Poster Session A, Saturday, March 23, 1:30 pm - 3:30 pm, Pacific Concourse
Tactile agnosia after white matter disconnection due to stroke
Krista Schendel1, Timothy J. Herron1, Brian Curran1, Nina Dronkers2, Juliana Baldo1; 1VA Northern California Health Care System, 2University of California, Berkeley
While disconnection resulting from lesions or dissections of the corpus callosum have been reported, it is less understood how lesions in the white matter adjacent to the corpus callosum may impact behavior. Here we report a case study in which a focal left hemisphere stroke involving the white matter adjacent to the body of the corpus callosum resulted in the disruption of interhemispheric transfer of sensory information between the right and left hemispheres. The patient (female in her 40s with no prior neurologic history) suffered a white matter stroke primarily involving the left superior corona radiata. Tractography revealed a marked reduction in the fiber tracts extending laterally from the body of the corpus callosum into the left hemisphere. Tests of apraxia and astereognosis were administered, and the patient was asked to name letters and numbers that were “drawn” on either her left or right hand. Based on previous studies of callosal lesions, the prediction was that naming and tactile recognition of objects in the left hand would be impaired relative the that of the right hand due to impaired transfer of sensory information from the left hand (right hemisphere) to left hemisphere language regions. As predicted, the patient performed at chance for naming letters, numbers, and objects drawn/presented in her left hand (transfer condition). The combined brain imaging and behavioral data highlight the importance of white matter tract integrity in interhemispheric transfer between right hemisphere somatosensory cortex and left hemisphere language regions.
Topic Area: PERCEPTION & ACTION: Multisensory