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EEG Power Spectra (eeg + power_spectrum)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Localized transmeningeal muscimol prevents neocortical seizures in rats and nonhuman primates: Therapeutic implications

EPILEPSIA, Issue 4 2009
Nandor Ludvig
Summary Purpose:, To determine whether muscimol delivered epidurally or into the subarachnoid space can prevent and/or terminate acetylcholine (Ach),induced focal neocortical seizures at concentrations not affecting behavior and background electroencephalography (EEG) activity. Methods:, Rats (n = 12) and squirrel monkeys (n = 3) were chronically implanted with an epidural or subarachnoid drug delivery device, respectively, over the right frontal/parietal cortex, with adjacent EEG electrodes. Recordings were performed in behaving rats and chaired monkeys. Via the implants, either a control solution (artificial cerebrospinal fluid, ACSF) or muscimol (0.25,12.5 mm) was delivered locally as a "pretreatment," followed by the similar delivery of a seizure-inducing concentration of Ach. In five additional rats, the quantities of food-pellets consumed during epidural ACSF and muscimol (2.5 mm) exposures were measured. In a last group of four rats, muscimol (0.8,2.5 mm) was delivered epidurally during the ongoing, Ach-induced EEG seizure. Results:, In contrast to ACSF pretreatments, epidural muscimol pretreatment in rats completely prevented the seizures at and above 2.5 mm. In the monkeys, subarachnoid muscimol pretreatments at 2.5 mm completely prevented the focal-seizure,inducing effect of Ach, whereas similar deliveries of ACSF did not affect the seizures. Furthermore, 2.5 mm epidural muscimol left the eating behavior of rats intact and caused only slight changes in the EEG power spectra. Finally, muscimol delivery during Ach-induced EEG seizures terminated the seizure activity within 1,3 min. Conclusions:, The results of this study suggest that muscimol is a viable candidate for the transmeningeal pharmacotherapy of intractable focal epilepsy. [source]

An oscillatory interference model of grid cell firing

HIPPOCAMPUS, Issue 9 2007
Neil Burgess
Abstract We expand upon our proposal that the oscillatory interference mechanism proposed for the phase precession effect in place cells underlies the grid-like firing pattern of dorsomedial entorhinal grid cells (O'Keefe and Burgess (2005) Hippocampus 15:853,866). The original one-dimensional interference model is generalized to an appropriate two-dimensional mechanism. Specifically, dendritic subunits of layer II medial entorhinal stellate cells provide multiple linear interference patterns along different directions, with their product determining the firing of the cell. Connection of appropriate speed- and direction- dependent inputs onto dendritic subunits could result from an unsupervised learning rule which maximizes postsynaptic firing (e.g. competitive learning). These inputs cause the intrinsic oscillation of subunit membrane potential to increase above theta frequency by an amount proportional to the animal's speed of running in the "preferred" direction. The phase difference between this oscillation and a somatic input at theta-frequency essentially integrates velocity so that the interference of the two oscillations reflects distance traveled in the preferred direction. The overall grid pattern is maintained in environmental location by phase reset of the grid cell by place cells receiving sensory input from the environment, and environmental boundaries in particular. We also outline possible variations on the basic model, including the generation of grid-like firing via the interaction of multiple cells rather than via multiple dendritic subunits. Predictions of the interference model are given for the frequency composition of EEG power spectra and temporal autocorrelograms of grid cell firing as functions of the speed and direction of running and the novelty of the environment. © 2007 Wiley-Liss, Inc. [source]

Sleep electroencephalogram in children with a parental history of alcohol abuse/dependence

JOURNAL OF SLEEP RESEARCH, Issue 1p2 2010
LEILA TAROKH
Summary We examined the sleep electroencephalogram (EEG) in 9- and 10-year-old children with (PH+) and without (PH,) a parental history of alcohol abuse/dependence to determine whether sleep disturbances associated with alcohol precede the onset of alcohol use. Participants slept on a fixed sleep schedule that ensured at least a 10-h time in bed for 1 week before an adaptation and baseline night. Data were collected in a four-bed sleep research laboratory. Thirty healthy boys and girls aged 9 or 10 years were classified as either PH+ or PH, based on DSM-IV criteria applied to structured parental interviews. All-night polysomnography was performed, sleep data were scored visually in 30-s epochs, and EEG power spectra were calculated for each epoch. All-night EEG spectra were calculated for rapid eye movement (REM) and non-REM (NREM) sleep, and cycle-by-cycle spectra were calculated for NREM sleep. The two groups did not differ on any sleep stage variable. All-night analyses revealed normalized power in the delta band and spindle range were lower in PH+ children. Within NREM sleep cycles PH+ children exhibited less normalized power in the delta band and spindle range compared with PH, children. This effect occurred in the first four cycles and was most pronounced in the first sleep cycle of the night. We found no signs of sleep disruption in sleep stages for PH+ children. Sleep EEG spectral differences, however, suggest that certain circuits responsible for ,protecting' sleep may be impaired in PH+ children, which may lead to disrupted sleep later in life. [source]

Music and emotion: Electrophysiological correlates of the processing of pleasant and unpleasant music

PSYCHOPHYSIOLOGY, Issue 2 2007
Daniela Sammler
Abstract Human emotion and its electrophysiological correlates are still poorly understood. The present study examined whether the valence of perceived emotions would differentially influence EEG power spectra and heart rate (HR). Pleasant and unpleasant emotions were induced by consonant and dissonant music. Unpleasant (compared to pleasant) music evoked a significant decrease of HR, replicating the pattern of HR responses previously described for the processing of emotional pictures, sounds, and films. In the EEG, pleasant (contrasted to unpleasant) music was associated with an increase of frontal midline (Fm) theta power. This effect is taken to reflect emotional processing in close interaction with attentional functions. These findings show that Fm theta is modulated by emotion more strongly than previously believed. [source]