Research Areas
The NeuroCognitive Imaging Laboratory currently has a number of exciting studies underway in areas ranging from language acquisition to brain mapping. Some of these are discussed briefly below. For more information, please contact us at NCIL@dal.ca.
Aphasia Recovery
Aphasia is a loss of language abilities, that typically occurs after a stroke. Patients with aphasia retain their intellectual capacity, but are often unable to express it through words or understand the words of others. We are collaborating with Linda Carey and Ellina Kostopoulos, speech-language pathologists from Dalhousie's School of Human Communication Disorders who operate an intensive aphasia rehabilitation program called InteRACT. The rehab program involves 100+ hours of speech-language therapy over 4 weeks, along with physio, recreational therapy, and other community integration activities.
The research project involves scanning patients with fMRI and ERP before and after the therapy program. Our goal is to characterize neural correlates of improved language abilities, as well as to identify potential pre-therapy predictors of success in the program, which could help tailor the program to particular patient needs in the future.
Treatment for Hearing Disorders
This project is aimed at characterizing the extent to which auditory cortex may become "rewired" in cases of long-standing hearing loss, and how such rewiring might affect treatment outcomes. It involves two patient groups. One is persons with long-standing deafness who will receive cochlear implants. Prior to implantation, we will acquire fMRI, diffusion MRI (which shows the connections between different brain areas), and ERP (brainwave) data from them on a variety of visual processing paradigms. Post-implant, we will track the patients to determine their functional outcomes - how well they are able to use the implant in their day-to-day lives. The second group of patients have asymmetric hearing loss, with significant loss in one ear and less loss in the other ear. Subsequent to the neuroimaging tests, these patients will receive bone-anchored hearing aids. We will be testing these patients on all of the same visual paradigms as well as some auditory processing and attention paradigms. This research will produce tangible benefits by allowing us to more accurately predict the outcomes of these treatments in individual patients, and customize their post-surgery therapy more effectively.
Biological Motion in Sign Language Users
This study is an attempt to reconcile data suggesting leftward shifts in the lateralization of certain visual processing functions, including motion and faces, with our findings of robust right hemisphere activation for sign language in lifelong users of the language. We are collecting ERP and fMRI data from deaf and hearing signers, as well as nonsigners, while subjects view point-light displays of whole-body movements. Our question concerns how lifelong exposure to a language that depends on biological motion alters the brain areas that process that motion, both outside of a communicative context (in this study with whole-body actions like walking and cycling) and, in future studies, for processing gesture and sign language.
Second Language Acquisition
This is a combined fMRI and ERP study of adults who either (a) are native French speakers; (b) learned French in early immersion; or (c) learned French in late immersion. We are testing 3 aspects of French that are predicted to differ in the effects of age of acquisition: past tense inflection, syntactic gender, and word order. Our goal is to understand why it becomes harder to learn a language as one gets older, in terms of the brain areas being used for language. In the future we plan to extend this research to study children as they are actually learning French, tracking changes in their brain over time.
Presurgical Planning
This study is a collaboration involving researchers from the QEII, Dalhousie, and the National Research Council, including neurosurgeon David Clarke, neuropsychologist Gail Eskes, neuroscientist Ryan D'Arcy, and physicist Gerhard Stroink, as well as the NeuroCognitive Imaging Lab. We are developing tests to be used in mapping brain regions critical to functions such as speech, hand movement, and memory using fMRI. fMRI uses an MRI scanner to take pictures of the brain in action, by showing which areas receive the most oxygen. These maps will be used by neurosurgeons to help guide them in planning and conducting surgeries with tumour and epilepsy patients. Traditionally, neurosurgeons have used a technique pioneered by Dr. Wilder Penfield in Montreal in the first half of the 20th century. This technique involves stimulating different parts of the brain with an electrode while the patient is on the operating table. While this is considered the "gold standard" even today, it is desirable for the surgeon to know which parts of the brain do what before they start the surgery, so that they can plan the safest and most effective course of treatment. The functional MRI tests that we are developing will allow just that.
While fMRI is used routinely to map "normal" brains, the presence of disease such as a tumour may cause reorganization of the brain, pushing things around so that the parts of the brain controlling a particular function, such as language, are not where they would normally be. This research, combined with cutting-edge technology, allows the surgeon to see the "hot spots" of activation on a computer screen in the OR, with the position of the surgical tools superimposed. The goal of this research is to allow for even better outcomes and faster recoveries from surgeries that will allow patients to resume normal lives after being debilitated by disease.
