Aphasia is an acquired impairment of language functions resulting from a brain lesion. It is usually accompanied by deficits in non-linguistic cognitive processes. This study aimed to investigate in patients with aphasia the complex interrelationships between selected cognitive functions: auditory speech comprehension, working memory, and temporal information processing in the millisecond time range. Thirty right-handed subjects aged from 27 to 82 years suffering from post-stroke aphasia participated in the study. Verbal working memory and spatial working memory were assessed with: a (...) receptive verbal test and the Corsi Block-Tapping Test, respectively. Both these WM tests used the forward tasks and backward tasks. Auditory comprehension was assessed by receptive language tests, and TIP efficiency was assessed by auditory perception of temporal order in the millisecond time range. We observed better performance of forward WM tasks than backward ones, independently of the type of material used. Furthermore, the severity of auditory comprehension impairment correlated with the efficiency on both forward and backward VWM tasks and the backward SWM task. Further analysis revealed that TIP plays a crucial role only in the latter task. These results indicate the divergent pattern of interactions between WM and TIP depending on the type of WM tasks. Level of verbal competency appeared to play an important role in both VWM tasks, whereas TIP appeared to be important for SWM, but only on the backward task. (shrink)

Although Grodzinsky's target article has merit, it neglects the importance of neural mechanisms underlying language functions. We present results from our clinical studies on different levels of temporal information processing in aphasic patients and briefly review the existing data on neurobiology of language to cast new light on the main thesis of the target article.