Brain Mechanism for Enhanced Hand Function with Remote Sensory Stimulation

The neurological bases for remote vibration enhanced sensory feedback and motor function are yet poorly understood. The purpose of this dissertation was to identify and examine the effect of vibration on finger tactile sensation in healthy adults and how imperceptible random vibration applied to the wrist changes cortical activity for fingertip sensation and precision grip. In a series of studies on healthy adults, white-noise vibration was applied to one of four locations (dorsum hand by the second knuckle, thenar and hypothenar areas, and volar wrist) at one of four intensities (zero, 60%, 80%, and 120% of the sensory threshold for each vibration location), while the fingertip sensation, the smallest vibratory signal that could be perceived on the thumb and index fingertip pads, was assessed. Vibration intensities significantly affected the fingertip sensation (p.01), all compared with the zero vibration condition. The next step was to examine the cortical activity for this vibration-enhanced fingertip sensation. We measured somatosensory evoked potentials to assess peak-to-peak response to light touch of the index fingertip with applied wrist vibration versus without. We observed increased peak-to-peak somatosensory evoked potentials with wrist vibration, especially with increased amplitude of the later component for the somatosensory, motor, and premotor cortex with wrist vibration. These findings corroborate an enhanced cortical-level sensory response motivated by vibration. It is possible that the cortical modulation observed here is the result of the establishment of transient networks for improved perception. Finally, we examined the effect of imperceptible vibration applied to the wrist on cortical control for precision grip. We measured β-band power to assess peak-to-peak response while subjects performed precision pinch with wrist vibration versus without. We observed increased peak-to-peak β-band power amplitude with wrist vibration, especially with event-related synchronization for the prefrontal, sensorimotor, motor, premotor, and supplementary motor areas with vibration. The enhanced motor function may possibly be a result of higher recalibration following movement and faster motor learning

Effect of Imperceptible Vibratory Noise Applied to Wrist Skin On Fingertip Touch Evoked Potentials – An EEG Study

Random vibration applied to skin can change the sense of touch. Specifically, low amplitude white-noise vibration can improve fingertip touch perception. In fact, fingertip touch sensation can improve even when imperceptible random vibration is applied to other remote upper extremity areas such as wrist, dorsum of the hand, or forearm. As such, vibration can be used to manipulate sensory feedback and improve dexterity, particularly during neurological rehabilitation. Nonetheless, the neurological bases for remote vibration enhanced sensory feedback are yet poorly understood. This study examined how imperceptible random vibration applied to the wrist changes cortical activity for fingertip sensation. We measured somatosensory evoked potentials to assess peak-to-peak response to light touch of the index fingertip with applied wrist vibration versus without. We observed increased peak-to-peak somatosensory evoked potentials with wrist vibration, especially with increased amplitude of the later component for the somatosensory, motor, and premotor cortex with wrist vibration. These findings corroborate an enhanced cortical-level sensory response motivated by vibration. It is possible that the cortical modulation observed here is the result of the establishment of transient networks for improved perception

A finite element analysis of the carpal arch with various locations of carpal tunnel release

ObjectiveThe purpose of this study was to investigate the effects of the location of transverse carpal ligament (TCL) transection on the biomechanical property of the carpal arch structure. It was hypothesized that carpal tunnel release would lead to an increase of the carpal arch compliance (CAC) in a location-dependent manner.MethodsA pseudo-3D finite element model of the volar carpal arch at the distal carpal tunnel was used to simulate arch area change under different intratunnel pressures (0–72 mmHg) after TCL transection at different locations along the transverse direction of the TCL.ResultsThe CAC of the intact carpal arch was 0.092 mm2/mmHg, and the simulated transections ranging from 8 mm ulnarly to 8 mm radially from the center point of the TCL led to increased CACs that were 2.6–3.7 times of that of the intact carpal arch. The CACs after radial transections were greater than those ulnarly transected carpal arches.ConclusionThe TCL transection in the radial region was biomechanically favorable in reducing carpal tunnel constraint for median nerve decompression

The effect of combining action observation in virtual reality with kinesthetic motor imagery on cortical activity

IntroductionIn the past, various techniques have been used to improve motor imagery (MI), such as immersive virtual-reality (VR) and kinesthetic rehearsal. While electroencephalography (EEG) has been used to study the differences in brain activity between VR-based action observation and kinesthetic motor imagery (KMI), there has been no investigation into their combined effect. Prior research has demonstrated that VR-based action observation can enhance MI by providing both visual information and embodiment, which is the perception of oneself as part of the observed entity. Additionally, KMI has been found to produce similar brain activity to physically performing a task. Therefore, we hypothesized that utilizing VR to offer an immersive visual scenario for action observation while participants performed kinesthetic motor imagery would significantly improve cortical activity related to MI.MethodsIn this study, 15 participants (9 male, 6 female) performed kinesthetic motor imagery of three hand tasks (drinking, wrist flexion-extension, and grabbing) both with and without VR-based action observation.ResultsOur results indicate that combining VR-based action observation with KMI enhances brain rhythmic patterns and provides better task differentiation compared to KMI without action observation.DiscussionThese findings suggest that using VR-based action observation alongside kinesthetic motor imagery can improve motor imagery performance

Applications of Brain-Computer Interface in Action Observation and Motor Imagery

Motor imagery (MI) and action observation (AO) are vital elements in brain-computer interface (BCI) applications. MI involves mentally simulating movements and physical execution, while AO involves observing others perform actions. Both activate crucial brain areas linked to movement, making them valuable for BCI-assisted motor rehabilitation. This chapter explores studies in sports, occupational therapy, and neurorehabilitation, focusing on combining AO and MI (AO + MI) in BCI applications. Results show the positive impact of AO + MI interventions on motor performance aspects such as imagery ability, reaction time, and muscle activation across various tasks. The fusion of virtual reality (VR) with MI proves potent in neurorehabilitation, especially in stroke and Parkinson’s disease rehab and cognitive enhancement. Additionally, VR-based AO combined with kinesthetic motor imagery (KMI) influences cortical activity, refining brain patterns and task performance. These findings suggest that combining VR-based action observation with KMI can significantly enhance BCI-assisted motor rehabilitation for individuals with motor deficits. This approach holds promise for improving motor control and fostering neuroplasticity

Sex-related differences in carpal arch morphology.

The purpose of this study was to investigate the sex-based differences in the carpal arch morphology. Carpal arch morphology was quantified using palmar bowing and area of the arch formed by the transverse carpal ligament. The carpal arch was imaged at the distal and proximal tunnel levels using ultrasonography in 20 healthy young adults (10 women and 10 men). It was found that females had a smaller carpal arch height compared to men at both distal and proximal levels (p<0.05) and smaller carpal arch width only at the proximal level (p<0.05) but not distally. Palmar bowing index, the carpal arch height to width ratio, was significantly smaller in females at the distal level (p<0.05) but not at the proximal level. Carpal arch cross-sectional area normalized to the wrist cross-sectional area was found to be significantly smaller in females at both tunnel levels compared to men (p<0.05). This study demonstrates that females have a smaller carpal arch compared to men with a reduced palmar bowing distally and a smaller arch area at both tunnel levels. The findings help explain the higher incidence of carpal tunnel syndrome in women as a smaller carpal arch makes the median nerve more vulnerable to compression neuropathy

Evaluation of EEG Oscillatory Patterns and Classification of Compound Limb Tactile Imagery

Objective: The purpose of this study was to investigate the cortical activity and digit classification performance during tactile imagery (TI) of a vibratory stimulus at the index, middle, and thumb digits within the left hand in healthy individuals. Furthermore, the cortical activities and classification performance of the compound TI were compared with similar compound motor imagery (MI) with the same digits as TI in the same subjects. Methods: Twelve healthy right-handed adults with no history of upper limb injury, musculoskeletal condition, or neurological disorder participated in the study. The study evaluated the event-related desynchronization (ERD) response and brain–computer interface (BCI) classification performance on discriminating between the digits in the left-hand during the imagery of vibrotactile stimuli to either the index, middle, or thumb finger pads for TI and while performing a motor activity with the same digits for MI. A supervised machine learning technique was applied to discriminate between the digits within the same given limb for both imagery conditions. Results: Both TI and MI exhibited similar patterns of ERD in the alpha and beta bands at the index, middle, and thumb digits within the left hand. While TI had significantly lower ERD for all three digits in both bands, the classification performance of TI-based BCI (77.74 ± 6.98%) was found to be similar to the MI-based BCI (78.36 ± 5.38%). Conclusions: The results of this study suggest that compound tactile imagery can be a viable alternative to MI for BCI classification. The study contributes to the growing body of evidence supporting the use of TI in BCI applications, and future research can build on this work to explore the potential of TI-based BCI for motor rehabilitation and the control of external devices

Feasibility and usability of a virtual-reality-based sensorimotor activation apparatus for carpal tunnel syndrome patients.

PurposeThis study aimed to assess the usability of a virtual reality-assisted sensorimotor activation (VRSMA) apparatus for individual digit rehabilitation. The study had two main objectives: Firstly, to collect preliminary data on the expectations and preferences of patients with carpal tunnel syndrome (CTS) regarding virtual reality (VR) and an apparatus-assisted therapy for their affected digits. Secondly, to evaluate the usability of the VRSMA apparatus that was developed.MethodsThe VRSMA system consists of an apparatus that provides sensory and motor stimulation via a vibratory motor and pressure sensor attached to a button, and a virtual reality-based visual cue provided by texts overlaid on top of a 3D model of a hand. The study involved 10 CTS patients who completed five blocks of VRSMA with their affected hand, with each block corresponding to the five digits. The patients were asked to complete a user expectations questionnaire before experiencing the VRSMA, and a user evaluation questionnaire after completing the VRSMA. Expectations for VRSMA were obtained from the questionnaire results using a House of Quality (HoQ) analysis.ResultsIn the survey for expectations, participants rated certain attributes as important for a rehabilitation device for CTS, with mean ratings above 4 for attributes such as ease of use, ease of understanding, motivation, and improvement of hand function based on clinical evidence. The level of immersion and an interesting rehabilitation regime received lower ratings, with mean ratings above 3.5. The survey evaluating VRSMA showed that the current prototype was overall satisfactory with a mean rating of 3.9 out of 5. Based on the HoQ matrix, the highest priority for development of the VRSMA was to enhance device comfort and usage time. This was followed by the need to perform more clinical studies to provide evidence of the efficacy of the VRSMA. Other technical characteristics, such as VRSMA content and device reliability, had lower priority scores.ConclusionThe current study presents a potential for an individual digit sensorimotor rehabilitation device that is well-liked by CTS patients

Developing a tablet-based brain-computer interface and robotic prototype for upper limb rehabilitation

Background The current study explores the integration of a motor imagery (MI)-based BCI system with robotic rehabilitation designed for upper limb function recovery in stroke patients. Methods We developed a tablet deployable BCI control of the virtual iTbot for ease of use. Twelve right-handed healthy adults participated in this study, which involved a novel BCI training approach incorporating tactile vibration stimulation during MI tasks. The experiment utilized EEG signals captured via a gel-free cap, processed through various stages including signal verification, training, and testing. The training involved MI tasks with concurrent vibrotactile stimulation, utilizing common spatial pattern (CSP) training and linear discriminant analysis (LDA) for signal classification. The testing stage introduced a real-time feedback system and a virtual game environment where participants controlled a virtual iTbot robot. Results Results showed varying accuracies in motor intention detection across participants, with an average true positive rate of 63.33% in classifying MI signals. Discussion The study highlights the potential of MI-based BCI in robotic rehabilitation, particularly in terms of engagement and personalization. The findings underscore the feasibility of BCI technology in rehabilitation and its potential use for stroke survivors with upper limb dysfunctions