Primary Role of the Right Cerebral Hemisphere in Working Memory Updating: A Connectome-based Lesion-Symptom Mapping Study

Poster Session B - Sunday, April 14, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Emilie Marti¹, Sélim Coll¹, Naz Doganci¹, Radek Ptak^1,2; ¹Laboratory of Cognitive Neurorehabilitation, Faculty of Medicine, University of Geneva, ²Division of Neurorehabilitation, Department of Clinical Neurosciences, Geneva University Hospitals

Working Memory (WM) is a cognitive system crucial for temporarily holding and manipulating information. Neuroimaging evidence suggests that verbal WM is typically associated with left hemisphere function while the processing of visuospatial information in WM more specifically activates the right hemisphere. In contrast, lesion evidence provides contradictory findings indicating the involvement of prefrontal and posterior parietal cortex of both hemispheres. Using connectome-based lesion-symptom mapping on data from 90 participants with focal brain damage (69 right damaged, 21 left damaged), we examined how gray and white matter disconnections affect WM updating in an N-back task, while considering task modality (verbal, spatial) and cognitive load (1-back, 2-back). Behavioral outcomes indicated that right brain damage patients showed more pronounced deficits in WM updating compared to left brain damage patients, regardless of task modality or difficulty. This observation is supported by whole-brain voxel-based analysis, revealing associations between WM deficits and gray matter clusters exclusively in the right hemisphere, such as the superior temporal gyrus for verbal and the middle temporal gyrus for spatial information. Additionally, white matter analyses also identified severely impacted tracts in the right hemisphere, predicting deficits in both verbal and spatial WM. Our findings highlight the primary role of the right cerebral hemisphere in mental manipulation of both verbal and spatial information. Behavioral and neuroanatomical evidence suggests that the updating component of WM predominantly relies on the integrity of the right cerebral hemisphere, irrespective of the specific type of information held in mind.

Topic Area: EXECUTIVE PROCESSES: Working memory