Shared and distinct anatomical correlates of semantic and phonemic fluency revealed by lesion-symptom mapping in patients with ischemic stroke.
Semantic and phonemic fluency tasks are frequently used to test executive functioning, speed and attention, and access to the mental lexicon. In semantic fluency tasks, subjects are required to generate words belonging to a category (e.g., animals) within a limited time window, whereas in phonemic fluency tasks subjects have to generate words starting with a given letter. Anatomical correlates of semantic and phonemic fluency are currently assumed to overlap in left frontal structures, reflecting shared executive processes, and to be distinct in left temporal and right frontal structures, reflecting involvement of distinct memory processes and search strategies. Definite evidence for this assumption is lacking. To further establish the anatomical correlates of semantic and phonemic fluency, we applied assumption-free voxel-based and region-of-interest-based lesion-symptom mapping in 93 patients with ischemic stroke. Fluency was assessed by asking patients to name animals (semantic), and words starting with the letter N and A (phonemic). Our findings indicate that anatomical correlates of semantic and phonemic fluency overlap in the left inferior frontal gyrus and insula, reflecting shared underlying cognitive processes. Phonemic fluency additionally draws on the left rolandic operculum, which might reflect a search through phonological memory, and the middle frontal gyrus. Semantic fluency additionally draws on left medial temporal regions, probably reflecting a search through semantic memory, and the right inferior frontal gyrus, which might reflect the application of a visuospatial mental imagery strategy in semantic fluency. These findings establish shared and distinct anatomical correlates of semantic and phonemic fluency.
Department of Neurology, Utrecht Stroke Center, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO box 85500, G.03.232, 3508 GA, Utrecht, The Netherlands. j.m.biesbroek@umcutrecht.nl.
J Matthijs
JM
Biesbroek
Department of Neurology, Utrecht Stroke Center, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO box 85500, G.03.232, 3508 GA, Utrecht, The Netherlands.|Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, The Netherlands.
Martine J E
MJ
van Zandvoort
Department of Neurology, Utrecht Stroke Center, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO box 85500, G.03.232, 3508 GA, Utrecht, The Netherlands.
L Jaap
LJ
Kappelle
Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
Birgitta K
BK
Velthuis
Department of Neurology, Utrecht Stroke Center, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO box 85500, G.03.232, 3508 GA, Utrecht, The Netherlands.
Geert Jan
GJ
Biessels
Department of Neurology, Utrecht Stroke Center, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO box 85500, G.03.232, 3508 GA, Utrecht, The Netherlands.|Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, The Netherlands.
Albert
A
Postma
D002545:Brain Ischemia / Q000473:pathology / Q000523:psychology; D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000473:pathology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010700:Phonetics; D017397:Prefrontal Cortex / Q000033:anatomy & histology* / Q000473:pathology; D012660:Semantics; D020521:Stroke / Q000473:pathology / Q000523:psychology
Anatomical correlates; Fluency; Lesion-symptom mapping; Neural substrate; Phonemic; Semantic