The Experts below are selected from a list of 17631 Experts worldwide ranked by ideXlab platform
Roozbeh Behroozmand - One of the best experts on this subject based on the ideXlab platform.
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effects of aging on temporal predictive mechanisms of speech and hand Motor Reaction Time
Aging Clinical and Experimental Research, 2018Co-Authors: Karim Johari, Dirkbart Den Ouden, Roozbeh BehroozmandAbstract:Evidence from previous studies has suggested that movement execution in younger adults is accelerated in response to temporally predictable vs. unpredictable sensory stimuli. This effect indicates that external temporal information can modulate Motor behavior; however, how aging can influence temporal predictive mechanisms in Motor system has yet to be understood. The objective of the present study was to investigate aging effects on the initiation and inhibition of speech and hand movement Reaction Times in response to temporally predictable and unpredictable sensory stimuli. Fifteen younger (mean age 22.6) and fifteen older (mean age 63.8) adults performed a randomized speech vowel vocalization or button press initiation and inhibition tasks in two counterbalanced blocks in response to temporally predictable and unpredictable visual cue stimuli. Results showed that Motor Reaction Time was accelerated in both younger and older adults for predictable vs. unpredictable stimuli during initiation and inhibition of speech and hand movement. However, older adults were significantly slower than younger adults in Motor execution of speech and hand movement when stimulus timing was unpredictable. Moreover, we found that overall, Motor inhibition of speech and hand was executed faster than their initiation. Our findings suggest that older adults can compensate age-related decline in Motor Reaction Times by incorporating external temporal information and execute faster movement in response to predictable stimuli, whereas unpredictable temporal information cannot counteract aging effects efficiently and lead to less accurate Motor timing predictive codes for speech production and hand movement.
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Temporal predictive mechanisms modulate Motor Reaction Time during initiation and inhibition of speech and hand movement
Human Movement Science, 2017Co-Authors: Karim Johari, Roozbeh BehroozmandAbstract:Skilled movement is mediated by Motor commands executed with extremely fine temporal precision. The question of how the brain incorporates temporal information to perform Motor actions has remained unanswered. This study investigated the effect of stimulus temporal predictability on response timing of speech and hand movement. Subjects performed a randomized vowel vocalization or button press task in two counterbalanced blocks in response to temporally-predictable and unpredictable visual cues. Results indicated that speech and hand Reaction Time was decreased for predictable compared with unpredictable stimuli. This finding suggests that a temporal predictive code is established to capture temporal dynamics of sensory cues in order to produce faster movements in responses to predictable stimuli. In addition, results revealed a main effect of modality, indicating faster hand movement compared with speech. We suggest that this effect is accounted for by the inherent complexity of speech production compared with hand movement. Lastly, we found that movement inhibition was faster than initiation for both hand and speech, suggesting that movement initiation requires a longer processing Time to coordinate activities across multiple regions in the brain. These findings provide new insights into the mechanisms of temporal information processing during initiation and inhibition of speech and hand movement.
Karim Johari - One of the best experts on this subject based on the ideXlab platform.
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effects of aging on temporal predictive mechanisms of speech and hand Motor Reaction Time
Aging Clinical and Experimental Research, 2018Co-Authors: Karim Johari, Dirkbart Den Ouden, Roozbeh BehroozmandAbstract:Evidence from previous studies has suggested that movement execution in younger adults is accelerated in response to temporally predictable vs. unpredictable sensory stimuli. This effect indicates that external temporal information can modulate Motor behavior; however, how aging can influence temporal predictive mechanisms in Motor system has yet to be understood. The objective of the present study was to investigate aging effects on the initiation and inhibition of speech and hand movement Reaction Times in response to temporally predictable and unpredictable sensory stimuli. Fifteen younger (mean age 22.6) and fifteen older (mean age 63.8) adults performed a randomized speech vowel vocalization or button press initiation and inhibition tasks in two counterbalanced blocks in response to temporally predictable and unpredictable visual cue stimuli. Results showed that Motor Reaction Time was accelerated in both younger and older adults for predictable vs. unpredictable stimuli during initiation and inhibition of speech and hand movement. However, older adults were significantly slower than younger adults in Motor execution of speech and hand movement when stimulus timing was unpredictable. Moreover, we found that overall, Motor inhibition of speech and hand was executed faster than their initiation. Our findings suggest that older adults can compensate age-related decline in Motor Reaction Times by incorporating external temporal information and execute faster movement in response to predictable stimuli, whereas unpredictable temporal information cannot counteract aging effects efficiently and lead to less accurate Motor timing predictive codes for speech production and hand movement.
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Temporal predictive mechanisms modulate Motor Reaction Time during initiation and inhibition of speech and hand movement
Human Movement Science, 2017Co-Authors: Karim Johari, Roozbeh BehroozmandAbstract:Skilled movement is mediated by Motor commands executed with extremely fine temporal precision. The question of how the brain incorporates temporal information to perform Motor actions has remained unanswered. This study investigated the effect of stimulus temporal predictability on response timing of speech and hand movement. Subjects performed a randomized vowel vocalization or button press task in two counterbalanced blocks in response to temporally-predictable and unpredictable visual cues. Results indicated that speech and hand Reaction Time was decreased for predictable compared with unpredictable stimuli. This finding suggests that a temporal predictive code is established to capture temporal dynamics of sensory cues in order to produce faster movements in responses to predictable stimuli. In addition, results revealed a main effect of modality, indicating faster hand movement compared with speech. We suggest that this effect is accounted for by the inherent complexity of speech production compared with hand movement. Lastly, we found that movement inhibition was faster than initiation for both hand and speech, suggesting that movement initiation requires a longer processing Time to coordinate activities across multiple regions in the brain. These findings provide new insights into the mechanisms of temporal information processing during initiation and inhibition of speech and hand movement.
Billy R Hammond - One of the best experts on this subject based on the ideXlab platform.
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a double blind placebo controlled study on the effects of lutein and zeaxanthin on neural processing speed and efficiency
PLOS ONE, 2014Co-Authors: Emily R Bovier, Lisa M Renzi, Billy R HammondAbstract:Lutein and zeaxanthin are major carotenoids in the eye but are also found in post-receptoral visual pathways. It has been hypothesized that these pigments influence the processing of visual signals within and post-retina, and that increasing lutein and zeaxanthin levels within the visual system will lead to increased visual processing speeds. To test this, we measured macular pigment density (as a biomarker of lutein and zeaxanthin levels in brain), critical flicker fusion (CFF) thresholds, and visual Motor Reaction Time in young healthy subjects (n = 92). Changes in these outcome variables were also assessed after four months of supplementation with either placebo (n = 10), zeaxanthin only (20 mg/day; n = 29) or a mixed formulation containing 26 mg/day zeaxanthin, 8 mg/day lutein, and 190 mg/day mixed omega-3 fatty acids (n = 25). Significant correlations were found between retinal lutein and zeaxanthin (macular pigment) and CFF thresholds (p<0.01) and visual Motor performance (overall p<0.01). Supplementation with zeaxanthin and the mixed formulation (considered together) produced significant (p<0.01) increases in CFF thresholds (∼12%) and visual Motor Reaction Time (∼10%) compared to placebo. In general, increasing macular pigment density through supplementation (average increase of about 0.09 log units) resulted in significant improvements in visual processing speed, even when testing young, healthy individuals who tend to be at peak efficiency.
Stanley E Lunde - One of the best experts on this subject based on the ideXlab platform.
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brainstem frequency following response and simple Motor Reaction Time
International Journal of Psychophysiology, 2000Co-Authors: Gary C Galbraith, Bryan C Chae, Jason R Cooper, Mark M Gindi, Benny S Kim, Diana A Mankowski, Stanley E LundeAbstract:Simple Motor Reaction Times (RT) in humans show marked trial-to-trial variations. In the present study, a brief tone (400 Hz, 37.5 ms duration) that was the imperative stimulus in a RT paradigm evoked the brainstem frequency-following response (FFR). Horizontal and vertical montage FFRs were recorded to evaluate neural responses with putative origins in auditory nerve and central brainstem, respectively. The main question concerned the possible relationship between trial-to-trial variations in RT speed and FFR response properties. The results showed a reliable pattern in which fast RT trials yielded larger amplitudes (relative to slow trials) in earlier milliseconds of the FFR, and slow RT trials yielded relatively larger amplitudes in later milliseconds of the response. These results support the conclusion that early processing in the auditory brainstem is not automatic and invariant. Rather, short-latency evoked potentials appear to reflect trial-to-trial variations related to events far removed from the first synapes of sensory coding, perhaps depending upon cortically mediated influences such as cognition or attention.
Yoshikazu Ugawa - One of the best experts on this subject based on the ideXlab platform.
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effects of thirty minute mobile phone use on visuo Motor Reaction Time
Clinical Neurophysiology, 2006Co-Authors: Yasuo Terao, Tomoko Okano, Toshiaki Furubayashi, Yoshikazu UgawaAbstract:Abstract Objective To investigate whether exposure to pulsed high-frequency electromagnetic field (pulsed EMF) emitted by a mobile phone has short-term effects on the visuo-Motor choice Reaction Time (RT) and movement Time (MT). Methods A double blind, counterbalanced crossover design was employed. In 16 normal subjects, we studied the performance of a visuo-Motor precued choice Reaction Time task (PCRT) before and after exposure to EMF emitted by a mobile phone for 30 minutes or sham exposure. Results The RTs and MTs under different conditions of precue information were not affected by exposure to pulsed EMF emitted by a mobile phone or by sham phone use. Conclusions Thirty minutes of mobile phone use has no significant short-term effect on the cortical visuo-Motor processing as studied by the present PCRT task. Significance This is the first study to investigate visuo-Motor behavior in relation to mobile phone exposure. No significant effect of mobile phone use was demonstrated on the performance of the visuo-Motor Reaction Time task.