Consciousness, EEG, Sleep and Emotions
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2020
Electroencephalography is the recording of the spontaneous electrical activity of the brain. The electroencephalogram (EEG) is generated by the superficial layer of pyramidal cells by changes in postsynaptic potentials in the dendrites oriented perpendicular to the cortical surface. The current is the result of the summation of EPSPs and IPSPs. The electrical potentials of an EEG are the algebraic summation of the postsynaptic potentials of pyramidal cells. The rhythm of cortical activity is controlled by the thalamus. The thalamus in turn has its rhythmic activity modulated by inputs from the reticular activating system. Input from the reticular formation interrupts these rhythmic potential changes and causes a desynchronization of the cortical waves. The recorded potentials range from 0 to 200 μV, and their frequencies range from once every few seconds to 50 or more per second.
Electrical Brain Stimulation to Treat Neurological Disorders
Bahman Zohuri, Patrick J. McDaniel in Electrical Brain Stimulation for the Treatment of Neurological Disorders, 2019
The following is the list of disadvantages that goes with Electroencephalography, and they are: Low spatial resolution on the scalp. fMRI, for example, can directly display areas of the brain that are active, while EEG requires intense interpretation just to hypothesize what areas are activated by a particular response.EEG poorly measures neural activity that occurs below the upper layers of the brain (the cortex).Unlike PET and MRS, cannot identify specific locations in the brain at which various neurotransmitters, drugs, etc. can be found.Often takes a long time to connect a subject to EEG, as it requires precise placement of dozens of electrodes around the head and the use of various gels, saline solutions, and/or pastes to keep them in place (although a cap can be used). While the length of time differs depending on the specific EEG device used, as a general rule, it takes considerably less time to prepare a subject for MEG, fMRI, MRS, and SPECT.Signal-to-noise ratio is poor, so sophisticated data analysis and relatively large numbers of subjects are needed to extract useful information from EEG.
Assessing the Effectiveness of Treatment
Stanley R. Resor, Henn Kutt in The Medical Treatment of Epilepsy, 2020
Even with the most motivated patients and families it is not always easy to obtain an accurate seizure count. Absences can be particularly difficult to quantify. Children frequently do not know when they have absences. Adults may only occasionally be able to tell. When accuracy is crucial (e.g., when determining whether it is safe for a patient to operate a motor vehicle), electroencephalographic (EEG) monitoring in some form is usually required. The timing of monitoring is important. It should be scheduled at the time of day or month when the patient has typically been most likely to have seizures (e.g., after awakening in the morning, in the late afternoon, when tired, or at the onset of the menses). If bursts of generalized spike-and-wave occur, responsiveness testing must be done.
Driver drowsiness detection methods using EEG signals: a systematic review
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Raed Mohammed Hussein, Firas Sabar Miften, Loay E. George
Electroencephalography (EEG) is a neuroimaging method that measures the brain's electrical activity. It enables vital medical diagnostic and brain research investigations. Despite its sensitivity to noise, EEG is the most effective method for recording and analyzing brain activity because it is non-invasive, portable, cost-effective, relatively simple to use, and has an exceptional temporal resolution of less than one millisecond (Gevins et al. 1999). EEG utilizes electrodes placed on the scalp to measure the brain's electrical activity. The recorded signal waves contain valuable information about the brain's health. EEG records electric potential differences of tens of microvolts (μV) reaching the scalp when pyramidal neurons generate tiny excitatory postsynaptic potentials in the brain's cortical layers. Numerous electrode positioning systems are typically utilized for EEG signal recording. The EEG signal processing and analysis consist of four steps:Preprocessing the raw signals with filtering or other techniquesExtracting the essential information in the form of featuresApplying feature selection methods for more optimized resultsAnalyzing the results
Use of Neurofeedback and Mindfulness to Enhance Response to Hypnosis Treatment in Individuals with Multiple Sclerosis: Results from a Pilot Randomized Clinical Trial
Published in International Journal of Clinical and Experimental Hypnosis, 2018
Mark P. Jensen, Samuel L. Battalio, Joy F. Chan, Karlyn A. Edwards, Melissa A. Day, Leslie H. Sherlin, Dawn M. Ehde
Another strategy that has the potential to enhance response to hypnosis treatments is to identify brain activity markers associated with positive responses to hypnosis treatment, and then provide interventions that influence those markers prior to initiating hypnosis (Jensen et al., 2014). One such viable marker is theta bandwidth activity, as measured by electroencephalography (Jensen, Adachi, & Hakimian, 2015). Electroencephalography (EEG) measures brain activity via electrodes that are placed on the scalp. Raw EEG data—which reflects the combined activity of billions of neurons—can then be divided into different frequency bandwidths, the most common being delta (0.5–4.0 Hz), theta (4.0–8.0 Hz), alpha (8.0–13.0 Hz), beta (13.0–30.0 Hz), gamma (30.0–60 Hz), and high gamma (60–200 Hz), although the cut points for the different bandwidths can vary somewhat across studies. Once the bandwidths are identified, EEG data can be transformed to measure the amplitude (also known as “power”) of activity in the different bandwidths. This measure reflects the overall activity of the neuronal assemblies that fire within the specified bandwidth.
Does familial Mediterranean fever affect cognitive function in children? Electrophysiological preliminary study
Published in International Journal of Neuroscience, 2018
Gonca Keskindemirci, Gökçer Eskikurt, Nuray Aktay Ayaz, Mustafa Çakan, Numan Ermutlu, Ümmühan İşoğlu Alkaç
Cognitive functioning includes the processing of mental events such as attention, recognition, memory, and executive functions. Electroencephalography (EEG) is a method for recording the electrical activity of the brain along the scalp. Event-related potentials (ERPs) are derived from EEGs and are commonly used as noninvasive physiological measures of cognitive function. ERPs are obtained by averaging EEG sweeps that are time-locked to stimuli or related to a mental operation concerning stimuli, such as paying attention to a certain type of stimulus. P300, a component of ERP, appears at nearly 300 ms post-stimulus, is positively deflected waveform, and has been linked to the cognitive processes involved in the allocation of attention, context updating, context closure, event categorization, and working memory [5–8]. The amplitude of P300 is thought to reflect the quantity of attentional resources devoted to a given task, and its latency is considered to be a measure of stimulus classification speed or evaluation time [9–11]. Developmental studies have shown that the latency of auditory P300 is significantly shortened in teenagers and that visual latency decreases steadily with age [12]. Additionally, P300 abnormalities have been reported in association with mental disorders involving attention and memory [13]. A few studies have investigated ERPs in adult patients with inflammatory disease such as Behçet disease [13,14]. Although there is no definitive evaluation of FMF in the literature, we aimed to determine the cognitive function of children with FMF by comparing their ERPs-P300 to those of healthy controls.
Related Knowledge Centers
- Allocortex
- Electrocorticography
- Neocortex
- Postsynaptic Potential
- Quantitative Electroencephalography
- Brain
- Scalp
- Electrogram
- Biosignal
- 10–20 System