NEUROCOGNITIVE CORRELATES OF REDUCTION OF VERBAL FLUENCY FOLLOWING RIGHT-HEMISPHERIC STROKE

The study aimed at evaluating of verbal fluency in right hemisphere-damaged patients. Forty-six vascular right hemisphere-damaged (RHD) and 30 control subjects were submitted to a verbal fluency task for which criteria were either phonemic or semantic. The strategies that the participants used spontaneously in order to maximize word production, namely clustering (CL) and switching (SW) techniques, were evaluated. Results showed (a) that RHD subjects do show a significant reduction of verbal fluency as compared to controls, (b) that this reduction is more prominent for the phonetic criterion, and (c) that verbal fluency impairment in the RHD subjects is predominantly a consequence of dysfunction to the frontal cortex and subcortical nuclei (i.e. striatum and thalamus). Both CL and SW strategies were related to total word production on both tasks. These results tend to agree with a general theory on a right-hemisphere contribution to lexical processing, and more specifically, to its phonological aspects, as well as to executive component of verbal fluency.