which used maskers to control the broadened excitation pattern in humans at levels of up to 34 dB above threshold. Differences in findings might be attributed to higher SPLs used in the present study. The data taken in noise backgrounds are not consistent with explanations for broadening based on an increase in the width of excitation patterns, but instead support the suggestion that the filter itself is nonlinear. Moreover, comparisons of PTCs in quiet and noise suggest that "off-frequency" listening acts at any given measurement level to artificially sharpen PTCs.
Acoustic Stimulation↗
The species-specific nature of the ototoxicity of dihydrostreptomycin in the patas monkey.
The remarkable susceptibility of the inner ear of the patas monkey (Erythrocebus patas) to the ototoxic action of dihydrostreptomycin (DHSM) (and streptomycin (SM)) is well established in this paper and affords a rare example of a species-specific reaction to a restricted class of compounds within the aminoglycoside group of antibiotics. In a series of experiments, behavioral and morphological observations together provided the following profile of DHSM ototoxicity in the patas monkey: Sudden onset of hearing loss beginning after 7-9 weeks of treatment; Substantial, though often partial, hearing impairment beginning at the high frequencies and progressing with or without continued treatment to the low frequencies; In the inner ear, a corresponding and selective loss of nerve fibers and of outer hair cells, relative to inner hair cells, beginning in the base of the cochlea and proceeding toward the apex; Continued and progressive loss of hearing for several months after cessation of drug treatment; and Non-auditory effects in some animals on the kidney and vestibular system. Results from control experiments confirmed this special relationship between the patas monkey and DHSM: Other nonhuman primates (macaques and vervet monkeys) were essentially unaffected by DHSM; The patas showed no equivalent sensitivity to other aminoglycosides such as kanamycin or to other forms of ototraumatic insult such as intense noise.
Animals↗
Sound localization of frequency-modulated sinusoids by Old World monkeys.
Directional hearing acuity, as measured by the minimum audible angle (MAA), was determined in four Old World monkeys, Macaca radiata. The acoustic stimuli were linear changes in frequency (sweeps) for different frequency ranges and sweep rates. The sweeps ranged between 0.5 and 1.3 kHz, at two durations, 100 and 200 ms. In upsweeps which began at 0.5 kHz and were 200 ms in duration, MAA decreased as sweep rate and frequency range increased. These thresholds were compared to MAAs of sweeps which traversed the same range of frequencies but at a different rate, to MAAs of sweeps with identical rates but over different frequency ranges, and to the MAAs of downsweeps. These comparisons indicated that range, and not sweep rate, exerts the greatest effect on the MAA. Interaural phase differences derived from the upper limits of the frequency range are discussed as potential FM localization cues.
Acoustic Stimulation↗
The role of frequency modulation in the perception of complex stimuli by primates.
Frequency modulation is a common feature of acoustic communication signals, including both human speech and many animal calls. In this study, linear frequency upsweeps were used as simple abstractions of the modulations found in communication signals. Macaque monkeys were trained using positive reinforcement operant conditioning procedures to respond when an ongoing repetitive acoustic signal changed from unmodulated (pure tone) to modulated (sweep). Thresholds for detecting modulation were determined using the psychophysical method of constant stimuli. In the first experiment, it was shown that the monkeys were most sensitive to modulation around a center frequency of 500 Hz. Subsequent experiments were carried out at that frequency, and varied stimulus duration and the frequency relationship between standard and comparison stimuli. The results of these studies indicated that subjects were responding primarily to discrete frequency cues rather than to the presence of modulation. When a premium was placed on attending to modulation by presenting discrete shifts between successive unmodulated stimuli thereby making such shifts an unreliable indicator of the presence of modulation, subjects continued to respond to the presence of the discrete shifts. These results are taken as evidence that the auditory system may deal with frequency modulation near threshold by recoding it as a discrete frequency percept.
Animal Communication↗
Species-specific perceptual processing of vocal sounds by monkeys.
Monkeys of four species were trained to discriminate between sets of natural tonal calls of Japanese macaques (Macaca fuscata) by the position of a frequency-inflection peak or by initial pitch. The Japanese macaques consistently performed best on peak position and the other species on pitch. The results imply special strategies for perceptional processing of vocal sounds and suggest parallels with human speech perception.
Animals↗
Electrocochleography and experimentally induced loudness recruitment.
The relationship between changes in loudness and the cochlear whole-nerve potential following experimentally produced deafness was studied in an animal model. Reaction time of a subject's response to an auditory stimulus has been shown to be an index of loudness in human experiments and has been adapted to nonhuman primates. In a series of experiments, four macaque monkeys were operantly conditioned to respond to 8-kHz tones over a range of 3--80 dB SPL, and their reaction times to pure tone stimuli were measured. Whole-nerve cochlear action potentials were recorded from chronic inner-ear electrodes. The relationship between behavioral and electrical measures of loudness recruitment were examined in animals with both temporary and permanent noise-induced hearing loss. Loudness recruitment was demonstrated experimentally after a 1-h exposure to a high-intensity 8-kHz octave band of noise. Excellent agreement was observed between the reaction time function and the action potential input-output function at intervals of 0.5, 12, 24, 48, and 84 h after exposure. Permanent hearing loss was produced in some of these animals by a much longer duration of exposure to the 8-kHz octave band of noise. Recruitment was observed in both the behavioral and the electrical measures. Histological studies of these damaged cochleas revealed primarily outer hair cell destruction, with a relative sparing of inner hair cells and nerve supply. The findings of this study are interpreted as strong support for the clinical electrocochleogram as an objective indicator of the presence of loudness recruitment.
Action Potentials↗
Hearing thresholds with outer and inner hair cell loss.
Hearing impairment and related cochlear histopathologic changes were evaluated in experimental animals after treatment with aminoglycoside antibiotics or exposure to intense sound. In the course of treatment with kanamycin, neomycin, or dihydrostreptomycin, permanent hearing loss in monkeys and guinea pigs occurred first at the high frequencies and progressed toward the lows. Exposure to different octave bands of noise at 120 dB SPL in monkeys and chinchillas produced permanent hearing loss at frequencies related to the spectral characteristics of the octave band. In most instances loss of outer hair cells was substantially greater than that of inner hair cells. In fact, the pattern and location of missing outer hair cells on the basilar membrane were most often correlated with threshold shifts of 50 dB or less. Generally inner hair cell loss was observed when the threshold shift was greater than 50 dB. Our data support the place principle and the inference that the outer hair cells are essential for hearing from threshold to about 50 dB SL. The inner hair cells, if functioning normally, apparently take over above that level. Although there is little doubt that such a generalization will, in the long term, be found to have been greatly oversimplified, there is every reason to believe that a combination of behavioral and morphologic procedures, as used in this study, will play an important part in elucidating the differences in functional significance of the two types of hair cells.
Animals↗
Perception of conspecific vocalizations by Japanese macaques. Evidence for selective attention and neural lateralization.
Japanese macaques (Macaca fuscata) and control species (vervet, pigtailed macaque, bonnet macaque) were trained for food to respond to one class of recorded fuscata vocalizations and do not respond to a second class. A measure of neural lateralization was obtained by presenting the stimuli randomly to the right or the left ear, and comparing performance in the two ears (ear advantage method). Vocalizations were from Steven Green's field tapes. In experiment I, the two classes were Green's 'smooth early high coos' (SE) and 'smooth late high coos' (SL). Experiment II utilized the same vocalizations, but sorted into a high-pitched and a low-pitched class, i.e., orthogonally to the communication-relevant dimension. We found that (a) Japanese macaques learned the SE-SL discrimination faster than the pitch discrimination; (b) the reverse was true for the controls; (c) Japanese macaques showed a right-ear advantage (presumed left hemisphere advantage) for the SE-SL distinction, but not for the pitch discrimination, and (d) controls (with one exception) showed no ear advantage for either discrimination. These demonstrations of selective attention to communication-relevant parameters of conspecific vocalizations, and neural lateralization in the perception of these vocalizations, parallel similar findings in human speech perception.
Animals↗
Comparative behavioral toxicology.
Behavioral conditioning together with conventional sensory testing methods may be used in the evaluation of toxic effects on sensory systems in experimental animal models. Such procedures yield precise quantitative estimates of impairment in absolute and differential acuity and in sensory perception. Additionally, these behavioral changes can be related to the presence of histopathology in peripheral sensory structures; this orderly relation between structure and function may aid in our understanding of the basis for sensory coding in the normal end organ.
Aminoglycosides↗