INS NYC 2024 Program

Poster	Poster Session 10 Program Schedule 02/17/2024 09:00 am - 10:15 am Room: Shubert Complex (Posters 1-60) Poster Session 10: Neurodevelopmental \| Congenital Conditions Final Abstract #38 A Family Study of Audio-Motor Synchronization of Speech and Underpinning Neural Mechanisms in Autism Janna Guilfoyle, Northwestern University, Chicago, United States Grace Johnson, Northwestern University, Evanston, United States Joseph Lau, Northwestern University, Evanston, United States Kritika Nayar, Rush University Medical Center, Chicago, United States M. Assaneo, Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico Nina Kraus, Northwestern University, Evanston, United States Molly Losh, Northwestern University, Evanston, United States Category: Autism Spectrum Disorders/Developmental Disorders/Intellectual Disability Keyword 1: autism spectrum disorder Keyword 2: language Keyword 3: speech Objective: The unconscious tendency to synchronize with external stimuli supports many aspects of human cognition and behavior, particularly language and social development. Spontaneous synchrony of speech rhythm in the general population demonstrates a robust bimodal pattern of variability wherein some people align speech output spontaneously and effectively with external rhythms (~60%), while others are impervious to them (~40%) (Assaneo, 2019, 2020, 2021). High synchronizers show enhanced neural connectivity (auditory/speech/language areas), increased brain-to-stimulus entrainment, and advantages in language learning. This project examines spontaneous audio-motor synchronization of speech among autistic individuals and their first-degree relatives as a potential mechanism underlying broader speech/language difficulties, given evidence of atypical speech prosody and reduced speech/language synchrony socially in both groups (Patel, 2020, 2022, 2023). Successful speech synchronization requires successful initial perceptual encoding of the acoustic cues in speech, thus relationships with neural speech perception were examined. Studying how such variability in rhythmic synchronization may differ in autistic and broad autistic populations may provide important insights into the genetic and neuro-mechanistic underpinnings of core speech/language difficulties in autism. Participants and Methods: Participants include 17 autistic individuals (ASD), 19 parents of autistic individuals (ASD-Par), and 288 controls (Controls). The spontaneous speech synchrony (SSS) task was used to assess rhythmic synchronization of speech output to an external rhythmic syllable stream. Phase locking values (PLV) between the envelopes of the produced speech and the stimuli characterize the degree of synchrony. Entrainment is calculated by improvement in PLV across trials. A gaussian mixture model, fit to the bimodal distribution of synchrony values from existing normative data of typically developing adults, was used to determine the probability of a participant falling in either the “high” or “low” synchrony groups for dichotomization. Neural encoding was characterized via the frequency following response (FFR) to a synthesized /ya/ syllable; response consistency and pitch tracking metrics were used in analysis. Results: A disproportionate number of ASD and ASD-Par participants were classified as low synchronizers, at 82% and 77%, respectively, as compared to 40% of Controls (X² = 30.79, p < .00001). The average PLVs of the ASD and ASD-Par groups were not statistically different from one another (p=.89) but were both significantly lower than the Control group (ps<.01). ASD-par, but not ASD, demonstrated reduced entrainment across trials relative to controls (p<.05). Greater speech entrainment was associated with greater fidelity of neural sound encoding (more consistent FFRs, better tracking of speech acoustics, rs>.45, ps<.05). Conclusions: Results provide compelling early evidence of disruptions in spontaneous rhythmic synchronization of speech in autism and first-degree relatives. Relationships with FFR suggest that speech synchrony is rooted in variability in neural perception of speech sounds. Such mechanistic differences may underlie downstream speech and language characteristics, including speech prosody and synchronizing one’s prosody with that of their social partner’s. That this pattern emerged in clinically unaffected parents suggests that it may be influenced by genetic variability associated with autism. Taken together, spontaneous audio-motor synchronization offers an objective, measurable, potential endophenotypic marker of autism, warranting further investigation into it’s impact on broader clinical and language features.

Poster

02/17/2024
09:00 am - 10:15 am
Room: Shubert Complex (Posters 1-60)

Poster Session 10: Neurodevelopmental | Congenital Conditions

Final Abstract #38

A Family Study of Audio-Motor Synchronization of Speech and Underpinning Neural Mechanisms in Autism

Janna Guilfoyle, Northwestern University, Chicago, United States
Grace Johnson, Northwestern University, Evanston, United States
Joseph Lau, Northwestern University, Evanston, United States
Kritika Nayar, Rush University Medical Center, Chicago, United States
M. Assaneo, Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico
Nina Kraus, Northwestern University, Evanston, United States
Molly Losh, Northwestern University, Evanston, United States

Category: Autism Spectrum Disorders/Developmental Disorders/Intellectual Disability

Keyword 1: autism spectrum disorder
Keyword 2: language
Keyword 3: speech

Objective:

The unconscious tendency to synchronize with external stimuli supports many aspects of human cognition and behavior, particularly language and social development. Spontaneous synchrony of speech rhythm in the general population demonstrates a robust bimodal pattern of variability wherein some people align speech output spontaneously and effectively with external rhythms (~60%), while others are impervious to them (~40%) (Assaneo, 2019, 2020, 2021). High synchronizers show enhanced neural connectivity (auditory/speech/language areas), increased brain-to-stimulus entrainment, and advantages in language learning. This project examines spontaneous audio-motor synchronization of speech among autistic individuals and their first-degree relatives as a potential mechanism underlying broader speech/language difficulties, given evidence of atypical speech prosody and reduced speech/language synchrony socially in both groups (Patel, 2020, 2022, 2023). Successful speech synchronization requires successful initial perceptual encoding of the acoustic cues in speech, thus relationships with neural speech perception were examined. Studying how such variability in rhythmic synchronization may differ in autistic and broad autistic populations may provide important insights into the genetic and neuro-mechanistic underpinnings of core speech/language difficulties in autism.

Participants and Methods:

Participants include 17 autistic individuals (ASD), 19 parents of autistic individuals (ASD-Par), and 288 controls (Controls). The spontaneous speech synchrony (SSS) task was used to assess rhythmic synchronization of speech output to an external rhythmic syllable stream. Phase locking values (PLV) between the envelopes of the produced speech and the stimuli characterize the degree of synchrony. Entrainment is calculated by improvement in PLV across trials. A gaussian mixture model, fit to the bimodal distribution of synchrony values from existing normative data of typically developing adults, was used to determine the probability of a participant falling in either the “high” or “low” synchrony groups for dichotomization. Neural encoding was characterized via the frequency following response (FFR) to a synthesized /ya/ syllable; response consistency and pitch tracking metrics were used in analysis.

Results:

A disproportionate number of ASD and ASD-Par participants were classified as low synchronizers, at 82% and 77%, respectively, as compared to 40% of Controls (X² = 30.79, p < .00001). The average PLVs of the ASD and ASD-Par groups were not statistically different from one another (p=.89) but were both significantly lower than the Control group (ps<.01). ASD-par, but not ASD, demonstrated reduced entrainment across trials relative to controls (p<.05). Greater speech entrainment was associated with greater fidelity of neural sound encoding (more consistent FFRs, better tracking of speech acoustics, rs>.45, ps<.05).

Conclusions:

Results provide compelling early evidence of disruptions in spontaneous rhythmic synchronization of speech in autism and first-degree relatives. Relationships with FFR suggest that speech synchrony is rooted in variability in neural perception of speech sounds. Such mechanistic differences may underlie downstream speech and language characteristics, including speech prosody and synchronizing one’s prosody with that of their social partner’s. That this pattern emerged in clinically unaffected parents suggests that it may be influenced by genetic variability associated with autism. Taken together, spontaneous audio-motor synchronization offers an objective, measurable, potential endophenotypic marker of autism, warranting further investigation into it’s impact on broader clinical and language features.