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Chang A, Teng X, Assaneo MF, Poeppel D. The human auditory system uses amplitude modulation to distinguish music from speech. PLoS Biol 2024; 22:e3002631. [PMID: 38805517 PMCID: PMC11132470 DOI: 10.1371/journal.pbio.3002631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Accepted: 04/17/2024] [Indexed: 05/30/2024] Open
Abstract
Music and speech are complex and distinct auditory signals that are both foundational to the human experience. The mechanisms underpinning each domain are widely investigated. However, what perceptual mechanism transforms a sound into music or speech and how basic acoustic information is required to distinguish between them remain open questions. Here, we hypothesized that a sound's amplitude modulation (AM), an essential temporal acoustic feature driving the auditory system across processing levels, is critical for distinguishing music and speech. Specifically, in contrast to paradigms using naturalistic acoustic signals (that can be challenging to interpret), we used a noise-probing approach to untangle the auditory mechanism: If AM rate and regularity are critical for perceptually distinguishing music and speech, judging artificially noise-synthesized ambiguous audio signals should align with their AM parameters. Across 4 experiments (N = 335), signals with a higher peak AM frequency tend to be judged as speech, lower as music. Interestingly, this principle is consistently used by all listeners for speech judgments, but only by musically sophisticated listeners for music. In addition, signals with more regular AM are judged as music over speech, and this feature is more critical for music judgment, regardless of musical sophistication. The data suggest that the auditory system can rely on a low-level acoustic property as basic as AM to distinguish music from speech, a simple principle that provokes both neurophysiological and evolutionary experiments and speculations.
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Affiliation(s)
- Andrew Chang
- Department of Psychology, New York University, New York, New York, United States of America
| | - Xiangbin Teng
- Department of Psychology, Chinese University of Hong Kong, Hong Kong SAR, China
| | - M. Florencia Assaneo
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, México
| | - David Poeppel
- Department of Psychology, New York University, New York, New York, United States of America
- Ernst Struengmann Institute for Neuroscience, Frankfurt am Main, Germany
- Center for Language, Music, and Emotion (CLaME), New York University, New York, New York, United States of America
- Music and Audio Research Lab (MARL), New York University, New York, New York, United States of America
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Paraouty N, Yao JD, Varnet L, Chou CN, Chung S, Sanes DH. Sensory cortex plasticity supports auditory social learning. Nat Commun 2023; 14:5828. [PMID: 37730696 PMCID: PMC10511464 DOI: 10.1038/s41467-023-41641-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 09/11/2023] [Indexed: 09/22/2023] Open
Abstract
Social learning (SL) through experience with conspecifics can facilitate the acquisition of many behaviors. Thus, when Mongolian gerbils are exposed to a demonstrator performing an auditory discrimination task, their subsequent task acquisition is facilitated, even in the absence of visual cues. Here, we show that transient inactivation of auditory cortex (AC) during exposure caused a significant delay in task acquisition during the subsequent practice phase, suggesting that AC activity is necessary for SL. Moreover, social exposure induced an improvement in AC neuron sensitivity to auditory task cues. The magnitude of neural change during exposure correlated with task acquisition during practice. In contrast, exposure to only auditory task cues led to poorer neurometric and behavioral outcomes. Finally, social information during exposure was encoded in the AC of observer animals. Together, our results suggest that auditory SL is supported by AC neuron plasticity occurring during social exposure and prior to behavioral performance.
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Affiliation(s)
- Nihaad Paraouty
- Center for Neural Science New York University, New York, NY, 10003, USA.
| | - Justin D Yao
- Department of Otolaryngology, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Léo Varnet
- Laboratoire des Systèmes Perceptifs, UMR 8248, Ecole Normale Supérieure, PSL University, Paris, 75005, France
| | - Chi-Ning Chou
- Center for Computational Neuroscience, Flatiron Institute, Simons Foundation, New York, NY, USA
- School of Engineering & Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - SueYeon Chung
- Center for Neural Science New York University, New York, NY, 10003, USA
- Center for Computational Neuroscience, Flatiron Institute, Simons Foundation, New York, NY, USA
| | - Dan H Sanes
- Center for Neural Science New York University, New York, NY, 10003, USA
- Department of Psychology, New York University, New York, NY, 10003, USA
- Department of Biology, New York University, New York, NY, 10003, USA
- Neuroscience Institute, NYU Langone Medical Center, New York, NY, 10003, USA
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Nocon JC, Gritton HJ, James NM, Mount RA, Qu Z, Han X, Sen K. Parvalbumin neurons enhance temporal coding and reduce cortical noise in complex auditory scenes. Commun Biol 2023; 6:751. [PMID: 37468561 PMCID: PMC10356822 DOI: 10.1038/s42003-023-05126-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Accepted: 07/10/2023] [Indexed: 07/21/2023] Open
Abstract
Cortical representations supporting many cognitive abilities emerge from underlying circuits comprised of several different cell types. However, cell type-specific contributions to rate and timing-based cortical coding are not well-understood. Here, we investigated the role of parvalbumin neurons in cortical complex scene analysis. Many complex scenes contain sensory stimuli which are highly dynamic in time and compete with stimuli at other spatial locations. Parvalbumin neurons play a fundamental role in balancing excitation and inhibition in cortex and sculpting cortical temporal dynamics; yet their specific role in encoding complex scenes via timing-based coding, and the robustness of temporal representations to spatial competition, has not been investigated. Here, we address these questions in auditory cortex of mice using a cocktail party-like paradigm, integrating electrophysiology, optogenetic manipulations, and a family of spike-distance metrics, to dissect parvalbumin neurons' contributions towards rate and timing-based coding. We find that suppressing parvalbumin neurons degrades cortical discrimination of dynamic sounds in a cocktail party-like setting via changes in rapid temporal modulations in rate and spike timing, and over a wide range of time-scales. Our findings suggest that parvalbumin neurons play a critical role in enhancing cortical temporal coding and reducing cortical noise, thereby improving representations of dynamic stimuli in complex scenes.
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Affiliation(s)
- Jian Carlo Nocon
- Neurophotonics Center, Boston University, Boston, 02215, MA, USA
- Center for Systems Neuroscience, Boston University, Boston, 02215, MA, USA
- Hearing Research Center, Boston University, Boston, 02215, MA, USA
- Department of Biomedical Engineering, Boston University, Boston, 02215, MA, USA
| | - Howard J Gritton
- Department of Comparative Biosciences, University of Illinois, Urbana, 61820, IL, USA
- Department of Bioengineering, University of Illinois, Urbana, 61820, IL, USA
| | - Nicholas M James
- Neurophotonics Center, Boston University, Boston, 02215, MA, USA
- Center for Systems Neuroscience, Boston University, Boston, 02215, MA, USA
- Hearing Research Center, Boston University, Boston, 02215, MA, USA
- Department of Biomedical Engineering, Boston University, Boston, 02215, MA, USA
| | - Rebecca A Mount
- Neurophotonics Center, Boston University, Boston, 02215, MA, USA
- Center for Systems Neuroscience, Boston University, Boston, 02215, MA, USA
- Hearing Research Center, Boston University, Boston, 02215, MA, USA
- Department of Biomedical Engineering, Boston University, Boston, 02215, MA, USA
| | - Zhili Qu
- Department of Comparative Biosciences, University of Illinois, Urbana, 61820, IL, USA
- Department of Bioengineering, University of Illinois, Urbana, 61820, IL, USA
| | - Xue Han
- Neurophotonics Center, Boston University, Boston, 02215, MA, USA
- Center for Systems Neuroscience, Boston University, Boston, 02215, MA, USA
- Hearing Research Center, Boston University, Boston, 02215, MA, USA
- Department of Biomedical Engineering, Boston University, Boston, 02215, MA, USA
| | - Kamal Sen
- Neurophotonics Center, Boston University, Boston, 02215, MA, USA.
- Center for Systems Neuroscience, Boston University, Boston, 02215, MA, USA.
- Hearing Research Center, Boston University, Boston, 02215, MA, USA.
- Department of Biomedical Engineering, Boston University, Boston, 02215, MA, USA.
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Damera SR, Malone PS, Stevens BW, Klein R, Eberhardt SP, Auer ET, Bernstein LE, Riesenhuber M. Metamodal Coupling of Vibrotactile and Auditory Speech Processing Systems through Matched Stimulus Representations. J Neurosci 2023; 43:4984-4996. [PMID: 37197979 PMCID: PMC10324991 DOI: 10.1523/jneurosci.1710-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 03/10/2023] [Accepted: 04/29/2023] [Indexed: 05/19/2023] Open
Abstract
It has been postulated that the brain is organized by "metamodal," sensory-independent cortical modules capable of performing tasks (e.g., word recognition) in both "standard" and novel sensory modalities. Still, this theory has primarily been tested in sensory-deprived individuals, with mixed evidence in neurotypical subjects, thereby limiting its support as a general principle of brain organization. Critically, current theories of metamodal processing do not specify requirements for successful metamodal processing at the level of neural representations. Specification at this level may be particularly important in neurotypical individuals, where novel sensory modalities must interface with existing representations for the standard sense. Here we hypothesized that effective metamodal engagement of a cortical area requires congruence between stimulus representations in the standard and novel sensory modalities in that region. To test this, we first used fMRI to identify bilateral auditory speech representations. We then trained 20 human participants (12 female) to recognize vibrotactile versions of auditory words using one of two auditory-to-vibrotactile algorithms. The vocoded algorithm attempted to match the encoding scheme of auditory speech while the token-based algorithm did not. Crucially, using fMRI, we found that only in the vocoded group did trained-vibrotactile stimuli recruit speech representations in the superior temporal gyrus and lead to increased coupling between them and somatosensory areas. Our results advance our understanding of brain organization by providing new insight into unlocking the metamodal potential of the brain, thereby benefitting the design of novel sensory substitution devices that aim to tap into existing processing streams in the brain.SIGNIFICANCE STATEMENT It has been proposed that the brain is organized by "metamodal," sensory-independent modules specialized for performing certain tasks. This idea has inspired therapeutic applications, such as sensory substitution devices, for example, enabling blind individuals "to see" by transforming visual input into soundscapes. Yet, other studies have failed to demonstrate metamodal engagement. Here, we tested the hypothesis that metamodal engagement in neurotypical individuals requires matching the encoding schemes between stimuli from the novel and standard sensory modalities. We trained two groups of subjects to recognize words generated by one of two auditory-to-vibrotactile transformations. Critically, only vibrotactile stimuli that were matched to the neural encoding of auditory speech engaged auditory speech areas after training. This suggests that matching encoding schemes is critical to unlocking the brain's metamodal potential.
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Affiliation(s)
- Srikanth R Damera
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20007
| | - Patrick S Malone
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20007
| | - Benson W Stevens
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20007
| | - Richard Klein
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20007
| | - Silvio P Eberhardt
- Department of Speech Language & Hearing Sciences, George Washington University, Washington, DC 20052
| | - Edward T Auer
- Department of Speech Language & Hearing Sciences, George Washington University, Washington, DC 20052
| | - Lynne E Bernstein
- Department of Speech Language & Hearing Sciences, George Washington University, Washington, DC 20052
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