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Background: Aphasia is often accompanied by impairment of non-language cognitive functions. Assessment of cognitive capacity in people with aphasia (PWA) with standard neuropsychological methods may be problematic due to their language difficulties. Numerous experimental studies indicate that P300 may be considered as an index of cognitive capacity in both healthy and clinical samples. Accordingly, the measurement of event-related potentials enables the investigation of behaviourally non-observable mental processes underlying the cognitive functions that are assessed with neuropsychological tests. Aims: To investigate in PWA the relationship between P300 parameters and cognitive function efficiency measured with neuropsychological methods. Methods & Procedures: A total of 25 PWA after left-hemispheric stroke participated in the study. Electrophysiological (EEG) signals were recorded during the performance of a visual Go-No Go task. P300 was identified on nine electrodes, which were then pooled in three lines: left (F3, C3, P3), central (Fz, Cz, Pz) and right (F4, C4, P4). The neuropsychological assessment of cognitive functions included mental speed, short-term memory, divided attention, executive functions, auditory language comprehension and expression. Outcomes & Results: P300 latency correlated with indices of several cognitive functions: temporal resolution, psychomotor speed, spatial short-term memory, planning, word and sentence comprehension, as well as verbal fluency. Shorter P300 latencies were accompanied by greater efficiency of the abovementioned functions. In contrast, significant correlations between P300 amplitudes and cognitive measures were fragmentary. Conclusions & Implications: In PWA, P300 latency might be related to cognitive functioning, especially to measures that rely heavily on the speed of information processing. However, P300 seems to be unrelated to more complex cognitive functions. P300 latency may be used as a neurophysiological correlate of cognitive efficiency in PWA and might have potential applications in monitoring the effects of therapeutic interventions in this patient group.

Stroke and subsequent neuroregenerative processes cause changes in neural organization of attentional functions. In this study, we attempted to identify differences in neural synchronization patterns during a visual Go/No-Go task in people with post-stroke aphasia in both subacute and chronic stroke phases. To identify neuronal underpinnings of the behavioral differences we investigated pairwise connectivity patterns using corrected imaginary phase locking value and graph-theoretic measures (efficiency, modularity and clustering coefficient) at global and local level in subacute (n = 13) and chronic stroke phases (n = 14) during a Go/No-Go task. We observed significantly lower phase synchronization in the Subacute Group in the alpha band in the connections spanning frontal and central areas of both hemispheres alongside lower local efficiency and clustering coefficient in the left frontal region. Additionally, we observed higher modularity in the beta band in the unaffected right parietal region in the Subacute Group which may denote inhibition of motor and attention functions. Those mechanisms could serve to align cognitive abilities between the damaged and healthy hemispheres, harmonizing the activity of the neuronal networks of both hemispheres disrupted by the effects of the stroke. Our findings have potential implications for rehabilitation therapies, which should take into account the pattern of connectivity changes during different phases of reovery. [ABSTRACT FROM AUTHOR]

Background: Temporal information processing (TIP) underlies many aspects of cognitive functions like language, motor control, learning, memory, attention, etc. Millisecond timing may be assessed by sequencing abilities, e.g. the perception of event order. It may be measured with auditory temporal-order-threshold (TOT), i.e. a minimum time gap separating two successive stimuli necessary for a subject to report their temporal order correctly, thus the relation 'before-after'. Neuropsychological evidence has indicated elevated TOT values (corresponding to deteriorated time perception) in different clinical groups, such as aphasic patients, dyslexic subjects or children with specific language impairment. Aims: To test relationships between elevated TOT and declined cognitive functions in brain-injured patients suffering from post-stroke aphasia. Methods & Procedures: We tested 30 aphasic patients (13 male, 17 female), aged between 50 and 81 years. TIP comprised assessment of TOT. Auditory comprehension was assessed with the selected language tests, i.e. Token Test, Phoneme Discrimination Test (PDT) and Voice-Onset-Time Test (VOT), while two aspects of attentional resources (i.e. alertness and vigilance) were measured using the Test of Attentional Performance (TAP) battery. Outcomes & Results: Significant correlations were indicated between elevated values of TOT and deteriorated performance on all applied language tests. Moreover, significant correlations were evidenced between elevated TOT and alertness. Finally, positive correlations were found between particular language tests, i.e. (1) Token Test and PDT; (2) Token Test and VOT Test; and (3) PDT and VOT Test, as well as between PDT and both attentional tasks. Conclusions & Implications: These results provide further clinical evidence supporting the thesis that TIP constitutes the core process incorporated in both language and attentional resources. The novel value of the present study is the indication for the first time in Slavic language users a clear coexistence of the "timing-auditory comprehension-attention" relationships.