Neuroscience
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Randomized Controlled Trial
Correlation between audio-visual enhancement of speech in different noise environments and SNR: a combined behavioral and electrophysiological study.
In the present study, we investigated the multisensory gain as the difference of speech recognition accuracies between the audio-visual (AV) and auditory-only (A) conditions, and the multisensory gain as the difference between the event-related potentials (ERPs) evoked under the AV condition and the sum of the ERPs evoked under the A and visual-only (V) conditions in different noise environments. Videos of a female speaker articulating the Chinese monosyllable words accompanied with different levels of pink noise were used as the stimulus materials. The selected signal-to-noise ratios (SNRs) were -16, -12, -8, -4 and 0 dB. ⋯ The behavioral results showed that the maximum gain as the difference of speech recognition accuracies between the AV and A conditions was at the -12 dB SNR. The ERP results showed that the multisensory gain as the difference between the ERPs evoked under the AV condition and the sum of ERPs evoked under the A and V conditions at the -12 dB SNR was significantly higher than those at the other SNRs in the time window of 130-200 ms in the area from frontal to central region. The multisensory gains in audio-visual speech recognition at different SNRs were not completely accordant with the principle of inverse effectiveness, but confirmed to cross-modal stochastic resonance.
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Randomized Controlled Trial
Illumination influences working memory: an EEG study.
Illumination conditions appear to influence working efficacy in everyday life. In the present study, we obtained electroencephalogram (EEG) correlates of working-memory load, and investigated how these waveforms are modulated by illumination conditions. We hypothesized that illumination conditions may affect cognitive performance. ⋯ The fact that the illumination condition affects brain activity but not behavioral performance suggests that the lighting conditions used in the present study did not influence the performance stage of behavioral processing. Nevertheless, our findings provide objective evidence that illumination conditions modulate brain activity. Further studies are necessary to refine the optimal lighting parameters for facilitating working memory.
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Randomized Controlled Trial
The temporal dynamics of enhancing a human declarative memory during reconsolidation.
When a consolidated memory is reactivated, it can become labile and prone to enhancement or disruption, a process known as reconsolidation. The reconsolidation hypothesis has challenged the traditional view that memories after consolidation are fixed and unchangeable. Recent studies suggest that the mechanisms mediating memory retrieval and the mechanisms that underlie the behavioral expression of memory can be dissociated, offering a new promise for the understanding of human memory persistence. ⋯ Interestingly, when a recognition test was applied instead of a cued-recall test, memory performance was still robust at both 1 and 3 weeks after training. Here we show that the period in which this memory can be reactivated and become labile largely exceeds the period in which that memory is recalled, proving evidence that conscious access is not needed for reconsolidation. Present results are consistent with dissociation between the mechanisms mediating memory labilization and the mechanisms that underlie the behavioral expression of memory.
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Randomized Controlled Trial
Training-induced cortical plasticity compared between three tongue-training paradigms.
The primary aim of this study was to investigate the effect of different training types and secondary to test gender differences on the training-related cortical plasticity induced by three different tongue-training paradigms: (1) therapeutic tongue exercises (TTE), (2) playing computer games with the tongue using the Tongue Drive System (TDS) and (3) tongue-protrusion task (TPT). Forty-eight participants were randomized into three groups with 1h of TTE, TDS, or TPT. Stimulus-response curves of motor evoked potentials (MEPs) and motor cortex mapping for tongue muscles and first dorsal interosseous (FDI) (control) were established using transcranial magnetic stimulation at three time-points: (1) before tongue-training, (2) immediately after training, (3) 1h after training. ⋯ Training with TDS was most motivating and fun (P<0.001) and TTE was rated the most painful (P<0.001). Fatigue level was not different between groups (P>0.071). These findings suggest a differential effect of tongue-training paradigms on training-induced cortical plasticity and subject-based scores of fun, motivation and pain in healthy participants.
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Randomized Controlled Trial
Adaptation and generalization to opposing perturbations in walking.
Little is known on how the CNS would select its movement options when a person faces a novel or recurring perturbation of two opposing types (slip or trip) while walking. The purposes of this study were (1) to determine whether young adults' adaptation to repeated slips would interfere with their recovery from a novel trip, and (2) to investigate the generalized strategies after they were exposed to a mixed training with both types of perturbation. Thirty-two young adults were assigned to either the training group, which first underwent repeated-slip training before encountering a novel, unannounced trip while walking, or to the control group, which only experienced the same novel, unannounced trip. ⋯ As a result, they did not have to take a longer compensatory step for trip recovery than did the controls. After the mixed training, subjects were able to converge effectively the motion state of their center of mass (in its position and velocity space) to a stable and generalized "middle ground" steady-state. Such movement strategies not only further strengthened their robust reactive control of stability, but also reduced the CNS' overall reliance on accurate context prediction and on feedback correction of perturbation-induced movement error.