Planning of Ballistic Movement following Stroke

Insights from the Startle Reflex

Claire Honeycutt, Eric Jon Perreault

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Following stroke, reaching movements are slow, segmented, and variable. It is unclear if these deficits result from a poorly constructed movement plan or an inability to voluntarily execute an appropriate plan. The acoustic startle reflex provides a means to initiate a motor plan involuntarily. In the presence of a movement plan, startling acoustic stimulus triggers non-voluntary early execution of planned movement, a phenomenon known as the startReact response. In unimpaired individuals, the startReact response is identical to a voluntarily initiated movement, except that it is elicited 30-40 ms. As the startReact response is thought to be mediated by brainstem pathways, we hypothesized that the startReact response is intact in stroke subjects. If startReact is intact, it may be possible to elicit more task-appropriate patterns of muscle activation than can be elicited voluntarily. We found that startReact responses were intact following stroke. Responses were initiated as rapidly as those in unimpaired subjects, and with muscle coordination patterns resembling those seen during unimpaired volitional movements. Results were striking for elbow flexion movements, which demonstrated no significant differences between the startReact responses elicited in our stroke and unimpaired subject groups. The results during planned extension movements were less straightforward for stroke subjects, since the startReact response exhibited task inappropriate activity in the flexors. This inappropriate activity diminished over time. This adaptation suggests that the inappropriate activity was transient in nature and not related to the underlying movement plan. We hypothesize that the task-inappropriate flexor activity during extension results from an inability to suppress the classic startle reflex, which primarily influences flexor muscles and adapts rapidly with successive stimuli. These results indicate that stroke subjects are capable of planning ballistic elbow movements, and that when these planned movements are involuntarily executed they can be as rapid and appropriate as those in unimpaired individuals.

Original languageEnglish (US)
Article numbere43097
JournalPLoS One
Volume7
Issue number8
DOIs
StatePublished - Aug 30 2012
Externally publishedYes

Fingerprint

Startle Reflex
Ballistics
reflexes
stroke
Muscle
planning
Stroke
Planning
Acoustics
elbows
Elbow
Muscles
muscles
acoustics
Chemical activation
brain stem
Brain Stem

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Planning of Ballistic Movement following Stroke : Insights from the Startle Reflex. / Honeycutt, Claire; Perreault, Eric Jon.

In: PLoS One, Vol. 7, No. 8, e43097, 30.08.2012.

Research output: Contribution to journalArticle

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