Impaired finger dexterity in Parkinson's disease is associated with praxis function

A controversial concept suggests that impaired finger dexterity in Parkinson’s disease may be related to limb kinetic apraxia that is not explained by elemental motor deficits such as bradykinesia. To explore the nature of dexterous difficulties, the aim of the present study was to assess the relationship of finger dexterity with ideomotor praxis function and parkinsonian symptoms. Twenty-five patients with Parkinson’s disease participated in the study. Their left and right arms were tested independently. Testing was done in an OFF and ON state as defined by a modified version of the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS). Finger dexterity was assessed by a coin rotation (CR) task and ideomotor praxis using a novel test of upper limb apraxia (TULIA), in which the patients were requested to imitate and pantomime 48 meaningless, as well as communicative and tool-related gestures. Coin rotation significantly correlated with TULIA irrespective of the motor state and arm involved, but not with the MDS-UPDRS. This association was significantly influenced by Hoehn and Yahr stage.The strong association of finger dexterity with praxis function but not the parkinsonian symptoms indicates that impaired finger dexterity in Parkinson’s disease may be indeed apraxic in nature, yet, predominantly in advanced stages of the disease when cortical pathology is expected to develop. The findings are discussed within a cognitive-motor model of praxis function.     

Revisiting the suitability of antisaccade performance as an endophenotype in schizophrenia

Poor performance on the antisaccade task has been proposed as a candidate endophenotype in schizophrenia. Caveats to this proposal, however, include inconsistent findings in first-degree relatives of individuals with schizophrenia, and substantial heterogeneity in individuals with the disorder. In this study, we examined antisaccade performance in patients and relatives, and sought to establish whether antisaccade measures could differentiate between two patients clusters identified in the Western Australian Family Study of Schizophrenia with either pervasive cognitive deficits (CD) or cognitively spared (CS). Ninety-three patients (CD = 47, CS = 46), 99 relatives and 62 healthy controls carried out a standard antisaccade task. Results showed: (i) significantly greater error rate, and prolonged latencies to correct responses and self-correction saccades in patients compared with controls; (ii) high error rates in relatives of poorly performing patients; (iii) longer latencies of self-correction saccades in relatives compared to controls; and (iv) higher error rate and longer latencies of self-correction saccades in the CD subgroup compared with CS. Unaffected relatives as a group were unimpaired in error rate as compared to healthy controls. These findings suggest that the antisaccade error rate and latency of self-correction saccades are useful measures in specific applications of genetic research in schizophrenia, without fully meeting endophenotype co-familiality requirements.     

Distributed attentional deficits in chronic methamphetamine abusers: evidence from the Attentional Network Task (ANT)

Objective

The goal of the present study was to examine distributed attentional functions in long-term but currently abstinent methamphetamine (MA) abusers using a task that measures attentional alertness, orienting, and conflict resolution.

Methods

Thirty currently abstinent MA abusers (1 month-5 years) and 22 healthy non-substance using adults were administered a multimodal version of the Attentional Network Task (ANT-I). In this task subjects identified the direction of a centrally presented arrow using a key press. Analyses examined the interaction between alerting tones, location cueing and congruency between the target arrows and flanking distractor stimuli.

Results

All participants were faster when an auditory tone preceded the trial onset (p < 0.001), on trials in which a valid cue preceded the location of the target arrow (p < 0.001), and on congruent trials (i.e., when all display arrows faced in the same direction) (p < 0.001). Of primary interest was the finding that MA abusers were more influenced by the conflict between the peripheral arrows and the central target arrow (p = 0.009). There were also correlations between length of drug sobriety and executive function as well as between drug-induced psychiatric symptoms and alertness.

Conclusions

These results suggest that chronic MA abusers display cognitive deficits that may reflect a specific vulnerability to distraction on a task of executive function. These findings are consistent with other studies that have reported deficits in anterior attentional systems and top-down cognitive control.     

Asymmetrical brain activity induced by voluntary spatial attention depends on the visual hemifield: a functional near-infrared spectroscopy study

The effect of the visual hemifield to which spatial attention was oriented on the activities of the posterior parietal and occipital visual cortices was examined using functional near-infrared spectroscopy in order to investigate the neural substrates of voluntary visuospatial attention. Our brain imaging data support the theory put forth in a previous psychophysical study, namely, the attentional resources for the left and right visual hemifields are distinct. Increasing the attentional load asymmetrically increased the brain activity. Increase in attentional load produced a greater increase in brain activity in the case of the left visual hemifield than in the case of the right visual hemifield. This asymmetry was observed in all the examined brain areas, including the right and left occipital and parietal cortices. These results suggest the existence of asymmetrical inhibitory interactions between the hemispheres and the presence of an extensive inhibitory network.     

Motor execution affects action prediction

Previous studies provided evidence of the claim that the prediction of occluded action involves real-time simulation. We report two experiments that aimed to study how real-time simulation is affected by simultaneous action execution under conditions of full, partial or no overlap between observed and executed actions. This overlap was analysed by comparing the body sides and the movement kinematics involved in the observed and the executed action. While performing actions, participants observed point-light (PL) actions that were interrupted by an occluder, followed by a test pose. The task was to judge whether the test pose depicted a continuation of the occluded action in the same depth angle. Using a paradigm proposed by Graf et al., we independently manipulated the duration of the occluder and the temporal advance of the test pose relative to occlusion onset (occluder time and pose time, respectively). This paradigm allows the assessment of real-time simulation, based on prediction performance across different occluder time/pose time combinations (i.e., improved task performance with decreasing time distance between occluder time and pose time is taken to reflect real-time simulation). The PL actor could be perceived as from the front or back, as indicated by task instructions. In Experiment 1 (front view instructions), evidence of action simulation was obtained for partial overlap (i.e., observed and performed action corresponded either in body side or movement kinematics), but not for full or no overlap conditions. The same pattern was obtained in Experiment 2 (back view instructions), ruling out a spatial compatibility explanation for the real-time pattern observed. Our results suggest that motor processes affect action prediction and real-time simulation. The strength of their impact varies as a function of the overlap between observed and executed actions.     

Mechanism of isoflavone aglycone's effect on cognitive performance of senescence-accelerated mice

This study investigated the effect of isoflavone aglycone (IA) on the learning and memory performance of senescence-accelerated mice, and explored its neural protective mechanism. Results showed that SAM-P/8 senescence-accelerated mice treated with IA performed significantly better in the Y-maze cognitive test than the no treatment control (P<0.05). The cortex AchE activity, serum SOD and GSH-Px activities were notably higher (P<0.05). MDA concentration and the β-secretase activity in the hippocampal tissue were both lower (P<0.05). Additionally, the number of hippocampal neurons was increased and cell morphology was significantly improved. Data suggested that IA could indirectly increase concentration of the cholinergic neural transmitter Ach through regulation of AchE, therefore improving the central cholinergic function and enhancing the learning and memory ability. By reducing the β-secretase activity, IA could decrease the formation and deposition of insoluble Adebris, relieve the resulted toxicity and damage to neurons, and thereby effectively protect the nervous system.     

Repetition blindness reveals differences between the representations of manipulable and nonmanipulable objects

We used repetition blindness to investigate the nature of the representations underlying identification of manipulable objects. Observers named objects presented in rapid serial visual presentation streams containing either manipulable or nonmanipulable objects. In half the streams, 1 object was repeated. Overall accuracy was lower when streams contained 2 different manipulable objects than when they contained only nonmanipulable objects or a single manipulable object. In addition, nonmanipulable objects induced repetition blindness, whereas manipulable objects were associated with a repetition advantage. These findings suggest that motor information plays a direct role in object identification. Manipulable objects are vulnerable to interference from other objects associated with conflicting motor programs, but they show better individuation of repeated objects associated with the same action. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

儿童的模仿和语言发展

某些关于儿童语言获得研究者认为,模仿与言语获得没有关系(Slobin,1967).早在六十年代,不少人研究了儿童直接模仿成人句子的效果(Brown,Bellugi,1964;Cazden1965).他们认为,尽管模仿在儿童语音、新词语的获得和习惯语表达方面起着重要作用,但是,并不能说明模仿在儿童句法获得中起作用.Slobin(1967)指出,在某种情况下,儿童能对成人的句子正确地模仿,只是能模仿的这些句子比儿童自发的句子(Spontaneous sentences)稍长或稍复杂些.我们认为,这种模仿能加强儿童的句法能力,因此有利于儿童下一阶段句法能力的发展.近些年来,Bloom,Hood和Lightbown(1974)提供了儿童早期言语发展的证据,表明有模仿倾向的儿童似乎是通过模仿来掌握新的语义句法关系以及新的词汇、习语.有模仿倾向的儿童在语气材料和上下文知识的处理中是积极的.这些研究涉及到句法,也涉及到发展方面的作用.     

Young adults with severe congenital hypothyroidism: cognitive event related potentials (ERPs) and the significance of an early start of thyroxine treatment

Congenital hypothyroidism (CH) has devastating effects upon brain development if left untreated. Despite early start of thyroxine treatment, patients still show subtle cognitive deficits compared to controls. We aimed to study auditory event related potentials (ERPs) in young CH adults (N = 12) to verify previous reports of normal attention functions measured by P3 in CH children. We also include ERP components (P1, N1, P2) allowing assessment of a wider range of auditory processing functions. No significant change in P3 latency or amplitude was found in the CH group, but a more subtle change in amplitude topography. A later start of thyroxine treatment was related to increased P3 latency and reduced amplitude. Group differences were found in early ERP components tapping sensory processing, sensory gating and selective attention. The results suggest persisting abnormalities in auditory processing and selective attention that may have influenced cognitive development.     

The influence of learning style and cognitive ability on recall of names and faces in an older population

The present study examined whether, for older adults, a verbal or imagery cognitive style is associated with recall of names and faces learned in an experimental condition. Cognitive abilities that are represented in current models of face recognition and name recall were also examined. Those abilities included picture naming, verbal fluency (i.e., naming items within a given category), vocabulary comprehension, visual memory, and the learning of unassociated word pairs. Fifty older adults attempted to learn first and last names of 20 student actors and actresses pictured on videotapes (40 names total). On average, participants learned the most first names, followed by last names, and the fewest full names. The greater the number of responses on a questionnaire associated with an imagery cognitive style, the more the names of faces were correctly identified by participants. There was no significant relationship between a verbal cognitive style and the number of names and faces recalled. As for cognitive abilities, all of the abilities measured--with the exception of vocabulary comprehension--were significantly associated with the number of names and faces learned. A regression analysis indicated that the best predictor of successful name-face learning was the participants' ability to learn and recall 5 unrelated word pairs. When that cognitive measure was deleted from the regression analysis, delayed visual memory and verbal fluency were the next best predictors of the older adults' ability to learn names and faces.