Effects of internal clock and memory disorders on duration reproductions and duration productions in patients with Parkinson's disease

Patients with Parkinson's disease (PD) exhibit deficits in perceptual and motor timing as well as impairments in memory and attentional processes that are related to dysfunction of dopaminergic systems in the basal ganglia. The aim of the present study was to assess the relationships existing between impaired duration judgments and defective memory and attention in PD patients. We compared time performance of medicated PD patients and control subjects on a duration reproduction task that is highly memory-dependent, and on a duration production task that could reveal effects of changes in the speed of internal time-keeping mechanisms. Each task was performed in a control counting condition and in a condition requiring divided attention between the temporal task and a concurrent reading task. Moreover, PD patients and control subjects were assessed on memory and attention using a battery of neuropsychological tests. The results revealed that in the concurrent reading condition of the reproduction task, duration judgments tended to be more variable in PD patients than in control subjects. Moreover, variability of duration reproductions was correlated with both measures of memory and of disease severity. In the concurrent reading condition of the production task, duration judgments were significantly shorter in PD patients than in control subjects, and accuracy of duration productions was correlated with scores on sub-tests of short-term memory. The findings suggest that the administration of dopamine did not entirely remove the memory deficits in PD patients. Moreover, DA treatment would have abnormally accelerated the rate of the internal clock leading to shorter duration productions in PD patients. The whole results indicate that dopamine administration in patients might have overshadowed the slowing rate of the internal clock usually reported in non medicated PD patients, without entirely restoring all of the memory functions.     

Age and prospective memory

This paper reports an investigation into the effects of age, intelligence, and retrospective memory on performance in a prospective memory task in which subjects aged between 52 and 95 were required to telephone once a day either between two times or at an exact time. The most important influence on performance was how subjects chose to remember to make the telephone calls. The best performance was from subjects who telephoned either in conjunction with another routine event or engaged in some form of advanced planning of the daily schedule. The worst performance was from those who relied on internal cues from their own memory. Performance was intermediate from those who used external cues such as notes or diary entries. Subjects in the between condition were less likely to choose internal cues than those in the exact condition, possibly because the task appeared more difficult, and this resulted in their showing superior performance. The effect of age was influenced by the cue used. For subjects using internal cues, those who forgot were older than those who remembered, whereas for subjects using the other cues, those who forgot were younger than those who remembered. Regardless of cue, self-ratings of cognitive failures were related to performance such that those who reported more minor everyday mistakes were indeed more likely to forget to telephone. While there was some indirect effect of general intelligence on performance in the task, there was no relationship between retrospective memory scores and whether or not subjects remembered to telephone.     

Decomposition of warning effects in Parkinson's disease

ABSTRACT

Neutral warning signals speed voluntary reactions by reducing temporal uncertainty and by triggering a brief burst of arousal. We attempted to isolate the phasic arousal mechanism in people with Parkinson's disease (PD) using a clock display to minimize temporal uncertainty. In this condition, the speeding of responses in a color-discrimination task by an accessory stimulus was the fully equivalent to the effect in age-matched control subjects. This indicates preserved phasic arousal in PD. Temporal preparation based on warning cues also appeared to be normal. By contrast, in a condition with high temporal uncertainty, the accessory stimulus (an air puff to the foot) impaired accuracy for the patients but not the neurologically normal subjects. The data are consistent with the view that PD disrupts internal but not external control of alertness.     

Decomposition of warning effects in Parkinson's disease

Neutral warning signals speed voluntary reactions by reducing temporal uncertainty and by triggering a brief burst of arousal. We attempted to isolate the phasic arousal mechanism in people with Parkinson's disease (PD) using a clock display to minimize temporal uncertainty. In this condition, the speeding of responses in a color-discrimination task by an accessory stimulus was the fully equivalent to the effect in age-matched control subjects. This indicates preserved phasic arousal in PD. Temporal preparation based on warning cues also appeared to be normal. By contrast, in a condition with high temporal uncertainty, the accessory stimulus (an air puff to the foot) impaired accuracy for the patients but not the neurologically normal subjects. The data are consistent with the view that PD disrupts internal but not external control of alertness.     

An fMRI study of temporal sequencing of motor regulation guided by an auditory cue—a comparison with visual guidance

The neuronal system to process and transfer auditory information to the higher motor areas was investigated using fMRI. Two different types of internal modulation of auditory pacing (1 Hz) were combined to design a 2×2 condition experiment, and the activation was compared with that under a visual guidance. The bilateral anterior portion of the BA22 (ant-BA22) and the left BA41/42 were more extensively activated by the combined modulation condition under the auditory cue than that under the visual cue. Among the four auditory conditions with or without the two types of internal modulation, the activation in the ant-BA22 was augmented only on the left side by the combined modulation condition. The left ant-BA22 may be especially involved in integrating the external auditory cue with internal modulation, while the activation on the right side did not depend on the complexity. The role of the left BA41/42 in motor regulation may be more specific to the processing of an auditory cue than that on the right side. These two areas in the left temporal lobe may be organized as a subsystem to handle the timing of complex movements under auditory cues, while the higher motor areas in the frontal lobe support both sensory modalities for the cue. This architecture may be considered as ‘audio-motor control’, which is similar to the visuo-motor control of the front-parietal network.     

Eye-Hand Coordination in Aging and in Parkinson’s Disease

Aiming movements to defined target positions were performed as fast and as accurately as possible by younger and older subjects and by patients in the early stages of Parkinson's disease (PD). Movement time and accuracy were tested in two conditions: with and without a centre cue. Older subjects exhibited slower movement time relative to the younger subjects only when the centre cue was present suggesting inefficient feedback processing. The performance of patients with PD was found to be as precise as that of older subjects. The movements of PD subjects, however, were slower in both conditions. Finally, the performance of subjects improved over trials. The data suggest that there is no difference in the nature of the control processes used by older and early-stage PD subjects, but that there is a reduction in the speed of these processes in PD.     

The impact of Parkinson's disease on sequence learning: perceptual pattern learning and executive function

The current study examined the contribution of brain areas affected by Parkinson's disease (PD) to sequence learning, with a specific focus on response-related processes, spatial attentional control, and executive functioning. Patients with mild PD, patients with moderate PD, and healthy age-matched participants performed three tasks-a sequence learning task with a spatial pattern that was incidental to response selection, a spatial cuing task, and neuropsychological tests of executive function. Whereas moderate PD patients failed to show significant sequence learning, mild PD patients performed comparably with controls. Neither group of PD patients was impaired in the control of spatial attention. Sequence learning was correlated with neuropsychological measures of executive function but not with the ability to control spatial attention. These results suggest that the contribution of the brain areas affected by PD to sequence learning extends beyond motor learning to include the learning of perceptual patterns and involves executive function, including cognitive flexibility and set shifting.     

Index to Volume 117

In some individuals, noise appears to have an adverse effect on memory recall. This decrement may result from a shift in the memory strategy being employed. Studies have shown memory strategies used by persons with an internal locus of control differ from those used by persons with an external locus of control. The present investigation asked subjects who were classified as either internal or external in locus of control to recall words presented under conditions of noise and of quiet. Word recall was aided by providing subjects with potential memory strategies. Each word list included words from meaningful content categories (which favor a semantic strategy) and word pairs that rhymed (which favor a perceptual strategy). Though internal and external subjects did not differ in total words recalled, they did differ in their use of strategies. Whereas internal subjects' strategies were unaffected by noise, external subjects decreased their use of the higher level semantic memory strategy (content categories) and increased their use of lower level perpetual (rhymes) strategy in the noise condition. The results are discussed in terms of a differential arousal hypothesis.     

Hemispheric visual atentional imbalance in patients with traumatic brain injury

We find a spatially asymmetric allocation of attention in patients with traumatic brain injury (TBI) despite the lack of obvious asymmetry in neurological indicators. Identification performance was measured for simple spatial patterns presented briefly to a locus 5 degrees into the left or right hemifield, after precuing attention to the same (ipsilateral) or opposite (cross-hemifield) side. Though the cue was non-predictive of target location overall, performance was significantly slower for cross than for ipsilateral trials in both patients and controls. We tested 21 TBI patients without overt focal brain damage and nine control subjects. Only patients demonstrated significantly worse performance for left side presentation in the ipsilateral condition. Furthermore, in the cross-hemifield condition, the left-right difference seen in TBI patients was significantly larger-reflecting a failure in producing a leftward attention shift. Again no significant difference was found in controls. These hemifield effects suggest an asymmetry in the ability of TBI patients in shifting attention to the left hemifield, whether from central fixation or from a cue in the contra-lateral hemifield. The results support basic hypotheses regarding visual attention: Attentional control may be asymmetric and attention may be a distributed, rather than localized cortical function.     

The impact of lesion laterality on neuropsychological change following posterior pallidotomy: a review of current findings

This paper reviews seven studies evaluating the impact of lesion laterality on the neuropsychological sequelae of posterior pallidotomy for treatment of Parkinson's disease. Left lesions of the internal globus pallidus (GPi) were associated with subtle deficits on measures sensitive to frontal lobe function. The findings of a randomized clinical trial including a patient control group indicated that many of these deficits were transient, resolving by 6 months following surgery. Right GPi lesions were not consistently associated with neuropsychological deficit, except in one study that included a significant proportion of demented patients. It is hypothesized that when neuropsychological decline is present following surgery, this reflects impingement of posterior GPi lesions into proximal regions such as anterior GPi or the external pallidum that participate in cognitive basal ganglia-thalamocortical circuits. The findings from neuroimaging will be important for elucidating the relationship between lesion locus and neuropsychological sequelae.     

The crucial role of postcue encoding in directed forgetting and context-dependent forgetting

People can intentionally forget previously studied material if, after study, a forget cue is provided and new material is learned. It has recently been suggested that such list-method directed forgetting arises because the forget cue induces a change in internal context and causes context-dependent forgetting of the studied material (L. Sahakyan & C. M. Kelley, 2002). The authors compared directed forgetting and context-dependent forgetting by examining whether, like a forget cue, a change in internal context needs subsequent learning of new material to be effective. Participants studied an item list and, after study, received a remember cue or a forget cue or their internal context was changed through an imagination task. In each condition, half the participants learned a second list, and the other half fulfilled an unrelated distractor task. Both the forget cue and the change in internal context induced forgetting of the first list only when learning of the second list was interpolated. These results suggest that postcue encoding of new material is crucial for both directed forgetting and (some forms of) context-dependent forgetting.     

Emotion and object processing in Parkinson’s disease

The neuropsychological literature on the processing of emotions in Parkinson’s disease (PD) reveals conflicting evidence about the role of the basal ganglia in the recognition of facial emotions. Hence, the present study had two objectives. One was to determine the extent to which the visual processing of emotions and objects differs in PD. The other was to assess the impact of cognitive load on the processing of these types of information. Thirty-one patients with idiopathic PD (IPD) under dopamine replacement therapy (DRT) were compared to 30 control subjects on emotion and object recognition tasks. Recognition of objects was more accurate and faster than recognition of facial expressions of emotion, for both groups of subjects. In a second experiment using an N-back procedure with the same stimuli—a more demanding task with a higher cognitive load—patients with IPD were as accurate as control subjects in detecting the correct sequential presentation of stimuli, but were much slower in their decision responses. This indicates that IPD patients under DRT are not impaired in encoding emotion or object information, but that they have difficulty with the processing demands of the N-back task. Thus, patients with IPD appear to be more sensitive to cognitive load than to type of information, whether facial emotions or objects. In this perspective, one must consider that a deafferented dopaminergic system has problems processing more complex information before one can posit the existence of deficits affecting a specific type of information.     

Evidence of Incomplete Motor Programming in Parkinson's Disease

One of the essential questions regarding movement deficits in Parkinson's disease (PD) is whether they stem from impaired selecting and switching among movements, impaired use of predictive information to prepare movement, or impaired execution of movement. PD subjects (n = 9) and age-matched control subjects (n = 8) performed a cued, sequential-response RT task. The cue provided either no information, accurate information, or inaccurate information about the upcoming response. PD subjects used predictive information to prepare and to switch among movement sequences normally, but second and third key press latencies were prolonged in comparison with the first key press latency. In Experiments 2 and 3, the effects of choice set and sequence length on key press latencies were examined. These results provide evidence that PD subjects initiate movement before the entire response sequence is prepared. PD does not impair motor programming or execution processes themselves but impairs the smooth coordination of those processes.     

Inescapable shock and attention to internal versus external cues in a water discrimination escape task

In these experiments we examined discrimination learning in a water escape task following exposure to escapable, yoked inescapable, or no electric shock. Inescapable shock did not have an effect on swim speeds in any of the experiments. Inescapable shock interfered with the acquisition of a position (left-right) discrimination when an irrelevant brightness cue (black and white stimuli) was present. However, inescapable shock did not affect the acquisition of the position discrimination when the irrelevant brightness cue was removed. Inescapably shocked subjects showed facilitated learning relative to escapably shocked and nonshocked subjects when the brightness cue was included as a relevant cue. These data may resolve discrepancies between studies that did, and did not, find inescapable shock to interfere with the acquisition of discriminations. Moreover, they point to attentional processes as one locus of the cognitive changes produced by inescapable shock and suggest that exposure to inescapable shock biases attention away from "internal" response-related cues toward "external" cues.     

The effect of informational stimuli on instrumental response rate: Signalling reward versus signalling the availability of reward

Rats were trained to press a lever for food on an interval schedule and were given a brief cue (0.5 sec) between the operative response and the reward (C condition). Some control subjects in Experiments 1, 2 and 4 were given their cue either following the end of the temporal interval during which reward had been unavailable (SD condition), or randomly with respect to food (R condition). Other control subjects in Experiments 2 and 4 received both the food-correlated cue and the temporal-interval stimulus (B condition). In all experiments, rate of responding was lowest for the C subjects and for B animals when the two cues were from different modalities. Food-correlated and temporal-interval cues did not interact, suggesting that a reward-correlated signal does not affect response rate simply by enhancing the salience of the temporal interval offset.     

阈下情绪面孔的注视线索提示效应

采用线索-靶子范式，利用2个预实验和1个正式实验，考察阈下不同情绪面孔的注视线索提示效应。要求被试在具有表情与注视线索的面孔呈现完毕后，快速而准确地对目标的位置进行判断。记录被试反应时间。结果显示，当被试未有意识的觉察到注视线索与面孔表情时，注视线索提示效应存在，并受到表情的调节。表现为：在注视线索有效并伴有恐惧表情时，被试对于目标的判断更加迅速；当比较不同表情下线索无效与线索有效条件下的反应时差异时发现，恐惧表情面孔出现时，线索无效与线索有效条件之间反应时的差异最大。结果表明，阈下情绪刺激能够激发个体更原始的生物性反应；在早期注意阶段，个体对于恐惧信息更加敏感，注意存在负向情绪偏差。     

Ability in perceiving nonnative contrasts: Performance on natural and synthetic speech stimuli

The perception of the distinction between /r/ and /l/ by native speakers of American English and of Japanese was studied using natural and synthetic speech. The American subjects were all nearly perfect at recognizing the natural speech sounds, whereas there was substantial variation among the Japanese subjects in their accuracy of recognizing /r/ and /l/ except in syllable-final position. A logit model, which additively combined the acoustic information conveyed byF1-transition duration and byF3-onset frequency, provided a good fit to the perception of synthetic /r/ and /l/ by the American subjects. There was substantial variation among the Japanese subjects in whether theF1 andF3 cues had a significant effect on their classifications of the synthetic speech. This variation was related to variation in accuracy of recognizing natural /r/ and /l/, such that greater use of both theF1 cue and theF3 cue in classifying the synthetic speech sounds was positively related to accuracy in recognizing the natural sounds. However, multiple regression showed that use of theF1 cue did not account for significant variance in natural speech performance beyond that accounted for by theF3 cue, indicating that theF3 cue is more important than theF1 cue for Japanese speakers learning English. The relation between performance on natural and synthetic speech also provides external validation of the logit model by showing that it predicts performance outside of the domain of data to which it was fit.     

Achievement and self-concept of students with learning disabilities

The internal/external frame of reference (I/E) model by Marsh (Am Educ Res J 23:129–149, 1986) assumes that, besides social comparisons with their classmates, students engage in intraindividual, dimensional comparisons, comparing their own achievement in one subject with their achievement in other subjects. These dimensional comparison processes are assumed to result in negative paths from achievement in one subject (e.g., math) to self-concept in another (e.g., the verbal domain). In a study with N = 270 students, we investigated the generalizability of the I/E model to students with learning disabilities. Analyses showed positive correlations between math and German achievement and positive effects of achievement in both subjects on the corresponding domain-specific self-concept. Verbal and math self-concepts were almost uncorrelated. Moreover, there were negative effects of achievement in one domain on self-concept in the other. Our results therefore indicate that the I/E model can be generalized to students with learning disabilities.     

Exploring the association of the Comprehensive Trail Making Test with driving indexes in patients with Parkinson’s disease

The Trail Making test (TMT) has been identified as predictor of driving ability in patients with Parkinson’s disease (PD). However, previous research has not explored the effectiveness of an alternative version of the TMT, namely of the Comprehensive Trail Making Test (CTMT; Reynolds, 2002) to show associations with measures related to driving fitness. Main objective of the current work was to evaluate the capacity of the CTMT to detect associations with fitness to drive related measures in patients with PD. Inclusion criteria were the presence of a valid driver’s license, regular car driving, a CDR score ≤ 0.5, and a Hoehn & Yahr score between 1 and 3. Twelve individuals with PD (Age: Mean = 63.75, SD = 10.50) and 12 cognitively intact individuals (Age: Mean = 63.50, SD = 10.43) were introduced in the study. Collection of data included a comprehensive neurological/neuropsychological assessment and a driving simulation experiment. Certain subtests of the CTMT were more strongly associated with a variety of driving indexes in individuals with PD as compared to the original TMT. In addition, according to the stepwise regression models that were applied, the CTMT was recognized as a more effective predictor of driving behavior than the TMT. The pattern of findings that was observed supports the usefulness of CTMT on detecting associations with fitness to drive related-measures in patients with PD. Underlying factors that may explain the effectiveness of the CTMT could be related to the greater variety of set shifting and inhibition processes that this alternative option integrates as compared to the original TMT.     

Evidence of Incomplete Motor Programming in Parkinson's Disease

One of the essential questions regarding movement deficits in Parkinson's disease (PD) is whether they stem from impaired selecting and switching among movements, impaired use of predictive information to prepare movement, or impaired execution of movement. PD subjects (n equals 9) and age-matched control subjects (n equals 8) performed a cued, sequential-response RT task. The cue provided either no information, accurate information, or inaccurate information about the upcoming response. PD subjects used predictive information to prepare and to switch among movement sequences normally, but second and third key press latencies were prolonged in comparison with the first key press latency. In Experiments 2 and 3, the effects of choice set and sequence length on key press latencies were examined. These results provide evidence that PD subjects initiate movement before the entire response sequence is prepared. PD does not impair motor programming or execution processes themselves but impairs the smooth coordination of those processes.