Impact of motor task execution on an individual’s ability to mirror forearm positions

Abstract

This work is motivated by our goal of determining why individuals with stroke are impaired when locating their arms in space. We assessed the ability of individuals without neurological impairments to mirror their forearms during various motor tasks so that we could identify baseline performance in an unimpaired population. Nine right-hand dominant participants without neurological impairments mirrored forearm positions bi-directionally (i.e., right forearm mirrors left forearm, vice versa) for three motor tasks (i.e., passive, passive/active, and active) and two position identification modes (i.e., mirroring to a position stored in working memory versus concurrently felt by the opposite arm). During each trial, the participant's reference forearm moved to a flexion ([Formula: see text]) or extension ([Formula: see text]) position, and then, their opposite forearm mirrored the position of their reference forearm. The main finding across all tested conditions is that participants mirrored forearm positions with an average magnitude of error [Formula: see text]. When controlling their forearms' movements (active motor task), participants mirrored forearm positions more accurately by up to, on average, [Formula: see text] at the flexion location than at the extension location. Moreover, participants mirrored forearm positions more accurately by up to, on average, [Formula: see text] when their forearms were moved for them rather than when they controlled their forearms' movements. Task directionality and position identification mode did not significantly affect participant arm mirroring accuracy. These findings are relevant for interpreting in future work the reason why impairments occur, on similar tasks, in individuals with altered motor commands, working memory, and arm impedance, e.g., post-stroke hemiparesis.

Ability of individuals with chronic hemiparetic stroke to locate their forearms during single-arm and between-arms tasks

“…Movements of the robotic device and passive measurement device were controlled by the motor and by the participant and experimenter, respectively. As demonstrated in [ 48 ], the torque response of the robotic device and passive measurement device was comparable for the interaction velocities tested (i.e., <10°/s). Additional information about the robotic device and passive measurement device can be found in [ 4 ] and [ 48 ].…”

“…A robotic system and automated protocol were used to quantify every participant’s ability to match and mirror forearm positions within each arm and between arms, respectively. A discussion of the tested participants, setup, and data collection protocol for each experiment is provided below and is presented in more detail in [ 4 ] and [ 48 ].…”

“…Inclusion criteria for all participants included an ability to understand and perform the task; absence of serious upper-extremity injury, peripheral nerve injury, and antispastic pharmacological agents that may impact task performance; ability to actively control arm movements at <10°/s, which was needed to successfully complete the position-matching and position-mirroring tasks [ 48 ]; intact direction of movement sense; and capacity to provide informed consent, which was determined based on an individual’s ability to respond to questions and engage in conversation during the recruitment process, followed by a screening with a licensed physical therapist (co-author Dr. Justin Drogos, PT/DPT/NCS).…”

“…They were comprised of five females and four males. For the between-arms experiment, we reference the controls’ data in [ 48 ]. The study included nine controls who were comprised of seven females and two males, were all right-hand dominant, and had a median age of 61 (lower/upper quartile: 57/62; range: 46-66).…”

Dynamic Information Flow Based on EEG and Diffusion MRI in Stroke: A Proof-of-Principle Study

“…There is growing evidence indicating an increased usage of ipsilateral (contralesional) cortical motor network associated with the loss of independent joint control (van Kordelaar et al, 2012 , 2013 , 2014 ) or the expression of the flexion synergy in the paretic upper limb following hemiparetic stroke (Yao et al, 2009 ; Wilkins et al, 2017 ; McPherson et al, 2018 ). However, less is known regarding changes of somatosensory cortical networks in this cohort (Gurari et al, 2017 , 2018 ; Vlaar et al, 2017 ). Our results could provide new evidence of reconfiguration of somatosensory cortical networks in individuals with hemiparetic stroke, which cannot be revealed by current clinical assessments.…”