2 research outputs found

    Mapping & decoding cortical engagement during motor imagery, mental arithmetic, and silent word generation using MEG

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    Accurate quantification of cortical engagement during mental imagery tasks remains a challenging brain-imaging problem with immediate relevance to developing brain–computer interfaces. We analyzed magnetoencephalography (MEG) data from 18 individuals completing cued motor imagery, mental arithmetic, and silent word generation tasks. Participants imagined movements of both hands (HANDS) and both feet (FEET), subtracted two numbers (SUB), and silently generated words (WORD). The task-related cortical engagement was inferred from beta band (17–25 Hz) power decrements estimated using a frequency-resolved beamforming method. In the hands and feet motor imagery tasks, beta power consistently decreased in premotor and motor areas. In the word and subtraction tasks, beta-power decrements showed engagements in language and arithmetic processing within the temporal, parietal, and inferior frontal regions. A support vector machine classification of beta power decrements yielded high accuracy rates of 74 and 68% for classifying motor-imagery (HANDS vs. FEET) and cognitive (WORD vs. SUB) tasks, respectively. From the motor-versus-nonmotor contrasts, excellent accuracy rates of 85 and 80% were observed for hands-versus-word and hands-versus-sub, respectively. A multivariate Gaussian-process classifier provided an accuracy rate of 60% for the four-way (HANDS-FEET-WORD-SUB) classification problem. Individual task performance was revealed by within-subject correlations of beta-decrements. Beta-power decrements are helpful metrics for mapping and decoding cortical engagement during mental processes in the absence of sensory stimuli or overt behavioral outputs. Markers derived based on beta decrements may be suitable for rehabilitation purposes, to characterize motor or cognitive impairments, or to treat patients recovering from a cerebral stroke

    Dataset for: Working memory alpha-beta band oscillatory signatures in adolescents and young adults

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    The timing of neural activity is an intriguing way of exposing behaviourally-relevant neural activity, as neural populations exploit transient windows of synchronized activations to exchange dynamic communications in the service of various cognitive operations. The link between neural synchrony and working memory (WM) has been supported at the theoretical and empirical level. However, findings have also shown that WM encoding is also related to significant alpha-beta desynchronization. These findings have been primarily recorded during subsequent memory effect paradigms that compare correct with incorrect encoding trials. The dissociable contribution imparted by various processes to WM performance suggests that incorrect performance may not be directly translatable to unsuccessful encoding. Here, we address the relationship between alpha-beta desynchronization and encoding through the use of an alternative paradigm design by contrasting frontal and parietal human scalp EEG activity during the encoding interval of a delayed-matching to sample task with that recorded during a control task. The additional use of nonverbal/semantic visual stimulation and recruitment of typically developing adolescent subjects, has led us to the conclusion that encoding-relevant alpha-beta decrements can be replicated via a nonverbal/semantic delayed matching to sample task and these are also evident in typically developing adolescents, in addition to adults, as has been previously demonstrated. The identification of encoding-related alpha-beta decrements in adolescent subjects performing such WM tasks may open new avenues to explore whether such a rhythmic signature may explain WM and electrophysiological deficits that emerge in various adolescent neuropsychiatric disorders such as ADHD
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