Role of frontal cortex in inferential reasoning: evidence from the word context test.
OBJECTIVE
Inferential reasoning in language involves the ability to deduce information based on context and prior experience. This ability has been generally studied as a right-hemisphere function. Recent research, however, has suggested that inferencing involves anterior regions of both the left and right hemispheres.


METHODS
We further explored this idea by testing a group of non-aphasic, focal frontal patients (right and left hemisphere) on a new test of inferencing, the Word Context Test. The Word Context Test requires examinees to identify the meaning of a made-up word (e.g., prifa) based on its use in a series of sentences.


RESULTS
Patients with frontal lobe lesions were significantly impaired on this task relative to a group of age- and education-matched controls. Contrary to earlier research focusing on a special role for the right hemisphere in inferencing, there was considerable overlap in performance of right- and left-frontal patients, with right-frontal patients performing better.


CONCLUSIONS
These findings suggest that inferencing is disrupted following focal frontal injury and have implications for discourse comprehension in non-aphasic patients.
Keil
Katrina
K
Transitional Living Center, Casa Colina Centers for Rehabilitation, 255 East Bonita Ave., Pomona, CA 91769-6001, USA. trina.keil@aya.yale.edu
Baldo
Juliana
J
Kaplan
Edith
E
Kramer
Joel
J
Delis
Dean C
DC
D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000473:pathology / Q000503:physiopathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D032882:Comprehension / Q000502:physiology*; D004292:Dominance, Cerebral; D005260:Female; D005625:Frontal Lobe / Q000293:injuries / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011340:Problem Solving / Q000502:physiology*