C3 Electrodes Research Articles

Ethanol-Induced Alterations in Electroencephalographic Activity in Adult Males

The present investigation examined the effects of placebo (P), low-dose (LD), and high-dose (HD) ethanol on electroencephalographic (EEG) activity in 21 healthy, adult males (X = 22.7 years). Only one condition (P, LD, or HD) was presented per day and the condition order was randomized. For each subject, blood-alcohol levels measured via breathalyzer and EEG activity, using the entire 10/20 International System, were recorded both prior to and at intervals of 35, 70, 105, and 140 minutes after P, LD, or HD administration. The Fast Fourier Transform was used to calculate power spectral densities for each EEG recording. Measures of the relative areas under the power spectral curve were made for each of the following frequency bands: slow alpha (7.5 to 10 Hz); fast alpha (10.5 to 13.0 Hz); slow beta (13.5 to 19.5 Hz); and fast beta (20 to 26 Hz) at electrodes F3, F4, C3, C4, P3, P4, O1, and O2. Repeated-measures multivariate analysis of variance performed on normalized relative area values revealed that ethanol had significant effects on EEG activity at anterior sites: frontal (F3, F4) and central (C3, C4) that presented as increased activity in the slow alpha frequency band. These results suggest a differential responsivity of both cortical region and EEG frequency band to the effects of ethanol ingestion.

Tonic changes in alpha power during immersion of the hand in cold water

Phasic event-related desynchronization (ERD) of alpha activity briefly follows many types of stimulation. In order to define EEG changes resulting from longer stimulation, EEG records were made before and during hand immersion into cool and painfully cold water (cold pressor). Five minutes of 13-lead EEG records were obtained from 14 subjects for each condition. EEG frequency analysis was performed on artifact-free epochs from 60 to 240 sec following immersion. Following an initial phasic decrease in alpha power during cold water immersion, there was an augmentation of alpha power (8–12 Hz) in bilateral frontal and posterior electrodes. This augmentation was largely the result of an increase in the low alpha band (8–18 Hz). Alpha power at both central electrodes C3 and C4 changed little during cold water immersion. Cool water immersion produced less alpha power augmentation than cold water immersion. These observed changes were primarily in the high alpha band (10–12 Hz) and were larger in electrodes ipsilateral rather than contralateral to the stimulation. There was also an increase of beta bilaterally in frontal and posterior regions with cold water immersion. Our data demonstrate sustained topographic EEG responses during tonic stimulation from hand immersion in painfully cold water. These changes differ from those produced by stimulation with cool water immersion.

Functional topography during sensorimotor activation studied with event-related desynchronization mapping.

Event-related desynchronization (ERD) of alpha components was studied in four subjects during self-paced voluntary movements and somatosensory stimulation. EEG was recorded from 29 electrodes with a common right ear reference; local average reference derivations were calculated and used for computing ERD maps at 250-ms intervals. It was found that upper alpha components were desynchronized close to electrodes C3 and C4 overlying the primary sensorimotor cortex during voluntary movements and somatosensory stimulation. ERD started contralaterally more than 2 s before the movement and some hundreds of milliseconds before the stimulation. During the performance of unilateral movement and unilateral stimulation, ERD was bilaterally symmetric. Desynchronization of lower alpha components was found over the superior parietal cortex, clearly starting some hundreds of milliseconds after the desynchronization of upper frequency components. Therefore, the desynchronization of lower and upper alpha components reflects activation of different neuronal structures.

Breach rhythm: The EEG related to skull defects

From 33 patients with skull defects 89 EEGs were recorded, most with X ray control of the electrode sites. In 10 patients records were made shortly before and about 10 days after bone replacement. The remaining cases had EEGs either with or without bone replacement. The amplitude of alpha and frontal fast rhythms might be increased over or near unilateral posterior and frontal defects respectively. This enhancement was by a factor of less than 3. Since the electrode involved might not be in the defect but on adjacent bone this does not seem to be an effect of greater proximity to the generators. In 21 cases with defects involving or near to electrodes C3(4) and T3(4) sharply focal mu-like rhythms at 6–11 c/sec, usually with faster components, were seen. They formed two groups, at C3(4), responsive to fist clenching and other stimuli (not to eye opening) and at T3(4), unresponsive to any stimulus. In both groups the waves often had spike-like negative phases, but true spikes and also random slow waves with the same restricted focus and responsiveness were sometimes seen. Because of this complexity we prefer the term breach rhythm to mu or mu-like. Bone (or acrylic) replacement abolished central breach rhythm in 3 cases, but not in others and it might or might not restore the symmetry of alpha rhythm or fast rhythm, but burr holes, saw cuts etc., always remain after craniotomy. It is argued that, with the possible exception of 2 patients, the breach rhythms described in this series do not represent enhanced normal mu rhythm. Breach rhythm, even when very spike-like, appears to have little relationship to epilepsy and is not an indicator of recurrence of a tumour.

Communication of brain areas during the processing of noxious intracutaneous stimuli in patients with major depression and normal controls

Event Abstract Back to Event Communication of brain areas during the processing of noxious intracutaneous stimuli in patients with major depression and normal controls Lutz Leistritz1*, Thomas Lehmann1, Jaroslav Ionov1, Karl-Jürgen Bär1 and Thomas Weiss1 1 Radboud University, Netherlands Aim: It has been found in clinical practice that depression is a common comorbidity of chronic pain. Conversely, chronic pain represents a common additional symptom of depressed patients. We hypothesized that the processing in the so-called "pain matrix" might be different in patients with major depression (MD). The study investigates the processing of noxious stimuli and interactions within the pain matrix in patients with MD by means of generalized partial directed coherence (gPDC). Methods: 16 patients with MD and 16 controls underwent stimulations on both the right and left middle finger with moderately painful intracutaneous electrical stimuli. The connectivity analysis was based the nine selected EEG electrodes F3, Fz, F4, C3, Cz, C4, P3, Pz, and P4. These electrodes were chosen in order to minimize the dimensionality, and because they are situated above important regions of pain processing, attention, and depression. The relevant frequency range for the connectivity analysis based on the evoked potentials is the delta-, theta- and the alpha-band (1 to 13 Hz, -700 to 0 ms pre-stimulus, 0 to 700 ms post-stimulus). For a consolidated analysis, the mean gPDCs of these frequencies were considered. Surrogate data were utilized to identify significant interactions. Missing values (appr. 3%) were multiple imputed by conditionally specified logistic regression models. Results: We could show stimulus-induced changes of the gPDC in a pre/post stimulus comparison and changes in the connectivity pattern in the post stimulus condition. Furthermore, we could identify network changes correlating to the side stimulated, as well as differences between the controls and MD patients. In a pre/post stimulus comparison, one can observe that patients with MD show less changes in comparison to the controls. In the post-stimulus condition, we can observe both group and side differences in the network structure. Considering the total number of interactions, we could not identify significant changes in the MD group, while we found a significant increase in the control group post stimulus. Conclusion: The gPDC shows networks that include both an attentional area, especially in the frontal regions, as well as a nociceptive area, containing connections in the centroparietal region. Differences between groups in the posterior region might be explained by differences in attentional processes, in processes of stimulus evaluation, or by a temporoparietal dysfunction in depressive patients. Acknowledgments: Bernstein Group 01GQ0703, COST Action BM0601 NEUROMATH. Conference: NeuroMath COST Action BM0601: Neurodynamic Insight into Functional Connectivity, Cognition, and Consciousness, Dubrovnik, Croatia, 27 Mar - 28 Mar, 2010. Presentation Type: Oral Presentation Topic: Talks Citation: Leistritz L, Lehmann T, Ionov J, Bär K and Weiss T (2010). Communication of brain areas during the processing of noxious intracutaneous stimuli in patients with major depression and normal controls. Front. Neurosci. Conference Abstract: NeuroMath COST Action BM0601: Neurodynamic Insight into Functional Connectivity, Cognition, and Consciousness. doi: 10.3389/conf.fnins.2010.05.00011 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 24 Jul 2010; Published Online: 24 Jul 2010. * Correspondence: Lutz Leistritz, Radboud University, Nijmegen, Netherlands, Lutz.Leistritz@mti.uni-jena.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Lutz Leistritz Thomas Lehmann Jaroslav Ionov Karl-Jürgen Bär Thomas Weiss Google Lutz Leistritz Thomas Lehmann Jaroslav Ionov Karl-Jürgen Bär Thomas Weiss Google Scholar Lutz Leistritz Thomas Lehmann Jaroslav Ionov Karl-Jürgen Bär Thomas Weiss PubMed Lutz Leistritz Thomas Lehmann Jaroslav Ionov Karl-Jürgen Bär Thomas Weiss Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.