EEG Changes in Time and Time-Frequency Domain During Movement Preparation and Execution in Stroke Patients

Why the fuck are we measuring potential rather than actual? Survivors don't care about 'potential', they want actual. Your mentors and senior researchers need to be fired for allowing this.  

EEG Changes in Time and Time-Frequency Domain During Movement Preparation and Execution in Stroke Patients

Hai Li^1,2*, Gan Huang³, Qiang Lin^2,4, Jiangli Zhao², Qiang Fu^3,5, Le Li², Yurong Mao², Xijun Wei¹, Wanzhang Yang¹, Bingshui Wang¹, Zhiguo Zhang³ and Dongfeng Huang^2,6*

• ¹Neurorehabilitation Laboratory, Department of Rehabilitation Medicine, Shenzhen Hospital, Southern Medical University, Shenzhen, China
• ²Department of Rehabilitation Medicine, Guangdong Engineering Technology Research Center for Rehabilitation Medicine and Clinical Translation, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
• ³Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China
• ⁴Department of Rehabilitation Medicine, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
• ⁵Ira A. Fulton Schools of Engineering, Arizona State University, Tempe, AZ, United States
• ⁶Department of Rehabilitation Medicine, The Seventh Affiliated Hospital, Sun Yat-sen University, Guangzhou, China

This study investigated electroencephalogram (EEG) changes during movement preparation and execution in stroke patients. EEG-based event-related potential (ERP) technology was used to measure brain activity changes. Seventeen stroke patients participated in this study and completed ERP tests that were designed to measure EEG changes during unilateral upper limb movements in preparation and execution stages, with Instruction Response Movement (IRM) and Cued Instruction Response Movement (CIRM) paradigms. EEG data were analyzed using motor potential (MP) in the time domain and the mu-rhythm and beta frequency band response mean value (R-means) in the time–frequency domain. In IRM, the MP amplitude at Cz was higher during hemiplegic arm movement than during unaffected arm movement. MP latency was shorter at Cz and the contralesional motor cortex during hemiplegic arm movement in CIRM compared to IRM. No significant differences were found in R-means among locations, between movement sides in both ERP tests. This study presents the brain activity changes in the time and time–frequency domains in stroke patients during movement preparation and execution and supports the contralesional compensation and adjacent-region compensation mechanism of post-stroke brain reconstruction. These findings may contribute to future rehabilitation research about neuroplasticity and technology development such as the brain–computer interface.

Introduction

Motor control dysfunction is one of the most common disabilities that result from a stroke (Winstein et al., 2016). Understanding the brain activity changes in the motor cortex during movement preparation and execution is critical for the study of brain plasticity and develop rehabilitation strategies for stroke patients. Animal experiments suggested that after stroke, the central nervous system generates recovery through reconstruction mechanisms such as contralesional hemisphere compensation (Liu et al., 2019), activation of the brain structures surrounding damage, and redistribution of the cortical representative regions (Hara, 2015). The motor cortex was reported to show laterality changes after stroke. During unilateral extremity movements, brain activation was observed to be the strongest in the contralesional motor cortical area in the early stage of a stroke. When the movement pattern gradually normalized through recovery, the brain activation center gradually shifted back to the lesioned side (Liu et al., 2019). Contralesional compensation of the motor cortex showed a positive correlation with the severity of brain damage (Dijkhuizen et al., 2001, 2003; Hsu and Jones, 2006). Another cortical reorganization pattern in stroke rehabilitation, which is adjacent undamaged area compensation, was observed by Starkey and colleagues using antegrade and retrograde tracing techniques and intracortical microstimulation techniques in stroke model rats (Starkey et al., 2012).

Movement-related cortical potentials (MR) are commonly used event-related potential (ERP) measures in the electroencephalogram (EEG) time domain (Peters et al., 2018). The negativity amplitude of MRCPs may reflect energy consumption during movements (Wright et al., 2011) and may show a larger MP amplitude in stroke patients during movement, suggesting an increased energy demand for the injured brain hemisphere (Wiese et al., 2005; Yilmaz et al., 2013). Event-related desynchronization (ERD) reflects the brain’s activity changes that are related to events or movements in the time–frequency domain (Schomer and Lopes da Silva, 2011). ERD occurs not only during movement preparation and execution but also during movement observation, within different frequency band (alpha, beta, and theta, etc.) (Miller et al., 2007; Babiloni et al., 2016, 2017; Angelini et al., 2018). ERD magnitude in the damaged hemisphere in stroke patients showed a positive correlation with the remaining motor ability in the paretic limb (Bartur et al., 2019). In patients with unilateral hemiplegia, damages in the motor area of one hemisphere generally affect the movement function of the contralesion limbs. However, studies on brain injury patients with hemiplegia have found that unilateral brain injury could affect not only the contralateral limb but also the ipsilateral limb motor function (Smutok et al., 1989). EEG studies report that patients with chronic stroke with different lesion locations show different EEG lateralization feature during movement (Park et al., 2016). These studies suggested that lateralization features in behavior and movement-related EEG in patients with unilateral hemiplegia need further investigation, and the lesion location should be considered as an important factor linking the clinical functions and the EEG findings. In our previous study, we combined MRCPs and ERD to investigate the movement preparation and execution in 34 healthy participants and found different lateralization features in the time domain and time–frequency domain. Both hemispheres were involved in the unilateral movement execution stage with evidence from MRCPs and ERD record, while mu-ERD was found to have stronger contralateralization features in the movement preparation stage (Li et al., 2018).

The present study investigated EEG changes during movement preparation and execution in stroke patients in both the time and time–frequency domains. Our hypothesis is that brain activity changes during movement in stroke patients might show specific topographical features in the time and time–frequency domains that differ from healthy people, which reflect the brain reconstruction mechanisms that are found in animal studies.