Stimulus timing by people with Parkinson's disease

Previous literature suggests that Parkinson’s disease is marked by deficits in timed behaviour. However, the majority of studies of central timing mechanisms in patients with Parkinson’s disease have used timing tasks with a motor component. Since the motor abnormalities are a defining feature of the condition, the status of timing in Parkinson’s disease remains uncertain. Data are reported from patients with mild to moderate Parkinson’s disease (both on and off medication) and age- and IQ-matched controls on a range of stimulus timing tasks without counting. Tasks used were temporal generalization, bisection, threshold determination, verbal estimation, and a memory for duration task. Performance of patients was generally “normal” on all tasks, but significant differences from performance of controls were found on the memory for duration task. Among the “normal” effects noted were arithmetic mean bisection, asymmetric temporal generalization gradients, and subjective shortening on the memory for duration task. The results suggest (a) that some previous reports of timing “deficits” in Parkinson’s patients were possibly due to the use of tasks requiring a timed manual response and (b) small differences between patients and controls may be found on tasks where two stimuli are presented on each trial, whether patients are on medication or off it.     

Global and local evaluations of public speaking performance in social anxiety

Differences in the relative use of global and local information (seeing the forest vs. the trees) may explain why people with social anxiety often do not benefit from corrective feedback, even though they pay close attention to details in social situations. In the current study, participants high (n = 43) or low (n = 47) in social anxiety symptoms gave a series of brief speeches, and then self-rated their speaking performance on items reflecting global and local performance indicators (self-assessment) and also received standardized performance feedback from an experimenter. Participants then completed a questionnaire asking how they thought the experimenter would rate their performance based on the feedback provided (experimenter assessment). Participants completed the self- and experimenter assessments again after 3 days, in addition to a measure of postevent processing (repetitive negative thinking) about their speech performance. Results showed that, as hypothesized, the High SA group rated their performance more negatively than the Low SA group. Moreover, the High SA group's ratings of global aspects of their performance became relatively more negative over time, compared to their ratings of local aspects and the Low SA group's ratings. As expected, postevent processing mediated the relationship between social anxiety group status and worsening global performance evaluations. These findings point to a pattern of progressively more negative global evaluations over time for persons high in social anxiety.     

Mechanism of action of methylphenidate: insights from PET imaging studies

Methylphenidate (MPH) is the most commonly prescribed drug for the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD). We have used Positron Emission Tomography (PET) to investigate the mechanism of action of MPH in the human brain. We have shown (a) that oral MPH reaches peak concentration in the brain 60-90 minutes after its administration, (b) that therapeutic doses of MPH block more than 50% of the dopamine transporters (DAT), and (c) that of the two enantiomers that compose MPH, it is d-threo-methylphenidate (d-MPH) and not l-threo-methylphenidate (l-MPH) that binds to the DAT. We have also shown that therapeutic doses of MPH significantly enhance extracellular dopamine (DA) in the basal ganglia, which is an effect that appears to be modulated by the rate of DA release and that is affected by age (older subjects show less effect). Thus, we postulate (a) that MPH's therapeutic effects are in part due to amplification of DA signals, (b) that variability in responses is in part due to differences in DA tone between subjects, and (c) that MPH's effects are context dependent. Because DA enhances task specific neuronal signaling and decreases noise, we also postulate that MPH-induced increases in DA could improve attention and decrease distractibility; and that since DA modulates motivation, the increases in DA would also enhance the saliency of the task facilitating the 'interest it elicits' and thus improving performance.     

Origins of timing errors in human sensorimotor coordination

The authors analyzed fluctuations in timing errors when 8 human participants attempted to coordinate movement with external rhythmic signals. The temporal dynamics of the errors is usually described in terms of simple, self-correcting models. Here the authors demonstrate that timing errors are characterized by a 1/f(alpha) type of long memory process. The value of the exponent alpha differentiates different types of coordination states: synchronization and syncopation. More interesting, evidence was found that alpha can be changed when participants use different coordination strategies. Together with the authors' understanding of the generation mechanism for long memory processes, these results suggest that 1/f(alpha) type of long-range correlated timing errors are of higher cortical origin and are likely the outcome of distributed neural processes acting on multiple time scales.     

Relations of perceived motivational climate and feelings of belonging in physical education in urban schools

The current pilot study examined the relationship between feelings of belonging and perceptions of motivational climate in physical education classes among 87 African-American, inner-city high school students (41 boys, 46 girls). Motivational climate was assessed by the Perceived Motivational Climate Questionnaire and feelings of belonging were assessed by the Belonging Scale. Contrary to the hypothesis, scores for both the task- and ego-involved subscales of the Perceived Motivational Climate Questionnaire had moderate positive correlations with scores on the Belonging Scale, indicating the relationship between these specific motivational climates and social-emotional outcomes in physical education is not clear and direct. Further research is warranted to assess these findings and to identify what experiences and instructional strategies are most effective in promoting social-emotional outcomes in physical education in urban schools.     

暴力犯罪者对负性情绪信息注意偏向的ERP研究

采用视觉搜索范式,探讨了暴力犯罪者对情绪刺激（愤怒面孔与高兴面孔）的注意偏向特点。行为数据显示,相比非暴力组,暴力组对愤怒面孔的反应要显著快于高兴面孔,初步验证了暴力犯罪者对负性情绪信息存在注意偏向。ERP数据进一步表明,当目标刺激为愤怒面孔时,暴力组N2pc的潜伏期要显著小于非暴力组,说明暴力犯罪者对愤怒面孔的觉察早于高兴面孔,对负性情绪刺激更为敏感。由于N2pc的波幅不存在显著差异,差异主要表现在反应时和潜伏期,说明暴力犯能够更快的觉察到负性情绪面孔,但并没有对其投入更多的注意资源,出现回避模式,表明暴力犯对负性情绪信息的加工是一种警觉—回避模式。     

Brain activations associated with sign production using word and picture inputs in deaf signers

Effective literacy education in deaf students calls for psycholinguistic research revealing the cognitive and neural mechanisms underlying their written language processing. When learning a written language, deaf students are often instructed to sign out printed text. The present fMRI study was intended to reveal the neural substrates associated with word signing by comparing it with picture signing. Native deaf signers were asked to overtly sign in Chinese Sign Language (CSL) common objects indicated with written words or presented as pictures. Except in left inferior frontal gyrus and inferior parietal lobule where word signing elicited greater activation than picture signing, the two tasks engaged a highly overlapping set of brain regions previously implicated in sign production. The results suggest that word signing in the deaf signers relies on meaning activation from printed visual forms, followed by similar production processes from meaning to signs as in picture signing. The present study also documents the basic brain activation pattern for sign production in CSL and supports the notion of a universal core neural network for sign production across different sign languages.     

Concreteness effects in the processing of Chinese words

The present study examined the relationship between word concreteness and word frequency using event-related potential (ERP) measurements during a lexical decision task. Potential effects of concreteness in the processing of verbs were also examined. ERPs were recorded from 119 scalp electrodes in 23 right-handed participants. The results showed that concrete nouns were associated with a more negative ERP than abstract nouns at 200-300 and 300-500 ms after stimulus onset, regardless of word frequency. Between 300 and 500 ms, concrete nouns and abstract nouns produced differentiated scalp distributions, respectively. In terms of verbs, concreteness only produced small difference in ERP primarily in the central-parietal sites of the left hemisphere.     

Inactivation of the anterior cingulate cortex blocks expression of remote, but not recent, conditioned taste aversion memory

Previous studies have shown that medial prefrontal cortical regions, such as the anterior cingulate cortex (ACC), play a key role in the expression of remote spatial and contextual memory. To evaluate whether this role is conserved in hippocampal-independent tasks we trained mice in the conditioned taste aversion (CTA) paradigm. Lidocaine-induced inactivation of the ACC blocked the expression of CTA tested one month (remote), but not one day (recent), after conditioning with either a weak or strong unconditioned stimulus (US). These data suggest that the ACC may play a conserved role in remote memory, regardless of memory strength or content.