The aim of this study was to investigate the patterns of contralateral motor overflow (i.e. mirror movement) between the homologous body parts on the right and left side, in stroke patients during single-finger and multi-finger maximum force production tasks. Forty subjects, including stroke (n = 20) and normal subjects (n = 20), participated in this study. The stroke subjects maximally pressed force sensors with their fingers in a flexed position using a single (index, middle, ring, or little) or all fingers (all 4 fingers) using the impaired (IH) or unimpaired (UIH) hand, while the non-patient subjects used their right hands for the same tasks. The maximal voluntary forces in the ipsilateral and unintended pressing forces of each contralateral finger were recorded during the tasks. The magnitude of motor overflow to the contralateral side was calculated using the index of contralateral independence (CI). During the single finger tasks, the finger CI was significantly decreased in the UIH (91%) compared with that in the IH (99%) or normal hands (99%). Likewise, the multiple finger tasks showed that the CI was significantly lower in the UIH (84%) compared with that in the IH (96%) or normal hands (99%). However, the maximal forces were significantly lower in the IH relative to those in the UIH and normal hands. These data demonstrate that stroke patients have greater motor overflow from the UIH to the IH. 相似文献
The study evaluated the off-line relationship of attention, memory and other cognitive performances with the auditory event-related potentials P3 (P300) and N2. The sample comprised 200 middle-aged construction workers. Verbal, visuomotor and memory tests were administered. Attentional domains were examined using CogniSpeed software. Slowed reaction times in the test of sustained attention (vigilance) were associated with delayed P3 latency (p < 0.001) and decreased P3 amplitude (p = 0.005), as well as with delayed N2 latency (p < 0.001). Visuomotor slowing in Digit Symbol was also related to delayed P3 latency (p = 0.030) and decreased P3 amplitude (p = 0.014). In contrast, mild cognitive impairment, short- and long-term memory, and concentrating or sharing attention with high working memory demands were not related to P3. The results suggest that P3 is linked to attentional performance with low working memory demands rather than to effortful working memory updating, retrieval from memory stores, or mild cognitive impairment. 相似文献
There is a growing literature associating anxiety disorders with an inability to inhibit defensive responding during safety conditions of threatening tasks. However, investigations on the relation between panic disorder (PD) and defensive responding to safety have yielded mixed results. A recent study from our laboratory revealed that intolerance of uncertainty (IU) moderates this association, such that only individuals with PD and a high IU exhibit heightened startle potentiation during safety. The mechanism underlying this relationship is unknown. Given that safety conditions typically alternate with periods of threat, cognitive flexibility (i.e., the ability to adjust one's habitual responding to a situation, given the input of new information) may be involved in the ongoing reappraisal of danger and adjustment of defensive responding. Thus, the present study sought to investigate whether deficits in cognitive flexibility mediate the association between IU and defensive responding to safety among a sample of 71 adults diagnosed with PD. As hypothesised, cognitive flexibility mediated the relationship between IU and heightened startle potentiation during safety conditions. This finding suggests that within this subgroup, a failure to inhibit defensive responding during safety conditions may be due to deficits in cognitive flexibility. 相似文献
In this study, we investigated motor and cognitive procedural learning in typically developing children aged 8–12 years with a serial reaction time (SRT) task and a probabilistic classification learning (PCL) task. The aims were to replicate and extend the results of previous SRT studies, to investigate PCL in school-aged children, to explore the contribution of declarative knowledge to SRT and PCL performance, to explore the strategies used by children in the PCL task via a mathematical model, and to see whether performances obtained in motor and cognitive tasks correlated. The results showed similar learning effects in the three age groups in the SRT and in the first half of the PCL tasks. Participants did not develop explicit knowledge in the SRT task whereas declarative knowledge of the cue–outcome associations correlated with the performances in the second half of the PCL task, suggesting a participation of explicit knowledge after some time of exposure in PCL. An increasing proportion of the optimal strategy use with increasing age was observed in the PCL task. Finally, no correlation appeared between cognitive and motor performance. In conclusion, we extended the hypothesis of age invariance from motor to cognitive procedural learning, which had not been done previously. The ability to adopt more efficient learning strategies with age may rely on the maturation of the fronto-striatal loops. The lack of correlation between performance in the SRT task and the first part of the PCL task suggests dissociable developmental trajectories within the procedural memory system. 相似文献
Understanding and modeling the influence of mobile phone use on pedestrian behaviour is important for several safety and performance evaluations. Mobile phone use affects pedestrian perception of the surrounding traffic environment and reduces situation awareness. This study investigates the effect of distraction due to mobile phone use (i.e., visual and auditory) on pedestrian reaction time to the pedestrian signal. Traffic video data was collected from four crosswalks in Canada and China. A multilevel mixed-effects accelerated failure time (AFT) approach is used to model pedestrian reaction times, with random intercepts capturing the clustered-specific (countries) heterogeneity. Potential reaction time influencing factors were investigated, including pedestrian demographic attributes, distraction characteristics, and environment-related parameters. Results show that pedestrian reaction times were longer in Canada than in China under the non-distraction and distraction conditions. The auditory and visual distractions increase pedestrian reaction time by 67% and 50% on average, respectively. Pedestrian reactions were slower at road segment crosswalks compared to intersection crosswalks, at higher distraction durations, and for males aged over 40 compared to other pedestrians. Moreover, pedestrian reactions were faster at higher traffic awareness levels. 相似文献
Objective: Self-affirmation has repeatedly been shown to reduce adverse psychological and physiological responses to stress. However, it is plausible that self-affirmation could exacerbate negative reactions to stress under certain conditions. The current research explored whether self-affirmation would increase negative psychological responses to a stressor occurring in a central life domain characterised by low levels of control.
Design: Female participants (Study 1 N = 132; Study 2 N = 141) completed baseline measures of anxiety and mood. They were then randomly allocated to complete a self-affirmation or control task, before reading a narrative documenting a stressful birth and imagining themselves in the place of the woman giving birth. After completing this task, participants again reported their levels of anxiety and positive mood.
Main outcome measures: Anxiety and positive mood assessed at follow-up.
Results: Study 1 demonstrated that self-affirmed women experienced increased anxiety and less positive mood at follow-up, compared both to baseline and to women in the control condition. Study 2 revealed that the effect of self-affirmation on outcomes was moderated by fear of childbirth.
Conclusion: These results provide preliminary evidence that self-affirmation may worsen negative responses to stressors under certain conditions and for certain individuals. 相似文献
The Serial Reaction Time Task (SRTT) is thought to assess implicit learning, which seems to be preserved with age. However, the reaction time (RT) measures employed on implicit-like tasks might be too unreliable to detect individual differences. We investigated whether RT-based measures mask age effects by comparing the performance of 43 younger and 35 older adults on SRTT and an explicit-like Predictive Sequence Learning Task (PSLT). RT-based measures (difference scores and a ratio) were collected for both tasks, and accuracy was additionally measured for PSLT. We also measured fluid abilities. The RT-difference scores indicated preserved SRTT and PSLT performance with age and did not correlate with fluid abilities, while ratio RT and the accuracy-based measures indicated age-related decline and correlated with fluid abilities. Therefore, RT-difference scores might mask individual differences, which compromises the interpretation of previous studies using SRTT. 相似文献
In this article, we sought to isolate the processing demands of combining the concepts of modifier‐noun phrases from those of other language comprehension processes. Probe reaction time (RT) was used as an indication of the processing resources required for combining concepts. Phrase frequency (as measured by Google hit rates) was used as a metric of the degree of conceptual combination required for each phrase. Participants were asked to interpret modifier‐noun phrases using a sense‐nonsense decision (Experiment 1) and a phrase meaning access task (Experiment 2). Experiment 2 also used a lexical decision task to activate the word's individual meanings. Regression analyses for both experiments indicated that phrase frequency (indicating novelty) predicts a significant portion of the probe RT variance, such that low‐frequency phrases required more processing resources than high‐frequency phrases, when controlling for associative strength, word frequency, letter length, and lexical‐semantic activation. Overall, this study indicates that conceptual combination requires processing resources beyond those of other language processes. 相似文献