The primary goal of our research program is to understand neural mechanisms that support language and related cognitive processes. Our aim is to identify factors that are involved in recovery of function, and to guide development of treatment approaches combining speech-language therapy with noninvasive brain stimulation techniques that modulate brain activity.
Neural Basis of Language
The guiding question: How does the neural circuitry of the brain support language and cognition?
Efficient language processing requires that multiple brain regions interact in an efficient manner. This interaction happens across different dimensions including time and space. We study this interaction at several different levels using behavioral assessments, neuropsychological measurements, structural and functional MRI and electrophysiology (EEG/ERPs). This area of our research has revealed that neural oscillations can reflect neuroprotective effects in aging and also signal cognitive decline in dementia or stroke.
Publications
Neurolinguistics
Drawing from behavioral assessments of various language skills and neuroimaging data, we seek to understand the brain’s capacity for language and the cognitive and neural mechanisms that make it possible. To accomplish these goals we combine various theoretical approaches and techniques to understand how language shapes thought and behavior. We examine how phonology (sounds) and semantics (meaning) of language shape how people process language. In addition we investigate how characteristics of words such as frequency, familiarity and age of acquisition influence how unimpaired adults and individuals with aphasia use language.
Publications
Neural Plasticity and Recovery
Guiding Question: How does the brain adapt and change to support language recovery when language centers in the brain are damaged?
The language regions of the brain can be damaged in many different ways, including stroke, neurodegeneration, or trauma. One of the most common causes of aphasia is stroke to the left hemisphere. About 2,500,000 people in the US are currently living with this debilitating language disorder, and this number is growing, as each year an estimated 250,000 (40%) of new stroke survivors are diagnosed with aphasia leading to chronic disability. The goal of our work in this area is to understand how the brain recovers after the damage, and why some individuals experience successful recovery while others continue to struggle. We are working to identify patterns of brain reorganization and cognitive processes that underlie successful recovery.
Publications
In contrast to the sudden and relatively localized damage caused by stroke, primary progressive aphasia results from progressive degradation of efficiency and decreased activity in the brain’s language network. In my laboratory, we are working to identify factors that predict language decline in this disease.
Informed by our neurolinguistic studies, we have been developing cutting edge noninvasive brain stimulation methods that can promote neuroplastic changes leading to positive outcomes for people with post-stroke aphasia and primary progressive aphasia.
Our research team is working to develop an evidence based treatment approach that includes noninvasive brain stimulation to modulate brain activity and potentiate recovery of language. In this area of our research we examine effects of non-invasive brain stimulation on language processing in the brain. In these studies, the brain stimulation is combined with language therapy with a goal to enhance recovery by modulating brain plasticity.
Transcranial Direct Current Stimulation (tDCS)
Guiding Question: How can we stimulate neuroplastic potential of the brain to maximize recovery in neurological disorders?
Transcranial direct current stimulation, or tDCS, is a form of noninvasive brain stimulation that uses weak electric currents applied to the scalp to modulate brain responsiveness by temporarily altering neuronal activation.
In our research we apply tDCS in combination with speech-language therapy to the brain regions that show reduced activation but still are structurally intact. The goal is to promote neuroplastic changes in the neurons of the brain to slow disease progression and improve cognitive skills.
In a type of language disorder called primary progressive aphasia (PPA), brain regions that subserve language undergo neurodegenerative changes Symptom onset can take years, and affected regions remain involved in language function despite losing efficiency and ultimately functional and structural integrity. Neuromodulation with tDCS is a promising therapeutic option for language recovery in neurodegenerative disorders because we have time to identify affected but still engaged regions and apply interventions that preserve or even restore their functionality.
Publications & Presentations
Nickels, K., Beeson, P. M., Rising, K., Jebahi, F., Kielar, A. (October, 2023). Treatment Outcomes Following Phonological Intervention in Logopenic and Nonfluent/Agrammatic Variant Primary Progressive Aphasia: Results from a Double-Blind, Sham-Controlled, Crossover Trial. Platform Presentation, Academy of Aphasia 61st Annual Meeting, Reading, England. (Invited Presentation)
Kielar A. (September, 2023). Treatment of language in Alzheimer’s Disease: Combining behavioral therapy with noninvasive neuromodulation). Arizona Alzheimer’s Consortium 24th Annual Scientific Conference, Mayo Clinic and Arizona State University
Kielar, A., Nickels, K.V., Beeson, P.M., Jebahi, F., Frazier, N.J. (September, 2023). Rehabilitating language in primary progressive aphasia with targeted phonological treatment and transcranial direct current stimulation (TDCS). Treatment Outcomes in Primary Progressive Aphasia after Phonological Treatment with tDCS. Poster presentation at the annual Arizona Alzheimer’s Consortium Scientific Conference, Tempe, AZ.
Kielar A. (May, 2023). Innovations in Healthy Aging Summit Building Resiliency with Healthy Aging Research. University of Arizona Washington, D.C. Center for Outreach & Collaboration
Repetitive Transcranial Magnetic Stimulation (rTMS)
Another neurostimulation technique that we are using in our research is repetitive Transcranial Magnetic Current Stimulation or rTMS. TMS works by generating magnetic fields, which can temporarily change activity in the brain’s cells when the magnet is applied directly on the surface of the head. The magnetic pulses generate a weak electrical current in the brain tissue that briefly activates neurons in the targeted regions. When done repetitively, such as every day for a month, rTMS is an effective and safe FDA-approved therapy for migraines and drug-resistant depression.
When performed irregularly or in a single session there are only temporary changes to the activity in the targeted neurons that rapidly dissipate. rTMS is increasingly used in research studies in order to better understand the brain function in both health and disease. The goal of our research is to enhance our understanding of how non-invasive brain stimulation techniques can be used to treat post-stroke language impairments, progressive aphasias and related conditions.