Title Evaluation of electrical brain responses to linear chirp-modulated tones: effect of task and changes in neuropsychiatric disorders /
Translation of Title Galvos smegenų elektrinių atsakų į tonus, kurių amplitudė moduliuota tiesiniu čirpu, įvertinimas: užduoties įtaka ir pokyčiai neuropsichiatrinių sutrikimų metu.
Authors Pipinis, Evaldas
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Pages 92
Keywords [eng] chirp ; auditory steady-state response ; electroencephalography ; schizophrenia ; disorders of consciousness
Abstract [eng] There is a great need for objective neurophysiological biomarkers that could be used in diagnostics of neuropsychiatric disorders. Electroencephalogram which represents rhythmic neural activation has been widely utilized for this purpose. By using the basic property of the nervous system to “follow” periodic stimulation the ability of the brain to generate particular frequencies can be tested. However, testing broad frequency range requires long recording times and is challenging to the subjects. To overcome the long duration of the assessment procedure, the stimulation with changing sound modulation frequencies - chirps - was proposed. This dissertation includes three separate studies: 1) Evaluation of attentional effects on chirp-evoked responses; 2) Study of changes of chirp-evoked responses in schizophrenia; 3) Study of changes of chirp-evoked responses in disorder of consciousness. Results show that brief (500 ms) low-carrier tones (440 Hz) amplitude modulated by chirp stimuli elicit clear responses that do not depended on the subject’s level of attention. In a clinical sample of schizophrenia patients, chirp-evoked responses reveal impaired brain ability to synchronize at theta-beta and high gamma ranges and highlight association between response in 32-43 Hz range and hallucination symptoms. Chirp-evoked responses at the low gamma range differ between vegetative and minimally conscious state patients and are associated with the degree of consciousness impairment.
Dissertation Institution Vilniaus universitetas.
Type Doctoral thesis
Language English
Publication date 2020