Geo Kartheiser, Gallaudet’s second Ph.D. in Educational Neuroscience doctoral student successfully defends dissertation

The Neuroplasticity of Spatial Working Memory in Signed Language Processing.”/h2>

Photo courtesy of Kennesha Baldwin.

Mr. George Scott Kartheiser, Dr. Laura-Ann Petitto’s doctoral student in Gallaudet University’s Ph.D. in Educational Neuroscience (PEN) program and a graduate research assistant in Dr. Petitto’s Brain & Language Laboratory for Neuroimaging (BL2), successfully defended his dissertation on “The Neuroplasticity of Spatial Working Memory in Signed Language Processing.” Learn more about Mr. Kartheiser’s research results. Geo will be the PEN program’s second doctoral graduate.

Dr. Gaurav Mathur, Dean of Gallaudet University’s Graduate School, noted:

Spatial cognition has been shown to be enhanced in early-exposed deaf signers of signed languages, possibly because signed languages are spatial in nature.
However, spatial cognition is generally considered malleable across the lifespan. This raises the question of how age of language exposure impacts the brain’s neural systems when processing a signed language (typically impacted by the age of language exposure)-a language that occurs in space and involves spatial cognition (typically not presumed to be impacted by age of exposure). Mr. Kartheiser’s study addresses whether the age of exposure and proficiency in American Sign Language (ASL) impacts the neural activity related to aspects of spatial working memory required in the processing of signed language. Three groups of hearing, adult signers participated in this study: native signers (adults who had early exposure to ASL); proficient signers (adults with strong signing skills irrespective of the age of ASL exposure), and new signers (adults learning ASL for the first time). Participants were recorded with functional Near Infrared Spectroscopy (fNIRS) brain recording while completing a working memory n-back task. As expected, all three groups showed equal behavioral performance (as measured by accuracy) across all n-back conditions. However, only native, early- exposed signers, showed significantly greater brain activity in the left dorsolateral prefrontal cortex, a key brain site for spatial working memory especially with n-back tests, across all n-back conditions and in the right ventrolateral prefrontal cortex for 1-back when compared with proficient and new signers. Taken together, these results show that early exposure to a visuospatial language impacts the way the brain processes spatial information-a finding that suggests that spatial cognition may be vulnerable to sensitive periods in development. The work also carries Educational Neuroscience implications for transformative translation in the possibility that early exposure to a signed language may be used as a way to improve spatial cognition abilities in the general population.

Below are the members of Mr. Kartheiser’s dissertation committee:

• Professor Laura-Ann Petitto, Ph.D. Program in Educational Neuroscience and Department of Psychology, chair of the dissertation committee
• Professor Deborah Chen Pichler, Department of Linguistics
• Dr. Clifton Langdon, Ph.D. Program in Educational Neuroscience
• Professor Pilar Piñar, World Languages and Cultures Department
• Professor David Uttal, Department of Psychology, Northwestern University

Please join the University and the PEN Program in congratulating Geo on his accomplishment!