Characterising Upper Limb Movements in Huntington's Disease and the Impact of Restricted Visual Cues

Action impulsivity and attention deficits in patients at an early stage of Huntington disease

Huntington's disease (HD) is characterized by a combination of motor, cognitive, and neuropsychiatric impairments. Among them, impulsivity and attention deficits are clinical features usually described in HD, impacting the quality of life of patients and their caregivers. Twenty early-stage HD patients (PHD) and 20 age and gender-matched control participants (CP) performed a "Simon" reaction time (RT) task allowing us to explore action impulsivity and attention deficits. Surface EMG recordings aimed at revealing the presence and characterizing the nature of impulsivity in PHD. Correlational analyses between error rates or chronometric data, and clinical or neuropsychological data were examined. (1) Analysis of the accuracy and EMG patterns revealed no difference between PHD and CP, indicating absence of motor impulsivity at the early stage of HD. (2) Chronometric indices revealed a general slowing of information processing in PHD, involving central information processing but sparing the latest stages of motor execution, consistent with performed correlational analysis. (3) Sequential analysis of RT patterns showed a failure to allocate attention appropriately. These indices of attentional deficits nicely correlated with performance in neuropsychological tests exploring attentional processes. (1) Central information processing slows down at the early stage of HD but the latest steps of motor execution are unaffected. (2) In the progression of HD, attentional deficits typically should appear first among dysexecutive problems, without significant action impulsivity.

Impact of Upper Limb Function on Activities of Daily Living and Quality of Life in Huntington's Disease

Background/Objectives: Huntington's disease (HD) is a neurodegenerative movement disorder associated with significant disability and impairment of Activities of Daily Living (ADLs). The impact of upper limb disability on quality of life (QoL) and its influence on ADLs is not well known yet. The aim of this study was to describe the manipulative dexterity, strength, and manual eye coordination of patients with manifest and premanifest-HD compared to healthy individuals and to analyze its influence on ADLs and QoL. Methods: We performed an observational, cross-sectional study including 71 ambulatory participants (27 manifest-HD patients, 15 premanifest-HD, and 29 controls). We gathered sociodemographic data, as well as clinical data, including cognition (MMSE), HD motor severity (Unified HD rating scale, UHDRS-TMS), QoL (Neuro-QoL), and ADLs (HD-ADL). Hand dexterity and strength in the dominant and non-dominant hand were assessed with the Nine Hole Peg Test, Ten Neurotest, Nut and Bolt Test, dynamometry, and Late-Life FDI. Analysis of covariance (ANCOVA) models were performed to investigate differences in hand function between manifest-HD, premanifest-HD, and controls. Results: Manifest-HD patients had significantly worse performance in manual and finger dexterity, fine-motor coordination, and poorer handgrip strength than premanifest-HD and controls. Premanifest-HD required more time to complete the test than controls. Significant correlations were found between hand variables and Late-Life FDI, Neuro-QoL, HD-ADL, and UHDRS-TMS. Conclusions: HD affects manipulative dexterity and hand function in premanifest and manifest patients. Therefore, to prevent disability and decreased QoL, evaluating the progression of upper limb dysfunction in HD is important to offer the best possible therapeutic interventions.

Evaluation of motor capacity and neuromotor control for tapping and sliding movements reveals differences in visuomotor control

The Fitts' task is a simple and effective method for evaluating motor capacity that can be used to reveal detailed aspects of visuomotor control when hand and eye kinematics are recorded simultaneously. With advances in technology, the classical Fitts' reciprocal tapping task was modified for use with digitizer tablets and computer screens that require sliding rather than tapping hand movements, which may rely on different visuomotor control strategies. Given the ubiquity of digital devices and touchscreens that often require execution of sliding movements, it is important to compare the underlying visuomotor control and eye-hand coordination involved in reciprocal sliding and tapping movements, which was the aim of the current study. Twelve young adults performed both tasks while their hand and eye movements were recorded. Results revealed motor capacity was significantly higher (p < 0.0001, d = 2.67) in the tapping task (19.62 ± 5.89 bits/s) compared to the sliding task (7.87 ± 2.02 bits/s). Examining hand kinematics showed the deceleration interval was significantly longer in the sliding compared to the tapping task at the lowest task difficulty (ID 2.28: 0.160 s ± 0.026 vs 0.129 s ± 0.017; p < 0.01), which was exacerbated as task difficulty increased (ID 6.97: 0.355 s ± 0.059 vs 0.226 s ± 0.020, p < 0.0001), indicating greater reliance on visual feedback during the sliding task. Examining temporal eye-hand coordination pattern showed that hand movement initiation tended to precede eye movement in both tasks. Overall, the results of this study provide a comprehensive examination of eye and hand kinematics demonstrating salient differences in visuomotor control between tapping and sliding movements. The findings also reveal a novel insight into the temporal pattern of eye-hand coordination for reciprocal tapping and sliding movements, which is in contrast to previous studies that examined discrete (rather than reciprocal) target-directed pointing movements where the eyes typically precede the hand by approximately 100 ms. In conclusion, the current study revealed substantial differences between the two tasks, one major finding being the sliding movements were performed slower compared to parabolic tapping hand movements, which may have implications for designing interactive digital devices and assessment of eye-hand coordination.

Influence of aging, disease, exercise, and injury on human hand movements: A systematic review

The human hand is a versatile organ that performs a variety of activities in daily life. The coordination of digits allows them to deal with objects of various sizes and shapes with an appropriate range of motions (ROM). A systematic literature review was performed to identify the clinical and non-clinical factors which affected the normal ROM, grip strength (GS), and dexterity of hand. The overall outcomes of the systematic review showed that: the performance of the individual declined as the age progressed; the performance of the dominant hand (DH) of an individual was better compared to his/her non-dominant hand (NDH); the tasks performed by a healthy hand was more efficient compared to a diseased one; appropriate rehabilitation programs/exercise techniques after a disease or injury improved the ROM, GS, and dexterity of hand post-surgery on par to a healthy hand.

Dual Task Effects on Speed and Accuracy During Cognitive and Upper Limb Motor Tasks in Adults With Stroke Hemiparesis

Background

Adults with stroke need to perform cognitive-motor dual tasks during their day-to-day activities. However, they face several challenges owing to their impaired motor and cognitive functions.

Objective

This case-controlled pilot study investigates the speed and accuracy tradeoffs in adults with stroke while performing cognitive-upper limb motor dual tasks.

Methods

Ten adults with stroke and seven similar-aged controls participated in this study. The participants used a robotic arm for the single motor task and participated in either the serial sevens (S7) or the controlled oral word association test (COWAT) for single-cognitive task. For the dual task, the participants performed the motor and cognitive components simultaneously. Their speed and accuracy were measured for the motor and cognitive tasks, respectively.

Results

Two-sample t-statistics indicated that the participants with stroke exhibited a lower motor accuracy in the cross task than in the circle task. The cognitive speed and motor accuracy registered by the subjects with stroke in the dual task significantly decreased. There was a negative linear correlation between motor speed and accuracy in the subjects with stroke when the COWAT task was performed in conjunction with the cross task (ρ = -0.6922, p = 0.0388).

Conclusions

This study proves the existence of cognitive-upper limb motor interference in adults with stroke while performing dual tasks, based on the observation that their performance during one or both dual tasks deteriorated compared to that during the single task. Both speed and accuracy were complementary parameters that may indicate clinical effectiveness in motor and cognitive outcomes in individuals with stroke.

CRISPR Genome Editing Technology and its Application in Genetic Diseases: A Review

Gene therapy has been a long lasting goal for scientists, and there are many optimal methods and tools to correct disease-causing mutations in humans. Recently, the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) technology has been progressively adopted for the assessment a treatment of human diseases, including thalassemia, Parkinson's disease, cystic fibrosis, glaucoma, Huntington's disease, and Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS). CRISPR sequences belong to the bacterial immune system, which includes the nuclease Cas enzyme and an RNA sequence. The RNA sequence is unique and pathogen-specific, and identifies and binds to the DNA of invasive viruses, allowing the nuclease Cas enzyme to cut the identified DNA and destroy the invasive viruses. This feature provides the possibility to edit mutations in the DNA sequence of live cells by replacing a specific targeted RNA sequence with the RNA sequence in the CRISPR system. Previous studies have reported the improvement steps in confrontation with human diseases caused by single-nucleotide mutations using this system. In this review, we first introduce CRISPR and its functions and then elaborate on the use of CRISPR in the treatment of human diseases.

Rethinking Functional Outcome Measures: The Development of a Novel Upper Limb Token Transfer Test to Assess Basal Ganglia Dysfunction

The basal ganglia are implicated in a wide range of motor, cognitive and behavioral activities required for normal function. This region is predominantly affected in Huntington's disease (HD), meaning that functional ability progressively worsens. However, functional outcome measures for HD, particularly those for the upper limb, are limited meaning there is an imperative for well-defined, quantitative measures. Here we describe the development and evaluation of the Moneybox test (MBT). This novel, functional upper limb assessment was developed in accordance with translational neuroscience and physiological principles for people with a broad disease manifestation, such as HD. Participants with HD (n = 64) and healthy controls (n = 21) performed the MBT, which required subjects to transfer tokens into a container in order of size (Baseline Transfer), value (Complex Transfer) with and without reciting the alphabet (Dual Transfer). Disease specific measures of motor, cognition, behavior, and function were collected. HD patients were grouped into disease stage, from which, discriminative and convergent validity was assessed using Analysis of Variance and Pearson's correlation respectively. Manifest HD participants were slower than pre-manifest and control participants, and achieved significantly lower MBT total scores. Performance in the Complex Transfer and Dual Transfer tasks were significantly different between pre-manifest and stage 1 HD. All MBT performance variables significantly correlated with routinely used measures of motor, cognition, behavior, and function. The MBT provides a valid, sensitive, and affordable functional outcome measure. Unlike current assessments, MBT performance significantly distinguished the subtle differences between the earliest disease stages of HD, which are the populations typically targeted in clinical trials.