Evidence for Startle Effects due to Externally Induced Lower Limb Movements: Implications in Neurorehabilitation

Castellote, Juan M.; Kofler, Markus; Mayr, Andreas; Saltuari, Leopold

doi:10.1155/2017/8471546

Cited by 16 publications

(25 citation statements)

References 98 publications

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“…Owing to this, the forces would be higher as transferring of the weight is from a greater vertical height. This observed increase in weight acceptance force could be ascribed to the shorter time in peak force with concomitant changes in joint kinematics [ 25 , 26 ]. These disproportionate forces and greater loading at the short leg could have affected soft tissue damage [ 27 ].…”

Section: Discussionmentioning

confidence: 99%

Leg Length Discrepancy: Dynamic Balance Response during Gait

Azizan

Basaruddin

Salleh

et al. 2018

Journal of Healthcare Engineering

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Balance in the human body's movement is generally associated with different synergistic pathologies. The trunk is supported by one's leg most of the time when walking. A person with poor balance may face limitation when performing their physical activities on a daily basis, and they may be more prone to having risk of fall. The ground reaction forces (GRFs), centre of pressure (COP), and centre of mass (COM) in quite standing posture were often measured for the evaluation of balance. Currently, there is still no experimental evidence or study on leg length discrepancy (LLD) during walking. Analysis of the stability parameters is more representative of the functional activity undergone by the person who has a LLD. Therefore, this study hopes to shed new light on the effects of LLD on the dynamic stability associated with VGRF, COP, and COM during walking. Eighteen healthy subjects were selected among the university population with normal BMIs. Each subject was asked to walk with 1.0 to 2.0 ms−1 of walking speed for three to five trials each. Insoles of 0.5 cm thickness were added, and the thickness of the insoles was subsequently raised until 4 cm and placed under the right foot as we simulated LLD. The captured data obtained from a force plate and motion analysis present Peak VGRF (single-leg stance) and WD (double-leg stance) that showed more forces exerted on the short leg rather than long leg. Obviously, changes occurred on the displacement of COM trajectories in the ML and vertical directions as LLD increased at the whole gait cycle. Displacement of COP trajectories demonstrated that more distribution was on the short leg rather than on the long leg. The root mean square (RMS) of COP-COM distance showed, obviously, changes only in ML direction with the value at 3 cm and 3.5 cm. The cutoff value via receiver operating characteristic (ROC) indicates the significant differences starting at the level 2.5 cm up to 4 cm in long and short legs for both AP and ML directions. The present study performed included all the proposed parameters on the effect of dynamic stability on LLD during walking and thus helps to determine and evaluate the balance pattern.

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Section: Discussionmentioning

confidence: 99%

Leg Length Discrepancy: Dynamic Balance Response during Gait

Azizan

Basaruddin

Salleh

et al. 2018

Journal of Healthcare Engineering

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“…While the presence or absence of SCM activity has previously been used in the literature in an attempt to separate responses that may or may not activate neurophysiological mechanisms responsible for the StartReact effect, this is not always reliable (Leow et al, ; Marinovic & Tresilian, ). For example, short latency responses indicative of the StartReact effect can be observed in the absence of SCM activity (Castellote, Kofler, Mayr, & Saltuari, ; Valls‐Solé, Kofler, Kumru, Castellote, & Sanegre, ). Furthermore, longer latency responses can occur in the presence of SCM activity (Marinovic & Tresilian, ).…”

Section: Methodsmentioning

confidence: 99%

Neural gain induced by startling acoustic stimuli is additive to preparatory activation

et al. 2019

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Loud acoustic stimuli presented during movement preparation can shorten reaction time and increase response forcefulness. We examined how efferent connectivity of an agonist muscle to reticulospinal and corticospinal pathways, and the level of prepared movement force, affect reaction time and movement execution when the motor response is triggered by an intense acoustic stimulus. In Experiment 1, participants executed ballistic wrist flexion and extension movements of low and high force in response to visual stimuli. A loud acoustic stimulus (LAS; 105 dBa) was presented simultaneously with the visual imperative stimulus in probe trials. In Experiment 2, participants executed ballistic wrist flexion movements ranging from 10%–50% of maximum voluntary contraction with a LAS presented in probe trials. The shortening of response initiation was not affected by movement type (flexion or extension) or prepared movement force. Enhancement of response magnitude, however, was proportionally greater for low force movements and for the flexor muscle. Changes in peak force induced by the intense acoustic stimulus indicated that the neural activity introduced to motor program circuits by acoustic stimulation is additive to the voluntary neural activity that occurs due to movement preparation, rather than multiplicative.

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“…The auditory domain has also been used to disentangle the underlying mechanisms of accelerated voluntary motor responses ascribed either to a high-intensity stimuli alone, or to an additional StartReact effect [ 6 ]. One advantage of auditory stimuli, similar to electrical or visual stimuli, is their short duration in comparison to others also used in stimulus-response studies, such as vestibular, proprioceptive, kinematic, or contact heat [ 21 , 22 , 23 , 24 , 25 , 26 ]. For short-lasting stimuli, stimulus onset can be considered the relevant time-point of stimulation, hence response latency measurements are rather easily performed with sufficient accuracy.…”

Section: Introductionmentioning

confidence: 99%

StartReact effects in first dorsal interosseous muscle are absent in a pinch task, but present when combined with elbow flexion

Castellote

Kofler²

2018

PLoS ONE

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ObjectiveTo provide a neurophysiological tool for assessing sensorimotor pathways, which may differ for those involving distal muscles in simple tasks from those involving distal muscles in a kinetic chain task, or proximal muscles in both.MethodsWe compared latencies and magnitudes of motor responses in a reaction time paradigm in a proximal (biceps brachii, BB) and a distal (first dorsal interosseous, FDI) muscle following electrical stimuli used as imperative signal (IS) delivered to the index finger. These stimuli were applied during different motor tasks: simple tasks involving either one muscle, e.g. flexing the elbow for BB (FLEX), or pinching a pen for FDI (PINCH); combined tasks engaging both muscles by pinching and flexing simultaneously (PINCH-FLEX). Stimuli were of varying intensity and occasionally elicited a startle response, and a StartReact effect.ResultsIn BB, response latencies decreased gradually and response amplitudes increased progressively with increasing IS intensities for non-startling trials, while for trials containing startle responses, latencies were uniformly shortened and response amplitudes similarly augmented across all IS intensities in both FLEX and PINCH-FLEX. In FDI, response latencies decreased gradually and response amplitudes increased progressively with increasing IS intensities in both PINCH and PINCH-FLEX for non-startling trials, but, unlike in BB for the simple task, in PINCH for trials containing startle responses as well. In PINCH-FLEX, FDI latencies were uniformly shortened and amplitudes similarly increased across all stimulus intensities whenever startle signs were present.ConclusionsOur results suggest the presence of different sensorimotor pathways supporting a dissociation between simple tasks that involve distal upper limb muscles (FDI in PINCH) from simple tasks involving proximal muscles (BB in FLEX), and combined tasks that engage both muscles (FDI and BB in PINCH-FLEX), all in accordance with differential importance in the control of movements by cortical and subcortical structures.SignificanceSimple assessment tools may provide useful information regarding the differential involvement of sensorimotor pathways in the control of both simple and combined tasks that engage proximal and distal muscles.

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Evidence for Startle Effects due to Externally Induced Lower Limb Movements: Implications in Neurorehabilitation

Cited by 16 publications

References 98 publications

Leg Length Discrepancy: Dynamic Balance Response during Gait

Leg Length Discrepancy: Dynamic Balance Response during Gait

Neural gain induced by startling acoustic stimuli is additive to preparatory activation

StartReact effects in first dorsal interosseous muscle are absent in a pinch task, but present when combined with elbow flexion

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