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Higgins NC, Scurry AN, Jiang F, Little DF, Alain C, Elhilali M, Snyder JS. Adaptation in the sensory cortex drives bistable switching during auditory stream segregation. Neurosci Conscious 2023; 2023:niac019. [PMID: 36751309 PMCID: PMC9899071 DOI: 10.1093/nc/niac019] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 10/17/2022] [Accepted: 12/26/2022] [Indexed: 02/06/2023] Open
Abstract
Current theories of perception emphasize the role of neural adaptation, inhibitory competition, and noise as key components that lead to switches in perception. Supporting evidence comes from neurophysiological findings of specific neural signatures in modality-specific and supramodal brain areas that appear to be critical to switches in perception. We used functional magnetic resonance imaging to study brain activity around the time of switches in perception while participants listened to a bistable auditory stream segregation stimulus, which can be heard as one integrated stream of tones or two segregated streams of tones. The auditory thalamus showed more activity around the time of a switch from segregated to integrated compared to time periods of stable perception of integrated; in contrast, the rostral anterior cingulate cortex and the inferior parietal lobule showed more activity around the time of a switch from integrated to segregated compared to time periods of stable perception of segregated streams, consistent with prior findings of asymmetries in brain activity depending on the switch direction. In sound-responsive areas in the auditory cortex, neural activity increased in strength preceding switches in perception and declined in strength over time following switches in perception. Such dynamics in the auditory cortex are consistent with the role of adaptation proposed by computational models of visual and auditory bistable switching, whereby the strength of neural activity decreases following a switch in perception, which eventually destabilizes the current percept enough to lead to a switch to an alternative percept.
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Affiliation(s)
- Nathan C Higgins
- Department of Communication Sciences and Disorders, University of South Florida, 4202 E. Fowler Avenue, PCD1017, Tampa, FL 33620, USA
| | - Alexandra N Scurry
- Department of Psychology, University of Nevada, 1664 N. Virginia Street Mail Stop 0296, Reno, NV 89557, USA
| | - Fang Jiang
- Department of Psychology, University of Nevada, 1664 N. Virginia Street Mail Stop 0296, Reno, NV 89557, USA
| | - David F Little
- Department of Electrical and Computer Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Claude Alain
- Rotman Research Institute, Baycrest Health Sciences, 3560 Bathurst Street, Toronto, ON M6A 2E1, Canada
| | - Mounya Elhilali
- Department of Electrical and Computer Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Joel S Snyder
- Department of Psychology, University of Nevada, 4505 Maryland Parkway Mail Stop 5030, Las Vegas, NV 89154, USA
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2
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Thomassen S, Hartung K, Einhäuser W, Bendixen A. Low-high-low or high-low-high? Pattern effects on sequential auditory scene analysis. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 152:2758. [PMID: 36456271 DOI: 10.1121/10.0015054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 10/17/2022] [Indexed: 06/17/2023]
Abstract
Sequential auditory scene analysis (ASA) is often studied using sequences of two alternating tones, such as ABAB or ABA_, with "_" denoting a silent gap, and "A" and "B" sine tones differing in frequency (nominally low and high). Many studies implicitly assume that the specific arrangement (ABAB vs ABA_, as well as low-high-low vs high-low-high within ABA_) plays a negligible role, such that decisions about the tone pattern can be governed by other considerations. To explicitly test this assumption, a systematic comparison of different tone patterns for two-tone sequences was performed in three different experiments. Participants were asked to report whether they perceived the sequences as originating from a single sound source (integrated) or from two interleaved sources (segregated). Results indicate that core findings of sequential ASA, such as an effect of frequency separation on the proportion of integrated and segregated percepts, are similar across the different patterns during prolonged listening. However, at sequence onset, the integrated percept was more likely to be reported by the participants in ABA_low-high-low than in ABA_high-low-high sequences. This asymmetry is important for models of sequential ASA, since the formation of percepts at onset is an integral part of understanding how auditory interpretations build up.
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Affiliation(s)
- Sabine Thomassen
- Cognitive Systems Lab, Faculty of Natural Sciences, Chemnitz University of Technology, 09107 Chemnitz, Germany
| | - Kevin Hartung
- Cognitive Systems Lab, Faculty of Natural Sciences, Chemnitz University of Technology, 09107 Chemnitz, Germany
| | - Wolfgang Einhäuser
- Physics of Cognition Group, Faculty of Natural Sciences, Chemnitz University of Technology, 09107 Chemnitz, Germany
| | - Alexandra Bendixen
- Cognitive Systems Lab, Faculty of Natural Sciences, Chemnitz University of Technology, 09107 Chemnitz, Germany
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3
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Jayakody DMP, Menegola HK, Yiannos JM, Goodman-Simpson J, Friedland PL, Taddei K, Laws SM, Weinborn M, Martins RN, Sohrabi HR. The Peripheral Hearing and Central Auditory Processing Skills of Individuals With Subjective Memory Complaints. Front Neurosci 2020; 14:888. [PMID: 32982675 PMCID: PMC7475691 DOI: 10.3389/fnins.2020.00888] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 07/30/2020] [Indexed: 11/22/2022] Open
Abstract
Purpose This study examined the central auditory processing (CAP) assessment results of adults between 45 and 85 years of age with probable pre-clinical Alzheimer’s disease – i.e., individuals with subjective memory complaints (SMCs) as compared to those who were not reporting significant levels of memory complaints (non-SMCs). It was hypothesized that the SMC group would perform significantly poorer on tests of central auditory skills compared to participants with non-SMCs (control group). Methods A total of 95 participants were recruited from the larger Western Australia Memory Study and were classified as SMCs (N = 61; 20 males and 41 females, mean age 71.47 ±7.18 years) and non-SMCs (N = 34; 10 males, 24 females, mean age 68.85 ±7.69 years). All participants completed a peripheral hearing assessment, a CAP assessment battery including Dichotic Digits, Duration Pattern Test, Dichotic Sentence Identification, Synthetic Sentence Identification with Ipsilateral Competing Message (SSI-ICM) and the Quick-Speech-in-Noise, and a cognitive screening assessment. Results The SMCs group performed significantly poorer than the control group on SSI-ICM −10 and −20 dB signal-to-noise conditions. No significant differences were found between the two groups on the peripheral hearing threshold measurements and other CAP assessments. Conclusions The results suggest that individuals with SMCs perform poorly on specific CAP assessments in comparison to the controls. The poor CAP in SMC individuals may result in a higher cost to their finite pool of cognitive resources. The CAP results provide yet another biomarker that supports the hypothesis that SMCs may be a primary indication of neuropathological changes in the brain. Longitudinal follow up of individuals with SMCs, and decreased CAP abilities should inform whether this group is at higher risk of developing dementia as compared to non-SMCs and those SMC individuals without CAP difficulties.
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Affiliation(s)
- Dona M P Jayakody
- Ear Science Institute Australia, Subiaco, WA, Australia.,Ear Sciences Centre Faculty of Health and Medical Sciences, The University of Western Australia, Crawley, WA, Australia
| | | | - Jessica M Yiannos
- Ear Science Institute Australia, Subiaco, WA, Australia.,School of Human Sciences, The University of Western Australia, Crawley, WA, Australia
| | | | - Peter L Friedland
- Department of Otolaryngology Head Neck Skull Base Surgery, Sir Charles Gairdner Hospital, Nedlands, WA, Australia.,School of Medicine, University Notre Dame, Fremantle, WA, Australia
| | - Kevin Taddei
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Simon M Laws
- Collaborative Genomics Group, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia.,School of Pharmacy and Biomedical Sciences, Faculty of Health Sciences, Curtin Health Innovation Research Institute, Curtin University, Bentley, WA, Australia
| | - Michael Weinborn
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia.,School of Psychological Science, The University of Western Australia, Nedlands, WA, Australia
| | - Ralph N Martins
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia.,Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Hamid R Sohrabi
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia.,Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia.,Centre for Healthy Ageing, School of Psychology and Exercise Science, Murdoch University, Murdoch, WA, Australia
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4
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Abstract
Humans and other animals use spatial hearing to rapidly localize events in the environment. However, neural encoding of sound location is a complex process involving the computation and integration of multiple spatial cues that are not represented directly in the sensory organ (the cochlea). Our understanding of these mechanisms has increased enormously in the past few years. Current research is focused on the contribution of animal models for understanding human spatial audition, the effects of behavioural demands on neural sound location encoding, the emergence of a cue-independent location representation in the auditory cortex, and the relationship between single-source and concurrent location encoding in complex auditory scenes. Furthermore, computational modelling seeks to unravel how neural representations of sound source locations are derived from the complex binaural waveforms of real-life sounds. In this article, we review and integrate the latest insights from neurophysiological, neuroimaging and computational modelling studies of mammalian spatial hearing. We propose that the cortical representation of sound location emerges from recurrent processing taking place in a dynamic, adaptive network of early (primary) and higher-order (posterior-dorsal and dorsolateral prefrontal) auditory regions. This cortical network accommodates changing behavioural requirements and is especially relevant for processing the location of real-life, complex sounds and complex auditory scenes.
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5
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Ruggles DR, Tausend AN, Shamma SA, Oxenham AJ. Cortical markers of auditory stream segregation revealed for streaming based on tonotopy but not pitch. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 144:2424. [PMID: 30404514 PMCID: PMC6909992 DOI: 10.1121/1.5065392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 10/05/2018] [Accepted: 10/08/2018] [Indexed: 06/08/2023]
Abstract
The brain decomposes mixtures of sounds, such as competing talkers, into perceptual streams that can be attended to individually. Attention can enhance the cortical representation of streams, but it is unknown what acoustic features the enhancement reflects, or where in the auditory pathways attentional enhancement is first observed. Here, behavioral measures of streaming were combined with simultaneous low- and high-frequency envelope-following responses (EFR) that are thought to originate primarily from cortical and subcortical regions, respectively. Repeating triplets of harmonic complex tones were presented with alternating fundamental frequencies. The tones were filtered to contain either low-numbered spectrally resolved harmonics, or only high-numbered unresolved harmonics. The behavioral results confirmed that segregation can be based on either tonotopic or pitch cues. The EFR results revealed no effects of streaming or attention on subcortical responses. Cortical responses revealed attentional enhancement under conditions of streaming, but only when tonotopic cues were available, not when streaming was based only on pitch cues. The results suggest that the attentional modulation of phase-locked responses is dominated by tonotopically tuned cortical neurons that are insensitive to pitch or periodicity cues.
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Affiliation(s)
- Dorea R Ruggles
- Department of Psychology, University of Minnesota, 75 East River Parkway, Minneapolis, Minnesota 55455, USA
| | - Alexis N Tausend
- Department of Psychology, University of Minnesota, 75 East River Parkway, Minneapolis, Minnesota 55455, USA
| | - Shihab A Shamma
- Electrical and Computer Engineering Department & Institute for Systems, University of Maryland, College Park, Maryland 20740, USA
| | - Andrew J Oxenham
- Department of Psychology, University of Minnesota, 75 East River Parkway, Minneapolis, Minnesota 55455, USA
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6
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Cai H, Screven LA, Dent ML. Behavioral measurements of auditory streaming and build-up by budgerigars ( Melopsittacus undulatus). THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 144:1508. [PMID: 30424658 DOI: 10.1121/1.5054297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/27/2018] [Indexed: 06/09/2023]
Abstract
The perception of the build-up of auditory streaming has been widely investigated in humans, while it is unknown whether animals experience a similar perception when hearing high (H) and low (L) tonal pattern sequences. The paradigm previously used in European starlings (Sturnus vulgaris) was adopted in two experiments to address the build-up of auditory streaming in budgerigars (Melopsittacus undulatus). In experiment 1, different numbers of repetitions of low-high-low triplets were used in five conditions to study the build-up process. In experiment 2, 5 and 15 repetitions of high-low-high triplets were used to investigate the effects of repetition rate, frequency separation, and frequency range of the two tones on the birds' streaming perception. Similar to humans, budgerigars subjectively experienced the build-up process in auditory streaming; faster repetition rates and larger frequency separations enhanced the streaming perception, and these results were consistent across the two frequency ranges. Response latency analysis indicated that the budgerigars needed a longer amount of time to respond to stimuli that elicited a salient streaming perception. These results indicate, for the first time using a behavioral paradigm, that budgerigars experience a build-up of auditory streaming in a manner similar to humans.
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Affiliation(s)
- Huaizhen Cai
- Department of Psychology, University at Buffalo, The State University of New York, Buffalo, New York 14260, USA
| | - Laurel A Screven
- Department of Psychology, University at Buffalo, The State University of New York, Buffalo, New York 14260, USA
| | - Micheal L Dent
- Department of Psychology, University at Buffalo, The State University of New York, Buffalo, New York 14260, USA
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7
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Knyazeva S, Selezneva E, Gorkin A, Aggelopoulos NC, Brosch M. Neuronal Correlates of Auditory Streaming in Monkey Auditory Cortex for Tone Sequences without Spectral Differences. Front Integr Neurosci 2018; 12:4. [PMID: 29440999 PMCID: PMC5797536 DOI: 10.3389/fnint.2018.00004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 01/16/2018] [Indexed: 11/13/2022] Open
Abstract
This study finds a neuronal correlate of auditory perceptual streaming in the primary auditory cortex for sequences of tone complexes that have the same amplitude spectrum but a different phase spectrum. Our finding is based on microelectrode recordings of multiunit activity from 270 cortical sites in three awake macaque monkeys. The monkeys were presented with repeated sequences of a tone triplet that consisted of an A tone, a B tone, another A tone and then a pause. The A and B tones were composed of unresolved harmonics formed by adding the harmonics in cosine phase, in alternating phase, or in random phase. A previous psychophysical study on humans revealed that when the A and B tones are similar, humans integrate them into a single auditory stream; when the A and B tones are dissimilar, humans segregate them into separate auditory streams. We found that the similarity of neuronal rate responses to the triplets was highest when all A and B tones had cosine phase. Similarity was intermediate when the A tones had cosine phase and the B tones had alternating phase. Similarity was lowest when the A tones had cosine phase and the B tones had random phase. The present study corroborates and extends previous reports, showing similar correspondences between neuronal activity in the primary auditory cortex and auditory streaming of sound sequences. It also is consistent with Fishman’s population separation model of auditory streaming.
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Affiliation(s)
- Stanislava Knyazeva
- Speziallabor Primatenneurobiologie, Leibniz-Institute für Neurobiologie, Magdeburg, Germany
| | - Elena Selezneva
- Speziallabor Primatenneurobiologie, Leibniz-Institute für Neurobiologie, Magdeburg, Germany
| | - Alexander Gorkin
- Speziallabor Primatenneurobiologie, Leibniz-Institute für Neurobiologie, Magdeburg, Germany.,Laboratory of Psychophysiology, Institute of Psychology, Moscow, Russia
| | | | - Michael Brosch
- Speziallabor Primatenneurobiologie, Leibniz-Institute für Neurobiologie, Magdeburg, Germany.,Center for Behavioral Brain Sciences, Otto-von-Guericke-University, Magdeburg, Germany
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8
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Sanders RD, Winston JS, Barnes GR, Rees G. Magnetoencephalographic Correlates of Perceptual State During Auditory Bistability. Sci Rep 2018; 8:976. [PMID: 29343771 PMCID: PMC5772671 DOI: 10.1038/s41598-018-19287-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 12/22/2017] [Indexed: 11/24/2022] Open
Abstract
Bistability occurs when two alternative percepts can be derived from the same physical stimulus. To identify the neural correlates of specific subjective experiences we used a bistable auditory stimulus and determined whether the two perceptual states could be distinguished electrophysiologically. Fourteen participants underwent magnetoencephalography while reporting their perceptual experience while listening to a continuous bistable stream of auditory tones. Participants reported bistability with a similar overall proportion of the two alternative percepts (52% vs 48%). At the individual level, sensor space electrophysiological discrimination between the percepts was possible in 9/14 participants with canonical variate analysis (CVA) or linear support vector machine (SVM) analysis over space and time dimensions. Classification was possible in 14/14 subjects with non-linear SVM. Similar effects were noted in an unconstrained source space CVA analysis (classifying 10/14 participants), linear SVM (classifying 9/14 subjects) and non-linear SVM (classifiying 13/14 participants). Source space analysis restricted to a priori ROIs showed discrimination was possible in the right and left auditory cortex with each classification approach but in the right intraparietal sulcus this was only apparent with non-linear SVM and only in a minority of particpants. Magnetoencephalography can be used to objectively classify auditory experiences from individual subjects.
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Affiliation(s)
- Robert D Sanders
- Institute of Cognitive Neuroscience University College London, Alexandra House, 17-19 Queen Square, London, WC1N 3AR, London, United Kingdom.
- Department of Anesthesiology, University of Wisconsin, Madison, USA.
| | - Joel S Winston
- Institute of Cognitive Neuroscience University College London, Alexandra House, 17-19 Queen Square, London, WC1N 3AR, London, United Kingdom
- Wellcome Trust Centre for Neuroimaging, University College London, London, WC1N 3BG, United Kingdom
| | - Gareth R Barnes
- Wellcome Trust Centre for Neuroimaging, University College London, London, WC1N 3BG, United Kingdom
| | - Geraint Rees
- Institute of Cognitive Neuroscience University College London, Alexandra House, 17-19 Queen Square, London, WC1N 3AR, London, United Kingdom
- Wellcome Trust Centre for Neuroimaging, University College London, London, WC1N 3BG, United Kingdom
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9
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Profant O, Roth J, Bureš Z, Balogová Z, Lišková I, Betka J, Syka J. Auditory dysfunction in patients with Huntington’s disease. Clin Neurophysiol 2017; 128:1946-1953. [DOI: 10.1016/j.clinph.2017.07.403] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 07/13/2017] [Accepted: 07/18/2017] [Indexed: 10/19/2022]
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10
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A Crucial Test of the Population Separation Model of Auditory Stream Segregation in Macaque Primary Auditory Cortex. J Neurosci 2017; 37:10645-10655. [PMID: 28954867 DOI: 10.1523/jneurosci.0792-17.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 08/29/2017] [Accepted: 09/05/2017] [Indexed: 11/21/2022] Open
Abstract
An important aspect of auditory scene analysis is auditory stream segregation-the organization of sound sequences into perceptual streams reflecting different sound sources in the environment. Several models have been proposed to account for stream segregation. According to the "population separation" (PS) model, alternating ABAB tone sequences are perceived as a single stream or as two separate streams when "A" and "B" tones activate the same or distinct frequency-tuned neuronal populations in primary auditory cortex (A1), respectively. A crucial test of the PS model is whether it can account for the observation that A and B tones are generally perceived as a single stream when presented synchronously, rather than in an alternating pattern, even if they are widely separated in frequency. Here, we tested the PS model by recording neural responses to alternating (ALT) and synchronous (SYNC) tone sequences in A1 of male macaques. Consistent with predictions of the PS model, a greater effective tonotopic separation of A and B tone responses was observed under ALT than under SYNC conditions, thus paralleling the perceptual organization of the sequences. While other models of stream segregation, such as temporal coherence, are not excluded by the present findings, we conclude that PS is sufficient to account for the perceptual organization of ALT and SYNC sequences and thus remains a viable model of auditory stream segregation.SIGNIFICANCE STATEMENT According to the population separation (PS) model of auditory stream segregation, sounds that activate the same or separate neural populations in primary auditory cortex (A1) are perceived as one or two streams, respectively. It is unclear, however, whether the PS model can account for the perception of sounds as a single stream when they are presented synchronously. Here, we tested the PS model by recording neural responses to alternating (ALT) and synchronous (SYNC) tone sequences in macaque A1. A greater effective separation of tonotopic activity patterns was observed under ALT than under SYNC conditions, thus paralleling the perceptual organization of the sequences. Based on these findings, we conclude that PS remains a plausible neurophysiological model of auditory stream segregation.
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11
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Comparison of perceptual properties of auditory streaming between spectral and amplitude modulation domains. Hear Res 2017; 350:244-250. [PMID: 28323019 DOI: 10.1016/j.heares.2017.03.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 02/20/2017] [Accepted: 03/15/2017] [Indexed: 11/21/2022]
Abstract
The two-tone sequence (ABA_), which comprises two different sounds (A and B) and a silent gap, has been used to investigate how the auditory system organizes sequential sounds depending on various stimulus conditions or brain states. Auditory streaming can be evoked by differences not only in the tone frequency ("spectral cue": ΔFTONE, TONE condition) but also in the amplitude modulation rate ("AM cue": ΔFAM, AM condition). The aim of the present study was to explore the relationship between the perceptual properties of auditory streaming for the TONE and AM conditions. A sequence with a long duration (400 repetitions of ABA_) was used to examine the property of the bistability of streaming. The ratio of feature differences that evoked an equivalent probability of the segregated percept was close to the ratio of the Q-values of the auditory and modulation filters, consistent with a "channeling theory" of auditory streaming. On the other hand, for values of ΔFAM and ΔFTONE evoking equal probabilities of the segregated percept, the number of perceptual switches was larger for the TONE condition than for the AM condition, indicating that the mechanism(s) that determine the bistability of auditory streaming are different between or sensitive to the two domains. Nevertheless, the number of switches for individual listeners was positively correlated between the spectral and AM domains. The results suggest a possibility that the neural substrates for spectral and AM processes share a common switching mechanism but differ in location and/or in the properties of neural activity or the strength of internal noise at each level.
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12
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Deike S, Deliano M, Brechmann A. Probing neural mechanisms underlying auditory stream segregation in humans by transcranial direct current stimulation (tDCS). Neuropsychologia 2016; 91:262-267. [PMID: 27546076 DOI: 10.1016/j.neuropsychologia.2016.08.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 08/15/2016] [Accepted: 08/17/2016] [Indexed: 11/27/2022]
Abstract
One hypothesis concerning the neural underpinnings of auditory streaming states that frequency tuning of tonotopically organized neurons in primary auditory fields in combination with physiological forward suppression is necessary for the separation of representations of high-frequency A and low-frequency B tones. The extent of spatial overlap between the tonotopic activations of A and B tones is thought to underlie the perceptual organization of streaming sequences into one coherent or two separate streams. The present study attempts to interfere with these mechanisms by transcranial direct current stimulation (tDCS) and to probe behavioral outcomes reflecting the perception of ABAB streaming sequences. We hypothesized that tDCS by modulating cortical excitability causes a change in the separateness of the representations of A and B tones, which leads to a change in the proportions of one-stream and two-stream percepts. To test this, 22 subjects were presented with ambiguous ABAB sequences of three different frequency separations (∆F) and had to decide on their current percept after receiving sham, anodal, or cathodal tDCS over the left auditory cortex. We could confirm our hypothesis at the most ambiguous ∆F condition of 6 semitones. For anodal compared with sham and cathodal stimulation, we found a significant decrease in the proportion of two-stream perception and an increase in the proportion of one-stream perception. The results demonstrate the feasibility of using tDCS to probe mechanisms underlying auditory streaming through the use of various behavioral measures. Moreover, this approach allows one to probe the functions of auditory regions and their interactions with other processing stages.
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Affiliation(s)
- Susann Deike
- Special Lab Non-invasive Brain Imaging, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany.
| | - Matthias Deliano
- Department of Systems Physiology of Learning, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
| | - André Brechmann
- Special Lab Non-invasive Brain Imaging, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
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13
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Mehta AH, Yasin I, Oxenham AJ, Shamma S. Neural correlates of attention and streaming in a perceptually multistable auditory illusion. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 140:2225. [PMID: 27794350 PMCID: PMC5849028 DOI: 10.1121/1.4963902] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 09/12/2016] [Accepted: 09/20/2016] [Indexed: 06/06/2023]
Abstract
In a complex acoustic environment, acoustic cues and attention interact in the formation of streams within the auditory scene. In this study, a variant of the "octave illusion" [Deutsch (1974). Nature 251, 307-309] was used to investigate the neural correlates of auditory streaming, and to elucidate the effects of attention on the interaction between sequential and concurrent sound segregation in humans. By directing subjects' attention to different frequencies and ears, it was possible to elicit several different illusory percepts with the identical stimulus. The first experiment tested the hypothesis that the illusion depends on the ability of listeners to perceptually stream the target tones from within the alternating sound sequences. In the second experiment, concurrent psychophysical measures and electroencephalography recordings provided neural correlates of the various percepts elicited by the multistable stimulus. The results show that the perception and neural correlates of the auditory illusion can be manipulated robustly by attentional focus and that the illusion is constrained in much the same way as auditory stream segregation, suggesting common underlying mechanisms.
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Affiliation(s)
- Anahita H Mehta
- Ear Institute, University College London, 332 Gray's Inn Road, London WC1X 8EE, United Kingdom
| | - Ifat Yasin
- Department of Computer Science, University College London, 66-72 Gower Street, London WC1E 6BT, United Kingdom
| | - Andrew J Oxenham
- Department of Psychology, University of Minnesota, 75 East River Parkway, Minneapolis, Minnesota 55455, USA
| | - Shihab Shamma
- Institute for Systems Research, 2203 A.V. Williams Building, University of Maryland, College Park, Maryland 20742, USA
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14
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Teki S, Barascud N, Picard S, Payne C, Griffiths TD, Chait M. Neural Correlates of Auditory Figure-Ground Segregation Based on Temporal Coherence. Cereb Cortex 2016; 26:3669-80. [PMID: 27325682 PMCID: PMC5004755 DOI: 10.1093/cercor/bhw173] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
To make sense of natural acoustic environments, listeners must parse complex mixtures of sounds that vary in frequency, space, and time. Emerging work suggests that, in addition to the well-studied spectral cues for segregation, sensitivity to temporal coherence-the coincidence of sound elements in and across time-is also critical for the perceptual organization of acoustic scenes. Here, we examine pre-attentive, stimulus-driven neural processes underlying auditory figure-ground segregation using stimuli that capture the challenges of listening in complex scenes where segregation cannot be achieved based on spectral cues alone. Signals ("stochastic figure-ground": SFG) comprised a sequence of brief broadband chords containing random pure tone components that vary from 1 chord to another. Occasional tone repetitions across chords are perceived as "figures" popping out of a stochastic "ground." Magnetoencephalography (MEG) measurement in naïve, distracted, human subjects revealed robust evoked responses, commencing from about 150 ms after figure onset that reflect the emergence of the "figure" from the randomly varying "ground." Neural sources underlying this bottom-up driven figure-ground segregation were localized to planum temporale, and the intraparietal sulcus, demonstrating that this area, outside the "classic" auditory system, is also involved in the early stages of auditory scene analysis."
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Affiliation(s)
- Sundeep Teki
- Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, UK
- Auditory Cognition Group, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Current address: Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Nicolas Barascud
- Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, UK
- Ear Institute, University College London, London WC1X 8EE, UK
| | - Samuel Picard
- Ear Institute, University College London, London WC1X 8EE, UK
| | | | - Timothy D. Griffiths
- Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, UK
- Auditory Cognition Group, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Maria Chait
- Ear Institute, University College London, London WC1X 8EE, UK
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15
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Functional magnetic resonance imaging confirms forward suppression for rapidly alternating sounds in human auditory cortex but not in the inferior colliculus. Hear Res 2016; 335:25-32. [PMID: 26899342 DOI: 10.1016/j.heares.2016.02.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 02/08/2016] [Accepted: 02/15/2016] [Indexed: 11/21/2022]
Abstract
Forward suppression at the level of the auditory cortex has been suggested to subserve auditory stream segregation. Recent results in non-streaming stimulation contexts have indicated that forward suppression can also be observed in the inferior colliculus; whether this holds for streaming-related contexts remains unclear. Here, we used cardiac-gated fMRI to examine forward suppression in the inferior colliculus (and the rest of the human auditory pathway) in response to canonical streaming stimuli (rapid tone sequences comprised of either one repetitive tone or two alternating tones). The first stimulus is typically perceived as a single stream, the second as two interleaved streams. In different experiments using either pure tones differing in frequency or bandpass-filtered noise differing in inter-aural time differences, we observed stronger auditory cortex activation in response to alternating vs. repetitive stimulation, consistent with the presence of forward suppression. In contrast, activity in the inferior colliculus and other subcortical nuclei did not significantly differ between alternating and monotonic stimuli. This finding could be explained by active amplification of forward suppression in auditory cortex, by a low rate (or absence) of cells showing forward suppression in inferior colliculus, or both.
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16
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Lewald J. Modulation of human auditory spatial scene analysis by transcranial direct current stimulation. Neuropsychologia 2016; 84:282-93. [PMID: 26825012 DOI: 10.1016/j.neuropsychologia.2016.01.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Revised: 01/24/2016] [Accepted: 01/25/2016] [Indexed: 10/22/2022]
Abstract
Localizing and selectively attending to the source of a sound of interest in a complex auditory environment is an important capacity of the human auditory system. The underlying neural mechanisms have, however, still not been clarified in detail. This issue was addressed by using bilateral bipolar-balanced transcranial direct current stimulation (tDCS) in combination with a task demanding free-field sound localization in the presence of multiple sound sources, thus providing a realistic simulation of the so-called "cocktail-party" situation. With left-anode/right-cathode, but not with right-anode/left-cathode, montage of bilateral electrodes, tDCS over superior temporal gyrus, including planum temporale and auditory cortices, was found to improve the accuracy of target localization in left hemispace. No effects were found for tDCS over inferior parietal lobule or with off-target active stimulation over somatosensory-motor cortex that was used to control for non-specific effects. Also, the absolute error in localization remained unaffected by tDCS, thus suggesting that general response precision was not modulated by brain polarization. This finding can be explained in the framework of a model assuming that brain polarization modulated the suppression of irrelevant sound sources, thus resulting in more effective spatial separation of the target from the interfering sound in the complex auditory scene.
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Affiliation(s)
- Jörg Lewald
- Auditory Cognitive Neuroscience Laboratory, Department of Cognitive Psychology, Ruhr University Bochum, D-44780 Bochum, Germany; Leibniz Research Centre for Working Environment and Human Factors, Ardeystraße 67, D-44139 Dortmund, Germany.
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17
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Evans S, McGettigan C, Agnew ZK, Rosen S, Scott SK. Getting the Cocktail Party Started: Masking Effects in Speech Perception. J Cogn Neurosci 2015; 28:483-500. [PMID: 26696297 DOI: 10.1162/jocn_a_00913] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Spoken conversations typically take place in noisy environments, and different kinds of masking sounds place differing demands on cognitive resources. Previous studies, examining the modulation of neural activity associated with the properties of competing sounds, have shown that additional speech streams engage the superior temporal gyrus. However, the absence of a condition in which target speech was heard without additional masking made it difficult to identify brain networks specific to masking and to ascertain the extent to which competing speech was processed equivalently to target speech. In this study, we scanned young healthy adults with continuous fMRI, while they listened to stories masked by sounds that differed in their similarity to speech. We show that auditory attention and control networks are activated during attentive listening to masked speech in the absence of an overt behavioral task. We demonstrate that competing speech is processed predominantly in the left hemisphere within the same pathway as target speech but is not treated equivalently within that stream and that individuals who perform better in speech in noise tasks activate the left mid-posterior superior temporal gyrus more. Finally, we identify neural responses associated with the onset of sounds in the auditory environment; activity was found within right lateralized frontal regions consistent with a phasic alerting response. Taken together, these results provide a comprehensive account of the neural processes involved in listening in noise.
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Affiliation(s)
| | | | - Zarinah K Agnew
- University College London.,University of California, San Francisco
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18
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Gutschalk A, Rupp A, Dykstra AR. Interaction of streaming and attention in human auditory cortex. PLoS One 2015; 10:e0118962. [PMID: 25785997 PMCID: PMC4364770 DOI: 10.1371/journal.pone.0118962] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 01/08/2015] [Indexed: 12/03/2022] Open
Abstract
Serially presented tones are sometimes segregated into two perceptually distinct streams. An ongoing debate is whether this basic streaming phenomenon reflects automatic processes or requires attention focused to the stimuli. Here, we examined the influence of focused attention on streaming-related activity in human auditory cortex using magnetoencephalography (MEG). Listeners were presented with a dichotic paradigm in which left-ear stimuli consisted of canonical streaming stimuli (ABA_ or ABAA) and right-ear stimuli consisted of a classical oddball paradigm. In phase one, listeners were instructed to attend the right-ear oddball sequence and detect rare deviants. In phase two, they were instructed to attend the left ear streaming stimulus and report whether they heard one or two streams. The frequency difference (ΔF) of the sequences was set such that the smallest and largest ΔF conditions generally induced one- and two-stream percepts, respectively. Two intermediate ΔF conditions were chosen to elicit bistable percepts (i.e., either one or two streams). Attention enhanced the peak-to-peak amplitude of the P1-N1 complex, but only for ambiguous ΔF conditions, consistent with the notion that automatic mechanisms for streaming tightly interact with attention and that the latter is of particular importance for ambiguous sound sequences.
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Affiliation(s)
- Alexander Gutschalk
- Department of Neurology, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
- * E-mail:
| | - André Rupp
- Department of Neurology, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Andrew R. Dykstra
- Department of Neurology, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
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19
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Golden HL, Agustus JL, Goll JC, Downey LE, Mummery CJ, Schott JM, Crutch SJ, Warren JD. Functional neuroanatomy of auditory scene analysis in Alzheimer's disease. Neuroimage Clin 2015; 7:699-708. [PMID: 26029629 PMCID: PMC4446369 DOI: 10.1016/j.nicl.2015.02.019] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 01/16/2015] [Accepted: 02/24/2015] [Indexed: 11/28/2022]
Abstract
Auditory scene analysis is a demanding computational process that is performed automatically and efficiently by the healthy brain but vulnerable to the neurodegenerative pathology of Alzheimer's disease. Here we assessed the functional neuroanatomy of auditory scene analysis in Alzheimer's disease using the well-known 'cocktail party effect' as a model paradigm whereby stored templates for auditory objects (e.g., hearing one's spoken name) are used to segregate auditory 'foreground' and 'background'. Patients with typical amnestic Alzheimer's disease (n = 13) and age-matched healthy individuals (n = 17) underwent functional 3T-MRI using a sparse acquisition protocol with passive listening to auditory stimulus conditions comprising the participant's own name interleaved with or superimposed on multi-talker babble, and spectrally rotated (unrecognisable) analogues of these conditions. Name identification (conditions containing the participant's own name contrasted with spectrally rotated analogues) produced extensive bilateral activation involving superior temporal cortex in both the AD and healthy control groups, with no significant differences between groups. Auditory object segregation (conditions with interleaved name sounds contrasted with superimposed name sounds) produced activation of right posterior superior temporal cortex in both groups, again with no differences between groups. However, the cocktail party effect (interaction of own name identification with auditory object segregation processing) produced activation of right supramarginal gyrus in the AD group that was significantly enhanced compared with the healthy control group. The findings delineate an altered functional neuroanatomical profile of auditory scene analysis in Alzheimer's disease that may constitute a novel computational signature of this neurodegenerative pathology.
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Affiliation(s)
- Hannah L Golden
- Dementia Research Centre, UCL Institute of Neurology, University College London, London, UK
| | - Jennifer L Agustus
- Dementia Research Centre, UCL Institute of Neurology, University College London, London, UK
| | - Johanna C Goll
- Dementia Research Centre, UCL Institute of Neurology, University College London, London, UK
| | - Laura E Downey
- Dementia Research Centre, UCL Institute of Neurology, University College London, London, UK
| | - Catherine J Mummery
- Dementia Research Centre, UCL Institute of Neurology, University College London, London, UK
| | - Jonathan M Schott
- Dementia Research Centre, UCL Institute of Neurology, University College London, London, UK
| | - Sebastian J Crutch
- Dementia Research Centre, UCL Institute of Neurology, University College London, London, UK
| | - Jason D Warren
- Dementia Research Centre, UCL Institute of Neurology, University College London, London, UK
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20
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Larson E, Maddox RK, Lee AKC. Improving spatial localization in MEG inverse imaging by leveraging intersubject anatomical differences. Front Neurosci 2014; 8:330. [PMID: 25368547 PMCID: PMC4202703 DOI: 10.3389/fnins.2014.00330] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 09/30/2014] [Indexed: 11/13/2022] Open
Abstract
Modern neuroimaging techniques enable non-invasive observation of ongoing neural processing, with magnetoencephalography (MEG) in particular providing direct measurement of neural activity with millisecond time resolution. However, accurately mapping measured MEG sensor readings onto the underlying source neural structures remains an active area of research. This so-called “inverse problem” is ill posed, and poses a challenge for source estimation that is often cited as a drawback limiting MEG data interpretation. However, anatomically constrained MEG localization estimates may be more accurate than commonly believed. Here we hypothesize that, by combining anatomically constrained inverse estimates across subjects, the spatial uncertainty of MEG source localization can be mitigated. Specifically, we argue that differences in subject brain geometry yield differences in point-spread functions, resulting in improved spatial localization across subjects. To test this, we use standard methods to combine subject anatomical MRI scans with coregistration information to obtain an accurate forward (physical) solution, modeling the MEG sensor data resulting from brain activity originating from different cortical locations. Using a linear minimum-norm inverse to localize this brain activity, we demonstrate that a substantial increase in the spatial accuracy of MEG source localization can result from combining data from subjects with differing brain geometry. This improvement may be enabled by an increase in the amount of available spatial information in MEG data as measurements from different subjects are combined. This approach becomes more important in the face of practical issues of coregistration errors and potential noise sources, where we observe even larger improvements in localization when combining data across subjects. Finally, we use a simple auditory N100(m) localization task to show how this effect can influence localization using a recorded neural dataset.
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Affiliation(s)
- Eric Larson
- Institute for Learning and Brain Sciences, University of Washington Seattle, WA, USA
| | - Ross K Maddox
- Institute for Learning and Brain Sciences, University of Washington Seattle, WA, USA
| | - Adrian K C Lee
- Institute for Learning and Brain Sciences, University of Washington Seattle, WA, USA ; Department of Speech and Hearing Sciences, University of Washington Seattle, WA, USA
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21
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Dolležal LV, Brechmann A, Klump GM, Deike S. Evaluating auditory stream segregation of SAM tone sequences by subjective and objective psychoacoustical tasks, and brain activity. Front Neurosci 2014; 8:119. [PMID: 24936170 PMCID: PMC4047832 DOI: 10.3389/fnins.2014.00119] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 05/03/2014] [Indexed: 11/13/2022] Open
Abstract
Auditory stream segregation refers to a segregated percept of signal streams with different acoustic features. Different approaches have been pursued in studies of stream segregation. In psychoacoustics, stream segregation has mostly been investigated with a subjective task asking the subjects to report their percept. Few studies have applied an objective task in which stream segregation is evaluated indirectly by determining thresholds for a percept that depends on whether auditory streams are segregated or not. Furthermore, both perceptual measures and physiological measures of brain activity have been employed but only little is known about their relation. How the results from different tasks and measures are related is evaluated in the present study using examples relying on the ABA- stimulation paradigm that apply the same stimuli. We presented A and B signals that were sinusoidally amplitude modulated (SAM) tones providing purely temporal, spectral or both types of cues to evaluate perceptual stream segregation and its physiological correlate. Which types of cues are most prominent was determined by the choice of carrier and modulation frequencies (f mod) of the signals. In the subjective task subjects reported their percept and in the objective task we measured their sensitivity for detecting time-shifts of B signals in an ABA- sequence. As a further measure of processes underlying stream segregation we employed functional magnetic resonance imaging (fMRI). SAM tone parameters were chosen to evoke an integrated (1-stream), a segregated (2-stream), or an ambiguous percept by adjusting the f mod difference between A and B tones (Δf mod). The results of both psychoacoustical tasks are significantly correlated. BOLD responses in fMRI depend on Δf mod between A and B SAM tones. The effect of Δf mod, however, differs between auditory cortex and frontal regions suggesting differences in representation related to the degree of perceptual ambiguity of the sequences.
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Affiliation(s)
- Lena-Vanessa Dolležal
- Animal Physiology and Behavior Group, Department for Neuroscience, School for Medicine and Health Sciences, Center of Excellence "Hearing4all," Carl von Ossietzky University Oldenburg Oldenburg, Germany
| | - André Brechmann
- Special Lab Non-invasive Brain Imaging, Leibniz Institute for Neurobiology Magdeburg, Germany
| | - Georg M Klump
- Animal Physiology and Behavior Group, Department for Neuroscience, School for Medicine and Health Sciences, Center of Excellence "Hearing4all," Carl von Ossietzky University Oldenburg Oldenburg, Germany
| | - Susann Deike
- Special Lab Non-invasive Brain Imaging, Leibniz Institute for Neurobiology Magdeburg, Germany
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22
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Zündorf IC, Karnath HO, Lewald J. The effect of brain lesions on sound localization in complex acoustic environments. ACTA ACUST UNITED AC 2014; 137:1410-8. [PMID: 24618271 DOI: 10.1093/brain/awu044] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Localizing sound sources of interest in cluttered acoustic environments--as in the 'cocktail-party' situation--is one of the most demanding challenges to the human auditory system in everyday life. In this study, stroke patients' ability to localize acoustic targets in a single-source and in a multi-source setup in the free sound field were directly compared. Subsequent voxel-based lesion-behaviour mapping analyses were computed to uncover the brain areas associated with a deficit in localization in the presence of multiple distracter sound sources rather than localization of individually presented sound sources. Analyses revealed a fundamental role of the right planum temporale in this task. The results from the left hemisphere were less straightforward, but suggested an involvement of inferior frontal and pre- and postcentral areas. These areas appear to be particularly involved in the spectrotemporal analyses crucial for effective segregation of multiple sound streams from various locations, beyond the currently known network for localization of isolated sound sources in otherwise silent surroundings.
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Affiliation(s)
- Ida C Zündorf
- 1 Centre of Neurology, Division of Neuropsychology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
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23
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Alain C, Zendel BR, Hutka S, Bidelman GM. Turning down the noise: The benefit of musical training on the aging auditory brain. Hear Res 2014. [DOI: 10.10.1016/j.heares.2013.06.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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24
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Chakalov I, Draganova R, Wollbrink A, Preissl H, Pantev C. Perceptual organization of auditory streaming-task relies on neural entrainment of the stimulus-presentation rate: MEG evidence. BMC Neurosci 2013; 14:120. [PMID: 24119225 PMCID: PMC3853018 DOI: 10.1186/1471-2202-14-120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 10/09/2013] [Indexed: 11/21/2022] Open
Abstract
Background Humans are able to extract regularities from complex auditory scenes in order to form perceptually meaningful elements. It has been shown previously that this process depends critically on both the temporal integration of the sensory input over time and the degree of frequency separation between concurrent sound sources. Our goal was to examine the relationship between these two aspects by means of magnetoencephalography (MEG). To achieve this aim, we combined time-frequency analysis on a sensor space level with source analysis. Our paradigm consisted of asymmetric ABA-tone triplets wherein the B-tones were presented temporally closer to the first A-tones, providing different tempi within the same sequence. Participants attended to the slowest B-rhythm whilst the frequency separation between tones was manipulated (0-, 2-, 4- and 10-semitones). Results The results revealed that the asymmetric ABA-triplets spontaneously elicited periodic-sustained responses corresponding to the temporal distribution of the A-B and B-A tone intervals in all conditions. Moreover, when attending to the B-tones, the neural representations of the A- and B-streams were both detectable in the scenarios which allow perceptual streaming (2-, 4- and 10-semitones). Alongside this, the steady-state responses tuned to the presentation of the B-tones enhanced significantly with increase of the frequency separation between tones. However, the strength of the B-tones related steady-state responses dominated the strength of the A-tones responses in the 10-semitones condition. Conversely, the representation of the A-tones dominated the B-tones in the cases of 2- and 4-semitones conditions, in which a greater effort was required for completing the task. Additionally, the P1 evoked fields’ component following the B-tones increased in magnitude with the increase of inter-tonal frequency difference. Conclusions The enhancement of the evoked fields in the source space, along with the B-tones related activity of the time-frequency results, likely reflect the selective enhancement of the attended B-stream. The results also suggested a dissimilar efficiency of the temporal integration of separate streams depending on the degree of frequency separation between the sounds. Overall, the present findings suggest that the neural effects of auditory streaming could be directly captured in the time-frequency spectrum at the sensor-space level.
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Affiliation(s)
- Ivan Chakalov
- Institute for Biomagnetism and Biosignalanalysis, University of Münster, Malmedyweg 15, 48149 Münster, Germany.
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25
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Gutschalk A, Dykstra AR. Functional imaging of auditory scene analysis. Hear Res 2013; 307:98-110. [PMID: 23968821 DOI: 10.1016/j.heares.2013.08.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 07/26/2013] [Accepted: 08/08/2013] [Indexed: 11/16/2022]
Abstract
Our auditory system is constantly faced with the task of decomposing the complex mixture of sound arriving at the ears into perceptually independent streams constituting accurate representations of individual sound sources. This decomposition, termed auditory scene analysis, is critical for both survival and communication, and is thought to underlie both speech and music perception. The neural underpinnings of auditory scene analysis have been studied utilizing invasive experiments with animal models as well as non-invasive (MEG, EEG, and fMRI) and invasive (intracranial EEG) studies conducted with human listeners. The present article reviews human neurophysiological research investigating the neural basis of auditory scene analysis, with emphasis on two classical paradigms termed streaming and informational masking. Other paradigms - such as the continuity illusion, mistuned harmonics, and multi-speaker environments - are briefly addressed thereafter. We conclude by discussing the emerging evidence for the role of auditory cortex in remapping incoming acoustic signals into a perceptual representation of auditory streams, which are then available for selective attention and further conscious processing. This article is part of a Special Issue entitled Human Auditory Neuroimaging.
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Affiliation(s)
- Alexander Gutschalk
- Department of Neurology, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany.
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26
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Alain C, Zendel BR, Hutka S, Bidelman GM. Turning down the noise: the benefit of musical training on the aging auditory brain. Hear Res 2013; 308:162-73. [PMID: 23831039 DOI: 10.1016/j.heares.2013.06.008] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 06/19/2013] [Accepted: 06/24/2013] [Indexed: 11/29/2022]
Abstract
Age-related decline in hearing abilities is a ubiquitous part of aging, and commonly impacts speech understanding, especially when there are competing sound sources. While such age effects are partially due to changes within the cochlea, difficulties typically exist beyond measurable hearing loss, suggesting that central brain processes, as opposed to simple peripheral mechanisms (e.g., hearing sensitivity), play a critical role in governing hearing abilities late into life. Current training regimens aimed to improve central auditory processing abilities have experienced limited success in promoting listening benefits. Interestingly, recent studies suggest that in young adults, musical training positively modifies neural mechanisms, providing robust, long-lasting improvements to hearing abilities as well as to non-auditory tasks that engage cognitive control. These results offer the encouraging possibility that musical training might be used to counteract age-related changes in auditory cognition commonly observed in older adults. Here, we reviewed studies that have examined the effects of age and musical experience on auditory cognition with an emphasis on auditory scene analysis. We infer that musical training may offer potential benefits to complex listening and might be utilized as a means to delay or even attenuate declines in auditory perception and cognition that often emerge later in life.
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Affiliation(s)
- Claude Alain
- Rotman Research Institute, Baycrest Centre for Geriatric Care, Canada; Department of Psychology, University of Toronto, Canada.
| | - Benjamin Rich Zendel
- International Laboratory for Brain, Music and Sound Research (BRAMS), Département de Psychologie, Université de Montréal, Québec, Canada; Centre de Recherche, Institut Universitaire de Gériatrie de Montréal, Québec, Canada
| | - Stefanie Hutka
- Rotman Research Institute, Baycrest Centre for Geriatric Care, Canada; Department of Psychology, University of Toronto, Canada
| | - Gavin M Bidelman
- Institute for Intelligent Systems & School of Communication Sciences and Disorders, University of Memphis, USA
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27
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Zündorf IC, Lewald J, Karnath HO. Neural correlates of sound localization in complex acoustic environments. PLoS One 2013; 8:e64259. [PMID: 23691185 PMCID: PMC3653868 DOI: 10.1371/journal.pone.0064259] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 04/09/2013] [Indexed: 12/05/2022] Open
Abstract
Listening to and understanding people in a “cocktail-party situation” is a remarkable feature of the human auditory system. Here we investigated the neural correlates of the ability to localize a particular sound among others in an acoustically cluttered environment with healthy subjects. In a sound localization task, five different natural sounds were presented from five virtual spatial locations during functional magnetic resonance imaging (fMRI). Activity related to auditory stream segregation was revealed in posterior superior temporal gyrus bilaterally, anterior insula, supplementary motor area, and frontoparietal network. Moreover, the results indicated critical roles of left planum temporale in extracting the sound of interest among acoustical distracters and the precuneus in orienting spatial attention to the target sound. We hypothesized that the left-sided lateralization of the planum temporale activation is related to the higher specialization of the left hemisphere for analysis of spectrotemporal sound features. Furthermore, the precuneus − a brain area known to be involved in the computation of spatial coordinates across diverse frames of reference for reaching to objects − seems to be also a crucial area for accurately determining locations of auditory targets in an acoustically complex scene of multiple sound sources. The precuneus thus may not only be involved in visuo-motor processes, but may also subserve related functions in the auditory modality.
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Affiliation(s)
- Ida C. Zündorf
- Division of Neuropsychology, Center of Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Jörg Lewald
- Department of Cognitive Psychology, Ruhr University Bochum, Bochum, Germany
- Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany
| | - Hans-Otto Karnath
- Division of Neuropsychology, Center of Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- Department of Psychology, University of South Carolina, Columbia, South Carolina, United States of America
- * E-mail:
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28
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Ramage EM, Weintraub DM, Allen DN, Snyder JS. Evidence for stimulus-general impairments on auditory stream segregation tasks in schizophrenia. J Psychiatr Res 2012; 46:1540-5. [PMID: 23017812 PMCID: PMC3485434 DOI: 10.1016/j.jpsychires.2012.08.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 06/26/2012] [Accepted: 08/27/2012] [Indexed: 11/30/2022]
Abstract
BACKGROUND Auditory impairments in schizophrenia have been demonstrated previously, especially for tasks requiring precise encoding of frequency, although it is unclear the extent to which they have difficulty using pitch information and other cues to segregate sounds. We determined the extent to which those with schizophrenia have difficulty using pitch information and other auditory cues to segregate sounds that are presented sequentially. METHODS Ten participants with schizophrenia and nine healthy/normal control participants completed a battery of tasks that tested for the ability to perform sequential auditory stream segregation using pitch, amplitude modulation, or inter-aural phase difference as cues to segregation. RESULTS All three sequential segregation tasks showed reduced tendency for those with schizophrenia to perceive segregated sounds, compared to control participants. CONCLUSIONS These findings extend prior research by demonstrating a general impairment on sequential sound segregation tasks in schizophrenia, and not just on tasks that require precise encoding of frequency. Together, the pattern of results provide evidence that auditory impairments in schizophrenia result from selective abnormalities in neural circuits that carry out specific computations necessary for stream segregation, as opposed to an impairment in processing specific cues.
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Affiliation(s)
- Erin M Ramage
- Department of Psychology, University of Nevada, Las Vegas, NV 89154-5030, USA
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Carl D, Gutschalk A. Role of pattern, regularity, and silent intervals in auditory stream segregation based on inter-aural time differences. Exp Brain Res 2012; 224:557-70. [PMID: 23161159 DOI: 10.1007/s00221-012-3333-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 10/31/2012] [Indexed: 11/25/2022]
Abstract
Tone triplets separated by a pause (ABA_) are a popular tone-repetition pattern to study auditory stream segregation. Such triplets produce a galloping rhythm when integrated, but isochronous rhythms when segregated. Other patterns lacking a pause may produce less-prominent rhythmic differences but stronger streaming. Here, we evaluated whether this difference is readily explained by the presence of the pause and potentially associated with the reduction of adaptation, or whether there is contribution of tone pattern per se. Sequences with repetitive ABA_ and ABAA patterns were presented in magnetoencephalography. A and B tones were separated by differences in inter-aural time differences (ΔITD). Results showed that the stronger streaming of ABAA was associated with a more prominent release from the adaptation of the P(1)m in auditory cortex. We further compared behavioral streaming responses for patterns with and without pauses, and varied the position of the pause and pattern regularity. Results showed a major effect of the pauses' presence, but no prominent effects of tone pattern or pattern regularity. These results make a case for the existence of an early, primitive streaming mechanism that does not require an analysis of the tone pattern at later stages suggested by predictive-coding models of auditory streaming. The results are better explained by the simpler population-separation model and stress the previously observed role of neural adaptation for streaming perception.
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Affiliation(s)
- David Carl
- Department of Neurology, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
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30
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Oberfeld D, Stahn P. Sequential grouping modulates the effect of non-simultaneous masking on auditory intensity resolution. PLoS One 2012; 7:e48054. [PMID: 23110174 PMCID: PMC3480468 DOI: 10.1371/journal.pone.0048054] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 09/26/2012] [Indexed: 11/22/2022] Open
Abstract
The presence of non-simultaneous maskers can result in strong impairment in auditory intensity resolution relative to a condition without maskers, and causes a complex pattern of effects that is difficult to explain on the basis of peripheral processing. We suggest that the failure of selective attention to the target tones is a useful framework for understanding these effects. Two experiments tested the hypothesis that the sequential grouping of the targets and the maskers into separate auditory objects facilitates selective attention and therefore reduces the masker-induced impairment in intensity resolution. In Experiment 1, a condition favoring the processing of the maskers and the targets as two separate auditory objects due to grouping by temporal proximity was contrasted with the usual forward masking setting where the masker and the target presented within each observation interval of the two-interval task can be expected to be grouped together. As expected, the former condition resulted in a significantly smaller masker-induced elevation of the intensity difference limens (DLs). In Experiment 2, embedding the targets in an isochronous sequence of maskers led to a significantly smaller DL-elevation than control conditions not favoring the perception of the maskers as a separate auditory stream. The observed effects of grouping are compatible with the assumption that a precise representation of target intensity is available at the decision stage, but that this information is used only in a suboptimal fashion due to limitations of selective attention. The data can be explained within a framework of object-based attention. The results impose constraints on physiological models of intensity discrimination. We discuss candidate structures for physiological correlates of the psychophysical data.
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Affiliation(s)
- Daniel Oberfeld
- Department of Psychology, Section Experimental Psychology, Johannes Gutenberg-Universität Mainz, Mainz, Germany.
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31
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Dolležal LV, Beutelmann R, Klump GM. Stream segregation in the perception of sinusoidally amplitude-modulated tones. PLoS One 2012; 7:e43615. [PMID: 22984436 PMCID: PMC3440405 DOI: 10.1371/journal.pone.0043615] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 07/26/2012] [Indexed: 11/25/2022] Open
Abstract
Amplitude modulation can serve as a cue for segregating streams of sounds from different sources. Here we evaluate stream segregation in humans using ABA- sequences of sinusoidally amplitude modulated (SAM) tones. A and B represent SAM tones with the same carrier frequency (1000, 4000 Hz) and modulation depth (30, 100%). The modulation frequency of the A signals (fmodA) was 30, 100 or 300 Hz, respectively. The modulation frequency of the B signals was up to four octaves higher (Δfmod). Three different ABA- tone patterns varying in tone duration and stimulus onset asynchrony were presented to evaluate the effect of forward suppression. Subjects indicated their 1- or 2-stream percept on a touch screen at the end of each ABA- sequence (presentation time 5 or 15 s). Tone pattern, fmodA, Δfmod, carrier frequency, modulation depth and presentation time significantly affected the percentage of a 2-stream percept. The human psychophysical results are compared to responses of avian forebrain neurons evoked by different ABA- SAM tone conditions [1] that were broadly overlapping those of the present study. The neurons also showed significant effects of tone pattern and Δfmod that were comparable to effects observed in the present psychophysical study. Depending on the carrier frequency, modulation frequency, modulation depth and the width of the auditory filters, SAM tones may provide mainly temporal cues (sidebands fall within the range of the filter), spectral cues (sidebands fall outside the range of the filter) or possibly both. A computational model based on excitation pattern differences was used to predict the 50% threshold of 2-stream responses. In conditions for which the model predicts a considerably larger 50% threshold of 2-stream responses (i.e., larger Δfmod at threshold) than was observed, it is unlikely that spectral cues can provide an explanation of stream segregation by SAM.
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Affiliation(s)
- Lena-Vanessa Dolležal
- Animal Physiology and Behavior Group, Department of Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.
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32
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Lin IF, Kashino M. Perceptual grouping over time within and across auditory and tactile modalities. PLoS One 2012; 7:e41661. [PMID: 22844509 PMCID: PMC3406017 DOI: 10.1371/journal.pone.0041661] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 06/25/2012] [Indexed: 11/18/2022] Open
Abstract
In auditory scene analysis, population separation and temporal coherence have been proposed to explain how auditory features are grouped together and streamed over time. The present study investigated whether these two theories can be applied to tactile streaming and whether temporal coherence theory can be applied to crossmodal streaming. The results show that synchrony detection between two tones/taps at different frequencies/locations became difficult when one of the tones/taps was embedded in a perceptual stream. While the taps applied to the same location were streamed over time, the taps applied to different locations were not. This observation suggests that tactile stream formation can be explained by population-separation theory. On the other hand, temporally coherent auditory stimuli at different frequencies were streamed over time, but temporally coherent tactile stimuli applied to different locations were not. When there was within-modality streaming, temporally coherent auditory stimuli and tactile stimuli were not streamed over time, either. This observation suggests the limitation of temporal coherence theory when it is applied to perceptual grouping over time.
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Affiliation(s)
- I-Fan Lin
- NTT Communication Science Laboratories, NTT Corporation, Atsugi, Kanagawa, Japan.
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Kashino M, Kondo HM. Functional brain networks underlying perceptual switching: auditory streaming and verbal transformations. Philos Trans R Soc Lond B Biol Sci 2012; 367:977-87. [PMID: 22371619 DOI: 10.1098/rstb.2011.0370] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Recent studies have shown that auditory scene analysis involves distributed neural sites below, in, and beyond the auditory cortex (AC). However, it remains unclear what role each site plays and how they interact in the formation and selection of auditory percepts. We addressed this issue through perceptual multistability phenomena, namely, spontaneous perceptual switching in auditory streaming (AS) for a sequence of repeated triplet tones, and perceptual changes for a repeated word, known as verbal transformations (VTs). An event-related fMRI analysis revealed brain activity timelocked to perceptual switching in the cerebellum for AS, in frontal areas for VT, and the AC and thalamus for both. The results suggest that motor-based prediction, produced by neural networks outside the auditory system, plays essential roles in the segmentation of acoustic sequences both in AS and VT. The frequency of perceptual switching was determined by a balance between the activation of two sites, which are proposed to be involved in exploring novel perceptual organization and stabilizing current perceptual organization. The effect of the gene polymorphism of catechol-O-methyltransferase (COMT) on individual variations in switching frequency suggests that the balance of exploration and stabilization is modulated by catecholamines such as dopamine and noradrenalin. These mechanisms would support the noteworthy flexibility of auditory scene analysis.
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Affiliation(s)
- Makio Kashino
- NTT Communication Science Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198, Japan.
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34
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Hill KT, Bishop CW, Miller LM. Auditory grouping mechanisms reflect a sound's relative position in a sequence. Front Hum Neurosci 2012; 6:158. [PMID: 22701410 PMCID: PMC3370426 DOI: 10.3389/fnhum.2012.00158] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 05/17/2012] [Indexed: 11/21/2022] Open
Abstract
The human brain uses acoustic cues to decompose complex auditory scenes into its components. For instance to improve communication, a listener can select an individual “stream,” such as a talker in a crowded room, based on cues such as pitch or location. Despite numerous investigations into auditory streaming, few have demonstrated clear correlates of perception; instead, in many studies perception covaries with changes in physical stimulus properties (e.g., frequency separation). In the current report, we employ a classic ABA streaming paradigm and human electroencephalography (EEG) to disentangle the individual contributions of stimulus properties from changes in auditory perception. We find that changes in perceptual state—that is the perception of one versus two auditory streams with physically identical stimuli—and changes in physical stimulus properties are reflected independently in the event-related potential (ERP) during overlapping time windows. These findings emphasize the necessity of controlling for stimulus properties when studying perceptual effects of streaming. Furthermore, the independence of the perceptual effect from stimulus properties suggests the neural correlates of streaming reflect a tone's relative position within a larger sequence (1st, 2nd, 3rd) rather than its acoustics. By clarifying the role of stimulus attributes along with perceptual changes, this study helps explain precisely how the brain is able to distinguish a sound source of interest in an auditory scene.
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Affiliation(s)
- Kevin T Hill
- Human Neuroimaging Laboratory, Virginia Tech, Virginia Tech Carilion Research Institue, Roanoke VA, USA
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35
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Haywood NR, Roberts B. Effects of inducer continuity on auditory stream segregation: comparison of physical and perceived continuity in different contexts. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2011; 130:2917-2927. [PMID: 22087920 DOI: 10.1121/1.3643811] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The factors influencing the stream segregation of discrete tones and the perceived continuity of discrete tones as continuing through an interrupting masker are well understood as separate phenomena. Two experiments tested whether perceived continuity can influence the build-up of stream segregation by manipulating the perception of continuity during an induction sequence and measuring streaming in a subsequent test sequence comprising three triplets of low and high frequency tones (LHL-[ellipsis (horizontal)]). For experiment 1, a 1.2-s standard induction sequence comprising six 100-ms L-tones strongly promoted segregation, whereas a single extended L-inducer (1.1 s plus 100-ms silence) did not. Segregation was similar to that following the single extended inducer when perceived continuity was evoked by inserting noise bursts between the individual tones. Reported segregation increased when the noise level was reduced such that perceived continuity no longer occurred. Experiment 2 presented a 1.3-s continuous inducer created by bridging the 100-ms silence between an extended L-inducer and the first test-sequence tone. This configuration strongly promoted segregation. Segregation was also increased by filling the silence after the extended inducer with noise, such that it was perceived like a bridging inducer. Like physical continuity, perceived continuity can promote or reduce test-sequence streaming, depending on stimulus context.
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Affiliation(s)
- Nicholas R Haywood
- Psychology, School of Life and Health Sciences, Aston University, Birmingham B4 7ET, United Kingdom.
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36
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Goll JC, Kim LG, Ridgway GR, Hailstone JC, Lehmann M, Buckley AH, Crutch SJ, Warren JD. Impairments of auditory scene analysis in Alzheimer's disease. Brain 2011; 135:190-200. [PMID: 22036957 PMCID: PMC3267978 DOI: 10.1093/brain/awr260] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Parsing of sound sources in the auditory environment or ‘auditory scene analysis’ is a computationally demanding cognitive operation that is likely to be vulnerable to the neurodegenerative process in Alzheimer’s disease. However, little information is available concerning auditory scene analysis in Alzheimer's disease. Here we undertook a detailed neuropsychological and neuroanatomical characterization of auditory scene analysis in a cohort of 21 patients with clinically typical Alzheimer's disease versus age-matched healthy control subjects. We designed a novel auditory dual stream paradigm based on synthetic sound sequences to assess two key generic operations in auditory scene analysis (object segregation and grouping) in relation to simpler auditory perceptual, task and general neuropsychological factors. In order to assess neuroanatomical associations of performance on auditory scene analysis tasks, structural brain magnetic resonance imaging data from the patient cohort were analysed using voxel-based morphometry. Compared with healthy controls, patients with Alzheimer's disease had impairments of auditory scene analysis, and segregation and grouping operations were comparably affected. Auditory scene analysis impairments in Alzheimer's disease were not wholly attributable to simple auditory perceptual or task factors; however, the between-group difference relative to healthy controls was attenuated after accounting for non-verbal (visuospatial) working memory capacity. These findings demonstrate that clinically typical Alzheimer's disease is associated with a generic deficit of auditory scene analysis. Neuroanatomical associations of auditory scene analysis performance were identified in posterior cortical areas including the posterior superior temporal lobes and posterior cingulate. This work suggests a basis for understanding a class of clinical symptoms in Alzheimer's disease and for delineating cognitive mechanisms that mediate auditory scene analysis both in health and in neurodegenerative disease.
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Affiliation(s)
- Johanna C Goll
- Dementia Research Centre, Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK
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Hill KT, Bishop CW, Yadav D, Miller LM. Pattern of BOLD signal in auditory cortex relates acoustic response to perceptual streaming. BMC Neurosci 2011; 12:85. [PMID: 21849065 PMCID: PMC3173374 DOI: 10.1186/1471-2202-12-85] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2011] [Accepted: 08/17/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Segregating auditory scenes into distinct objects or streams is one of our brain's greatest perceptual challenges. Streaming has classically been studied with bistable sound stimuli, perceived alternately as a single group or two separate groups. Throughout the last decade different methodologies have yielded inconsistent evidence about the role of auditory cortex in the maintenance of streams. In particular, studies using functional magnetic resonance imaging (fMRI) have been unable to show persistent activity within auditory cortex (AC) that distinguishes between perceptual states. RESULTS We use bistable stimuli, an explicit perceptual categorization task, and a focused region of interest (ROI) analysis to demonstrate an effect of perceptual state within AC. We find that AC has more activity when listeners perceive the split percept rather than the grouped percept. In addition, within this ROI the pattern of acoustic response across voxels is significantly correlated with the pattern of perceptual modulation. In a whole-brain exploratory test, we corroborate previous work showing an effect of perceptual state in the intraparietal sulcus. CONCLUSIONS Our results show that the maintenance of auditory streams is reflected in AC activity, directly relating sound responses to perception, and that perceptual state is further represented in multiple, higher level cortical regions.
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Affiliation(s)
- Kevin T Hill
- Center for Mind and Brain, University of California, Davis, 95616, USA
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38
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Dykstra AR, Halgren E, Thesen T, Carlson CE, Doyle W, Madsen JR, Eskandar EN, Cash SS. Widespread Brain Areas Engaged during a Classical Auditory Streaming Task Revealed by Intracranial EEG. Front Hum Neurosci 2011; 5:74. [PMID: 21886615 PMCID: PMC3154443 DOI: 10.3389/fnhum.2011.00074] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 07/19/2011] [Indexed: 11/30/2022] Open
Abstract
The auditory system must constantly decompose the complex mixture of sound arriving at the ear into perceptually independent streams constituting accurate representations of individual sources in the acoustic environment. How the brain accomplishes this task is not well understood. The present study combined a classic behavioral paradigm with direct cortical recordings from neurosurgical patients with epilepsy in order to further describe the neural correlates of auditory streaming. Participants listened to sequences of pure tones alternating in frequency and indicated whether they heard one or two "streams." The intracranial EEG was simultaneously recorded from sub-dural electrodes placed over temporal, frontal, and parietal cortex. Like healthy subjects, patients heard one stream when the frequency separation between tones was small and two when it was large. Robust evoked-potential correlates of frequency separation were observed over widespread brain areas. Waveform morphology was highly variable across individual electrode sites both within and across gross brain regions. Surprisingly, few evoked-potential correlates of perceptual organization were observed after controlling for physical stimulus differences. The results indicate that the cortical areas engaged during the streaming task are more complex and widespread than has been demonstrated by previous work, and that, by-and-large, correlates of bistability during streaming are probably located on a spatial scale not assessed - or in a brain area not examined - by the present study.
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Affiliation(s)
- Andrew R. Dykstra
- Program in Speech and Hearing Bioscience and Technology, Harvard-MIT Division of Health Sciences and TechnologyCambridge, MA, USA
- Cortical Physiology Laboratory, Department of Neurology, Massachusetts General Hospital and Harvard Medical SchoolBoston, MA, USA
| | - Eric Halgren
- Department of Radiology, University of California San DiegoSan Diego, CA, USA
- Department of Neurosciences, University of California San DiegoSan Diego, CA, USA
| | - Thomas Thesen
- Comprehensive Epilepsy Center, New York University School of MedicineNew York, NY, USA
| | - Chad E. Carlson
- Comprehensive Epilepsy Center, New York University School of MedicineNew York, NY, USA
| | - Werner Doyle
- Comprehensive Epilepsy Center, New York University School of MedicineNew York, NY, USA
| | - Joseph R. Madsen
- Department of Neurosurgery, Brigham and Women's Hospital and Harvard Medical SchoolBoston, MA, USA
| | - Emad N. Eskandar
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical SchoolBoston, MA, USA
| | - Sydney S. Cash
- Cortical Physiology Laboratory, Department of Neurology, Massachusetts General Hospital and Harvard Medical SchoolBoston, MA, USA
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Schadwinkel S, Gutschalk A. Transient bold activity locked to perceptual reversals of auditory streaming in human auditory cortex and inferior colliculus. J Neurophysiol 2011; 105:1977-83. [PMID: 21325685 DOI: 10.1152/jn.00461.2010] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Our auditory system separates and tracks temporally interleaved sound sources by organizing them into distinct auditory streams. This streaming phenomenon is partly determined by physical stimulus properties but additionally depends on the internal state of the listener. As a consequence, streaming perception is often bistable and reversals between one- and two-stream percepts may occur spontaneously or be induced by a change of the stimulus. Here, we used functional MRI to investigate perceptual reversals in streaming based on interaural time differences (ITD) that produce a lateralized stimulus perception. Listeners were continuously presented with two interleaved streams, which slowly moved apart and together again. This paradigm produced longer intervals between reversals than stationary bistable stimuli but preserved temporal independence between perceptual reversals and physical stimulus transitions. Results showed prominent transient activity synchronized with the perceptual reversals in and around the auditory cortex. Sustained activity in the auditory cortex was observed during intervals where the ΔITD could potentially produce streaming, similar to previous studies. A localizer-based analysis additionally revealed transient activity time locked to perceptual reversals in the inferior colliculus. These data suggest that neural activity associated with streaming reversals is not limited to the thalamo-cortical system but involves early binaural processing in the auditory midbrain, already.
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Affiliation(s)
- Stefan Schadwinkel
- Department of Neurology, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
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Riecke L, Walter A, Sorger B, Formisano E. Tracking vocal pitch through noise: neural correlates in nonprimary auditory cortex. J Neurosci 2011; 31:1479-88. [PMID: 21273432 PMCID: PMC6623603 DOI: 10.1523/jneurosci.3450-10.2011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2010] [Revised: 10/28/2010] [Accepted: 11/10/2010] [Indexed: 11/21/2022] Open
Abstract
In natural environments, a sound can be heard as stable despite the presence of other occasionally louder sounds. For example, when a portion in a voice is replaced by masking noise, the interrupted voice may still appear illusorily continuous. Previous research found that continuity illusions of simple interrupted sounds, such as tones, are accompanied by weaker activity in the primary auditory cortex (PAC) during the interruption than veridical discontinuity percepts of these sounds. Here, we studied whether continuity illusions of more natural and more complex sounds also emerge from this mechanism. We used psychophysics and functional magnetic resonance imaging in humans to measure simultaneously continuity ratings and blood oxygenation level-dependent activity to vowels that were partially replaced by masking noise. Consistent with previous results on tone continuity illusions, we found listeners' reports of more salient vowel continuity illusions associated with weaker activity in auditory cortex (compared with reports of veridical discontinuity percepts of physically identical stimuli). In contrast to the reduced activity to tone continuity illusions in PAC, this reduction was localized in the right anterolateral Heschl's gyrus, a region that corresponds more to the non-PAC. Our findings suggest that the ability to hear differently complex sounds as stable during other louder sounds may be attributable to a common suppressive mechanism that operates at different levels of sound representation in auditory cortex.
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Affiliation(s)
- Lars Riecke
- Department of Cognitive Neuroscience, Maastricht University, 6200 MD Maastricht, The Netherlands.
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41
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Ma L, Micheyl C, Yin P, Oxenham AJ, Shamma SA. Behavioral measures of auditory streaming in ferrets (Mustela putorius). ACTA ACUST UNITED AC 2011; 124:317-30. [PMID: 20695663 DOI: 10.1037/a0018273] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
An important aspect of the analysis of auditory "scenes" relates to the perceptual organization of sound sequences into auditory "streams." In this study, we adapted two auditory perception tasks, used in recent human psychophysical studies, to obtain behavioral measures of auditory streaming in ferrets (Mustela putorius). One task involved the detection of shifts in the frequency of tones within an alternating tone sequence. The other task involved the detection of a stream of regularly repeating target tones embedded within a randomly varying multitone background. In both tasks, performance was measured as a function of various stimulus parameters, which previous psychophysical studies in humans have shown to influence auditory streaming. Ferret performance in the two tasks was found to vary as a function of these parameters in a way that is qualitatively consistent with the human data. These results suggest that auditory streaming occurs in ferrets, and that the two tasks described here may provide a valuable tool in future behavioral and neurophysiological studies of the phenomenon.
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Affiliation(s)
- Ling Ma
- Neural Systems Laboratory, Department of Bioengineering, University of Maryland, College Park, MD 20742, USA.
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42
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Potential fMRI correlates of 40-Hz phase locking in primary auditory cortex, thalamus and midbrain. Neuroimage 2011; 54:495-504. [PMID: 20688174 DOI: 10.1016/j.neuroimage.2010.07.064] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 06/25/2010] [Accepted: 07/28/2010] [Indexed: 11/21/2022] Open
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Itatani N, Klump GM. Neural Correlates of Auditory Streaming of Harmonic Complex Sounds With Different Phase Relations in the Songbird Forebrain. J Neurophysiol 2011; 105:188-99. [DOI: 10.1152/jn.00496.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It has been suggested that successively presented sounds that are perceived as separate auditory streams are represented by separate populations of neurons. Mostly, spectral separation in different peripheral filters has been identified as the cue for segregation. However, stream segregation based on temporal cues is also possible without spectral separation. Here we present sequences of ABA- triplet stimuli providing only temporal cues to neurons in the European starling auditory forebrain. A and B sounds (125 ms duration) were harmonic complexes (fundamentals 100, 200, or 400 Hz; center frequency and bandwidth chosen to fit the neurons' tuning characteristic) with identical amplitude spectra but different phase relations between components (cosine, alternating, or random phase) and presented at different rates. Differences in both rate responses and temporal response patterns of the neurons when stimulated with harmonic complexes with different phase relations provide first evidence for a mechanism allowing a separate neural representation of such stimuli. Recording sites responding >1 kHz showed enhanced rate and temporal differences compared with those responding at lower frequencies. These results demonstrate a neural correlate of streaming by temporal cues due to the variation of phase that shows striking parallels to observations in previous psychophysical studies.
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Affiliation(s)
- Naoya Itatani
- Animal Physiology and Behaviour Group, Institute for Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Georg M. Klump
- Animal Physiology and Behaviour Group, Institute for Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
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Schadwinkel S, Gutschalk A. Functional dissociation of transient and sustained fMRI BOLD components in human auditory cortex revealed with a streaming paradigm based on interaural time differences. Eur J Neurosci 2010; 32:1970-8. [PMID: 21050277 DOI: 10.1111/j.1460-9568.2010.07459.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A number of physiological studies suggest that feature-selective adaptation is relevant to the pre-processing for auditory streaming, the perceptual separation of overlapping sound sources. Most of these studies are focused on spectral differences between streams, which are considered most important for streaming. However, spatial cues also support streaming, alone or in combination with spectral cues, but physiological studies of spatial cues for streaming remain scarce. Here, we investigate whether the tuning of selective adaptation for interaural time differences (ITD) coincides with the range where streaming perception is observed. FMRI activation that has been shown to adapt depending on the repetition rate was studied with a streaming paradigm where two tones were differently lateralized by ITD. Listeners were presented with five different ΔITD conditions (62.5, 125, 187.5, 343.75, or 687.5 μs) out of an active baseline with no ΔITD during fMRI. The results showed reduced adaptation for conditions with ΔITD ≥ 125 μs, reflected by enhanced sustained BOLD activity. The percentage of streaming perception for these stimuli increased from approximately 20% for ΔITD = 62.5 μs to > 60% for ΔITD = 125 μs. No further sustained BOLD enhancement was observed when the ΔITD was increased beyond ΔITD = 125 μs, whereas the streaming probability continued to increase up to 90% for ΔITD = 687.5 μs. Conversely, the transient BOLD response, at the transition from baseline to ΔITD blocks, increased most prominently as ΔITD was increased from 187.5 to 343.75 μs. These results demonstrate a clear dissociation of transient and sustained components of the BOLD activity in auditory cortex.
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Affiliation(s)
- Stefan Schadwinkel
- Department of Neurology, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
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Bee MA, Micheyl C, Oxenham AJ, Klump GM. Neural adaptation to tone sequences in the songbird forebrain: patterns, determinants, and relation to the build-up of auditory streaming. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2010; 196:543-57. [PMID: 20563587 DOI: 10.1007/s00359-010-0542-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 05/08/2010] [Accepted: 05/28/2010] [Indexed: 11/29/2022]
Abstract
Neural responses to tones in the mammalian primary auditory cortex (A1) exhibit adaptation over the course of several seconds. Important questions remain about the taxonomic distribution of multi-second adaptation and its possible roles in hearing. It has been hypothesized that neural adaptation could explain the gradual "build-up" of auditory stream segregation. We investigated the influence of several stimulus-related factors on neural adaptation in the avian homologue of mammalian A1 (field L2) in starlings (Sturnus vulgaris). We presented awake birds with sequences of repeated triplets of two interleaved tones (ABA-ABA-...) in which we varied the frequency separation between the A and B tones (DeltaF), the stimulus onset asynchrony (time from tone onset to onset within a triplet), and tone duration. We found that stimulus onset asynchrony generally had larger effects on adaptation compared with DeltaF and tone duration over the parameter range tested. Using a simple model, we show how time-dependent changes in neural responses can be transformed into neurometric functions that make testable predictions about the dependence of the build-up of stream segregation on various spectral and temporal stimulus properties.
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Affiliation(s)
- Mark A Bee
- Department of Ecology, Evolution, and Behavior, University of Minnesota, 100 Ecology, 1987 Upper Buford Circle, St. Paul, MN 55108, USA.
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Shamma SA, Micheyl C. Behind the scenes of auditory perception. Curr Opin Neurobiol 2010; 20:361-6. [PMID: 20456940 DOI: 10.1016/j.conb.2010.03.009] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 03/16/2010] [Accepted: 03/29/2010] [Indexed: 11/30/2022]
Abstract
'Auditory scenes' often contain contributions from multiple acoustic sources. These are usually heard as separate auditory 'streams', which can be selectively followed over time. How and where these auditory streams are formed in the auditory system is one of the most fascinating questions facing auditory scientists today. Findings published within the past two years indicate that both cortical and subcortical processes contribute to the formation of auditory streams, and they raise important questions concerning the roles of primary and secondary areas of auditory cortex in this phenomenon. In addition, these findings underline the importance of taking into account the relative timing of neural responses, and the influence of selective attention, in the search for neural correlates of the perception of auditory streams.
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Affiliation(s)
- Shihab A Shamma
- Department of Electrical and Computer Engineering & Institute for Systems Research, University of Maryland College Park, United States.
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Schadwinkel S, Gutschalk A. Activity associated with stream segregation in human auditory cortex is similar for spatial and pitch cues. Cereb Cortex 2010; 20:2863-73. [PMID: 20237241 DOI: 10.1093/cercor/bhq037] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Streaming is a perceptual mechanism by which the brain segregates information from multiple sound sources in our environment and assigns them to distinct auditory streams. Examples for streaming cues are differences in frequency spectrum, pitch, or space, and potential neural correlates for streaming based on spectral and pitch cues have been identified in the auditory cortex. Here, magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) were used to evaluate if response enhancement in auditory cortex associated with streaming represents a general pattern that is independent of the stimulus cue. Interaural time differences (ITDs) were used as a spatial streaming cue and were compared with streaming based on fundamental frequency (f(0)) differences. The MEG results showed enhancement of the P(1)m after 60-90 ms that was similar during streaming based on ITD and pitch. Sustained fMRI activity was enhanced at identical sites in Heschl's gyrus and planum temporale for both cues; no topographical specificity for space or pitch was found for the streaming-associated enhancement. These results support the hypothesis of an early convergence of the neural representation for auditory streams that is independent of the acoustic cue that the streaming is based on.
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Affiliation(s)
- Stefan Schadwinkel
- Department of Neurology, University of Heidelberg, Im Neuenheimer Feld 400, Heidelberg,Germany.
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Deike S, Scheich H, Brechmann A. Active stream segregation specifically involves the left human auditory cortex. Hear Res 2010; 265:30-7. [PMID: 20233603 DOI: 10.1016/j.heares.2010.03.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 02/15/2010] [Accepted: 03/11/2010] [Indexed: 11/27/2022]
Abstract
An important aspect of auditory scene analysis is the sequential grouping of similar sounds into one "auditory stream" while keeping competing streams separate. In the present low-noise fMRI study we presented sequences of alternating high-pitch (A) and low-pitch (B) complex harmonic tones using acoustic parameters that allow the perception of either two separate streams or one alternating stream. However, the subjects were instructed to actively and continuously segregate the A from the B stream. This was controlled by the additional instruction to listen for rare level deviants only in the low-pitch stream. Compared to the control condition in which only one non-separable stream was presented the active segregation of the A from the B stream led to a selective increase of activation in the left auditory cortex (AC). Together with a similar finding from a previous study using a different acoustic cue for streaming, namely timbre, this suggests that the left auditory cortex plays a dominant role in active sequential stream segregation. However, we found cue differences within the left AC: Whereas in the posterior areas, including the planum temporale, activation increased for both acoustic cues, the anterior areas, including Heschl's gyrus, are only involved in stream segregation based on pitch.
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Affiliation(s)
- Susann Deike
- Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany.
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Gutschalk A, Hämäläinen MS, Melcher JR. BOLD responses in human auditory cortex are more closely related to transient MEG responses than to sustained ones. J Neurophysiol 2010; 103:2015-26. [PMID: 20107131 DOI: 10.1152/jn.01005.2009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Blood oxygen level dependent-functional magnetic resonance imaging (BOLD-fMRI) and magnetoencephalographic (MEG) signals are both coupled to postsynaptic potentials, although their relationship is incompletely understood. Here, the wide range of BOLD-fMRI and MEG responses produced by auditory cortex was exploited to better understand the BOLD-fMRI/MEG relationship. Measurements of BOLD and MEG responses were made in the same subjects using the same stimuli for both modalities. The stimuli, 24-s sequences of click trains, had duty cycles of 2.5, 25, 72, and 100%. For the 2.5% sequence, the BOLD response was elevated throughout the sequence, whereas for 100%, it peaked after sequence onset and offset and showed a diminished elevation in between. On the finer timescale of MEG, responses at 2.5% consisted of a complex of transients, including N(1)m, to each click train of the sequence, whereas for 100% the only transients occurred at sequence onset and offset between which there was a sustained elevation in the MEG signal (a sustained field). A model that separately estimated the contributions of transient and sustained MEG signals to the BOLD response best fit BOLD measurements when the transient contribution was weighted 8- to 10-fold more than the sustained one. The findings suggest that BOLD responses in the auditory cortex are tightly coupled to the neural activity underlying transient, not sustained, MEG signals.
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Affiliation(s)
- Alexander Gutschalk
- Department of Neurology, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany.
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Involvement of the thalamocortical loop in the spontaneous switching of percepts in auditory streaming. J Neurosci 2009; 29:12695-701. [PMID: 19812344 DOI: 10.1523/jneurosci.1549-09.2009] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Perceptual grouping of successive frequency components, namely, auditory streaming, is essential for auditory scene analysis. Prolonged listening to an unchanging triplet-tone sequence produces a series of illusory switches between a single coherent stream (S1) and two distinct streams (S2). The predominant percept depends on the frequency difference (Deltaf) between high and low tones. Here, we combined the use of different Deltafs with an event-related fMRI design to identify whether the temporal dynamics of brain activity differs depending on the direction of perceptual switches. The results demonstrated that the activity of the medial geniculate body (MGB) in the thalamus occurred earlier during switching from nonpredominant to predominant percepts, whereas that of the auditory cortex (AC) occurred earlier during switching from predominant to nonpredominant percepts, regardless of Deltaf. The asymmetry of temporal precedence indicates that the MGB and AC activations play different roles in perceptual switching and depend on perceptual predominance rather than on S1 and S2 percepts per se. Our results suggest that feedforward and feedback processes in the thalamocortical loop are involved in the formation of percepts in auditory streaming.
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