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Review of the Human Brain and EEG Signals
Published in Teodiano Freire Bastos-Filho, Introduction to Non-Invasive EEG-Based Brain–Computer Interfaces for Assistive Technologies, 2020
Alessandro Botti Benevides, Alan Silva da Paz Floriano, Mario Sarcinelli-Filho, Teodiano Freire Bastos-Filho
To acquire EEG signals, the first step was given in 1958 by Herbert Jasper, who suggested a system for naming and placement of electrodes on the scalp, which is now worldwide used, called “International 10–20 System” [17]. Figure 1.17a shows that electrodes on the edges of the scalp are 10% distant of the horizontal line connecting the nasion to the inion through the preauricular point, where this percentage is related to the length of the line connecting the nasion to the inion through the vertex. All electrodes are positioned at a distance of 20% between each other. Then, numbers “10” and “20” of the “International 10–20 System” refer to these percentage values. The electrodes are named by a capital letter corresponding to the initial of the brain lobe where they are placed (F = Frontal, C = Central, P = Parietal, O = Occipital, and T = Temporal), followed by an even number for the right hemisphere and an odd number for the left hemisphere. Electrodes on the frontal pole are named Fp, and the letter “A” is used for electrodes placed in the ear (from “auricular”). For the electrodes in the line connecting the nasion to the inion, the letter “z” is added, which indicates “zero”, rather than a number, indicating the central division of the brain hemispheres (Figure 1.17b) [10].
Functional Neuroimaging of the Central Auditory System
Published in Stavros Hatzopoulos, Andrea Ciorba, Mark Krumm, Advances in Audiology and Hearing Science, 2020
David L. McPherson, Richard Harris, David Sorensen
Electrode montage refers to where and how many electrodes are placed across the scalp. Each electrode represents a channel on the input of the amplifier. In addition, how the electrodes are referenced may be part of the montage description, especially, in systems that have predefined protocols that are used in routine clinical service. The most common definition is the International 10–20 System (Fig. 10.6) first described by Jasper and Radmussen (1958) and updated by Jurcak et al. (2007). These descriptions are somewhat inadequate given that montages of 32, 64, 128, and 256 electrodes are common. Likewise, special montages may be constructed to more closely populate specific areas on the surface of the scalp. Since this can becomes rather intricate, both diagrams and tables are necessary to document procedures. Documentation occurs at the time the montage is constructed (or anything for that matter).
Bioelectric and Biomagnetic Signal Analysis
Published in Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam, Introduction to Computational Health Informatics, 2019
Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam
Leads are placed on the scalp using 10–20 scheme that uses 23 electrodes placed in a two-dimensional plane as shown in Figure 7.18. The arrangement is called 10–20 system because the skull perimeter is evenly divided into 10% on the transverse and 20% on the longitudinal lines. The nomenclature of the electrodes is based upon the placement location.
Comparison of Functional Connectivity during Visual-Motor Illusion, Observation, and Motor Execution
Published in Journal of Motor Behavior, 2022
Katsuya Sakai, Junpei Tanabe, Keisuke Goto, Ken Kumai, Yumi Ikeda
All channels were referenced to 10–20 system landmarks (nasion, inion, right, and left preauricular points) and recorded using a 3 D digitizer (3 SPACE®, Fastrak®, Polhemus Co., Ltd, Colchester, VT, USA) to determine which brain regions corresponded to each channel positions. All channels then converted these coordinates into the locations of 40 channels based on an estimated Montreal Neurological Institute (MNI) space using NIRS-statistical parametric mapping (NIRS-SPM) (Tsuzuki et al., 2007; Tsuzuki & Dan, 2014). NIRS-SPM transforms the functional image to MNI space using probabilistic registration in reference to 3D digitized data of all channels and landmark positions using the 10–20 system (Tsuzuki & Dan, 2014; Yamazaki et al., 2020). This analysis demonstrated that the regions of interest (ROI) were the dorsolateral prefrontal cortex (DLPFC, channels 1–4), frontal eye field (channels 5–9), PMC (channels 10–22), M1 (channels 23–27), somatosensory area (Sa, channels 28–31), and Pa (channels 32–40).
Wearable electroencephalography for ultra-long-term seizure monitoring: a systematic review and future prospects
Published in Expert Review of Medical Devices, 2021
Jonas Munch Nielsen, Dirk Rades, Troels Wesenberg Kjaer
Previous reviews have investigated either subcutaneous EEG [28] or noninvasive modalities (including surface EEG) [29–31] for seizure detection. Our objective is to review and discuss the current status on the field of wearable long-term surface- and subcutaneous EEG-based seizure detection. We focus on wearable setups with a limited number of surface electrodes (≤10) for two reasons. First, because the equipment should be mobile, somewhat easily self-applied and as discrete as possible. Second, to avoid confusions with standard EEG-recordings (10–20-system) for diagnostic purposes (e.g. home video-EEG). We define subcutaneous EEG as surgically implanted in the space between the cutis and the cranial bone, which leaves two options for implantation: either between the dermis and the galea (subcutaneous) or between the galea and the bone (subgaleal). Although these devices are surgically implanted, we refer to them as wearable because they generally require a wearable external companion for battery and storage and to emphasize their intended purpose of out-patient monitoring.
Differences in executive function of the attention network between athletes from interceptive and strategic sports
Published in Journal of Motor Behavior, 2021
We used event-related fNIRS to study the activation of the executive control network under different cue conditions. Brain activity associated with executive control was determined by subtracting brain activity under the incongruent flanker condition from that under the congruent flanker condition. The spatial cue was thought to add an orienting operation to the central cue prior to the occurrence of the target. The activity associated with different cues was obtained by subtracting the baseline to isolate regions that were more active in response to the spatial cue. We also assessed the changes in blood hemoglobin (Hb) concentration associated with increased neural activity during the LANT-R task using a multi-channel continuous-wave fNIRS instrument (NIRSport, Germany). The fNIRS probe consists of eight dual-wavelength sources (760 and 850 nm) and eight optical detectors, which covered the right FPN (see Figure 2). The distance between the source and the detector was 3.0 cm. The patch placement was related to the 10–20 system. The location of the 20 channels is shown in Figure 2. All optodes were arranged on a supporting plastic base and checked for adequate contact on each participant’s scalp. Subsequently, hair under the sensors was brushed away to ensure good skin contact. A channel represented the area measured by one probe-set pair, which was sufficient to measure depths between 2 and 3 cm from the scalp. The channel location was defined as the center position of the pair.