Comparative EEG study in normal and autistic children

The work represents the results of a comparative study of spectral power as well as averaged coherence in alpha, beta and gamma EEG bands in 5-to-7-year-old autistic and healthy boys in the state of rest and under cognitive load (mental calculation). The mean age of the examined children was 6 years 4 months. In both healthy and autistic children, there was a clear-cut baseline frontal-occipital gradient of the alpha activity. Performance of the cognitive task led to enhancement of spectral power in the alpha1 band and shifting its maximum to the left hemisphere, did not change the activity in the alpha2 band, and considerably increased the spectral power in the alpha3 band. In healthy children, the spectral power and average coherence of the fast rhythms increased in the central and frontal areas of the left hemisphere. The right-side dominance of the spectral power of the alpha band was revealed in autistic children both in the baseline and during cognitive task. The spectral power of the gamma band was higher in autistic children than in healthy children in the baseline. The cognitive task did not change this fast activity in autistic children.     

Peculiarities of EEG in hard-of-hearing children of primary school age

Electroencephalographic examination of 7-to 9-year-old children with sensorineural deafness of degrees II and III included EEG recording in the resting state, in the course of reaction of activation (at opening of the eyes), under conditions of rhythmic photostimulation with frequencies of 4, 6, 9, and 12 sec⁻¹ and under those of the hyperventilation test. The results allow us to conclude that systems responsible for generation of EEG in hard-of-hearing children demonstrate some functionally immaturity. The following facts confirm the above conclusion. As compared with the norm, greater normalized spectral powers (SPs) of the delta and theta rhythms, a higher intensity of electrogenesis (integral power of oscillations) within all frequency ranges, and a smaller mean frequency of the dominant rhythm were typical of hard-of-hearing children. In these children, the reaction of activation in the majority of cases looked like incomplete suppression of the alpha rhythm. Upon rhythmic photostimulation, hard-of-hearing boys and girls demonstrated following of the rhythm at frequencies of 4 and 6 sec⁻¹ while children with normal hearing demonstrated that at 9 and 12 sec⁻¹ frequencies. The characteristics of EEG reactions under the conditions of the hyperventilation test reflected the immaturity of the fronto-thalamic controlling system, as well as certain dysfunction of lower brainstem regions in children with disorders of hearing. Neirofiziologiya/Neurophysiology, Vol. 40, No. 2, pp. 137–146, March–April, 2008.     

Rhythmic components of the EEG of 6-month-old children

Spectral EEG characteristics were studied in 12 six-month healthy children in a state of attention, attracted by visual stimuli and also at lowering of the level of visual afferentation and in drowsiness. 12 parts of EEG records free from artefacts were used, with analysis epoch 5 s and discretion frequency 100 counts/s. Three independent rhythmic EEG components have been revealed in alertness state, corresponding by criteria of functional reactivity and topographic localization to theta, alpha and mu EEG rhythms of the adult man. It is suggested that formation of dominating EEG rhythm with age occurs due to changes in dominant relations of the key rhythmic successions with independent genesis.     

Predictability of EEG interictal spikes.

To determine whether EEG spikes are predictable, time series of EEG spike intervals were generated from subdural and depth electrode recordings from four patients. The intervals between EEG spikes were hand edited to ensure high accuracy and eliminate false positive and negative spikes. Spike rates (per minute) were generated from longer time series, but for these data hand editing was usually not feasible. Linear and nonlinear models were fit to both types of data. One patient had no linear or nonlinear predictability, two had predictability that could be well accounted for with a linear stochastic model, and one had a degree of nonlinear predictability for both interval and rate data that no linear model could adequately account for.     

Intrahemispheric coherence of the EEG depending on clinical manifestations of temporal epilepsy in children

In 53 children aged 3–14 years with temporal epilepsy, coherent analysis of the EEG was performed. Significant interhemispheric differences in coherence dependent on clinical manifestations of the disease were detected. In patients with epileptic seizures, a decrease in coherence on the side of the epileptic focus was recorded, which indicates destruction of the hemisphere. During clinical remission, the coherence on the side of the focus increased to values higher than in the contralateral, “healthy” hemisphere. It may be assumed that an increase in coherence against the background of clinical remission reflects the functioning of an antiepileptic system aimed at inhibiting the spread of the epileptic activity.     

Mu-delta opioid interactions. II: Beta-FNA inhibits DPDPE-induced increases in morphine EEG and EEG spectral power.

In the present study, the effects of beta-FNA on DPDPE-induced increases in morphine EEG and EEG power spectra were assessed. Adult female Sprague-Dawley rats were implanted with cortical EEG electrodes and permanent indwelling ICV and IV cannulae. Rats were administered ICV beta-FNA at 20 nmol or ICV sterile water. Then 18-24 h later, rats were administered ICV DPDPE at 2.5 nmol or ICV sterile water followed, 10 min later, by IV morphine at 3 mg/kg. Morphine-induced changes in EEG global (1-50 Hz) spectral parameters, the duration of morphine-induced high voltage EEG bursts, the period of EEG and behavioral excitation, and the latency to onset of slow-wave sleep were statistically analyzed using a one-way analysis of variance. beta-FNA pretreatment significantly decreased morphine-induced total spectral power seen in the DPDPE + morphine group. beta-FNA pretreatment also significantly decreased the duration of morphine-induced EEG bursts, the period of EEG and behavioral excitation, and the latency to onset of slow-wave sleep in the DPDPE + morphine group. These data, therefore, suggest that DPDPE may be increasing the effects of morphine on EEG through delta opioid receptors associated with the mu-delta opioid receptor complex.     

Effect of learning on EEG characteristics of children during the third year

Characteristics were studied of frequency spectrum and spatial-temporal organization of bioelectrical cerebral activity and also of heart rate dynamics in children of the third year of life in the state of quiet wakefulness and during orienting reaction. Changes were recorded in the parameters of the cerebral activity under the influence of developing learning and in particular of formation of symbolic thinking function. It has been established that the involvement of the child in the process of learning leads to definite shifts of the EEG of quiet wakefulness testifying to acceleration of the process of the CNS functional maturation. Mastering of a high degree of play symbolization causes not only changes in the EEG but also an increase of the child orientating-investigatory activity.     

Correlation of the characteristics of evoked EEG potentials with individual peculiarities of attention in children

We studied correlations of the main parameters of evoked EEG potentials (EP) with individual characteristics of attention in children and teenagers. One hundred and one healthy children (dextrals) took part in the tests. Among them, 26 and 30 children were 5 to 7 and 10 to 12 years old, while the third age group included 45 teenagers (15 to 16 years old). We recorded EP and measured the time of a sensorimotor reaction in the following experimental paradigm. Its program provided automated presentation of a pair of acoustic signals, preliminary and imperative; the subject had to perform a motor reaction, pushing a button with the right thumb, with a minimum delay after the second stimulus. Visual feedback signals informed the subject about the successful or inadequate performance of the reaction (time of reaction was shorter than or exceeded a limit value). Indices characterizing the level of attention were estimated using Find and delete and Schultes tables techniques. A well-manifested N2 component of the EP related to the preliminary signal was a specific feature in the group of 5- to 7-year-old children, while the contingent negative variation (CNV) preceding the motor reaction was poorly developed in this group. The best characteristics of attention in these and older (10 to 12 years old) children were typical of subjects with maximally expressed N1-P2 waves. In teenagers, the best attention was typical of subjects with the highest-amplitude P1 and P2 components, CNV, and P300 wave and with the lowest amplitude of the N1 component.Neirofiziologiya/Neurophysiology, Vol. 36, No. 4, pp. 313–321, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.