Functional brain activity in task switching in persons with aphasia (an fMRI study)
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The present work is dedicated to the role of gestures in overcoming lexical access problems in patients with motor aphasia. The study is based on a corpus of narratives by brain-damaged individuals – «Russian CliPS» (Clinical Pear Stories), the videos from which were annotated in the linguistic annotator «ELAN», with the gestural layout included in the analysis. The results suggest that most often the difficulties with lexical access were related to the search for nouns and verbs, and gestures (deictic and rhythmic gestures, beats) facilitated lexical access in patients.
We analyzed brain functional connectivity using data from a task-based fMRI study of explicit categorization of neutral and emotional faces. During the perception of emotional faces, the correlation of BOLD signal in the right posterior superior temporal sulcus (STS) with other regions of the core face system increased, as compared to neutral faces. Conversely, during the perception of neutral faces, we found an increased correlation of STS and other core face system regions with brain areas outside the core system. The functional connectivity of STS shows lateralization due to the presence or absence of emotional expression. The obtained results support the key role of STS in facial expression recognition.
Investigations of the neural correlates of face recognition have typically used old/new paradigms where subjects learn to recognize new faces or identify famous faces. Familiar faces, however, include one's own face, partner's and parents' faces. Using event-related fMRI, we examined the neural correlates of these personally familiar faces. Ten participants were presented with photographs of own, partner, parents, famous and unfamiliar faces and responded to a distinct target. Whole brain, two regions of interest (fusiform gyrus and cingulate gyrus), and multiple linear regression analyses were conducted. Compared with baseline, all familiar faces activated the fusiform gyrus; own faces also activated occipital regions and the precuneus; partner faces activated similar areas, but in addition, the parahippocampal gyrus, middle superior temporal gyri and middle frontal gyrus. Compared with unfamiliar faces, only personally familiar faces activated the cingulate gyrus and the extent of activation varied with face category. Partner faces also activated the insula, amygdala and thalamus. Regions of interest analyses and laterality indices showed anatomical distinctions of processing the personally familiar faces within the fusiform and cingulate gyri. Famous faces were right lateralized whereas personally familiar faces, particularly partner and own faces, elicited bilateral activations. Regression analyses show experiential predictors modulated with neural activity related to own and partner faces. Thus, personally familiar faces activated the core visual areas and extended frontal regions, related to semantic and person knowledge and the extent and areas of activation varied with face type.
The study of cerebral organization of usage of verbs and nouns was carried out by means of functional magnetic resonance imaging. The influence of strategy of word actualization (verbs and nouns extraction on paradigmatic and syntagmatic connections) and the level of automation of these processes on the pattern of cerebral cortex activation was shown.
Key characteristics of non-fluent (Broca, motor) aphasia are, among others, verb finding difficulties and effortful speech output. These characteristics are related to different levels of speech production (lexical retrieval and motor execution). This study was aimed at identifying normative brain activation related to verb production in healthy individuals, as well as patterns of its reorganization depending on the locus of the linguistic deficit in patients with non-fluent aphasia.