| Abstract/Results: | ABSTRACT:
The study was focused on functional brain abnormalities associated with autism in 3-8 years-old boys. EEG was recorded 1) under controlled condition of sustained visual attention and 2) during sequential presentation of short novel visual stimuli in two independent samples of boys with autism (BWA) from Moscow (N=21) and Gothenburg (N=23) and a corresponding number of age-matched typically developing boys. EEG spectral power (SP), SP interhemispheric asymmetry, inter-regional coherence within delta, theta, alpha, beta and gamma bands and stimulus-induced EEG alpha oscillatory response were analyzed. The main distinctive features of ongoing EEG in BWA of both samples were the excess of high frequency activity (beta and gamma) and atypical hemispheric asymmetry of slower (delta, theta and alpha) EEG oscillations. The increased amount of fast brain oscillations in EEG of BWA correlated with the degree of developmental delay and may reflect genetically mediated abnormalities of GABA mediator system found in autism. Atypical leftward broadband EEG asymmetry in BWA with a maximum effect over the mid-temporal regions was associated with decreased coherence within the theta band at mid-temporal regions of right hemisphere. Alpha blocking response to novel visual stimuli in BWA was abnormally reduced at higher-order visual areas of right hemisphere. These findings point to a decreased capacity of right hemispheric neural circuits to generate EEG rhythms and may indicate altered regional specialization as well as altered information processing in autism. The concurrent lack of normal leftward asymmetry of mu rhythm suggests that abnormalities in EEG lateralization in autism are regionally/functionally specific.
PUBLICATIONS:
Orekhova EV, Stroganova TA, Posikera IN, Elam M EEG theta rhythm in infants and preschool children. Clin Neurophysiol, 2006;117:1047-1062.; Orekhova EV, Stroganova TA, Nygren G, Tsetlin MM, Posikera IN, Gillberg C, Elam M Excess of high frequency EEG oscillations in boys with autism. Biological Psychiatry, 2007;62(9):1022-9.; Stroganova TA, Nygren G, Tsetlin MM, Posikera IN, Gillberg Ch, Elam M, Orekhova EV Abnormal EEG lateralization in boys with autism. Clinical Neurophysiology Clinical Neurophysiology, 2007;118(8):1842-54; Stroganova TA, Orekhova, E. V.; Prokofyev, A. O.; Posikera, I N; Morozov, A A; Obukhov, Y V.; Morozov, VA. (2007). Inverted event-related potentials response to illusory contour in boys with autism. Neuroreport, 11;18(9), 931-935.; Orekhova EV, Stroganova TA, Nygren G, Posikera IN, Gillberg C, Elam M, High frequency activity in ongoing EEG from young children with autism: A two sample study. International Journal of Psychophysiology, 2006, 61 (3): 347-347 Sp. Iss.; Stroganova TA, Orekhova EV, Nygren G, Tcetlin MM, Posikera
IN, Gillberg C, Elam M Atypical lateralization of spontaneous EEG in young children with autism: A two sample
study. Psychophysiology, 2006, 43: S95-S95 Suppl. 1.
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Reference:
| Stroganova, T. A., Elam, M., Orekhova, E. V., Tsetlin, M. M., & Morozov, A. A. (2008). Early neurophysiological correlates of autism: visual attention and EEG rhythms. In Aquém e além do cérebro. Behind and beyond the brain. Proceedings of the 7th Symposium of Fundação Bial. Porto: Fundação Bial.
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