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Block Building Task Identifies Distinct Groups of Left/Right-hand Choice Patterns After Unilateral Peripheral Nerve Injury

Numerous methods exist to assess hand and arm function after upper extremity peripheral nerve injury, but peripheral injuries are often unilateral, and ...

Washington University School of Medicine

Penn State College of Medicine

Penn State University

The C3 region in the international 10-20 system for electroencephalography (EEG) recording is assumed to represent the right motor hand area. Therefore, in the absence of transcranial magnetic stimulation (TMS) or a neuronavigational system, neuromodulation methods, such as transcranial direct current stimulation, target C3 or C4, based on the international 10-20 system, to influence the cortical excitability of the right and left hand, respectively. The purpose of this study is to compare the peak-to-peak motor evoked potential (MEP) amplitudes of the right first dorsal interosseus (FDI) muscle after single-pulse TMS at C3 and C1 in the 10-20 system and at the region between C3 and C1 (i.e., C3h in the 10-5 system). Using an intensity of 110% of the resting motor threshold, 15 individual MEPs from each of C3, C3h, C1, and hotspots were randomly recorded from FDI for sixteen right-handed undergraduate students. Average MEPs were greatest at C3h and C1, with both being larger than those recorded at C3. These data are congruent with recent findings using topographic analysis of individual MRIs that revealed poor correspondence between C3/C4 and the respective hand knob. Implications for the use of scalp locations determined using the 10-20 system for localizing the hand area are highlighted.

C3 in the 10-20 system may not be the best target for the motor hand area.

Little is known about how peripheral nerve injury affects human performance, behavior, and life. Hand use choices are important for rehabilitation after unilateral impairment, but rarely measured, and are not changed by the normal course of rehabilitation and daily life.

Patient Outcomes After Peripheral Nerve Injury Depend on Bimanual Dexterity and Preserved Use of the Affected Hand.

Reach-to-grasp actions are fundamental to the daily activities of human life, but few methods exist to assess individuals' reaching and grasping actions in unconstrained environments. The Block Building Task (BBT) provides an opportunity to directly observe and quantify these actions, including left/right hand choices. Here we sought to investigate the motor and non-motor causes of left/right hand choices, and optimize the design of the BBT, by manipulating motor and non-motor difficulty in the BBT's unconstrained reach-to-grasp task. We hypothesized that greater motor and non-motor (e.g. cognitive/perceptual) difficulty would drive increased usage of the dominant hand. To test this hypothesis, we modulated block size (large vs. small) to influence motor difficulty, and model complexity (10 vs. 5 blocks per model) to influence non-motor difficulty, in healthy adults (n = 57). Our data revealed that increased motor and non-motor difficulty led to lower task performance (slower task speed), but participants only increased use of their dominant hand only under the most difficult combination of conditions: in other words, participants allowed their performance to degrade before changing hand choices, even though participants were instructed only to optimize performance. These results demonstrate that hand choices during reach-to grasp actions are more stable than motor performance in healthy right-handed adults, but tasks with multifaceted difficulties can drive individuals to rely more on their dominant hand.

Healthy adults favor stable left/right hand choices over performance at an unconstrained reach-to-grasp task.

 The role of IL-13 on the airway epithelium in severe asthma leading to airway remodeling remains poorly understood.  To study IL-13-induced airway remodeling on goblet cells and cilia in the airway epithelium in severe asthma and the impact of an anti-IL4Rα antibody, dupilumab, .  Quantitative computed tomography of the lungs and endobronchial biopsies and brushings were obtained in 51 participants (22 with severe asthma, 11 with nonsevere asthma, and 18 healthy participants) in SARPIII (Severe Asthma Research Program III) and measured for mucin and cilia-related proteins. Epithelial cells were differentiated at air-liquid interface (ALI) with IL-13 with or without dupilumab and assessed for mucin, cilia, cilia beat frequency (CBF), and epithelial integrity (transepithelial electrical resistance [TEER]).  Increased Muc5AC (mucin 5AC) (Δ + 263.2 ± 92.7 luminosity/epithelial area) and decreased ciliated cells (Δ - 0.07 ± 0.03 Foxj1 cells/epithelial area) were observed in biopsies from patients with severe asthma when compared with healthy control subjects ( < 0.01 and  = 0.047, respectively). RNA sequencing of endobronchial cell brushings confirmed a  increase with a decrease in a five-gene cilia-related mean in patients with severe asthma compared with healthy subjects (all  < 0.05). IL-13 (5 ng/ml)-differentiated ALI cultures of healthy and asthmatic samples (from participants with severe and nonsevere asthma) increased Muc5AC, decreased cilia (α-aceytl-tubulin) in samples from healthy participants (Δ + 6.5% ± 1.5%, Δ - 14.1% ± 2.7%; all  < 0.001 respectively) and participants with asthma (Δ + 4.4% ± 2.5%, Δ - 13.1% ± 2.7%;  = 0.084,  < 0.001 respectively), and decreased epithelial integrity (TEER) in samples from healthy participants (-140.9 ± 21.3 [ohms],  < 0.001), while decreasing CBF in samples from participants with asthma (Δ - 4.4 ± 1.7 [Hz],  < 0.01). When dupilumab was added to ALI with IL-13, there was no significant decrease in Mu5AC, but there was restoration of cilia in healthy participants and participants with asthma (absolute increase of 67.5% and 32.5% cilia, all  < 0.05, respectively), whereas CBF increased (Δ + 3.6 ± 1.1 [Hz],  < 0.001) and TEER decreased (only in asthma, Δ - 37.8 ± 16.2 [ohms],  < 0.05).  IL-13 drives features of airway remodeling in severe asthma, which are partially reversed by inhibiting the IL-4Rα receptor .

Increased Muc5AC and Decreased Ciliated Cells in Severe Asthma Partially Restored by Inhibition of IL-4Rα Receptor.

The primary motor cortex (M1) is crucial for motor skill learning. We examined its role in interleaved practice, which enhances retention (vs. repetitive practice) through M1-dependent consolidation. We hypothesized that cathodal transcranial direct current stimulation (ctDCS) to M1 would disrupt retention. We found that ctDCS reduced retention due to weakened encoding during acquisition, not disrupted consolidation. These results highlight M1's broad role in encoding and retention of novel motor skills.

Taewon Kim

Program in Occupational Therapy

Washington University School of Medicine

Block Building Task Identifies Distinct Groups of Left/Right-hand Choice Patterns After Unilateral Peripheral Nerve Injury

Taewon Kim

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Program in Occupational Therapy

Washington University School of Medicine

Block Building Task Identifies Distinct Groups of Left/Right-hand Choice Patterns After Unilateral Peripheral Nerve Injury

Program in Occupational Therapy