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Beitel RE, Schreiner CE, Vollmer M. Spectral plasticity in monkey primary auditory cortex limits performance generalization in a temporal discrimination task. J Neurophysiol 2020; 124:1798-1814. [PMID: 32997564 DOI: 10.1152/jn.00278.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Auditory experience and behavioral training can modify perceptual performance. However, the consequences of temporal perceptual learning for temporal and spectral neural processing remain unclear. Specifically, the attributes of neural plasticity that underlie task generalization in behavioral performance remain uncertain. To assess the relationship between behavioral and neural plasticity, we evaluated neuronal temporal processing and spectral tuning in primary auditory cortex (AI) of anesthetized owl monkeys trained to discriminate increases in the envelope frequency (e.g., 4-Hz standard vs. >5-Hz targets) of sinusoidally amplitude-modulated (SAM) 1-kHz or 2-kHz carriers. Behavioral and neuronal performance generalization was evaluated for carriers ranging from 0.5 kHz to 8 kHz. Psychophysical thresholds revealed high SAM discrimination acuity for carriers from one octave below to ∼0.6 octave above the trained carrier frequency. However, generalization of SAM discrimination learning progressively declined for carrier frequencies >0.6 octave above the trained carrier frequency. Neural responses in AI showed that SAM discrimination training resulted in 1) increases in temporal modulation preference, especially at carriers close to the trained frequency, 2) narrowing of spectral tuning for neurons with characteristic frequencies near the trained carrier frequency, potentially limiting spectral generalization of temporal training effects, and 3) enhancement of firing-rate contrast for rewarded versus nonrewarded SAM frequencies, providing a potential cue for behavioral temporal discrimination near the trained carrier frequency. Our findings suggest that temporal training at a specific spectral location sharpens local frequency tuning, thus, confining the training effects to a narrow frequency range and limiting generalization of temporal discrimination learning across a wider frequency range.NEW & NOTEWORTHY Monkeys' ability to generalize amplitude modulation discrimination to nontrained carriers was limited to one octave below and 0.6 octave above the trained carrier frequency. Asymmetric generalization was paralleled by sharpening in cortical spectral tuning and enhanced firing-rate contrast between rewarded and nonrewarded SAM stimuli at carriers near the trained frequency. The spectral content of the training stimulus specified spectral and temporal plasticity that may provide a neural substrate for limitations in generalization of temporal discrimination learning.
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Affiliation(s)
- Ralph E Beitel
- Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, California
| | - Christoph E Schreiner
- Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, California
| | - Maike Vollmer
- Department of Otolaryngology-Head and Neck Surgery, University Hospital Magdeburg, Otto-von-Guericke University, Magdeburg, Germany.,Center for Learning and Memory Research, Leibniz Institute for Neurobiology, Magdeburg, Germany
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Gockel HE, Moore BC, Carlyon RP. Pitch perception at very high frequencies: On psychometric functions and integration of frequency information. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2020; 148:3322. [PMID: 33261392 PMCID: PMC7613188 DOI: 10.1121/10.0002668] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 10/30/2020] [Indexed: 06/12/2023]
Abstract
Lau et al. [J. Neurosci. 37, 9013-9021 (2017)] showed that discrimination of the fundamental frequency (F0) of complex tones with components in a high-frequency region was better than predicted from the optimal combination of information from the individual harmonics. The predictions depend on the assumption that psychometric functions for frequency discrimination have a slope of 1 at high frequencies. This was tested by measuring psychometric functions for F0 discrimination and frequency discrimination. Difference limens for F0 (F0DLs) and difference limens for frequency for each frequency component were also measured. Complex tones contained harmonics 6-10 and had F0s of 280 or 1400 Hz. Thresholds were measured using 210-ms tones presented diotically in diotic threshold-equalizing noise (TEN), and 1000-ms tones presented diotically in dichotic TEN. The slopes of the psychometric functions were close to 1 for all frequencies and F0s. The ratio of predicted to observed F0DLs was around 1 or smaller for both F0s, i.e., not super-optimal, and was significantly smaller for the low than for the high F0. The results are consistent with the idea that place information alone can convey pitch, but pitch is more salient when phase-locking information is available.
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Affiliation(s)
- Hedwig E. Gockel
- Cambridge Hearing Group, MRC Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Rd., Cambridge CB2 7EF, UK
| | - Brian C.J. Moore
- Cambridge Hearing Group, Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, UK
| | - Robert P. Carlyon
- Cambridge Hearing Group, MRC Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Rd., Cambridge CB2 7EF, UK
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Presacco A, Middlebrooks JC. Tone-Evoked Acoustic Change Complex (ACC) Recorded in a Sedated Animal Model. J Assoc Res Otolaryngol 2018; 19:451-466. [PMID: 29749573 DOI: 10.1007/s10162-018-0673-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 04/24/2018] [Indexed: 11/30/2022] Open
Abstract
The acoustic change complex (ACC) is a scalp-recorded cortical evoked potential complex generated in response to changes (e.g., frequency, amplitude) in an auditory stimulus. The ACC has been well studied in humans, but to our knowledge, no animal model has been evaluated. In particular, it was not known whether the ACC could be recorded under the conditions of sedation that likely would be necessary for recordings from animals. For that reason, we tested the feasibility of recording ACC from sedated cats in response to changes of frequency and amplitude of pure-tone stimuli. Cats were sedated with ketamine and acepromazine, and subdermal needle electrodes were used to record electroencephalographic (EEG) activity. Tones were presented from a small loudspeaker located near the right ear. Continuous tones alternated at 500-ms intervals between two frequencies or two levels. Neurometric functions were created by recording neural response amplitudes while systematically varying the magnitude of steps in frequency centered in octave frequency around 2, 4, 8, and 16 kHz, all at 75 dB SPL, or in decibel level around 75 dB SPL tested at 4 and 8 kHz. The ACC could be recorded readily under this ketamine/azepromazine sedation. In contrast, ACC could not be recorded reliably under any level of isoflurane anesthesia that was tested. The minimum frequency (expressed as Weber fractions (df/f)) or level steps (expressed in dB) needed to elicit ACC fell in the range of previous thresholds reported in animal psychophysical tests of discrimination. The success in recording ACC in sedated animals suggests that the ACC will be a useful tool for evaluation of other aspects of auditory acuity in normal hearing and, presumably, in electrical cochlear stimulation, especially for novel stimulation modes that are not yet feasible in humans.
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Affiliation(s)
- Alessandro Presacco
- Department of Otolaryngology, University of California at Irvine, Irvine, CA, 92697-5310, USA.
- Center for Hearing Research, University of California at Irvine, Irvine, CA, USA.
| | - John C Middlebrooks
- Department of Otolaryngology, University of California at Irvine, Irvine, CA, 92697-5310, USA
- Center for Hearing Research, University of California at Irvine, Irvine, CA, USA
- Department of Neurobiology and Behavior, University of California at Irvine, Irvine, CA, USA
- Department of Cognitive Sciences, University of California at Irvine, Irvine, CA, USA
- Department of Biomedical Engineering, University of California at Irvine, Irvine, CA, USA
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Henry KS, Amburgey KN, Abrams KS, Idrobo F, Carney LH. Formant-frequency discrimination of synthesized vowels in budgerigars (Melopsittacus undulatus) and humans. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 142:2073. [PMID: 29092534 PMCID: PMC5640449 DOI: 10.1121/1.5006912] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 08/29/2017] [Accepted: 09/28/2017] [Indexed: 05/31/2023]
Abstract
Vowels are complex sounds with four to five spectral peaks known as formants. The frequencies of the two lowest formants, F1and F2, are sufficient for vowel discrimination. Behavioral studies show that many birds and mammals can discriminate vowels. However, few studies have quantified thresholds for formant-frequency discrimination. The present study examined formant-frequency discrimination in budgerigars (Melopsittacus undulatus) and humans using stimuli with one or two formants and a constant fundamental frequency of 200 Hz. Stimuli had spectral envelopes similar to natural speech and were presented with random level variation. Thresholds were estimated for frequency discrimination of F1, F2, and simultaneous F1 and F2 changes. The same two-down, one-up tracking procedure and single-interval, two-alternative task were used for both species. Formant-frequency discrimination thresholds were as sensitive in budgerigars as in humans and followed the same patterns across all conditions. Thresholds expressed as percent frequency difference were higher for F1 than for F2, and were unchanged between stimuli with one or two formants. Thresholds for simultaneous F1 and F2 changes indicated that discrimination was based on combined information from both formant regions. Results were consistent with previous human studies and show that budgerigars provide an exceptionally sensitive animal model of vowel feature discrimination.
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Affiliation(s)
- Kenneth S Henry
- Department of Otolaryngology, University of Rochester, Rochester, New York 14642, USA
| | - Kassidy N Amburgey
- Department of Brain and Cognitive Sciences, University of Rochester, Rochester, New York 14642, USA
| | - Kristina S Abrams
- Department of Neuroscience, University of Rochester, Rochester, New York 14642, USA
| | | | - Laurel H Carney
- Department of Biomedical Engineering, University of Rochester, Rochester, New York 14642, USA
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An automated psychoacoustic testing apparatus for use in cats. Hear Res 2014; 309:1-7. [DOI: 10.1016/j.heares.2013.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 10/21/2013] [Accepted: 11/01/2013] [Indexed: 11/21/2022]
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Town SM, Bizley JK. Neural and behavioral investigations into timbre perception. Front Syst Neurosci 2013; 7:88. [PMID: 24312021 PMCID: PMC3826062 DOI: 10.3389/fnsys.2013.00088] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Accepted: 10/27/2013] [Indexed: 11/23/2022] Open
Abstract
Timbre is the attribute that distinguishes sounds of equal pitch, loudness and duration. It contributes to our perception and discrimination of different vowels and consonants in speech, instruments in music and environmental sounds. Here we begin by reviewing human timbre perception and the spectral and temporal acoustic features that give rise to timbre in speech, musical and environmental sounds. We also consider the perception of timbre by animals, both in the case of human vowels and non-human vocalizations. We then explore the neural representation of timbre, first within the peripheral auditory system and later at the level of the auditory cortex. We examine the neural networks that are implicated in timbre perception and the computations that may be performed in auditory cortex to enable listeners to extract information about timbre. We consider whether single neurons in auditory cortex are capable of representing spectral timbre independently of changes in other perceptual attributes and the mechanisms that may shape neural sensitivity to timbre. Finally, we conclude by outlining some of the questions that remain about the role of neural mechanisms in behavior and consider some potentially fruitful avenues for future research.
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Across-channel timing differences as a potential code for the frequency of pure tones. J Assoc Res Otolaryngol 2011; 13:159-171. [PMID: 22160791 PMCID: PMC3298616 DOI: 10.1007/s10162-011-0305-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 11/07/2011] [Indexed: 11/06/2022] Open
Abstract
When a pure tone or low-numbered harmonic is presented to a listener, the resulting travelling wave in the cochlea slows down at the portion of the basilar membrane (BM) tuned to the input frequency due to the filtering properties of the BM. This slowing is reflected in the phase of the response of neurons across the auditory nerve (AN) array. It has been suggested that the auditory system exploits these across-channel timing differences to encode the pitch of both pure tones and resolved harmonics in complex tones. Here, we report a quantitative analysis of previously published data on the response of guinea pig AN fibres, of a range of characteristic frequencies, to pure tones of different frequencies and levels. We conclude that although the use of across-channel timing cues provides an a priori attractive and plausible means of encoding pitch, many of the most obvious metrics for using that cue produce pitch estimates that are strongly influenced by the overall level and therefore are unlikely to provide a straightforward means for encoding the pitch of pure tones.
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Hienz RD, Jones AM, Weerts EM. The discrimination of baboon grunt calls and human vowel sounds by baboons. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2004; 116:1692-1697. [PMID: 15478436 DOI: 10.1121/1.1778902] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The ability of baboons to discriminate changes in the formant structures of a synthetic baboon grunt call and an acoustically similar human vowel (/epsilon/) was examined to determine how comparable baboons are to humans in discriminating small changes in vowel sounds, and whether or not any species-specific advantage in discriminability might exist when baboons discriminate their own vocalizations. Baboons were trained to press and hold down a lever to produce a pulsed train of a standard sound (e.g., /epsilon/ or a baboon grunt call), and to release the lever only when a variant of the sound occurred. Synthetic variants of each sound had the same first and third through fifth formants (F1 and F3-5), but varied in the location of the second formant (F2). Thresholds for F2 frequency changes were 55 and 67 Hz for the grunt and vowel stimuli, respectively, and were not statistically different from one another. Baboons discriminated changes in vowel formant structures comparable to those discriminated by humans. No distinct advantages in discrimination performances were observed when the baboons discriminated these synthetic grunt vocalizations.
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Affiliation(s)
- Robert D Hienz
- Division of Behavioral Biology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine/Bayview Campus, Baltimore, Maryland 21224-6823, USA.
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Abstract
This paper investigates phase-lock coding of frequency in the auditory system. One objective with the current model was to construct an optimal central estimation mechanism able to extract frequency directly from spike trains. The model bases estimates of the stimulus frequency on inter-spike intervals of spike trains phase-locked to a pure tone stimulus. Phase-locking is the tendency of spikes to cluster around multiples of the stimulus period. It is assumed that these clusters have Gaussian distributions with variance that depends on the amount of phase-locking. Inter-spike intervals are then noisy measurements of the actual period of the stimulus waveform. The problem of estimating frequency from inter-spike intervals can be solved optimally with a Kalman filter. It is shown that the number of inter-spike intervals observed in the stimulus interval determines frequency discrimination at low frequencies, while the variance of spike clusters dominates at higher frequencies. Timing information in spike intervals is sufficient to account for human frequency discrimination performance up to 5000 Hz. When spikes are available on each stimulus cycle, the model can accurately predict frequency discrimination thresholds as a function of frequency, intensity and duration.
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Affiliation(s)
- J J Hanekom
- Department of Electrical, Electronic and Computer Engineering, University of Pretoria, Pretoria, South Africa
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Schwartz JJ, Gerhardt HC. The neuroethology of frequency preferences in the spring peeper. Anim Behav 1998; 56:55-69. [PMID: 9710462 DOI: 10.1006/anbe.1998.0737] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We studied the relationship between auditory activity in the midbrain and selective phonotaxis in females of the treefrog, Pseudacris crucifer. Gravid females were tested in two-stimulus playback tests using synthetic advertisement calls of different frequencies (2600 versus 2875 Hz; 2800 versus 3500 Hz; 2600 versus 3500 Hz). Tests were conducted with and without a background of synthesized noise, which was filtered to resemble the spectrum of a chorus of spring peepers. There were no significant preferences for calls of any frequency in the absence of background noise. With background noise, females preferred calls of 3500 Hz to those of 2600 Hz. Multi-unit recordings of neural responses to synthetic sounds were made from the torus semicircularis of the same females following the tests of phonotaxis. We measured auditory threshold at 25 frequencies (1800-4200 Hz) as well as the magnitude of the neural response when stimulus amplitude was held constant and frequency was varied. This procedure yielded isointensity response contours, which we obtained at six amplitudes in the absence of noise and at the stimulus amplitude used during the phonotaxis tests with background noise. Individual differences in audiograms and isointensity responses were poorly correlated with behavioural data except for the test of 2600 Hz versus 3500 Hz calls in noise. The shape of the neural response contours changed with stimulus amplitude and in the presence of the simulated frog chorus. At 85 dB sound pressure level (SPL), the level at which females were tested, the contours of females were quite flat. The contours were more peaked at lower SPLs as well as during the broadcast of chorus noise and white noise at an equivalent spectrum level (45-46 dB/Hz). Peaks in the isointensity response plots of most females occurred at stimulus frequencies ranging from 3200 to 3400 Hz, frequencies close to the median best excitatory frequency (BEF) of 3357 Hz but higher than the mean of the mid-frequency of the male advertisement call (3011 Hz). Addition of background noise may cause a shift in the neural response-intensity level functions. Our results highlight the well-known nonlinearity of the auditory system and the danger inherent in focusing solely on threshold measures of auditory sensitivity when studying the proximate basis of female choice. The results also show an unexpected effect of the natural and noisy acoustic environment on behaviour and responses of the auditory system. Copyright 1998 The Association for the Study of Animal Behaviour.
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Affiliation(s)
- JJ Schwartz
- Division of Biological Sciences, University of Missouri
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