Abstract
BackgroundImpaired movement preparation of both anticipatory postural adjustments and goal directed movement as shown by a marked reduction in the incidence of StartReact responses during a standing reaching task was reported in individuals with stroke. We tested how transcranial direct current stimulation (tDCS) applied over the region of premotor areas (PMAs) and primary motor area (M1) affect movement planning and preparation of a standing reaching task in individuals with stroke.MethodsEach subject performed two sessions of tDCS over the lesioned hemisphere on two different days: cathodal tDCS over PMAs and anodal tDCS over M1. Movement planning and preparation of anticipatory postural adjustment-reach sequence was examined by startReact responses elicited by a loud acoustic stimulus of 123 dB. Kinetic, kinematic, and electromyography data were recorded to characterize anticipatory postural adjustment-reach movement response.ResultsAnodal tDCS over M1 led to significant increase of startReact responses incidence at loud acoustic stimulus time point − 500 ms. Increased trunk involvement during movement execution was found after anodal M1 stimulation compared to PMAs stimulation.ConclusionsThe findings provide novel evidence that impairments in movement planning and preparation as measured by startReact responses for a standing reaching task can be mitigated in individuals with stroke by the application of anodal tDCS over lesioned M1 but not cathodal tDCS over PMAs. This is the first study to show that stroke-related deficits in movement planning and preparation can be improved by application of anodal tDCS over lesioned M1.Trial registration ClinicalTrial.gov, NCT04308629, Registered 16 March 2020—Retrospectively registered, https://www.clinicaltrials.gov/ct2/show/NCT04308629
Highlights
StartReact (SR) responses triggered by a loud acoustic stimulus (LAS) during the planning and preparation of goal intended actions have been used to probe the state of brainstem neuronal excitability related to posture andYang et al J NeuroEngineering Rehabil (2021) 18:5 movement sequencing [1, 2]
Stratified analyses showed that SR incidence increased more after anodal Primary motor area (M1) stimulation compared to cathodal premotor areas (PMAs) stimulation when the LAS was at − 500 ms (p = 0.001)
It has been suggested that pontomedullary reticular formation (PMRF) is critically involved in generating posture responses [9, 10] and in the SR responses [19].We proposed that the abnormal hyperexcitability in PMAs due to chronic stroke may lead to excessive inhibitory input via the cortico-reticulospinal pathway, and impairs posture and movement planning, preparation, and execution
Summary
StartReact (SR) responses triggered by a loud acoustic stimulus (LAS) during the planning and preparation of goal intended actions have been used to probe the state of brainstem neuronal excitability related to posture andYang et al J NeuroEngineering Rehabil (2021) 18:5 movement sequencing [1, 2]. Animal studies [9, 10] have shown the activation in neurons in subcortical pontomedullary reticular formation (PMRF) were related to the APAs prior to the reaching movement. Abnormal hyperexcitability in PMAs due to chronic stroke [11] may lead to excessive inhibition of the PMRF and/or spinal cord resulting in an absence of and/or reduced magnitude of SR responses and a disruption of the normal sequencing between posture and movement [4]. Impaired movement preparation of both anticipatory postural adjustments and goal directed move‐ ment as shown by a marked reduction in the incidence of StartReact responses during a standing reaching task was reported in individuals with stroke. We tested how transcranial direct current stimulation (tDCS) applied over the region of premotor areas (PMAs) and primary motor area (M1) affect movement planning and preparation of a stand‐ ing reaching task in individuals with stroke
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