The Neural Coding of Speech Across Human Languages

NCT ID: NCT05014841

Last Updated: 2025-09-16

Basic Information

• Recruitment Status: ENROLLING_BY_INVITATION
• Clinical Phase: NA
• Total Enrollment: 52 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2015-09-14
• Study Completion Date: 2027-08-30

Brief Summary

The overall goal of this study is to reveal the fundamental neural mechanisms that underlie comprehension across human spoken languages. An understanding of how speech is coded in the brain has significant implications for the development of new diagnostic and rehabilitative strategies for language disorders (e.g. aphasia, dyslexia, autism, et alia). The basic mechanisms underlying comprehension of spoken language are unknown. Researchers are only beginning to understand how the human brain extracts the most fundamental linguistic elements (consonants and vowels) from a complex and highly variable acoustic signal. Traditional theories have posited a 'universal' phonetic inventory shared by all humans, but this has been challenged by other newer theories that each language has its own unique and specialized code. An investigation of the cortical representation of speech sounds across languages can likely shed light on this fundamental question. Previous research has implicated the superior temporal cortex in the processing of speech sounds. Most of this work has been entirely carried out in English. The recording of neural activity directly from the cortical surface from individuals with different language experience is a promising approach since it can provide both high spatial and temporal resolution. This study will examine the mechanisms of phonetic encoding, by utilizing neurophysiological recordings obtained during neurosurgical procedures. High-density electrode arrays, advanced signal processing, and direct electrocortical stimulation will be utilized to unravel both local and population encoding of speech sounds in the lateral temporal cortex. This study will also examine the neural encoding of speech in patients who are monolingual and bilingual in Mandarin, Spanish, and English, the most common spoken languages worldwide, and feature important contrastive differences of pitch, formant, and temporal envelope. A cross-linguistic approach is critical for a true understanding of language, while also striving to achieve a broader approach of diversity and inclusion in neuroscience of language.

Detailed Description

Experimental approaches with significantly greater spatial and temporal resolution are necessary to directly resolve, both local- and population- level, the contrastive encoding of speech sounds. This study proposes an innovative methodological approach using customized intracranial high-density electrode arrays to record neural activity directly from nonprimary auditory cortex in patients undergoing clinical neurosurgical procedures (acute intraoperative and chronic extraoperative). This approach overcomes obstacles in traditional neuroimaging by offering high signal-to-noise recordings, unprecedented detailed spatiotemporal resolution, and a large number of simultaneously recorded cortical sites in awake, behaving subjects. The research study team will leverage the diversity of languages spoken by patients that are treated at the large volume epilepsy and tumor brain mapping programs at the University of California, San Francisco. They will examine cortical responses to speech stimuli (natural speech corpora and control tokens) in Spanish, Mandarin, and English speakers (monolingual and bilingual). They will also focus on encoding models in three fundamental domains of acoustic-phonetic cues that are present in all languages: pitch, formants, and amplitude envelope. The aims of this study seeks to determine how pitch cues encode lexical tone processing in Mandarin (Aim 1), the cortical representation of vowels in Spanish and English (Aim 2), and the encoding of the speech amplitude envelope in Spanish and English (Aim 3). Together, these aims will elucidate mechanistic principles of speech encoding in the human auditory cortex to understand what is shared and different across human spoken languages. Abnormalities in these fundamental processes have been implicated in a host of communication disorders such as dyslexia, developmental language disorder, central hearing loss, and aphasia. These results should heavily impact current theories of speech processing and, therefore, will have significant implications for understanding and remediating human disorders across different languages.

Conditions

Epilepsy; Brain Tumor; Speech; Bilingualism

Study Design

• Allocation Method: NA
• Intervention Model: SINGLE_GROUP
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: NONE

Study Groups

Electrocorticography (ECoG) recording during Speech Tasks

Participants listened to 20-minute Speech Tasks while ECoG signals for neural activity was recorded during their intraoperative procedure or inpatient hospitalization at the University of California, San Francisco (UCSF).

Group Type: EXPERIMENTAL

Speech Tasks

Intervention Type: BEHAVIORAL

Listen to 20-minutes of speech sounds in English, Spanish, and/or Mandarin.

Interventions

Speech Tasks

Listen to 20-minutes of speech sounds in English, Spanish, and/or Mandarin.

Intervention Type: BEHAVIORAL

Eligibility Criteria

Inclusion Criteria

• Participants with epilepsy or brain tumors at UCSF undergoing surgical electrode implantation for seizure localization or for speech and language mapping and
• Participants with electrodes implanted in at least two regions of interest who are willing and able to cooperate with study tasks.

Exclusion Criteria

• Participants who lack capacity or decline to provide informed consent,
• Participants who have significant cerebral lesions or
• Participants with cognitive deficits that preclude reliable completion of study tasks.

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 70 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

University of California, Berkeley

OTHER

Sponsor Role: collaborator

Lawrence Livermore National Laboratory

OTHER

Sponsor Role: collaborator

The University of Hong Kong

OTHER

Sponsor Role: collaborator

National Institute of Neurological Disorders and Stroke (NINDS)

NIH

Sponsor Role: collaborator

University of California, San Francisco

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Edward F Chang, MD

Role: PRINCIPAL_INVESTIGATOR

University of California, San Francisco

Locations

University of California, San Francisco

San Francisco, California, United States

Countries

United States

Other Identifiers

U01NS117765

Identifier Type: NIH

Identifier Source: secondary_id

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U01NS117765

Identifier Type: NIH

Identifier Source: org_study_id

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