![]() Certain arrangements result in incorrect source localization, as they do not capture activity in vital parts of the brain. The distance between electrodes is 10%-20% of the maximum length (nasion to inion) or width (left preauricular point to the right preauricular point) ( Benbadis, S. A typical placement of the electrodes is known as the 10-20 system, in which electrodes are placed evenly between the four anatomical landmarks: nasion (1), inion (1), and preauricular points (2). The distance between electrodes and which electrodes that are considered in the sample can impact the reading of the EEG. Image: the “ double banana” is a type of bipolar montage also referred to as the longitudinal bipolar montage - the two will be used interchangeably throughout this paper - it is a widely-used montage method for its versatility. Montages tested in this study, including their strengths and weaknesses will be further discussed in the following paragraphs. Another widely known montage is the bipolar montage, where electrodes are arranged such that the channels of electrodes that are placed in series are subtracted from each other (see image below for an example). In referential montages, the center electrode, Cz, is typically used as the reference, as relatively, it is an electrically quiet spot on the brain and will not result in the omission of relevant activity. ![]() One type of montage is a referential montage, where all raw EEG data is subtracted from one reference electrode. A montage is an arrangement of raw EEG data that subtracts different electrical signals from others to decrease noise ( Benbadis, S. In recording the relative electric potential, EEGs are able to eliminate unnecessary noise from the reading. voltage.Īs aforementioned, EEGs measure brain activity, and this is accomplished by calculating the voltage via the difference in electric potential between electrodes ( see image above). In order to limit this noise, the calibration of electrodes (montages) are manipulated, and the effectiveness of these montages can be measured in their band power. Some relevant sources of artifact include muscle movement, physiological functioning, and even movement from the environment or the calibration of the electrodes. ![]() As a result, EEGs tend to detect alternate noise on top of cerebral activity, known as artifact. An EEG functions by detecting electrical activity however, by nature, it detects electrical activity from other areas besides the brain. A popular application of EEG tests is seizure detection, as it can not only identify abnormal brain activity, but also the readings it takes are also separated into channels that allow neurologists to locate the approximate location of the seizure onset zone (SOZ). EEGs can be utilized to detect abnormal brain activity correlated with brain disorders. While further trials are encouraged, the Cz referential montage had the greatest delta band power, and the longitudinal bipolar montage had the greatest theta, alpha, and beta band power.Īn electroencephalogram (EEG) is a type of brain test used to detect brain activity through electrodes that record synaptic potentials. The objective of our research was to build these montages and run sample data through them to identify their strengths and functionality by comparing raw EEG data and band power plots. The following montages were tested in this study: longitudinal, Laplacian, Cz referential, transverse, circumferential. Because neurologists rely on comparing and analyzing multiple montages to reach conclusions, we explored the most optimal montages that maximize the accuracy of SOZ localization using EEG recordings. ![]() However, EEGs are less sensitive and typically less effective for localization compared to invasive procedures such as Intracranial Electroencephalography (iEEG). Electroencephalography (EEG), a noninvasive method of monitoring electrical brain activity, can sometimes be used to determine the location of the SOZ. Abstract Epilepsy affects around 65 million people around the world, with 30% of patients being unreceptive to antiepileptic drugs and in need of other methods of treatment such as neurostimulation or resective surgery - both of which require the localization of the seizure onset zone (SOZ). ![]()
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