Research Interests
Research
in the Speech Imaging Lab focuses on the
neurophysiological basis of speech perception and in particular on the neural
mechanisms underlying the representation of sublexical phonemic
information in the temporal cortex of healthy adults. Phonemic
perception emerges when the acoustically rich, diverse and continuously
varying speech signals are represented as a limited set of discrete,
learned phonemic categories. This abstraction process results in
relatively better discrimination across than within phoneme categories,
a phenomenon well-known as categorical perception of speech. A main
research aim is to determine whether the characteristic pattern of
increased response in left ventral temporal regions during speech
perception is related to the categorical nature of this process rather
than strictly to its relevance for language.
Another focus of
research relates to the neural developmental changes associated with
the acquisition
of phonemic perception in typically developing children. Insights gained from these normative
studies can later be used to examine the role of speech perception
deficits in developmental learning disabilities affecting language
processing, such as dyslexia.
Additional
topics of interest include auditory cortical organization, auditory
attention and auditory scene analysis.
Methods used include structural and functional
magnetic resonance images, as well as electrophysiological
scalp-recorded responses in order to gain both spatial and temporal
information regarding the course of processing of phonemic information
in the brain. Simultaneous
fMRI/EEG is recorded and methods are developed for meaningful
integration of information across imaging modalities. Emphasis is also
placed on sound
synthesis to develop speech-like nonphonemic sounds.