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    Patterns of brain activity in choice or instructed go and no-go tasks
    (Springer Science and Business Media LLC, 2025-02-21)
    Sanaz Attaripour Isfahani
    ;
    Patrick McGurrin
    ;
    VIAL UNDURRAGA, FELIPE AGUSTIN  
    ;
    Mark Hallett
    The goal of this study was to investigate the decision making process for choosing what movements to make. We used electroencephalography (EEG) to investigate patterns of the contingent negative variation (CNV) associated with free-choice decisions to move or abstain, comparing them to conditions where actions were commanded. Our primary hypothesis was that choice tasks would differ significantly from each other and exhibit EEG patterns akin to their command-driven counterparts after the decisions were made, at least, in the 50 ms block of time prior to movement. A secondary analysis evaluated post hoc comparisons of time, in 50 ms blocks, to understand the temporal development of the CNV for each condition. We also conducted an exploratory analysis of EEG event-related desynchronization (ERD) to identify patterns of brain activity associated with the decision-making process. This approach was taken due to the exploratory nature of our hypotheses concerning the spatial and temporal characteristics of EEG activity during these free-choice versus commanded tasks. We studied 12 right-handed healthy volunteers (7 women, mean age 53 years, range 39–73 years) with no prior history of neurological or major psychiatric illness. A CNV paradigm encompassing commanded and choice tasks was devised, with a 2500 ms interval between S1 and S2, while recording EEG and electromyography (EMG). S1 provided full information about the upcoming task, which was to be executed at the time of S2. We assessed CNV and explored whole scalp EEG activity, including both voltage as well as power in the alpha and beta frequency ranges. Clear and similar CNVs were observed for command and choice go tasks prior to the movements, contrasting with near-zero CNVs for the command and choice no-go tasks. Separation of CNVs for command go and no-go tasks occurred around 1600 ms post-S1, and choice CNVs separated about 2150 ms post-S1. Exploratory analysis revealed that beta power provided information about decision and preparation processes much earlier. The left dorsolateral prefrontal cortex (DLPFC) exhibited the initial sign of decision approximately 500 ms post-S1 for all tasks, with subsequent preparation for movement or restraint involving distinct activity in various brain regions. The localization of effects in the left DLPFC was determined by visual analysis of the informative electrode sites. The CNVs separate about 2 s after S1, and it appears that this process represents preparation for movement (or no movement). Exploration of the beta activity suggests an earlier decision process which leads eventually to subsequent task preparation and activation. Choice decisions lag slightly behind command decisions, with the CNV apparently reflecting motor implementation rather than the decision-making process. In a simple motor task with an exploratory analysis, both commanded and choice-based decisions are rapidly initiated in the left DLPFC. While the CNV distinguishes between go and no-go conditions, it primarily appears to signify preparation for implementation of the task following the earlier decision. Further controlled studies will be needed to confirm these results.
    Scopus© Citations 3  1
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    Global Perceptions and Utilization of Clinical Neurophysiology in Movement Disorders
    (2024)
    Panagiotis Kassavetis
    ;
    Robert Chen
    ;
    Christos Ganos
    ;
    Mark Hallett
    ;
    Masashi Hamada
    <jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Clinical neurophysiology (CNP) involves the use of neurophysiological techniques to make an accurate clinical diagnosis, to quantify the severity, and to measure the treatment response. Despite several studies showing CNP to be a useful diagnostic tool in Movement Disorders (MD), its more widespread utilization in clinical practice has been limited.</jats:p></jats:sec><jats:sec><jats:title>Objectives</jats:title><jats:p>To better understand the current availability, global perceptions, and challenges for implementation of diagnostic CNP in the clinical practice of MD.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>The International Parkinson and Movement Disorders Society (IPMDS) formed a Task Force on CNP. The Task Force distributed an online survey via email to all the members of the IPMDS between August 5 and 30, 2021. Descriptive statistics were used for analysis of the survey results. Some results are presented by IPMDS geographical sections namely PanAmerican (PAS), European (ES), African (AFR), Asian and Oceanian (AOS).</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Four hundred and ninety‐one IPMDS members (52% males), from 196 countries, responded. The majority of responders from the AFR (65%) and PAS (63%) sections had no formal training in diagnostic CNP (40% for AOS and 37% for ES). The most commonly used techniques are electroencephalography (EEG) (72%) followed by surface EMG (71%). The majority of responders think that CNP is somewhat valuable or very valuable in the assessment of MD. All the sections identified “lack of training” as one of the biggest challenges for diagnostic CNP studies in MD.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>CNP is perceived to be a useful diagnostic tool in MD. Several challenges were identified that prevent widespread utilization of CNP in MD.</jats:p></jats:sec>
    Scopus© Citations 6  4
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    The Effect of Volitional Preemptive Abdominal Contraction on Biomechanical Measures During A Front Versus Back Loaded Barbell Squat
    (2023)
    Joseph B. McCormick
    ;
    Alexander S. Drusch
    ;
    Darragh J. Lynch
    ;
    Gesine H. Seeber
    ;
    Katherine F. Wilford
    <jats:sec id="background"> <jats:title>Background</jats:title> <jats:p>Weightlifting is growing in popularity among recreational and competitive athletes. The barbell back squat (BackS) is commonly included in these training programs, while the barbell front squat (FrontS) is commonly performed as a component of other lifts such as the power clean or clean and jerk, it is less commonly practiced in isolation.</jats:p> </jats:sec> <jats:sec id="hypothesispurpose"> <jats:title>Hypothesis/Purpose</jats:title> <jats:p>The purpose of this study was to examine the effects of VPAC performance on trunk muscle and LE biomechanical responses during loaded BackS versus FrontS in healthy subjects.</jats:p> </jats:sec> <jats:sec id="study-design"> <jats:title>Study Design</jats:title> <jats:p>Controlled Laboratory Study</jats:p> </jats:sec> <jats:sec id="methods"> <jats:title>Methods</jats:title> <jats:p>Healthy male subjects with the ability to perform a sub-maximal loaded barbell squat lift were recruited. Subjects completed informed consent, demographic/medical history questionnaires and an instructional video. Subjects practiced VPAC and received feedback. Surface electromyography (sEMG) electrodes and kinematic markers were applied. Muscles included were the internal oblique (IO), external oblique (EO), rectus abdominis, iliocostalis lumborum (ICL), superficial multifidi, rectus femoris, vastus lateralis, biceps femoris, and gluteus maximus. Maximal voluntary isometric contractions established reference sEMG values. A squat one-rep-max (1RM) was predicted by researchers using a three to five repetition maximum (3RM, 5RM) load protocol. Subjects performed BackS trials at 75% 1RM while FrontS trials were performed at 75% BackS weight, both with and without VPAC. Subjects performed three repetitions of each condition with feet positioned on two adjacent force plates. Significant interactions and main effects were tested using a 2(VPAC strategy) x 2(squat variation) and 2(VPAC strategy) x 2(direction) within-subject repeated measures ANOVAs. Tukey’s Post-Hoc tests identified the location of significant differences.</jats:p> </jats:sec> <jats:sec id="results"> <jats:title>Results</jats:title> <jats:p>Trunk muscle activity was significantly higher during FrontS versus BackS regardless of VPAC condition. (IO: p=0.018, EO: p&lt;0.001, ICL: p&lt;0.001) VPAC increased performance time for both squat variations (p=.0011), which may be associated with decreased detrimental force potential on the lumbar spine and knees. VPAC led to improved ability to maintain a neutral lumbar spine during both squat variations. This finding is associated with decreased detrimental force potential on the lumbar spine.</jats:p> </jats:sec> <jats:sec id="conclusions"> <jats:title>Conclusions</jats:title> <jats:p>Findings could help guide practitioners and coaches to choose squat variations and incorporate VPAC strategies during their treatments and/or training programs.</jats:p> </jats:sec> <jats:sec id="level-of-evidence"> <jats:title>Level of Evidence</jats:title> <jats:p>Level 3</jats:p> </jats:sec>
      1
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    The Frequency of Symptoms in Patients With a Diagnosis of Degenerative Cervical Myelopathy: Results of a Scoping Review
    (2023)
    Zhilin Jiang
    ;
    Benjamin Davies
    ;
    Carl Zipser
    ;
    Konstantinos Margetis
    ;
    Allan Martin
    <jats:sec><jats:title>Study Design</jats:title><jats:p> Delayed diagnosis of degenerative cervical myelopathy (DCM) is associated with reduced quality of life and greater disability. Developing diagnostic criteria for DCM has been identified as a top research priority. </jats:p></jats:sec><jats:sec><jats:title>Objectives</jats:title><jats:p> This scoping review aims to address the following questions: What is the diagnostic accuracy and frequency of clinical symptoms in patients with DCM? </jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p> A scoping review was conducted using a database of all primary DCM studies published between 2005 and 2020. Studies were included if they (i) assessed the diagnostic accuracy of a symptom using an appropriate control group or (ii) reported the frequency of a symptom in a cohort of DCM patients. </jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p> This review identified three studies that discussed the diagnostic accuracy of various symptoms and included a control group. An additional 58 reported on the frequency of symptoms in a cohort of patients with DCM. The most frequent and sensitive symptoms in DCM include unspecified paresthesias (86%), hand numbness (82%) and hand paresthesias (79%). Neck and/or shoulder pain was present in 51% of patients with DCM, whereas a minority had back (19%) or lower extremity pain (10%). Bladder dysfunction was uncommon (38%) although more frequent than bowel (23%) and sexual impairment (4%). Gait impairment is also commonly seen in patients with DCM (72%). </jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p> Patients with DCM present with many different symptoms, most commonly sensorimotor impairment of the upper extremities, pain, bladder dysfunction and gait disturbance. If patients present with a combination of these symptoms, further neuroimaging is indicated to confirm the diagnosis of DCM. </jats:p></jats:sec>
      17  3
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    Understanding the effect of window length and overlap for assessing sEMG in dynamic fatiguing contractions: A non-linear dimensionality reduction and clustering
    (2021)
    Carlos De la Fuente
    ;
    Eduardo Martinez-Valdes
    ;
    Jose Ignacio Priego-Quesada
    ;
    Alejandro Weinstein
    ;
    Oscar Valencia
    Scopus© Citations 8  20
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    How to Do an Electrophysiological Study of Myoclonus
    (2022)
    VIAL UNDURRAGA, FELIPE AGUSTIN  
    ;
    Shabbir Hussain I. Merchant
    ;
    Patrick McGurrin
    ;
    Mark Hallett
      1Scopus© Citations 6
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    Electrophysiological Characterization of a <scp><i>MYH7</i></scp> Variant with Tremor Phenotype
    (2023)
    VIAL UNDURRAGA, FELIPE AGUSTIN  
    ;
    Patrick McGurrin
    ;
    Thomas Osterholt
    ;
    Debra J. Ehrlich
    ;
    Susan T. Iannacone
    Scopus© Citations 2  1
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    Scopus© Citations 7  1
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      1Scopus© Citations 22  2
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    Physiology of Tremor Reduction by Putting the Hands Together in Essential Tremor
    (2021)
    Patrick McGurrin
    ;
    VIAL UNDURRAGA, FELIPE AGUSTIN  
    ;
    Thomas Osterholt
    ;
    Gina Norato
    ;
    Imran Khan
    Scopus© Citations 2  9