The perturbation paradigm modulates error-based learning in a highly automated task: outcomes in swallowing kinematics

Abstract

Traditional motor learning studies focus on highly goal-oriented, volitional tasks that often do not readily generalize to real-world movements. The goal of this study was to investigate how different perturbation paradigms alter error-based learning outcomes in a highly automated task. Swallowing was perturbed with neck surface electrical stimulation that opposes hyo-laryngeal elevation in 25 healthy adults (30 swallows: 10 preperturbation, 10 perturbation, and 10 postperturbation). The four study conditions were gradual-masked, gradual-unmasked, abrupt-masked, and abrupt-unmasked. Gradual perturbations increasingly intensified overtime, while abrupt perturbations were sustained at the same high intensity. The masked conditions reduced cues about the presence/absence of the perturbation (pre- and postperturbation periods had low stimulation), but unmasked conditions did not (pre- and postperturbation periods had no stimulation). Only hyo-laryngeal range of motion measures had significant outcomes; no timing measure demonstrated learning. Systematic-error reduction occurred only during the abrupt-masked and abrupt-unmasked perturbations. Only the abrupt-masked perturbation caused aftereffects. In this highly automated task, gradual perturbations did not induce learning similarly to findings of some volitional, goal-oriented adaptation task studies. Furthermore, our subtle and brief adjustment of the stimulation paradigm (masked vs. unmasked) determined whether aftereffects were present. This suggests that, in the unmasked group, sensory predictions of a motor plan were quickly and efficiently modified to disengage error-based learning behaviors.

Examination of swallowing maneuver training and transfer of practiced behaviors to laryngeal vestibule kinematics in functional swallowing of healthy adults

“…Perhaps this outcome is supported by theories presented by Wong et al (2016), where achieving target behaviors of LVC mechanics occur prior to the swallow. It is also supported by theories of implicit learning and reflexive learning (Bastian, 2008; Chandrasekaran, Yi, & Maddox, 2014), wherein what was learned cannot be explicitly verbalized or is largely unknown, but has been shown to lead to after-effects in swallowing airway protection kinematics in healthy adults (Anderson et al, 2015; Calvo et al, 2017; Humbert et al, 2015; Humbert, Christopherson, et al, 2012; Humbert, Lokhande, Christopherson, German, & Stone, 2012). …”

“…During pre-training swallowing, LVCrt was longer in 5ml water swallows (.21sec) than 10ml water swallows (.16sec) in participants in the long-hold training and longer in 5ml barium swallows (.21sec) than saliva swallows (.15sec) among participants in the short-hold experiment. Previous studies of healthy adults report LVCrt ranges of approximately .19sec to .36sec in 5ml water or thin liquid barium swallows (Anderson et al, 2015; Humbert et al, 2015; P. Macrae, Anderson, & Humbert, 2014).…”

“…Since the vLVC maneuver focuses on laryngeal vestibule closure, we included the two LVC kinematic measures that have been published in the research literature, including laryngeal vestibule closure reaction time (LVCrt) and the duration of laryngeal vestibule closure (dLVC). LVCrt (also known as duration to laryngeal vestibule closure or DTLVC) is the time interval between (a) swallow onset (marked by “hyoid burst”, which is the first superior and/or anterior rapid motion of the hyoid bone) and (b) the first frame when the laryngeal vestibule is closed and no airspace can be seen through the hyo-laryngeal structures (Anderson et al, 2015; Calvo, Sunday, Macrae, & Humbert, 2017; Humbert, Christopherson, & Lokhande, 2015; Young, Macrae, Anderson, Taylor-Kamara, & Humbert, 2015). dLVC is the time interval between (a) the first frame when the laryngeal vestibule is closed until (b) the first frame when the laryngeal vestibule reopens and airspace can be visualized as the epiglottis begins its return to rest position (Molfenter & Steele, 2012b).…”

Effects of chin‐up posture on the sequence of swallowing events

“…(b) The sequence of events will change over the course of several chin‐up swallows. Previous studies have shown that applying a perturbation or manipulation to swallowing can gradually impact swallowing kinematics across 20 to 30 consecutive swallows . Specifically, the swallowing system gradually adapted to overcome the effect of the perturbation or adapted to the novel experience.…”

“…Previous studies have shown that applying a perturbation or manipulation to swallowing can gradually impact swallowing kinematics across 20 to 30 consecutive swallows. 16,17,20 Specifically, the swallowing system gradually adapted to overcome the effect of the perturbation or adapted to the novel experience. We expected that during 30 consecutive chin-up swallows the system would gradually change to accommodate any effects of hyolaryngeal or bolus flow changes.…”