EEG Desynchronization Research Articles

The correlation between motor impairments and event-related desynchronization during motor imagery in ALS patients

BackgroundThe event-related desynchronization (ERD) in EEG is known to appear during motor imagery, and is thought to reflect cortical processing for motor preparation. The aim of this study is to examine the modulation of ERD with motor impairment in ALS patients. ERD during hand motor imagery was obtained from 8 ALS patients with a variety of motor impairments. ERD was also obtained from age-matched 11 healthy control subjects with the same motor task. The magnitude and frequency of ERD were compared between groups for characterization of ALS specific changes.ResultsThe ERD of ALS patients were significantly smaller than those of control subjects. Bulbar function and ERD were negatively correlated in ALS patients. Motor function of the upper extremities did was uncorrelated with ERD.ConclusionsALS patients with worsened bulbar scales may show smaller ERD. Motor function of the upper extremities did was uncorrelated with ERD.

Respiratory Component of the Orienting Reflex: A Novel Sensitive Index of Sensory-Induced Arousal in Rats

In humans, the integrated response to a novel stimulus (orienting reflex, OR) includes behavioral (head turning etc.) and well-characterized physiological components (changes in heart rate, respiration, skin conductance, and EEG patterns). In rodents, the physiological components of the OR include changes in heart rate and cutaneous vasoconstrictor tone, but respiratory changes have so far not been systematically documented. In the present study conducted in adult male Wistar rats, the OR was elicited by 60-dB acoustic tones while animals were in a whole-body plethysmograph for respiratory recordings. In addition to respiration, in different groups of animals we concurrently recorded either EEG, or heart rate (both by biotelemetry), or tail blood flow (using ultrasound Doppler). Acoustic stimuli provoked vigorous tachypneic responses with respiratory rate rising from 80–100 to 450–650 cpm, and with small and variable changes in tidal volume. This respiratory arousal response was often, but not always, accompanied by EEG desynchronization and by variable tail vasoconstriction, and by small and inconsistent changes in the heart rate. We conclude that tachypneic responses are a new highly sensitive index of sensory-induced arousal.

Critical Role of Peripheral Actions of Intravenous Nicotine in Mediating Its Central Effects

In addition to its direct action on central neurons, nicotine (NIC) activates multiple nicotinic acetylcholine receptors localized on afferent terminals of sensory nerves at the sites of its administration. Although the activation of these receptors is important in mediating the primary sensory and cardiovascular effects of NIC, their role in triggering and maintaining the neural effects of NIC remains unclear. Using high-speed electroencephalography (EEG) and electromyography (EMG) recordings in freely moving rats, we showed that NIC at low intravenous (i.v.) doses (10-30 μg/kg) induced rapid, strong, and prolonged EEG desynchronization both in the cortex and ventral tegmental area (with decreases in α and robust increases in β and γ frequencies) and neck EMG activation that began during the injection (∼5 s). EEG and EMG effects of NIC were drastically reduced by pre-treatment with hexamethonium, a peripherally acting NIC antagonist, and the immediate EEG effects of NIC were strongly inhibited during urethane anesthesia. Although NIC pyrrolidine methiodide, a quaternary NIC analog that cannot enter the brain, also induced rapid EEG desynchronization, its effects were much shorter and weaker than those of NIC. Therefore, NIC by acting on peripheral nicotinic receptors provides a major contribution to its rapid, excitatory effects following i.v. administration. Since this action creates a sensory signal that rapidly reaches the brain via neural pathways and precedes the slower and more prolonged direct actions of NIC on brain cells, it could have a major role in associative learning and changes in the behavioral and physiological effects of NIC following its repeated use.

Experience with novel actions modulates frontal alpha EEG desynchronization

There is growing interest in the effects of experience on the neural processes linking action execution and action perception. We tested whether experience with unfamiliar actions can alter desynchronization of alpha-range power in the EEG upon re-observation of those actions. In a training session, participants ( N = 21) watched videos of novel drawing movements. Half of the movements were imitated after each viewing, and half of the movements were seen but not imitated, thus forming two training conditions: visual plus motor experience (V + M), and visual experience only (VO). In a testing session the next day, participants were shown the same videos of both sets of movements, and were also shown a third, completely novel, set of movements. Imitative performance was better for both training conditions than for novel actions. Event-related EEG desynchronization in the upper alpha band during action observation differed between conditions at frontal electrode sites, with novel actions being associated with less frontal desynchronization compared to V + M and VO actions. Differences between conditions were not noted over other regions. This suggests that moderate amounts of initial experience with novel actions can alter the neural processing of these actions when viewed again, particularly over frontal regions.

Intravenous saline injection as an interoceptive signal in rats

Addictive drugs are commonly delivered in the organism by means of intravenous (i.v.) injections. Since saline mimics the blood environment by basic ionic properties and pH, it is generally assumed that it should not have any physiological effects, serving as a control for the effects induced by drugs. The aim of the study was to examine central, behavioral, and physiological effects of stress- and cue-free i.v. saline injection in freely moving rats. We examined how a typical low-volume and slow-speed saline injections affect cortical electroencephalograpy (EEG), neck electromyography (EMG), locomotor activity as well as central and peripheral temperatures. Saline injection made during slow-wave synchronized activity induces rapid transient EEG desynchronization, manifesting as a drop of EEG total power, decrease in alpha activity, and increases in beta and gamma activities. Saline injection did not affect locomotor activity as well as brain and body temperatures, but induced a transient increase in neck EMG activity and a rapid brief drop in skin temperature, suggesting peripheral vasoconstriction. These responses were virtually fully absent when saline injection was made during naturally occurring desynchronized EEG activity during behavioral activity. Since i.v. injection is able to produce a peripheral sensory signal that is transmitted rapidly to the CNS and followed by a more prolonged effect of the injected drug on brain cells, with repeated drug administrations, the injection itself could play a role of drug-related sensory cue, thus inducing conditioned physiological responses and altering the effects of injected drugs.

Effect of intravenous sodium salicylate administration prior to castration on plasma cortisol and electroencephalography parameters in calves

Nociception is an unavoidable consequence of many routine management procedures such as castration in cattle. This study investigated electroencephalography (EEG) parameters and cortisol levels in calves receiving intravenous sodium salicylate in response to a castration model. Twelve Holstein calves were randomly assigned to the following groups: (i) castrated, untreated controls, (ii) 50 mg/kg sodium salicylate IV precastration, were blood sampled at 0, 5, 10, 20, 30, 45, 60, 90, 120, 150, 180, 240, 360, and 480 min postcastration. The EEG recording included baseline, castration, immediate recovery (0-5 min after castration), middle recovery (5-10 min after castration), and late recovery (10-20 min after castration). Samples were analyzed by competitive chemiluminescent immunoassay and fluorescence polarization immunoassay for cortisol and salicylate, respectively. EEG visual inspection and spectral analysis were performed. Statistical analyses included anova repeated measures and correlations between response variable. No treatment effect was noted between the two groups for cortisol and EEG measurements, namely an attenuation of acute cortisol response and EEG desynchronization in sodium salicylate group. Time effects were noted for EEG measurements, cortisol and salicylates levels. Significant correlations between cortisol and EEG parameters were noted. These findings have implications for designing effective analgesic regimens, and they suggest that EEG can be useful to monitor pain attributable to castration.

Modulation of Event-related Desynchronization duringMotor Imagery with Transcranial Direct Current Stimulationin a Patient with Severe Hemiparetic Stroke: A Case Report

Recently, surface electroencephalogram (EEG)-based brain-machine interfaces (BMI) have been used for people with disabilities. As a BMI signal source, event-related desynchronization of alpha-band EEG (8-13 Hz) during motor imagery (mu ERD), which is interpreted as desynchronized activities of the activated neurons, is commonly used. However, it is often difficult for patients with severe hemiparesis to produce mu ERD of sufficient strength to activate BMI. Therefore, whether it is possible to modulate mu ERD during motor imagery with anodal transcranial direct-current stimulation (tDCS) was assessed in a severe left hemiparetic stroke patient. EEG was recorded over the primary motor cortex (M1), and mu ERD during finger flexion imagery was measured before and after a 5-day course of tDCS applied to M1. The ERD recorded over the affected M1 increased significantly after tDCS intervention. Anodal tDCS may increase motor cortex excitability and potentiate ERD during motor imagery in patients with severe hemiparetic stroke.

Neural correlates of action observation and execution in 14-month-old infants: an event-related EEG desynchronization study.

There is increasing interest in neurobiological methods for investigating the shared representation of action perception and production in early development. We explored the extent and regional specificity of EEG desynchronization in the infant alpha frequency range (6-9 Hz) during action observation and execution in 14-month-old infants. Desynchronization during execution was restricted to central electrode sites, while action observation was associated with a broader desynchronization across frontal, central, and parietal regions. The finding of regional specificity in the overlap between EEG responses to action execution and observation suggests that the rhythm seen in the 6-9 Hz range over central sites in infancy shares certain properties with the adult mu rhythm. The magnitude of EEG desynchronization to action perception and production appears to be smaller for infants than for adults and older children, suggesting developmental change in this measure.

Interictal epileptiform discharges and phasic phenomena of REM sleep

The objective of this study was to assess the effect of phasic rapid eye movement (REM) sleep events on interictal epileptiform discharges (IEDs). Twelve patients with focal epilepsy and IEDs during REM sleep were examined by video-EEG monitoring. The number of IEDs was calculated in different REM sleep episodes according to the rate of rapid eye movements. A negative correlation was identified between the occurrence of rapid eye movements and IEDs, indicating that the suppression of propagation of IEDs during REM sleep is enhanced by phasic REM sleep events, probably as a result of phasic activation of cholinergic neurons of the ponto-mesencephalic tegmentum. This study demonstrates that the degree of EEG desynchronization and IEDs is influenced by REM density.

Stimulus type does not affect infant arousal response patterns

Previous studies have examined infant arousal responses to various arousal stimuli; however it is unclear whether the patterns of responses to different stimuli are comparable within subjects across early development. The aim of the study was to compare the effects of both respiratory and somatosensory stimulation on arousal processes in the same infants throughout the first 6 months of life. Ten healthy term infants were studied with daytime polysomnography at 2-4 weeks, 2-3 and 5-6 months. Infants were challenged with both hypoxia (15% O(2), balanced N(2)) and a pulsatile air-jet to the nostrils. Stimulus-induced sub-cortical activations (SCA) and cortical arousals (CA) were expressed as percentages of total arousals. Heart rate (HR) changes and electroencephalogram (EEG) desynchronization were also contrasted for the two stimuli. During active sleep (AS), there was no significant effect of stimulus type on proportions of CA at any of the ages studied. During quiet sleep (QS), hypoxia elicited higher CA proportions than the air-jet at 2-3 and 5-6 months (P < 0.01). Overall, HR responses associated with SCA and CA and the duration of EEG desynchronization during CA were similar for both stimuli. Mild hypoxia and nasal air-jet stimulation produce qualitatively similar patterns of arousal responses during the first 6 months of life, supporting the concept of a final common neural pathway of cortical activation. Quantitatively, full CA from QS is more likely with hypoxia, in keeping with it being a life-threatening stimulus. This study supports the nasal air-jet as an appropriate stimulus for assessing developmental patterns of infant arousal process.

Changes in subthalamic activity during movement observation in Parkinson’s disease: Is the mirror system mirrored in the basal ganglia?

The observation of a voluntary movement executed by another person is associated with an alpha and beta EEG desynchronization over the motor cortex, thought to reflect activity from the human "mirror neuron" system. The aim of our work was to study the changes in local field potentials (LFP) recorded from the subthalamic nucleus (STN) and their relationship with cortical activity, during movement observation. Bilateral EEG and STN LFP recordings were acquired in 18 patients with Parkinson's disease, through surgically implanted electrodes for deep brain stimulation. Oscillatory changes during movement execution and movement observation were compared with two different control conditions (simple stimulus and rotating stimulus observation), in "off" and "on" motor states. Time-frequency transforms and event-related coherence were used for the analysis. Movement observation was accompanied by bilateral beta reduction in subthalamic power and cortico-STN coherence, which was smaller than the decrease observed during movement execution, but significant when compared with the two control conditions. Movement observation is accompanied by changes in the beta oscillatory activity of the STN, similar to those observed in the EEG. These changes suggest that the basal ganglia might be engaged by the activity of the human mirror system.

A central role for the periphery in the rapid action of cocaine on brain neurons:focus on “Rapid EEG desynchronization and EMG activation induced by intravenous cocaine in freely moving rats: a peripheral, nondopamine neural triggering”

back in the day when research in neuropharmacology was done almost exclusively on peripheral tissue, limited technology prevented sophisticated assessments of drug-induced changes in brain function. As technology improved, so did the scope of investigation, and researchers today study the brain

Behavioural and neurophysiological correlates of human cataplexy: A video-polygraphic study

To investigate the behavioural and neurophysiological pattern of cataplexy. Seven narcolepsy with cataplexy patients underwent daytime videopolygraphy using humorous movies or/and jokes to trigger cataplectic attacks. During segmental cataplectic attacks, EMG showed brief and irregular periods of silencing focally involving facial, neck, axial or limb muscles, sometimes coinciding with bursts of rapid eye movements. All patients enacted intentional movements in response to these segmental postural lapses. During global cataplectic attacks, EMG showed suppression of activity alternated with patterned enhancement, enhanced EMG activity in neck muscles preceding that of other cranial, axial and lower limb muscles. This waxing and waning EMG pattern ended with a complete body collapse and persistent muscle atonia. Breathing irregularities, heart rate (HR) instability and EEG desynchronization were observed during global cataplectic attacks without any appreciable blood pressure changes, but with HR deceleration and silencing of sympathetic skin response while in complete atonia. Patients subjectively perceived the involuntary postural lapses as startling and alarming. Cataplexy in our patients showed many of the features of tonic REM sleep. Cataplexy can be construed as a "freezing-like" perturbation of the orienting response with transient impairment of posture and movements resulting in a "patchwork-compromise-behaviour".

Cocaine action on peripheral, non-monoamine neural substrates as a trigger of electroencephalographic desynchronization and electromyographic activation following i.v. administration in freely moving rats

Many important physiological, behavioral and subjective effects of i.v. cocaine (COC) are exceptionally rapid and transient, suggesting a possible involvement of peripheral neural substrates in their triggering. In the present study, we used high-speed electroencephalographic (EEG) and electromyographic (EMG) recordings (4-s resolution) in freely moving rats to characterize the central electrophysiological effects of i.v. COC at low doses within a self-administration range (0.25–1.0 mg/kg). We found that COC induces rapid, strong, and prolonged desynchronization of cortical EEG (decrease in alpha and increase in beta and gamma activity) and activation of the neck EMG that begin within 2–6 s following the start of a 10-s injection; immediate components of both effects were dose-independent. The rapid effects of COC were mimicked by i.v. COC methiodide (COC-MET), a derivative that cannot cross the blood–brain barrier. At equimolar doses (0.33–1.33 mg/kg), COC-MET had equally fast and strong effects on EEG and EMG total powers, decreasing alpha and increasing beta and gamma activities. Rapid EEG desynchronization and EMG activation was also induced by i.v. procaine, a structurally similar, short-acting local anesthetic with virtually no effects on monoamine uptake; at equipotential doses (1.25–5.0 mg/kg), these effects were weaker and shorter in duration than those of COC. Surprisingly, i.v. saline injection delivered during slow-wave sleep (but not during quiet wakefulness) also induced a transient EEG desynchronization but without changes in EMG and motor activity; these effects were significantly weaker and much shorter than those induced by all tested drugs. These data suggest that in awake animals, i.v. COC induces rapid cortical activation and a subsequent motor response via its action on peripheral non-monoamine neural elements, involving neural transmission via visceral sensory pathways. By providing a rapid neural signal and triggering neural activation, such an action might play a crucial role in the sensory effects of COC, thus contributing to the learning and development of drug-taking behavior.

Mirror activity in the human brain while observing hand movements: A comparison between EEG desynchronization in the μ-range and previous fMRI results

Mu (μ) rhythms are EEG oscillations between 8–13 Hz distinguished from alpha by having more anterior distribution and being desynchronized by motor rather than visual activity. Evidence accumulating during the last decade suggests that the desynchronization of μ rhythms (μ suppression) might be also a manifestation of a human Mirror Neuron System (MNS). To further explore this hypothesis we used a paradigm that, in a previous fMRI study, successfully activated this putative MNS in humans. Our direct goal was to provide further support for a link between modulation of μ rhythms and the MNS, by finding parallels between the reported patterns of fMRI activations and patterns of μ suppression. The EEG power in the μ range has been recorded while participants passively observed either a left or a right hand, reaching to and grasping objects, and compared it with that recorded while participants observed the movement of a ball, and while observing static grasping scenes or still objects. Mirroring fMRI results (Shmuelof, L., Zohary, E., 2005. Dissociation between ventral and dorsal fMRI activation during object and action recognition. Neuron 47, 457–470), μ suppression was larger in the hemisphere contra-lateral to the moving hand and larger when the hands grasped different objects in different ways than when the movement was repetitive. No suppression was found while participants observed still objects but μ suppression was also found while seeing static grasping postures. These data are discussed in light of similar parallels between modulations of alpha waves and fMRI while recording EEG in the magnet. The present data support a link between μ suppression and a human MNS.

Long-term effect of vagus nerve stimulation on interictal epileptiform discharges in refractory epilepsy

BackgroundVagus nerve stimulation (VNS) therapy has been widely recognized as an effective alternative for the treatment of refractory epilepsy. However, the precise mechanism of VNS is poorly understood. The purpose of this study was to observe the long-term interictal EEG changes induced by VNS, and to investigate the probable mechanism of action of VNS in achieving seizure control. MethodsEight patients with VNS were selected from two epilepsy centers in China (Harbin and Shanghai) between 2001 and 2004. We studied the clinical efficacy by long-term follow-up, ranging from 37 to 81 months (mean 55.8 months). Moreover, serial EEGs were performed at the different time (preoperative baseline, 3, 6, 12, and 24 months after VNS initiation) and the different states of VNS stimulator (“activation”, “deactivation” and “reactivation”). ResultsA ≥50% seizure reduction was achieved in 12.5%, 62.5%, 75%, 62.5% and 75% of the total patients (n=8) at 6, 12, 18, 24 and 36 months of post-VNS, respectively. The results revealed a statistically significant progressive decrease in the number of IEDs (interictal epileptiform discharges) on EEG with time (P<0.01). Significant correlation had been highlighted after 6 months of VNS stimulation, between the reduction of seizure frequency and the decreasing of IEDs (P<0.01). Furthermore, statistically significant difference of IEDs was seen when comparing the state of “deactivation” with the states of “activation” and “reactivation”, respectively (P<0.01). However, there was no significant difference in IEDs between “activation” and “reactivation” (P>0.05). ConclusionsVNS is an efficient, well-tolerated therapy for refractory epilepsy. It can induce progressive electrophysiological effect on epileptiform activity over time. This may reflect the mechanism of chronic action of VNS with desynchronization of EEG in achieving seizure control.

Effects of brief imitative experience on EEG desynchronization during action observation

There is a good deal of evidence that observing the actions of other people is associated with activation of the observer's motor system, which may reflect involvement of the mirror neuron system (MNS) in certain aspects of action processing in humans. Furthermore, variation in the extent of this activation appears to be partly dependent on individuals’ experience with performing the observed actions. However, very little work has examined the processes through which the observation of unfamiliar actions – which are not in an observer's motor repertoire – might become associated with MNS activation. In the current study we examined differences in EEG desynchronization in alpha-range bands during action observation following very brief imitative experience with the observed actions, which were novel drawing movements. Compared to carrying out unrelated actions, brief imitative experience was specifically associated with a significantly larger desynchronization in the 11–13 Hz band at mid-frontal sites (F3 and F4) when a previously imitated action was viewed again. In addition, higher fidelity of imitation was significantly correlated with greater bilateral desynchronization of the lower mu band (8–10 Hz) at central sites (C3 and C4) during subsequent observation of the previously imitated action. Our findings point to the involvement of frontal cortical processing and the MNS in the early stages of imitative learning.

Research priorities in epilepsy for the next decade—A representative view of the European scientific community: Summary of the ILAE Epilepsy Research Workshop, Brussels, 17–18 January 2008

Research priorities in epilepsy for the next decade—A representative view of the European scientific community: Summary of the ILAE Epilepsy Research Workshop, Brussels, 17–18 January 2008

The involvement of cognitive processing in a perceptual-motor process examined with EEG time–frequency analysis

For motor activities, visual information is crucial for organizing a movement with respect to a given situation. The present study investigates how cognitive information processing is associated with this visuomotor process. Brain dynamics in executing two perceptual-motor tasks were examined in terms of event-related synchronization (ERS) and event-related desynchronization (ERD) of EEG. Those tasks were (1) reaching toward and grasping a visual object with a pinch grip, and (2) matching the pinch grip size with respect to the perceived object size. According to the aperture size in the task execution, both the tasks were affected by the perceived object size inducing the Ebbinghaus illusion. The alpha-ERD patterns were associated with the movement execution and appeared to be identical in both the tasks, whilst the gamma-ERS appeared only for the grasping motion. These results suggest that cognitive processing was involved not only in the matching task but also in the grasping task. These ERD/ERS patterns are thought to reflect the similarity and difference in the perceptual-motor processes between the two tasks. The analysis of ERD/ERS can provide insight on the qualitative feature in a visuomotor process associated with the involvement of cognitive processing.

Role of ascending activating systems in the regulation of sensory processing in rats

Event Abstract Back to Event Role of ascending activating systems in the regulation of sensory processing in rats Bálint Nagy1*, Tünde Hajnik1, A. Toth1 and L. Detari1 1 Department of Physiology and Neurobiology, Eötvös Loránd University, Hungary The mechanisms of cortical processing of sensory inputs can be investigated by studying evoked potentials. Configuration and amplitude of midlatency components in auditory evoked potentials depend not only on the stimuli, but on the background EEG as well. Decreased activation of the cortex (high delta intensity) causes increased amplitudes of these peaks. The appearance of the large delta waves (0.5 - 4.0 Hz) in the cortical EEG – generated by the slow oscillation of membrane potentials of pyramidal cells – depends on the diminished activity of the ascending activating systems. To investigate the contribution of decreased activity in the different ascending activating systems to the increased amplitude of midlatency evoked potential components, we examined the effects of cholinergic, adrenergic, dopaminergic, and serotoninergic drugs – all causing EEG desynchronization. The alpha-2 adrenergic receptor antagonist yohimbine and the selective serotonin reuptake inhibitor fluoxetine increased the evoked potential amplitudes, though decreased delta power. The cholinesterase inhibitor eserine decreased both peak amplitudes and background delta intensity. The dopaminergic agonist apomorphine first decreased then increased delta power, but caused low peak amplitudes and shortened peak latencies in both phases. Our results indicate that while ascending activating systems influence delta power similarly, they have differential effects on sensory processing. Conference: 12th Meeting of the Hungarian Neuroscience Society, Budapest, Hungary, 22 Jan - 24 Jan, 2009. Presentation Type: Poster Presentation Topic: Developmental neurobiology and subcortical functions Citation: Nagy B, Hajnik T, Toth A and Detari L (2009). Role of ascending activating systems in the regulation of sensory processing in rats. Front. Syst. Neurosci. Conference Abstract: 12th Meeting of the Hungarian Neuroscience Society. doi: 10.3389/conf.neuro.01.2009.04.069 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: 02 Mar 2009; Published Online: 02 Mar 2009. * Correspondence: Bálint Nagy, Department of Physiology and Neurobiology, Eötvös Loránd University, Budapest, Hungary, nagyblint@yahoo.com 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 Bálint Nagy Tünde Hajnik A. Toth L. Detari Google Bálint Nagy Tünde Hajnik A. Toth L. Detari Google Scholar Bálint Nagy Tünde Hajnik A. Toth L. Detari PubMed Bálint Nagy Tünde Hajnik A. Toth L. Detari 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.