The Neural Coding of Speech Across Human Languages

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.

Conditions

• Epilepsy
• Brain Tumor
• Speech
• Bilingualism

Interventions

BEHAVIORAL

Speech Tasks

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

Sponsors & Collaborators

• University of California, Berkeley

  collaborator OTHER

• Lawrence Livermore National Laboratory

  collaborator OTHER

• The University of Hong Kong

  collaborator OTHER

• National Institute of Neurological Disorders and Stroke (NINDS)

  collaborator NIH

• University of California, San Francisco

  lead OTHER

Principal Investigators

• Edward F Chang, MD · University of California, San Francisco

Study Design

Allocation

NA

Purpose

BASIC_SCIENCE

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Max Age

70 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2015-09-14

Primary Completion

2026-08-31

Completion

2027-08-30

Countries

• United States

Study Locations