Debra Mills, Ph.D.

Research Interests

Development of cerebral specializations for language and non-language cognitive functions in normally developing and atypical populations using the event-related potential (ERP) technique.

Language acquisition

These studies examine the development of cerebral specializations for different aspects of processing within language from normal and clinical populations. The ERP technique is especially well suited for studying these issues. In normal adults, semantic and syntactic processes elicit distinct patterns of ERPs that differ in timing, morphology and distribution. The characteristic patterns of ERPs have been taken as evidence that these different linguistic processes are subserved by distinct neural systems. Earlier studies of hearing and deaf adults suggest that early experience with language is important in shaping the organization of these systems. I am currently examining how experience effects changes in brain organization by studying children prospectively as they get older and attain new language milestones. The approach taken is to study the effects of experience as indexed by increasing vocabulary size by studying: 1) children who are the same age but differ in vocabulary size, 2) children who have similar vocabulary sizes but who differ in chronological age (early and late talkers), 3) children learning two languages at the same time who may have different vocabulary sizes for each language, 4) directly testing the effects of experience in training studies, 5) examining nonverbal correlates of language processing, and 6) investigating the effects of domain general processes on language development.

The current lines of research on language encompass both early word learning and sentence level processing:

1. The effects of word familiarity in 3- to 10-month old infants.
2. The role of working memory abilities in word learning.
3. Phonological processing in early word learning.
4. Infant-directed speech and early word learning.
5. Word segmentation and early word learning.
6. Gesture comprehension in early word learning.
7. Novel word learning.
8. Auditory sentence comprehension for semantic and syntactic anomalies in toddlers, children, young and elderly adults.

Language and non-language cognitive processes in atypical populations

The studies of children and adults with specific behavioral, neurological and genetic profiles, such as autism, Williams Syndrome, and infants of depressed mothers are designed to link specific changes in neural development with alterations in specific sensory, language, and socio-emotional cognitive abilities. I am particularly interested in how children process prosodic information, semantic and affective aspects of language, emotional expressions, and empathy.

William Syndrome: From cognition to brain to gene

Williams Syndrome is a specific genetic deletion associated with marked and specific alterations in cognitive development and brain structure. The unusual neurocognitive and genetic profiles in Williams Syndrome (WMS) provide an opportunity to examine how these factors interact to shape cerebral specializations for language and non-language cognitive functions.

One goal in this line of research is to link variability in the phenotypic expression of specific patterns of abnormal brain function in individuals with WMS to variability in brain structure, cognitive and genetic profiles. To date we have identified electrophysiological signatures of abnormal brain function linked to the processing of faces and auditory language and sensory processing typical of individuals with WS. These electrophysiological signatures are characteristic of all individuals with WMS, and have not been observed in normal or other clinical populations of adults or children. In other research we have found that cognitive processes that are relatively spared in WS show abnormal brain organization.

Current studies in adults and children with WMS include:

1. Face and object perception and recognition
2. Semantic and syntactic processing of auditory sentences
3. Processing of affective information in different modalities
4. Color and motion perception (magnocellular and parvocellular pathways)