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Rizzi R, Bidelman GM. Duplex perception reveals brainstem auditory representations are modulated by listeners' ongoing percept for speech. Cereb Cortex 2023; 33:10076-10086. [PMID: 37522248 PMCID: PMC10502779 DOI: 10.1093/cercor/bhad266] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/27/2023] [Accepted: 07/10/2023] [Indexed: 08/01/2023] Open
Abstract
So-called duplex speech stimuli with perceptually ambiguous spectral cues to one ear and isolated low- versus high-frequency third formant "chirp" to the opposite ear yield a coherent percept supporting their phonetic categorization. Critically, such dichotic sounds are only perceived categorically upon binaural integration. Here, we used frequency-following responses (FFRs), scalp-recorded potentials reflecting phase-locked subcortical activity, to investigate brainstem responses to fused speech percepts and to determine whether FFRs reflect binaurally integrated category-level representations. We recorded FFRs to diotic and dichotic stop-consonants (/da/, /ga/) that either did or did not require binaural fusion to properly label along with perceptually ambiguous sounds without clear phonetic identity. Behaviorally, listeners showed clear categorization of dichotic speech tokens confirming they were heard with a fused, phonetic percept. Neurally, we found FFRs were stronger for categorically perceived speech relative to category-ambiguous tokens but also differentiated phonetic categories for both diotically and dichotically presented speech sounds. Correlations between neural and behavioral data further showed FFR latency predicted the degree to which listeners labeled tokens as "da" versus "ga." The presence of binaurally integrated, category-level information in FFRs suggests human brainstem processing reflects a surprisingly abstract level of the speech code typically circumscribed to much later cortical processing.
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Affiliation(s)
- Rose Rizzi
- Department of Speech, Language, and Hearing Sciences, Indiana University, Bloomington, IN, United States
- Program in Neuroscience, Indiana University, Bloomington, IN, United States
- School of Communication Sciences and Disorders, University of Memphis, Memphis, TN, United States
| | - Gavin M Bidelman
- Department of Speech, Language, and Hearing Sciences, Indiana University, Bloomington, IN, United States
- Program in Neuroscience, Indiana University, Bloomington, IN, United States
- Cognitive Science Program, Indiana University, Bloomington, IN, United States
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Rizzi R, Bidelman GM. Duplex perception reveals brainstem auditory representations are modulated by listeners' ongoing percept for speech. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.09.540018. [PMID: 37214801 PMCID: PMC10197666 DOI: 10.1101/2023.05.09.540018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
So-called duplex speech stimuli with perceptually ambiguous spectral cues to one ear and isolated low- vs. high-frequency third formant "chirp" to the opposite ear yield a coherent percept supporting their phonetic categorization. Critically, such dichotic sounds are only perceived categorically upon binaural integration. Here, we used frequency-following responses (FFRs), scalp-recorded potentials reflecting phase-locked subcortical activity, to investigate brainstem responses to fused speech percepts and to determine whether FFRs reflect binaurally integrated category-level representations. We recorded FFRs to diotic and dichotic stop-consonants (/da/, /ga/) that either did or did not require binaural fusion to properly label along with perceptually ambiguous sounds without clear phonetic identity. Behaviorally, listeners showed clear categorization of dichotic speech tokens confirming they were heard with a fused, phonetic percept. Neurally, we found FFRs were stronger for categorically perceived speech relative to category-ambiguous tokens but also differentiated phonetic categories for both diotically and dichotically presented speech sounds. Correlations between neural and behavioral data further showed FFR latency predicted the degree to which listeners labeled tokens as "da" vs. "ga". The presence of binaurally integrated, category-level information in FFRs suggests human brainstem processing reflects a surprisingly abstract level of the speech code typically circumscribed to much later cortical processing.
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Affiliation(s)
- Rose Rizzi
- Department of Speech, Language, and Hearing Sciences, Indiana University, Bloomington, IN, USA
- Program in Neuroscience, Indiana University, Bloomington, IN, USA
- School of Communication Sciences and Disorders, University of Memphis, Memphis, TN, USA
| | - Gavin M. Bidelman
- Department of Speech, Language, and Hearing Sciences, Indiana University, Bloomington, IN, USA
- Program in Neuroscience, Indiana University, Bloomington, IN, USA
- Cognitive Science Program, Indiana University, Bloomington, IN, USA
- School of Communication Sciences and Disorders, University of Memphis, Memphis, TN, USA
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Wu M, Luo B, Yu Y, Li X, Gao J, Li J, Sorger B, Riecke L. Rhythmic musical-electrical trigeminal nerve stimulation improves impaired consciousness. Neuroimage Clin 2022; 36:103170. [PMID: 36063757 PMCID: PMC9460811 DOI: 10.1016/j.nicl.2022.103170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 07/27/2022] [Accepted: 08/23/2022] [Indexed: 12/14/2022]
Abstract
Accumulating evidence shows that consciousness is linked to neural oscillations in the thalamocortical system, suggesting that deficits in these oscillations may underlie disorders of consciousness (DOC). However, patient-friendly non-invasive treatments targeting this functional anomaly are still missing and the therapeutic value of oscillation restoration has remained unclear. We propose a novel approach that aims to restore DOC patients' thalamocortical oscillations by combining rhythmic trigeminal-nerve stimulation with comodulated musical stimulation ("musical-electrical TNS"). In a double-blind, placebo-controlled, parallel-group study, we recruited 63 patients with DOC and randomly assigned them to groups receiving gamma, beta, or sham musical-electrical TNS. The stimulation was applied for 40 min on five consecutive days. We measured patients' consciousness before and after the stimulation using behavioral indicators and neural responses to rhythmic auditory speech. We further assessed their outcomes one year later. We found that musical-electrical TNS reliably lead to improvements in consciousness and oscillatory brain activity at the stimulation frequency: 43.5 % of patients in the gamma group and 25 % of patients in the beta group showed an improvement of their diagnosis after being treated with the stimulation. This group of benefitting patients still showed more positive outcomes one year later. Moreover, patients with stronger behavioral benefits showed stronger improvements in oscillatory brain activity. These findings suggest that brain oscillations contribute to consciousness and that musical-electrical TNS may serve as a promising approach to improve consciousness and predict long-term outcomes in patients with DOC.
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Affiliation(s)
- Min Wu
- Department of Neurology & Brain Medical Centre, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China,Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands
| | - Benyan Luo
- Department of Neurology & Brain Medical Centre, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China,Corresponding author.
| | - Yamei Yu
- Department of Neurology & Brain Medical Centre, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiaoxia Li
- Department of Neurology & Brain Medical Centre, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Jian Gao
- Hangzhou Mingzhou Brain Rehabilitation Hospital, Hangzhou, China
| | - Jingqi Li
- Hangzhou Mingzhou Brain Rehabilitation Hospital, Hangzhou, China
| | - Bettina Sorger
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands
| | - Lars Riecke
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands
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Preisig BC, Riecke L, Hervais-Adelman A. Speech sound categorization: The contribution of non-auditory and auditory cortical regions. Neuroimage 2022; 258:119375. [PMID: 35700949 DOI: 10.1016/j.neuroimage.2022.119375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 05/13/2022] [Accepted: 06/10/2022] [Indexed: 11/26/2022] Open
Abstract
Which processes in the human brain lead to the categorical perception of speech sounds? Investigation of this question is hampered by the fact that categorical speech perception is normally confounded by acoustic differences in the stimulus. By using ambiguous sounds, however, it is possible to dissociate acoustic from perceptual stimulus representations. Twenty-seven normally hearing individuals took part in an fMRI study in which they were presented with an ambiguous syllable (intermediate between /da/ and /ga/) in one ear and with disambiguating acoustic feature (third formant, F3) in the other ear. Multi-voxel pattern searchlight analysis was used to identify brain areas that consistently differentiated between response patterns associated with different syllable reports. By comparing responses to different stimuli with identical syllable reports and identical stimuli with different syllable reports, we disambiguated whether these regions primarily differentiated the acoustics of the stimuli or the syllable report. We found that BOLD activity patterns in left perisylvian regions (STG, SMG), left inferior frontal regions (vMC, IFG, AI), left supplementary motor cortex (SMA/pre-SMA), and right motor and somatosensory regions (M1/S1) represent listeners' syllable report irrespective of stimulus acoustics. Most of these regions are outside of what is traditionally regarded as auditory or phonological processing areas. Our results indicate that the process of speech sound categorization implicates decision-making mechanisms and auditory-motor transformations.
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Affiliation(s)
- Basil C Preisig
- Donders Institute for Brain, Cognition, and Behaviour, Radboud University, 6500 HB Nijmegen, The Netherlands; Max Planck Institute for Psycholinguistics, 6525 XD Nijmegen, The Netherlands; Department of Psychology, Neurolinguistics, University of Zurich, 8050 Zurich, Switzerland; Department of Comparative Language Science, Evolutionary Neuroscience of Language, University of Zurich, 8050 Zurich, Switzerland; Neuroscience Center Zurich, University of Zurich and Eidgenössische Technische Hochschule Zurich, 8057 Zurich, Switzerland.
| | - Lars Riecke
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6229 ER Maastricht, The Netherlands
| | - Alexis Hervais-Adelman
- Department of Psychology, Neurolinguistics, University of Zurich, 8050 Zurich, Switzerland; Neuroscience Center Zurich, University of Zurich and Eidgenössische Technische Hochschule Zurich, 8057 Zurich, Switzerland
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Preisig BC, Hervais-Adelman A. The Predictive Value of Individual Electric Field Modeling for Transcranial Alternating Current Stimulation Induced Brain Modulation. Front Cell Neurosci 2022; 16:818703. [PMID: 35273479 PMCID: PMC8901488 DOI: 10.3389/fncel.2022.818703] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 02/02/2022] [Indexed: 11/13/2022] Open
Abstract
There is considerable individual variability in the reported effectiveness of non-invasive brain stimulation. This variability has often been ascribed to differences in the neuroanatomy and resulting differences in the induced electric field inside the brain. In this study, we addressed the question whether individual differences in the induced electric field can predict the neurophysiological and behavioral consequences of gamma band tACS. In a within-subject experiment, bi-hemispheric gamma band tACS and sham stimulation was applied in alternating blocks to the participants' superior temporal lobe, while task-evoked auditory brain activity was measured with concurrent functional magnetic resonance imaging (fMRI) and a dichotic listening task. Gamma tACS was applied with different interhemispheric phase lags. In a recent study, we could show that anti-phase tACS (180° interhemispheric phase lag), but not in-phase tACS (0° interhemispheric phase lag), selectively modulates interhemispheric brain connectivity. Using a T1 structural image of each participant's brain, an individual simulation of the induced electric field was computed. From these simulations, we derived two predictor variables: maximal strength (average of the 10,000 voxels with largest electric field values) and precision of the electric field (spatial correlation between the electric field and the task evoked brain activity during sham stimulation). We found considerable variability in the individual strength and precision of the electric fields. Importantly, the strength of the electric field over the right hemisphere predicted individual differences of tACS induced brain connectivity changes. Moreover, we found in both hemispheres a statistical trend for the effect of electric field strength on tACS induced BOLD signal changes. In contrast, the precision of the electric field did not predict any neurophysiological measure. Further, neither strength, nor precision predicted interhemispheric integration. In conclusion, we found evidence for the dose-response relationship between individual differences in electric fields and tACS induced activity and connectivity changes in concurrent fMRI. However, the fact that this relationship was stronger in the right hemisphere suggests that the relationship between the electric field parameters, neurophysiology, and behavior may be more complex for bi-hemispheric tACS.
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Affiliation(s)
- Basil C. Preisig
- Department of Psychology, Neurolinguistics, University of Zurich, Zurich, Switzerland
- Donders Institute for Cognitive Neuroimaging, Radboud University, Nijmegen, Netherlands
- Max Planck Institute for Psycholinguistics, Nijmegen, Netherlands
- Neuroscience Center Zurich, Eidgenössische Technische Hochschule Zurich, University of Zurich, Zurich, Switzerland
| | - Alexis Hervais-Adelman
- Department of Psychology, Neurolinguistics, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, Eidgenössische Technische Hochschule Zurich, University of Zurich, Zurich, Switzerland
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Preisig BC, Riecke L, Sjerps MJ, Kösem A, Kop BR, Bramson B, Hagoort P, Hervais-Adelman A. Selective modulation of interhemispheric connectivity by transcranial alternating current stimulation influences binaural integration. Proc Natl Acad Sci U S A 2021; 118:e2015488118. [PMID: 33568530 PMCID: PMC7896308 DOI: 10.1073/pnas.2015488118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Brain connectivity plays a major role in the encoding, transfer, and integration of sensory information. Interregional synchronization of neural oscillations in the γ-frequency band has been suggested as a key mechanism underlying perceptual integration. In a recent study, we found evidence for this hypothesis showing that the modulation of interhemispheric oscillatory synchrony by means of bihemispheric high-density transcranial alternating current stimulation (HD-TACS) affects binaural integration of dichotic acoustic features. Here, we aimed to establish a direct link between oscillatory synchrony, effective brain connectivity, and binaural integration. We experimentally manipulated oscillatory synchrony (using bihemispheric γ-TACS with different interhemispheric phase lags) and assessed the effect on effective brain connectivity and binaural integration (as measured with functional MRI and a dichotic listening task, respectively). We found that TACS reduced intrahemispheric connectivity within the auditory cortices and antiphase (interhemispheric phase lag 180°) TACS modulated connectivity between the two auditory cortices. Importantly, the changes in intra- and interhemispheric connectivity induced by TACS were correlated with changes in perceptual integration. Our results indicate that γ-band synchronization between the two auditory cortices plays a functional role in binaural integration, supporting the proposed role of interregional oscillatory synchrony in perceptual integration.
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Affiliation(s)
- Basil C Preisig
- Donders Institute for Brain, Cognition, and Behaviour, Radboud University, 6500 HB Nijmegen, The Netherlands;
- Max Planck Institute for Psycholinguistics, 6525 XD Nijmegen, The Netherlands
- Department of Psychology, Neurolinguistics, University of Zurich, 8050 Zurich, Switzerland
| | - Lars Riecke
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6229 GT Maastricht, The Netherlands
| | - Matthias J Sjerps
- Donders Institute for Brain, Cognition, and Behaviour, Radboud University, 6500 HB Nijmegen, The Netherlands
- Max Planck Institute for Psycholinguistics, 6525 XD Nijmegen, The Netherlands
| | - Anne Kösem
- Donders Institute for Brain, Cognition, and Behaviour, Radboud University, 6500 HB Nijmegen, The Netherlands
- Max Planck Institute for Psycholinguistics, 6525 XD Nijmegen, The Netherlands
- Lyon Neuroscience Research Center, Cognition Computation and Neurophysiology Team, Université Claude Bernard Lyon 1, 69500 Bron, France
| | - Benjamin R Kop
- Donders Institute for Brain, Cognition, and Behaviour, Radboud University, 6500 HB Nijmegen, The Netherlands
| | - Bob Bramson
- Donders Institute for Brain, Cognition, and Behaviour, Radboud University, 6500 HB Nijmegen, The Netherlands
| | - Peter Hagoort
- Donders Institute for Brain, Cognition, and Behaviour, Radboud University, 6500 HB Nijmegen, The Netherlands
- Max Planck Institute for Psycholinguistics, 6525 XD Nijmegen, The Netherlands
| | - Alexis Hervais-Adelman
- Department of Psychology, Neurolinguistics, University of Zurich, 8050 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and Eidgenössische Technische Hochschule Zurich, 8057 Zurich, Switzerland
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Jones KT, Johnson EL, Tauxe ZS, Rojas DC. Modulation of auditory gamma-band responses using transcranial electrical stimulation. J Neurophysiol 2020; 123:2504-2514. [PMID: 32459551 DOI: 10.1152/jn.00003.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Auditory gamma-band (>30 Hz) activity is a biomarker of cortical excitation/inhibition (E/I) balance in autism, schizophrenia, and bipolar disorder. We provide a comprehensive account of the effects of transcranial alternating current stimulation (tACS) and transcranial direct current stimulation (tDCS) on gamma responses. Forty-five healthy young adults listened to 40-Hz auditory click trains while electroencephalography (EEG) data were collected to measure stimulus-related gamma activity immediately before and after 10 min of 1 mA tACS (40 Hz), tDCS, or sham stimulation to left auditory cortex. tACS, but not tDCS, increased gamma power and phase locking to the auditory stimulus. However, both tACS and tDCS strengthened the gamma phase connectome, and effects persisted beyond the stimulus. Finally, tDCS strengthened the coupling of gamma activity to alpha oscillations after termination of the stimulus. No effects were observed in prestimulus gamma power, the gamma amplitude connectome, or any band-limited alpha measure. Whereas both stimulation techniques synchronize gamma responses between regions, tACS also tunes the magnitude and timing of gamma responses to the stimulus. Results reveal dissociable neurophysiological changes following tACS and tDCS and demonstrate that clinical biomarkers can be altered with noninvasive neurostimulation, especially frequency-tuned tACS.NEW & NOTEWORTHY Gamma frequency-tuned transcranial alternating current stimulation (tACS) adjusts the magnitude and timing of auditory gamma responses, as compared with both sham stimulation and transcranial direct current stimulation (tDCS). However, both tACS and tDCS strengthen the gamma phase connectome, which is disrupted in numerous neurological and psychiatric disorders. These findings reveal dissociable neurophysiological changes following two noninvasive neurostimulation techniques commonly applied in clinical and research settings.
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Affiliation(s)
- Kevin T Jones
- Colorado State University, Department of Psychology, Fort Collins, Colorado.,University of California-San Francisco, Department of Neurology, Neuroscape, San Francisco, California
| | - Elizabeth L Johnson
- University of California-Berkeley, Helen Wills Neuroscience Institute, Berkeley, California.,Wayne State University, Institute of Gerontology, Life-Span Cognitive Neuroscience Program, Detroit, Michigan
| | - Zoe S Tauxe
- Colorado State University, Department of Psychology, Fort Collins, Colorado.,University of California-San Diego, Department of Psychology, San Diego, California
| | - Donald C Rojas
- Colorado State University, Department of Psychology, Fort Collins, Colorado
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