Effects of transcranial direct current stimulation (tDCS) on posture, movement planning, and execution during standing voluntary reach following stroke

 Since this seems to work, WHERE THE HELL IS THE PROTOCOL LOACTED?

No protocol or not available to be found by survivors, then USELESS RESEARCH.

Effects of transcranial direct current stimulation (tDCS) on posture, movement planning, and execution during standing voluntary reach following stroke

• Chieh-ling Yang,
• Alon Gad,
• Robert A. Creath,
• Laurence Magder,
• Mark W. Rogers &
• Sandy McCombe Waller 

Journal of NeuroEngineering and Rehabilitation volume 18, Article number: 5 (2021) Cite this article

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Abstract

Background

Impaired 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.

Methods

Each 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.

Results

Anodal 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.

Conclusions

The 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(what is the objective lesion size this works for? Didn't measure, then you were incompetent.) 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

Introduction

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 and movement sequencing [1, 2]. Abnormal posture and movement planning and preparation as shown by an absence of SR responses during standing reaching have been found in previous studies [3, 4]. Premotor areas (PMAs) such as supplementary motor areas and premotor cortex are thought to be involved in posture and movement planning [5, 6]. In preparation for a movement, the neural pathways originating from PMAs to the spinal cord via the reticular formation modulate spinal circuitry through inhibitory effects in order to prevent premature release of the movement [7]. Previous studies also suggested that damage to the premotor cortex following stroke [6, 8] or temporary inhibition by transcranial magnetic stimulation (TMS) over the supplementary motor areas of healthy subjects [7] impair the anticipatory postural adjustments (APAs) preparation during voluntary stepping. Furthermore, 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. The signals for the APAs were possibly generated from higher cortical level such as PMAs via cortico-reticular pathway to the PMRF. We proposed that PMAs normally have a modulatory role in SR responses through inhibitory input to brainstem motor circuits and/or spinal cord via the PMRF. Hence, 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].

Cortical excitability can be modulated by the application of weak continuous direct electrical current over a specific location of the head by noninvasive transcranial direct current stimulation (tDCS) [8]. Depending on the direct current polarity, tDCS can either up-regulate neuronal excitability using anodal tDCS or down-regulate it using cathodal tDCS by hyperpolarizing or depolarizing the membrane potentials [8, 12]. Many studies have demonstrated beneficial effects of applying tDCS over M1 on arm, hand, and lower limb motor performance in individuals with stroke [13,14,15,16,17,18]. However, only one recent study demonstrated that SR response in ankle dorsiflexion, wrist flexion, and automatic postural responses could be facilitated by applying anodal tDCS over M1 in healthy subjects [19]. No studies have used tDCS over PMAs as a target for neuromodulation therapy to augment posture and movement planning, preparation, and execution following stroke.

The purpose of this study was to determine the modulatory role of the PMAs on SR responses following cathodal tDCS over PMAs in persons with stroke. Knowing that PMAs have projections to the M1, we included anodal tDCS over M1 as a control condition to validate that PMAs stimulation has additional modulatory effects. Our hypothesis was that applying cathodal tDCS over PMAs will reduce the neuronal excitability in PMAs thereby helping to improve posture and movement planning and preparation in persons with stroke, as measured by increased incidence and faster onset of the SR responses.