Verbs are considered to be mentally more complex than nouns and some other parts of speech, which is why children learn verbs later than nouns (in most languages) and some individuals with aphasia experience more difficulty retrieving verbs when speaking. As an illustration, here is how a person with aphasia described this picture.
"A tree. A car. A kite. A dog. A boat. A book. A flag. Some trees. A car. A radio. A blanket. A book. Some sage? A dog. A boat."
Difficulty in retrieving verbs also affects how well a person can speak in complete sentences. We investigate various aspects of verb production in individuals with aphasia and compare these with individuals who do not have aphasia (matched for age and education). We are particularly interested in examining which linguistic variables exacerbate aphasic individuals' difficulty with verbs and which variables ameliorate their production difficulties. One recent study investigated whether aphasic and unimpaired individuals extract information about the effector (i.e., body part used to perform an action) when they quickly read a verb. We found that both groups rapidly extract effector information, and that this information persists for about a second. That is, blowing and drinking both have the same effector (the mouth). These results are most consistent with the view that reading or listening to verbs results in mental simulation of the action they refer to (Embodied Cognition). Read more here.
Sometimes verbs may be produced with no ending or with the incorrect ending (e.g. Yesterday Mama going to the mall:
Girl eat cookies.) Several of our studies have investigated the factors that influence production of verb inflections. Read more here.
Sentence Production
The…the…the…woman…no-girl…the girl…kicking the man…no-kiss…kiss…girl kiss the man…uh…boy.
The lad is ficing her.
No doubt, the above two sentences are very different - but these were produced by two different aphasic individuals to describe the same picture of a woman kissing a child. Aphasia is a general term referring to a disruption in language production and comprehension after brain damage. In fact, there are several subtypes of aphasia. We are interested in comparing the sentence production patterns of individuals with different aphasia types in order to understand the underlying deficits and their manifestations. This information would inform about language impairments in aphasia, normal language processing, and well as treatment strategies for aphasic individuals. Read more here.
What is wrong with these sentences?
I went to school tomorrow.
I going to the movies.
Some individuals with aphasia produce such sentences. But are they able to detect their own errors or errors in other's sentences? And what is the relationship between their production and detection abilities? Our recent research has investigated comprehension (the ability to understand sentences) using reaction time measures as well as magnetoencephalography. Read more here.
A primary focus of our research is developing and testing treatment protocols for individuals with aphasia. We will use the findings of our behavioral studies to learn more about specific deficits and design treatment protocols. The treatment studies will focus on verbs and sentences. Our treatment studies involve individual treatment sessions, 4-5 times a week for 2-3 hours each. Treatment studies typically extend between 4-6 weeks, including all pre- treatment and post-treatment testing. Read more here and here.
The figure below shows the percentage of sentences correctly produced by one of our participants with aphasia during eight visits before the start of therapy (left portion) and then over the course of fifteen therapy sessions (right portion). Note that not all participants and not all therapies show such large treatment effects. There are individual differences in response to treatment.
Neuroimaging
Since aphasia results from injury to the brain, we are interested in learning more about the relationship between brain damage and language production-comprehension difficulties in individuals with and without aphasia. We are specifically interested in examining the neural correlates of verb production, verb morphology and sentence processing. Our research also aims at documenting changes in neural activity that might occur in patients who participate in our treatment efficacy studies (see above). We are using magnetoencephalogy (MEG) in conjunction with magnetic resonance imaging (MRI) for our studies.
Bilingualism
More than half the world's population is bilingual! Naturally, there are more bilingual individuals with aphasia than monolingual individuals with aphasia. Nonetheless, most research on aphasia has been done with monolingual speakers, and far less is known about sentence production, verb production, and treatment efficacy in bilingual aphasia.
Our most recent research in this area focused on treatment efficacy and generalization in multilingual aphasia. We observed that some treatment effects can extend to another untreated language depending on factors such as age of acquisition, language proficiency and structural distance between the treated and untreated languages. Click here and here to read more
Another study, headed by Dr. Viorica Marian, used functional Magnetic Resonance Imaging (fMRI) to examine the neural regions involved in lexical processing in bilinguals who learned their second language in their teenage years. Read more here.
Another study utilized magnetoencephalography to examine differences in brain activity related to cognate words in Spanish-English bilinguals. Click here to read more.
