Review of the Human Brain and EEG Signals
Teodiano Freire Bastos-Filho in Introduction to Non-Invasive EEG-Based Brain–Computer Interfaces for Assistive Technologies, 2020
Beyond the interference of technical and physiological artifacts, the EEG is also affected by the electrical activity of the brain itself. The EEG of an area of interest is a mixture of unrelated signals from cortical neighboring areas that are scattered around and attenuated by the skull and scalp. This is considered a special type of artifact, in which there are no exact solutions for unmixing it from the EEG signal. This problem is known as the inverse problem that traditionally has infinite solutions, due to the nature of its variables. A particular inverse solution uses the calculation of local field potential (LFP), which is invasive recording of the electric potential in the extracellular space in brain tissue [26]. Another solution uses the distribution of cortical extracellular currents, known as cortical current density (CCD) [27].
Sleep Promoting Improvement of Declarative Memory
Bahman Zohuri, Patrick J. McDaniel in Electrical Brain Stimulation for the Treatment of Neurological Disorders, 2019
Slow oscillations have been associated with iterative processes of memory formation during SWS in recent concepts based largely on cortical recordings in animals.55,56 The slow oscillation can also be identified in the human sleep EEG, in which a spectral peak in power at ∼0.8 Hz is found.57–60 Slow oscillations grasp the entire thalamocortical system. However, they can also be recorded in isolated slabs of neocortical tissue, which for this reason is considered as their primary generator. In humans, the negative half-wave of the slow oscillation corresponds to a depth-positive neocortical field potential that is associated with widespread intracellular hyperpolarization.60 Conversely, the positive half-wave marks a depth-negative extracellular field potential that reflects widespread cortical depolarization. Slow oscillations via corticothalamic fibers, therefore, exert a fundamental temporal grouping effect on spindle activity that is known to originate from the thalamic nucleus reticularis.52,62 Spindle activity is stimulated during the depolarizing “up” state and suppressed during the hyperpolarizing “down” state of the slow oscillation. However, the grouping effect of slow oscillations also extends to higher frequency bands, including β and γ activity.60
Neuronal Representations of Bimanual Movements
Alexa Riehle, Eilon Vaadia in Motor Cortex in Voluntary Movements, 2004
Single-unit activity and local field potentials were recorded from homologous sites in the two hemispheres, from the primary motor cortex (M1) and from SMA proper. (For details on recording sites see Donchin et al.14) The activity of 8 to 30 isolated neurons and up to eight local field potential (LFP) channels was recorded each session. The data discussed in this article were recorded from 3 monkeys and included the activity of more than 438 neurons (232 in M1 and 206 in SMA). To detect evoked activity, we tested the firing rate in a 500-msec period from 100 msec
A review on qualifications and cost effectiveness of induced pluripotent stem cells (IPSCs)-induced cardiomyocytes in drug screening tests
Published in Archives of Physiology and Biochemistry, 2023
Golrokh Malihi, Vahid Nikoui, Elliot L. Elson
Considering electrical conductance in cardiac functionality allowed researchers to characterise immaturity of iPSC-CMs, tissue health or disease state on cardiac model of iPSCs, and to distinguish between cell types in iPSC-CMs. Electrical conductance of iPSC-CMs is measured by extracellular field potential recordings, or sharp electrode recordings. Field potential recordings are easily measured by multi electrode array (MEA) plates. Field potential duration (FPD) correlates with the action potential duration (APD) in a single cardiomyocyte, and APD also correlates with the QT interval in EKG of the heart (Stett et al.2003). The technique, which has been used to test drug-induced arrhythmia (e.g. QT prolongation), is an important effect that can cause withdrawal of many drugs from the market. (Kehat et al.2002, Stett et al.2003, Yamazaki et al.2012).
Deep brain stimulation and stereotactic-assisted brain graft injection targeting fronto-striatal circuits for Huntington’s disease: an update
Published in Expert Review of Neurotherapeutics, 2022
Thomas Kinfe, Alessandro Del Vecchio, Martin Nüssel, Yining Zhao, Andreas Stadlbauer, Michael Buchfelder
To shed light under such circumstances, Ferrea et al. applied electrophysiological measures in terms of local field potential (LFP). The first step toward the assessment and definition of specific LFP bands was performed by the Surgical Approaches Task Force of the EHDN study group, which targeted the GPi as well as the GPe. Spectral analysis was performed for alpha (8–12 Hz), beta (13–30 Hz), and gamma (30–80 Hz) bands in a subset of 2 juvenile HD patients (Westphal variant) up to 12 months after GPi or GPe-DBS. Notably, alpha and beta oscillations displayed similar characters to those detected in other movement disorders with a kinetic-rigid and dystonic phenotype responsive to pallidal DBS. These findings contrasted with the negative clinical outcome of these both juvenile HD subjects compared to the late-onset HD subgroup treated with GPi or GPe stimulation, indicating GP DBS may have limitations in efficacy in the juvenile subset of stimulated HD subjects [9,24]. Indeed, it would have been of interest to explore LFP pattern in a larger and homogenous subset of HD patients to elucidate pallidal DBS effects on neural circuits relevant for HD pathophysiology. Enhanced neuroimaging techniques (functional and structural connectivity) may support not only the highly precise placement of DBS electrodes in the target region but may allow to specifically tailor DBS waveforms on an individual level as confirmed for different other DBS targets and DBS indications using a network-related approach.
Behavior and electrophysiological effects on striatum-nigra circuit after high frequency stimulation. Relevance to Parkinson and epilepsy
Published in International Journal of Neuroscience, 2023
Igor Tchaikovsky, Marilia Marinho Lucena, Belmira-Lara da Silveira Andrade da Costa, Norberto Garcia-Cairasco, Pedro V. Carelli, Marcelo Cairrao
Regarding the evoked potential, our initial hypothesis included possible increases or decreases in the local field potential after HFS in the striatum. It is described in literature that the striatum can undergo LTP or LTD, depending on stimulation parameters. Subsequently, it was speculated that behavioral changes would have any correspondence with the direction of the local field potential. But this was not the case. All rats showed the same behavior effects irrespective of the increase or decrease in the local field potential. A limitation of present study is that there was no fine identification of the pathways involved in the evoked potential, that is, direct or indirect. It is possible that in those rats where the evoked potential reached the indirect pathway, an inhibition of the substantia nigra was seen, and consequently a decrease in the local field potential. The opposite could also be true, that is, in those rats with direct pathway being recorded, the increase in the local field potential could have occurred. This study must be replied with pathway tracers and a more refined anatomical observation. Notwithstanding, present work reached its main goal that was to induce plasticity in the striatum and describe its behavioral and electrophysiological effects in the striatum-nigra effects. These experiments pave the way to new protocols of circuit modulation and impacts in the understanding of Parkinson´s disease.
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