The neurocognitive basis of semantic reading in stroke alexia

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

Ryan Staples¹ (ryan.staples6@gmail.com), J. Vivian Dickens^1,2, Sara Dyslin¹, Sarah Snider¹, Andrew DeMarco¹, Rhonda Friedman¹, Peter Turkeltaub^1,3; ¹Georgetown University Medical Center, Washington, DC, ²Hospital of the University of Pennsylvania, Philadelphia, PA, ³Medstar National Rehabilitation Hospital, Washington, DC

Semantics’ role in reading is controversial. The imageability advantage, whereby imageable words (e.g., “car”) are read faster and more accurately than non-imageable words (e.g., “justice”), is a measure of semantic influence on reading aloud. Imageability advantage changes in stroke-induced alexia could result from either a nonverbal semantic representation impairment, or from an impairment in semantic-phonology (SP) mappings. We leverage lesion symptom mapping and behavioral testing of the imageability effect to identify the neural and computational basis of semantic influence on reading. We performed voxel-based (VLSM) and structural connectome lesion-symptom mapping (CLSM) on the imageability advantage in 56 left hemisphere stroke survivors. Participants read aloud 200 single words varying in frequency, regularity, and imageability. Averaged accuracy on yes/no auditory category judgement and Pyramids and Palm Trees was used to assess nonverbal semantic representation. Averaged picture naming and word-to-picture matching accuracy assessed SP mappings. Left posterior superior temporal sulcus (lpSTS) lesions were associated with reduced imageability advantage. CLSM analyses showed that structural disconnections to the lpSTS reduced the imageability advantage (voxel/edgewise P<0.005, cluster FWER P<0.05). Participants’ accuracy on imageable words was predicted by SP mapping ability, but not nonverbal semantics. VLSM of the SP score implicates left superior temporal cortex, partially overlapping with the lpSTS imageability advantage result. Lower SP mapping scores were associated with disconnections in a left-lateralized language and semantic network. Our results suggest that the lpSTS underlies the influence of semantics on reading, and that reduced imageability advantage reflects impairment of SP mappings rather than impairment of semantic representation.

Topic Area: LANGUAGE: Semantic