Preprogramming and control activity of bimanual self-paced motor task in Parkinson's disease

Upper extremity asymmetry due to nerve injuries or central neurologic conditions: a scoping review

BACKGROUND

Peripheral nerve injuries and central neurologic conditions can result in extensive disabilities. In cases with unilateral impairment, assessing the asymmetry between the upper extremity has been used to assess outcomes of treatment and severity of injury. A wide variety of validated and novel tests and sensors have been utilized to determine the upper extremity asymmetry. The purpose of this article is to review the literature and define the current state of the art for describing upper extremity asymmetry in patients with peripheral nerve injuries or central neurologic conditions.

METHOD

An electronic literature search of PubMed, Scopus, Web of Science, OVID was performed for publications between 2000 to 2022. Eligibility criteria were subjects with neurological conditions/injuries who were analyzed for dissimilarities in use between the upper extremities. Data related to study population, target condition/injury, types of tests performed, sensors used, real-world data collection, outcome measures of interest, and results of the study were extracted. Sackett's Level of Evidence was used to judge the quality of the articles.

RESULTS

Of the 7281 unique articles, 112 articles met the inclusion criteria for the review. Eight target conditions/injuries were identified (Brachial Plexus Injury, Cerebral Palsy, Multiple Sclerosis, Parkinson's Disease, Peripheral Nerve Injury, Spinal Cord Injury, Schizophrenia, and stroke). The tests performed were classified into thirteen categories based on the nature of the test and data collected. The general results related to upper extremity asymmetry were listed for all the reviewed articles. Stroke was the most studied condition, followed by cerebral palsy, with kinematics and strength measurement tests being the most frequently used tests. Studies with a level of evidence level II and III increased between 2000 and 2021. The use of real-world evidence-based data, and objective data collection tests also increased in the same period.

CONCLUSION

Adequately powered randomized controlled trials should be used to study upper extremity asymmetry. Neurological conditions other than stroke should be studied further. Upper extremity asymmetry should be measured using objective outcome measures like motion tracking and activity monitoring in the patient's daily living environment.

The psychophysiology of "covert" goal-directed behavior

Covert behavior is defined as behavior that is not directly visible and is thus comparable to a type of behavioral silence that requires modern psychophysiological techniques to reveal. Goal-directed behavior is teleologically purposive. Fundamentally, there are two approaches to accounting for purposeful behavior. One is the cybernetic approach, which views behavior as homeostatic and largely reflexive. The other one views behavior as a cognitive process that involves an interaction between neural events representing the previous experience, the present state of the individual, and the occurrence of particular features in the environment. This review, based on published data, presents a non-invasive psychophysiological method for investigating the electrical brain activity associated with those "silent" behaviors such as intention, evaluation of results, and memorization. Movement-related potentials (MRPs) are ideal for studying these processes. The MRPs are recorded during the execution of the skilled performance task (SPT). This task requires the execution of fast ballistic movements with the thumbs of both hands, learning a precise and short time interval between the two thumb presses, and scoring the highest number of target performances. The subject receives real-time feedback about the results of his performance. The MRPs associated with this task and present during covert behavior are the Bereitschaftspotential (BP) present before the onset of movement and the Skilled Performance Positivity (SPP) after movement, which coincides with the subject's awareness of the success or failure of his performance. These potentials show a maturational trend, reaching the adult form around the age of 10 when formal and abstract thinking progress. SPT and MRPs are particularly suitable to study neurodevelopmental disorders. Children with developmental dyslexia show abnormal MRPs, both in latency and amplitude, in different brain areas.

Effects of Parkinson disease and antiparkinson medication on central adaptations to repetitive grasping

Cortical activity during motor task performance is attenuated in individuals with Parkinson disease (PD) relative to age-matched adults without PD, and this activity is enhanced with antiparkinson medication. It remains unclear, however, whether the relative change in cortical activity over the duration of the task, i.e., central adaptation, is affected individuals with PD, and if so, whether medication corrects for any unique behaviors. Movement-related cortical potentials (MRCPs) were recorded from scalp electrode sites Cz and C1 during 150 repetitive handgrip contractions at 70% of maximal voluntary contraction, in individuals with PD (n = 10) both ON and OFF of their PD medication, and neurologically normal age- and sex-matched controls (n = 10). Repetitions were divided into two Blocks (Block 1 and 2: repetitions 1-60 and 91-150, respectively), and the composite MRCP slopes were calculated during periods representing movement initiation (-2 s to movement onset) and execution (movement onset to 1 s). No significant interactions were noted for either comparison (PD OFF vs. control; PD OFF vs. PD ON), irrespective of electrode site (Cz or C1) or movement period (initiation or execution). Despite similar MRCP slopes and task performance, PD OFF endorsed greater perceived exertion during task performance than controls. In the present study, we observed attenuated task-related cortical activity among individuals with PD OFF relative to controls, but a similar relative adaptive response to a fatiguing task. Additionally, although antiparkinson medication enhanced cortical activity (PD OFF vs. PD ON), central adaptation was similar.

Cortical Potentials Prior to Movement in Parkinson's Disease

INTRODUCTION

Recording cortical potentials prior to movement (bereitschaftspotentials, BP) offer a good non invasive method for studying activity of motor related cortices in Parkinson's Disease (PD). Dopaminergic medications provide some symptomatic relief in advanced stages but they do not stop the progression of the disease. Assessing BP may be a good idea to see the response of anti PD drugs. It remains unclear whether the anti PD medications also improve cortical activity prior to movement even in advanced stages of the disease.

AIM

In this study we recorded scalp BP in patients with varying grades of severity to study the relationship between disease severity and various components of BP.

MATERIALS AND METHODS

We successfully recorded BP at Cz, C3 and C4 sites during self-initiated 100 right wrist movements in 12 male patients with PD having severity Hoehn and Yahn (H&Y) scale 4 (PD3 group). These potentials were compared with age matched patients with H&Y scale 2 (PD1) and scale 3 (PD2) and also with age matched healthy controls.

RESULTS

We found flatter waveforms with increasing severity of disease. Amplitude is first to be affected in mild severity as compared to controls (p=0.011); while with increasing severity early as well as late part of potentials is affected. Such changes are prominently seen at Cz site across the groups.

CONCLUSION

These findings imply that there is increasing defect in cortical activity during movement especially in supplementary motor area with increasing severity in PD in spite of dopaminergic medications. This dynamic nature of dysfunction in supplementary motor cortices must be taken in account while treating advanced cases using newer stimulation techniques.

Inter-limb coupling during diadochokinesis in Parkinson's and Huntington's disease

Patients with neurodegenerative diseases often exhibit deficits in bimanual coordination. One characteristic of bimanual movements is inter-limb coupling. It is the property of motor performance harmonization between hands during a bimanual task. The objective of this study was to identify whether spatial and temporal inter-limb coupling occurred in Parkinson's disease (PD) and Huntington's disease (HD) patients. Twenty-three PD patients and 15 healthy controls were tested. Data from 12 choreic HD patients were also taken from a databank. Participants were asked to perform a unimanual and bimanual rapid repetitive diadochokinesis task. The difference between hands in mean amplitude and mean duration of cycles was computed in the unimanual and bimanual tasks for each group. Results show that healthy controls exhibited temporal and spatial inter-limb coupling during the bimanual diadochokinesis task. Conversely, PD and HD patients exhibited temporal inter-limb coupling; but failed to exhibit spatial inter-limb coupling during the bimanual diadochokinesis task. Furthermore, HD patients exhibited reduced levels of structural coupling compared to controls and PD patients. These results suggest that alterations in basal ganglia-thalamo-cortical networks due to PD and HD do not affect temporal inter-limb coupling. However, common pathophysiological changes related to PD and HD may cause altered spatial inter-limb coupling during a rapid repetitive bimanual diadochokinesis task.

Timing accuracy in self-timed movements related to neural indicators of movement initiation

Timely movement initiation is crucial in quick reactions or when a series of movements has to be strung together in a timed fashion to create a coordinated sequence. Stochastic neural variability can lead to misinitiation errors as reaction time studies suggest. Higher reaction times occur when preparatory neural activity reaches an initiation threshold later relative to shorter reaction times. Whether this also applies to self-timed movements is harder to scrutinize because they lack an external event that could serve as a reference for timing accuracy estimations. By example of a self-timed goal-oriented throwing task, we used a method that synchronizes the throwing movements by their kinematic profiles to assess relative timing differences in throwing release. We determined neural preparatory processes of the release using the movement-related electrophysiological Bereitschaftspotential (BP). By analyzing differences in shape and timing of the BP in delayed and non-delayed throws, two variables could be extracted that are related to timing differences on the kinematic level. First, temporal deviations in BP curves partly meet the kinematic deviations. Second, delayed releases were preceded by a short flattening of the BP curves prior to release. Thus, temporal and shape deviations in the neural movement initiation are assumed to delay self-timed movements.

Speech skill learning of persons who stutter and fluent speakers under single and dual task conditions

Two studies compared the accuracy and efficiency of initiating oral reading of nonsense syllables by persons who stutter (PWS) and fluent speakers (PNS) over practise. Findings of Study One, comparing 12 PWS and 12 PNS, replicated previous findings of slow speech sequence initiation over practise by PWS relative to PNS. In Study Two, nine PWS and eight PNS practised reading syllable sequences under single, and then dual task conditions in which a colour recognition distracter task was introduced. The speech sequences of PWS were initiated significantly slower than those of PNS. Significant GroupxCondition interactions for reaction time and accuracy were interpreted to suggest that PNS, but not PWS, demonstrated the ability to switch between an attention-demanding movement strategy under dual task conditions and a relatively automatic (little attention required) movement strategy after practise under single task conditions.

Sequence skill learning in persons who stutter: implications for cortico-striato-thalamo-cortical dysfunction

The basal ganglia and cortico-striato-thalamo-cortical connections are known to play a critical role in sequence skill learning and increasing automaticity over practice. The current paper reviews four studies comparing the sequence skill learning and the transition to automaticity of persons who stutter (PWS) and fluent speakers (PNS) over practice. Studies One and Two found PWS to have poor finger tap sequencing skill and nonsense syllable sequencing skill after practice, and on retention and transfer tests relative to PNS. Studies Three and Four found PWS to be significantly less accurate and/or significantly slower after practice on dual tasks requiring concurrent sequencing and colour recognition over practice relative to PNS. Evidence of PWS' deficits in sequence skill learning and automaticity development support the hypothesis that dysfunction in cortico-striato-thalamo-cortical connections may be one etiological component in the development and maintenance of stuttering.

EDUCATIONAL OBJECTIVES

As a result of this activity, the reader will: (1) be able to articulate the research regarding the basal ganglia system relating to sequence skill learning; (2) be able to summarize the research on stuttering with indications of sequence skill learning deficits; and (3) be able to discuss basal ganglia mechanisms with relevance for theory of stuttering.

Self-paced saccades and saccades to oddball targets in Parkinson's disease

Patients with Parkinson's disease (PD) manifest difficulty in initiation and execution of movements, particularly when movements are sequential, simultaneous or repetitive. Eye movements are particularly effective in evaluating motor impairments. We utilized a series of saccadic eye movement paradigms to explore the ability of 13 patients with mild-moderate PD and 13 age-matched healthy controls to self-pace saccades between two continuously illuminated targets, before and after an externally cued tracking period, and respond to unexpected changes in task demand. The latter was explored by measuring saccadic responses to unexpected "oddball" targets that appeared during a well-learned reciprocating sequence of saccades, in either the opposite direction to that expected or at twice the anticipated extent. Results indicated that all participants demonstrated a marked increase in saccade amplitudes from the externally cued saccade tracking to the self-paced saccades. Unexpectedly, this difference was magnified in PD patients. Self-paced saccades before externally cueing were also more frequent than requested in the PD group, but timing improved following external cueing. The second key finding was that while patients were able to respond to unexpected changes in target amplitude, performance was more variable (in terms of latency and accuracy) when responding to unexpected changes in target direction. Hence, beneficial effects of external cueing on the timing of self-paced saccades may be mediated through cortical regions, placing less emphasis on striatal regions known to be compromised in PD. Additionally, responding to changes in saccade direction (but not amplitude) may rely on basal ganglia circuitry.

Negative symptoms: A review of schizophrenia, melancholic depression and Parkinson's disease

Negative symptoms generally refer to a reduction in normal functioning. In schizophrenia they encompass apathy, anhedonia, flat affect, avolition, social withdrawal and, on some accounts, psychomotor retardation. Negative symptoms have been identified in other psychiatric disorders, including melancholic depression, and also in neurological disorders, such Parkinson's disease. Achieving a better understanding of negative symptoms constitutes a priority in mental health. Primarily, negative symptoms represent an unrelenting, intractable and disabling feature for patients, often amounting to a severe burden on families, carers and the patients themselves. Identifying and understanding subgroups within disorders may also contribute to the clinical care and scientific understanding of the pathophysiology of these disorders. The purpose of this paper is to review the current literature on negative symptoms in schizophrenia and explore the idea that negative symptoms may play an important role not only in other psychiatric disorders such as melancholic depression, but also in neurological disorders, such as Parkinson's disease. In each disorder negative symptoms manifest with similar motor and cognitive impairments and are associated with comparable neuropathological and biochemical findings, possibly reflecting analogous impairments in the functioning of frontostriatal-limbic circuits.

Prolonged practice is of scarce benefit in improving motor performance in Parkinson's disease

Many studies have addressed practice effects in motor sequences in Parkinson's disease (PD). Most studied short-term practice and showed that treated patients with mild-to-moderate disease achieve normal or slightly abnormal improvement. Less attention has focused on practice effects after prolonged training (days), and the results are inconclusive. Here, we studied the kinematic changes induced by prolonged practice in a group of medicated patients with mild-to-moderate PD and a healthy control group. We did so by analyzing an internally determined sequential arm movement performed as fast and accurately as possible before and after a 2-week training period. After 1-day's practice, movement duration, pause duration, and movement accuracy improved similarly in patients and controls, indicating that patients benefitted normally from short-term practice. After 1-week's practice, movement and pause duration improved further in both groups, whereas movement accuracy remained unchanged. After 2-weeks' practice, healthy controls continued to improve but patients did not, indicating reduced prolonged practice benefit in PD. Because short-term practice benefit on motor performance is thought to be mediated predominantly by cerebellar activation, whereas long-term practice benefit relies predominantly on the basal ganglia, we attribute our findings to the underlying basal ganglia dysfunction in PD. Our study may be relevant for planning and executing rehabilitation programs in these patients.

Malfunctions of Central Control of Movement Studied with Slow Brain Potentials in Neurological Patients

Abstract Studies are reviewed that used movement-related EEG potentials to investigate impairments of movement control in neurological patients. The EEG potentials reviewed are the Bereitschaftspotential (BP), Contingent Negative Variation (CNV), and components of the lateralized readiness potential (LRP). Patient groups included in this review are patients with infarction of the middle cerebral artery, Parkinson's disease, cerebellar disease, and amyotrophic lateral sclerosis. A rich body of evidence has been collected on Parkinson's disease, and somewhat less on cerebellar atrophy, contributing to an understanding of the impairments caused by these diseases. In contrast, not much research has been done in amyotrophic lateral sclerosis and in infarction patients. The latter is particularly striking since utility of this method for assessing residual capacities of affected motor areas seems rather obvious.

Motor preparation is more impaired in Parkinson's disease when sensorimotor integration is involved

OBJECTIVE

This study aimed to investigate changes in spatio-temporal, event-related (de)synchronization (ERD/ERS) patterns recorded with respect to the more akinetic versus the less akinetic side during performance of a visuo-guided targeting movement when compared to an index finger extension.

METHODS

Twelve de novo parkinsonian patients were recorded. ERD/ERS in mu and beta frequency bands was computed from 21 source derivations.

RESULTS

When the index finger extension was performed with the less akinetic limb, mu ERD focused over contralateral central region appeared 2 s before movement. With the targeting movement, additional pre-movement mu ERD was observed over the parietal region, as well as earlier ipsilateral mu ERD. When the same movements were performed with the more akinetic limb, we observed delayed mu ERD over contralateral regions, earlier ipsilateral mu ERD and a lack of contralateral parietal mu ERD before the targeting movement. Following index finger extension for the less akinetic limb, a focused contralateral central beta ERS was recorded, increasing and spreading after the targeting movement. In contrast, for the more akinetic limb, beta ERS was dramatically attenuated and remained unchanged after the targeting movement.

CONCLUSIONS

These results confirm the fact that motor programming is delayed, and provide some insight into what may well be impaired sensorimotor integration in Parkinson's disease.

L-dopa effects on preprogramming and control activity in a skilled motor act in Parkinson's disease

OBJECTIVES

The authors investigated whether preprogramming (Bereitschaftspotential, BP) and control activity (skilled performance positivity, SPP) in a bimanual, sequential skilled performance task (SPT) is sensitive to L-dopa administration in non-demented Parkinson's disease (PD) patients.

METHODS

Movement related potentials (MRPs) were recorded in 12 non-demented parkinsonian patients before and after acute L-dopa administration, and in 17 control subjects, all of whom were performing SPT for the first time. BP, SPP and correct performances were evaluated both as a grand average and in sequential blocks in order to verify the learning effect.

RESULTS

After L-dopa administration the PD patients scored a significantly higher percentage of correct performances (P<0.05), linked to a decreased BP amplitude (P<0.001) and an increased SPP amplitude (P<0.005), than before therapy. Dynamic evaluation through the block analysis did not show any learning effect in off-therapy patients but showed that L-dopa intake improved learning, linked to a BP amplitude decrease (P<0.005) and a SPP amplitude increase (P<0.05). Furthermore, L-dopa minimized differences in the learning trend between off-therapy PD patients and controls.

CONCLUSIONS

Our findings suggest that skilled motor learning is impaired in non-demented untreated PD patients. Dopaminergic drug administration seems to restore the ability of PD patients to use more automatic motor strategies, as demonstrated by the electrophysiological and behavioural pattern, which became more similar to that of normal subjects.

Bimanual coordination in Parkinson's disease: deficits in movement frequency, amplitude, and pattern switching

Six patients with idiopathic Parkinson's disease (PD) and six age-matched controls participated in a variety of rhythmic bimanual coordination tasks. The main goal of the task was to perform inphase or antiphase patterns of pronation and supination of the forearms at a specified tempo, and to switch from one pattern to the other upon presentation of a visual cue. The availability of advance information was varied to examine whether deficits would emerge under choice versus pre-cue constraints. In pre-cue conditions, the subjects knew in advance which hand would be cued to initiate pattern change. In choice conditions, the cued hand was not known until the imperative stimulus was presented. Overall, the PD patients made movements with significantly lower frequencies and smaller amplitudes relative to controls. Patients exhibited spontaneous pattern switching from antiphase to inphase at significantly lower movement frequencies than controls. During intentional switching trials, the control group was significantly faster at initiating pattern change. PD and control groups differed in the time to initiate pattern switching to a greater extent under choice conditions, suggesting that patients used advance information to increase the speed of their response. The control group exhibited a preference for spontaneous switching and intentional switching through the subdominant hand. Patients exhibited a switching preference using the impaired limb (whether or not it was subdominant). The control group made more correct responses when the subdominant side was either pre-cued or presented in choice conditions. The patients maintained the subdominant/impaired side advantage under pre-cue conditions but not choice. In the maintenance of rhythmic movement, individuals with PD were able to use advance information in terms of both speed and accuracy.

Effects of high frequency repetitive transcranial magnetic stimulation on P(300) event-related potentials

OBJECTIVE

Auditory event-related potentials (P(300)-ERPs) were analyzed before and after repetitive transcranial magnetic stimulation (rTMS).

METHODS

Two rTMS trains (10 Hz, 3 s, 100% motor threshold and 5 min interval) were delivered over the left frontal area in healthy subjects. P(300)-ERPs were recorded at 14 electrode sites on the scalp using a typical oddball paradigm before and after rTMS. The latencies and amplitudes of N(100), P(200), N(200) and P(300) were measured and compared. The directed coherence (DCOH) was estimated to demonstrate information flow between different cortical areas.

RESULTS

rTMS significantly influenced P(300)-ERPs. The effects differed on the different components (P<0.001). The latency of P(300) significantly increased after stimulation, which was more obvious in the frontal and central areas. The changes in P(300) amplitude were not significant (P>0.05). The DCOH from the frontal, central, parietal and occipital areas to the temporal area was significantly higher than the DCOH from the temporal area to the former 4 areas (P<0.01).

CONCLUSIONS

rTMS with the present parameters can affect P(300)-ERPs, leading to a delayed P(300) component and changes in information connections around the stimulated site. Our data suggest that rTMS may postpone neuronal activities related to cognitive processing.