Materials and Methods
The human brain is divided into the left and right hemispheres by the corpus callosum, and can be mainly divided into six parts: frontal lobe, parietal lobe, occipital lobe, temporal lobe, cerebellum, and brainstem, as shown in Figure 2.1. (1) Frontal lobe: mainly responsible for cognitive functions of behavior and emotion, and can be divided into prefrontal lobe and posterior frontal lobe: the former is responsible for judgment and cognitive ability, and the latter is responsible for language and written expression ability [3,12]. (2) Parietal lobe: contains the sensory cortex that controls touch, and is mainly responsible for the ability to perceive spatial position. (3) Occipital lobe: located above the cerebellum, mainly responsible for receiving visual change information and distinguishing colors and shapes. (4) Temporal lobe: located near the left and right ears, mainly responsible for receiving auditory and olfactory discrimination abilities. (5) Cerebellum: Located at the back of the brain, it is mainly responsible for balance and muscle coordination. If the cerebellum is damaged, it will cause muscle incoordination. (6) Brainstem: Located at the bottom of the brain, its main functions are related to human survival (breathing, digestion, and heartbeat, etc.).
Figure 2.1 Brain functional area diagram
Brainwaves are primarily generated by nerve cells and represent the synthesis of the potentials of numerous brain cells within a specific timeframe. They function by transmitting and receiving electrical signals and can be used to assess changes in the electrical potentials of the cerebral cortex. This study employed...GES 300Electroencephalogram (EEG) device(GES, Electrical Geodesics Inc.)andElectrode bonding methodTesting was conducted, among whichElectrode placement is a non-invasive method that uses surface electrode sensors attached to the scalp. The resulting changes in electrical waves are transmitted from the brain waves generated by the cerebral cortex to the EEG machine via the electrodes. Furthermore, the most crucial aspect of EEG measurement is the collection of brain wave signals. Factors such as electrode placement, collection methods, and interference elimination all affect the system's operation and performance. To avoid inconsistencies in the brain waves obtained from different electrode placement methods for the same subject, which would prevent comparisons between different records, this study employed the international 10-20 system for electrode placement calibration to ensure consistency in electrode placement across all subjects. The 10-20 method of bonding uses 21 electrode positions, two of which are ear electrodes[12], and the other electrodes are distributed on the scalp, where F represents the frontal lobe, T represents the temporal lobe, C represents the central lobe, P represents the parietal lobe and O represents the occipital lobe[12]. The electrode numbers on the right side of the head are even numbers; the electrode numbers on the left side are odd numbers. This system is named according to this proportional relationship, and the electrode arrangement position has become the international standard for measuring brain waves (as shown in Figure 2.2). The head circumference is divided into the left half and the right half of the circumference by the distance from the glabella to the occipital protuberance. It is divided into six parts (5 electrode placement points) according to the proportion. The first part and the sixth part each occupy 10% of the total distance, and the remaining four parts are evenly distributed, so each occupies 20%. Looking at the right half, the five electrode placement points from the glabella to the occipital protuberance are Fp2, F8, T4, T6 and O2 in sequence, while the left half are Fp1, F7, T3, T5 and O1.
Figure 2.2 Electrode location diagram of the international 10-20 system
Brain waves are mainly reflected in the brain's electrical potential response. Currently, according to their different frequency ranges and amplitudes, brain waves are divided into four types: Alpha waves (α), Beta waves (β), Theta waves (θ), and Delta waves (δ). The frequency ranges and significance of the four types of brain waves are described below [15]: (1) Alpha (α): Brain waves with a frequency between 8 and 13 Hz [12]. They are most numerous and have the largest amplitude when the brain is conscious and in a quiet [3] resting state. They are most prominent in the occipital region and parietal region of the brain. (2) Beta (β): Brain waves with a frequency between 13 and 50 Hz. They are generally present when the brain is conscious and alert, ready to react to external stimuli, or when the brain is tense and emotionally excited or agitated. They are more prominent in the parietal region and frontal region and are waves that form a conscious surface. (3) Theta (θ): The frequency is between 4 and 8 Hz [2, 12]. It mainly appears in the parietal region and temporal region of children, or when a person's consciousness is interrupted, just falling asleep, or when the body is deeply relaxed. In addition, many patients with brain diseases [3] have this wave, which is a subconscious wave. (4) Delta (δ): The frequency is below 3. Normal adults do not have delta waves in the waking state. This waveform usually appears when the person is in deep sleep and difficult to wake up, under deep anesthesia, or in a state of hypoxia.
