# EEG Channel Selection for Stroke Patient Rehabilitation Using BAT Optimizer
## 4 Proposed Method
### Phase I: EEG Signal Acquisition  
In this study, the source of the dataset is from g.tec Medical Engineering GmbH, a standard EEG dataset; details about this dataset are explained in [8]. The EEG data of poststroke patients with hemiparesis of the upper extremities were studied. This study involved 8 poststroke patients treated with the recoveriX system (g.tec medical engineering  
Figure 3: A proposed method for electroencephalogram channel selection.  
GmbH), with a mean age of 22 years (\(SD=4.582\)). Each participant received BCI-based MI training for three months, with 2 training sessions each week (for a total of 25 training sessions). The study team conducted and analyzed two assessments (pre- and post-training). The pretraining evaluation was scheduled 30 to 35 days prior to the intervention, and the post-training evaluation was conducted a few days after the intervention (see Figure 4). The Ethikkommission des Landes Oberosterreich in Austria (#\(D\)-42-17) authorized this study protocol, and each patient signed an informed consent form prior to the preassessment. Finally, this dataset is captured with a sample rate of 256 Hz.  
According to system indications for an MI mental task, the patients were instructed to visualize dorsal wrist movement. Prior to and after EEG neurorehabilitation, the patients participated in 25 MI-based BCI sessions with follow-up evaluation visits to measure the functional changes. Each session consisted of 240 MI repetitions with both hands, broken down into three 80-trial runs. Each session lasted approximately one hour, including the time required for setup and cleanup. The MI-based BCI tasks were illustrated with randomized inter-trial intervals in a pseudo-random order.  
Figure 4: (**a**) EEG electrode distributions based on 10–20 system; (**b**) schematic diagram of EEG recording protocol.  
For capturing all the various neural processes that take place during stroke rehabilitation--involving cognitive, affective, and motor components--sixteen-channel active EEG caps were employed. The caps were made by the g.tec medical engineering GmbH company in Austria.  
According to the international 10-20 system, the EEG electrodes were positioned as follows: (_FC5_, _FC1_, _FCz_, _FC2_, _FC6_, _C5_, _C3_, _C1_, _Cz_, _C2_, _C4_, _C6_, _CP5_, _CP1_, _CP2_, and _CP6_). To the subject, a ground electrode was applied at _FPz_ and a reference electrode was affixed at the right earlobe.  
These channels are linked with different cognitive and sensorimotor processes which are in some way impaired in patients after a stroke. Particularly, the frontcentral channels (_FC5_, _FC1_, _FCz_, _FC2_, _FC6_) are associated with emotional regulation, working memory, and secondary motor area. Further, it is important to note that the central channels (_C5_, _C3_, _C1_, _Cz_, _C2_, _C4_, and _C6_) are related to sensory-motor integration and body movement representation. In addition, the centroparietal channels (_CP5_, _CP1_, _CP2_, _CP6_) are described to be involved in the process of integration of the exteroceptive and the proprioceptive inputs as well as in the regulation of the voluntary movements [22].