Pain Characteristics and Their Relationship With Motor Dysfunction in Individuals With Parkinson Disease-A Cross-Sectional Study.

BACKGROUND: Pain is a common symptom in Parkinson disease (PD). OBJECTIVES: To analyze the relationship between pain and motor dysfunction in individuals with PD. METHODS: Fifty-four individuals with PD were screened: Hoehn and Yahr scale score = 2.5 (1 to 4); median (range) age in the "on" period of anti-Parkinson medication was 66 (44 to 85) years. Pain was assessed using King's Parkinson's Disease Pain Scale (KPPS) and the Brief Pain Inventory (BPI). Performance in routine activities and motor function were assessed using Unified Parkinson Disease Rating Scale (UPDRS II and III); gait was assessed using the Dynamic Gait Index; and balance was assessed using the Mini-BESTest. RESULTS: Thirty-eight participants (70.3%) reported mild to moderate pain. A positive correlation was found between the total KPPS score and performance in general activities (UPDRS II) (rho = 0.29, P = 0.04); a negative correlation was found between pain intensity (BPI intensity) and motor function (UPDRS III; rho = -0.28, P = 0.04); and a negative correlation was found between pain intensity (BPI intensity) and the bradykinesia subscore of the UPDRS III (rho = -0.29, P = 0.04). There was no correlation between pain and gait performance or balance. The musculoskeletal pain was the predominant type (in 81.5% of subjects), followed by nocturnal pain (52.6%) and fluctuation-related pain (47.3%). The most painful areas were lower limbs (33.0%) and shoulders/cervical area (31.0%). Twenty-one of 38 participants (55.3%) reported pain interference in their working and walking ability and general activities. CONCLUSIONS: Pain was weakly correlated with performance in general activities and with bradykinesia but was not correlated with the remaining classic motor PD symptoms, either gait or balance performance. Pain was a prevalent symptom in the present sample, and the individuals reported its interference with functionality.

Perspective-taking in blindness: electrophysiological evidence of altered action representations.

It is well established that the mental simulation of actions involves visual and/or somatomotor representations of those imagined actions. To investigate whether the total absence of vision affects the brain activity associated with the retrieval of motor representations, we recorded the readiness potential (RP), a marker of motor preparation preceding the execution, as well as the motor imagery of the right middle-finger extension in the first-person (1P; imagining oneself performing the movement) and in the third-person (3P; imagining the experimenter performing the movement) modes in 19 sighted and 10 congenitally blind subjects. Our main result was found for the single RP slope values at the Cz channel (likely corresponding to the supplementary motor area). No difference in RP slope was found between 1P and 3P in the sighted group, suggesting that similar motor preparation networks are recruited to simulate our own and other people's actions in spite of explicit instructions to perform the task in 1P or 3P. Conversely, reduced RP slopes in 3P compared with 1P found in the blind group indicated that they might have used an alternative, nonmotor strategy to perform the task in 3P. Moreover, movement imagery ability, assessed both by means of mental chronometry and a modified version of the Movement Imagery Questionnaire-Revised, indicated that blind and sighted individuals had similar motor imagery performance. Taken together, these results suggest that complete visual loss early in life modifies the brain networks that associate with others' action representations.

Partial Body Weight-Supported Treadmill Training in Spinocerebellar Ataxia.

BACKGROUND AND PURPOSE: The motor impairments related to gait and balance have a huge impact on the life of individuals with spinocerebellar ataxia (SCA). Here, the aim was to assess the possibility of retraining gait, improving cardiopulmonary capacity, and challenging balance during gait in SCA using a partial body weight support (BWS) and a treadmill. Also, the effects of this training over functionality and quality of life were investigated. METHODS: Eight SCA patients were engaged in the first stage of the study that focused on gait training and cardiovascular conditioning. From those, five took part in a second stage of the study centered on dynamic balance training during gait. The first and second stages lasted 8 and 10 weeks, respectively, both comprising sessions of 50 min (2 times per week). RESULTS: The results showed that gait training using partial BWS significantly increased gait performance, treadmill inclination, duration of exercise, and cardiopulmonary capacity in individuals with SCA. After the second stage, balance improvements were also found. CONCLUSION: Combining gait training and challenging tasks to the postural control system in SCA individuals is viable, well tolerated by patients with SCA, and resulted in changes in capacity for walking and balance.

Corticospinal excitability preceding the grasping of emotion-laden stimuli.

Evolutionary theories posit that emotions prime organisms for action. This study examined whether corticospinal excitability (CSE) is modulated by the emotional valence of a to-be-grasped stimulus. CSE was estimated based on the amplitude of motor evoked potentials (MEPs) elicited using transcranial magnetic stimulation (TMS) and recorded on the first dorsal interosseous (FDI) muscle. Participants were instructed to grasp (ACTION condition) or just look at (NO-ACTION condition) unpleasant, pleasant and neutral stimuli. TMS pulses were applied randomly at 500 or 250 ms before a go signal. MEP amplitudes were normalized within condition by computing a ratio for the emotion-laden stimuli by reference to the neutral stimuli. A divergent valence effect was observed in the ACTION condition, where the CSE ratio was higher during the preparation to grasp unpleasant compared to pleasant stimuli. In addition, the CSE ratio was lower for pleasant stimuli during the ACTION condition compared to the NO-ACTION condition. Altogether, these results indicate that motor preparation is selectively modulated by the valence of the stimulus to be grasped. The lower CSE for pleasant stimuli may result from the need to refrain from executing an imminent action.

Preparing to grasp emotionally laden stimuli.

BACKGROUND: Contemporary theories of motor control propose that motor planning involves the prediction of the consequences of actions. These predictions include the associated costs as well as the rewarding nature of movements' outcomes. Within the estimation of these costs and rewards would lie the valence, that is, the pleasantness or unpleasantness of a given stimulus with which one is about to interact. The aim of this study was to test if motor preparation encompasses valence. METHODOLOGY/PRINCIPAL FINDINGS: The readiness potential, an electrophysiological marker of motor preparation, was recorded before the grasping of pleasant, neutral and unpleasant stimuli. Items used were balanced in weight and placed inside transparent cylinders to prompt a similar grip among trials. Compared with neutral stimuli, the grasping of pleasant stimuli was preceded by a readiness potential of lower amplitude, whereas that of unpleasant stimuli was associated with a readiness potential of higher amplitude. CONCLUSIONS/SIGNIFICANCE: We show for the first time that the sensorimotor cortex activity preceding the grasping of a stimulus is affected by its valence. Smaller readiness potential amplitudes found for pleasant stimuli could imply in the recruitment of pre-set motor repertoires, whereas higher amplitudes found for unpleasant stimuli would emerge from a discrepancy between the required action and their aversiveness. Our results indicate that the prediction of action outcomes encompasses an estimate of the valence of a stimulus with which one is about to interact.