Clinical Research Directory

Word Learning in Bilingual Typical and Late Talking Children: The Role of Meaning and Input

The goal of this clinical trial is to understand how different types of word categories, along with the language children hear from their parents, support bilingual toddlers' word learning. This study will address two main questions: (1) How are the words toddlers know related to the words their parents use? and (2) How does what toddlers already know help them learn new words in two languages? The investigators will compare bilingual toddlers with typical development to those with language delay to determine whether they learn new words in similar ways. Children's vocabulary knowledge will be assessed using standardized parent-report checklists. To examine how different types of categories support learning, the study will focus on two early-acquired categories: animals and clothing. The investigators will compare what parents report about their children's vocabulary with how children learn new words within each category. To understand the role of parent input, children and their parents will engage in shared book reading and play activities using materials from one of the target categories. Parent-child interactions will be video recorded. Children will also complete an eye-tracking task in which they learn new words in two languages within the same category.

The Neural Coding of Speech Across Human Languages

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.