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1

Does brain ability to synchronize with 40 Hz auditory stimulation change with age?

100%
Griskova-Bulanova I., Dapsys K., Maciulis V.
Acta Neurobiologiae Experimentalis
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2013
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tom 73
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nr 4
Auditory steady-state responses (ASSRs) are widely applied to test brain ability to follow external stimulation and this appeared to be a promising method in neuropsychiatry disorders. Nevertheless, there is no established conclusion on the way aging affects phase-locking measures of ASSRs in healthy subjects. We aimed to identify the effects of aging on phase- locking measures of 40 Hz ASSR. The effect of aging was tested in a sample of 46 healthy male subjects (20-58 years old) during eyes open condition. Stimuli were 500 ms trains, consisting of 20 identical clicks (1.5 ms burst of white noise) delivered binaurally. Time-frequency analysis of the data was performed and phase-locking index, evoked amplitude and total intensity measures were extracted and decomposed by non-negative multi-way factorization. As shown by curve-fitting analyses, phase-locking index and evoked amplitudes were diminishing with age in the linear manner. This was also proven by ANOVA testing when sample was divided into age groups. No effect of age on the total intensity was found. The complexity of the factors modulating the 40 Hz ASSR is not entirely solved; nevertheless, the current results suggest that the ability to synchronize to high frequency external stimulation diminishes with age. This should be taken into account, particularly when ASSRs are used in clinical practice, comparing patients and healthy subjects.
2

Evaluation of new MMN parameters in schizophrenia

100%
Korostenskaja M., Dapsys K., Maciulis V., Ruksenas O.
Acta Neurobiologiae Experimentalis
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2003
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tom 63
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nr 4
3

P50 potential-associated gamma band activity: Modulation by distraction

88%
Griskova-Bulanova I., Ruksenas O., Dapsys K., Maciulis V., Arnfred S. M.
Acta Neurobiologiae Experimentalis
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2012
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tom 72
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nr 1
We aimed to evaluate the effect of changing attentional demands towards stimulation in healthy subjects on P50 potential- related high-frequency beta and gamma oscillatory responses, P50 and N100 peak amplitudes and their gating measures. There are no data showing effect of attention on P50 potential-related beta and gamma oscillatory responses and previous results of attention effects on P50 and N100 amplitudes and gating measures are inconclusive. Nevertheless the variation in the level of attention may be a source of variance in the recordings as well as it may provide additional information about the pathology under study. Nine healthy volunteers participated in the study. A standard paired stimuli auditory P50 potential paradigm was applied. Four stimulation conditions were selected: focused attention (stimuli pair counting), unfocused attention (sitting with open eyes), easy distraction (reading a magazine article), and difficult distraction (searching for Landolt rings with appropriate gap orientation). Time-frequency responses to both S1 and S2 were evaluated in slow beta (13-16 Hz, 45-175 ms window); fast beta (20-30 Hz, 45-105 ms window) and gamma (32-46 Hz, 45-65 ms window) ranges. P50 and N100 peak amplitudes in response to both S1 and S2 and their ratio were evaluated. The phase-locked P50 potential-associated gamma activity was attenuated during distraction tasks as compared to focused attention and an unfocused attention condition. The amplitudes and gating measures of P50 and N100 waves and beta activity were not sensitive to the competing distraction task performance. The use of a distraction task is not favorable when phase-locked gamma range activity is a key interest in auditory potential studies.
4

Effects of risperidone on auditory information processing in neuroleptic-naive patients with schizophrenia spectrum disorders

76%
Korostenskaja M., Dapsys K., Siurkute A., Maciulis V., Ruksenas O., Kahkonen S.
Acta Neurobiologiae Experimentalis
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2006
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tom 66
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nr 2
5

The use of MR - less MNI based neuronavigation for 10 Hz rTMS depression therapy: electrophysiological and clinical implications\\r\\n

76%
Valiulis V., Gerulskis G., Dapsys K., Valaviciute K., Siurkute A., Maciulis V.
Acta Neurobiologiae Experimentalis
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2018
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tom 78
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nr 3
Repetitive transcranial magnetic stimulation (rTMS) is a popular and effective treatment for drug resistant depression. However, there is considerable variability in clinical outcomes, in previous studies and between patients. Because of high requirements for the use of fMRI based neuronavigation, many practitioners of rTMS still choose to use a standard 5 cm rule for rTMS coil placement which leads to large variations in which brain regions are being stimulated. We decided to test the possibilities of a MNI based MR‑less neuronavigation system in rTMS depression treatment, by comparing the physiological effects and clinical outcomes of 3 distinct stimulation targets. Forty‑six patients (thirty‑three female, thirteen male) from the Republican Vilnius psychiatric hospital, all with drug resistant depressive disorder, participated in the study. All patients received high frequency (10 Hz) stimulation for 10 to 15 daily rTMS sessions. However, before the treatment they were randomly sorted into 3 groups according to stimulation target in MNI map: Group 1 received rTMS at point ‑40; 48; 35; Group 2 received rTMS at point ‑46; 45; 38; Group 3 received rTMS at point ‑38; 44; 26. Electroencephalography (EEG) recordings and clinical tests were obtained the day before the rTMS course and after the last session. There were some notable differences in physiological changes between the groups, with the largest EEG band spectral power increases found in Group 1 patients and the lowest in Group 2 patients. There was a significantly larger decrease of the Hamilton Depression Rating Scale (HAM-D) scores in the Group 3 (66.94%) compared to Group 1 (57.52%) and Group 2 (56.02%). This suggests it is possible to achieve higher clinical efficacy and less physiological impact on the brain when using different targets in a neuronavigated MNI based MR‑less rTMS system.
6

Electrophysiological differences between high and low frequency rTMS protocols in dispersion treatment

76%
Valiulis V., Gerulskis G., Dapsys K., Vistartaite G., Siurkute A., Maciulis V.
Acta Neurobiologiae Experimentalis
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2012
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tom 72
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nr 3
Repetitive transcranial magnetic stimulation (rTMS) is a rapidly expanding mean in drug resistant depression treatment. Yet, despite vast research in this field, exact neurophysiological mechanism of rTMS therapy still remains unclear. This results in difficulties choosing suitable rTMS parameters in advance and compromises thorough evaluation of efficacy after the treatment. In order to obtain more explicit assessment of rTMS therapy in the psychiatric field, we evaluated and compared the influence of two most widely used antidepressive rTMS protocols on EEG band power spectrum and relation to clinical test scores (MADRS, BDI, HAM-D17). Forty-five patients (12 male, 33 female, mean age 52.16 years) participated in the study. Twenty-three patients received high frequency (10 Hz) stimulation, the rest 22 were stimulated using low frequency (1 Hz) protocol. Both groups received 10 to 15 daily rTMS sessions. EEG recordings and clinical tests were obtained the day before rTMS course and same day after the last session. Majority (57.78%) of patients showed considerable improvement after the treatment. There were no notable differences in clinical test score drop between the two rTMS protocols. However, we found that different protocols resulted in significantly different electrophysiological changes. High frequency (10 Hz) rTMS resulted in widespread changes off EEG band power, including delta power increase on the left hemisphere and alpha power growth on the right. Theta power increase was also obtained in parietal-occipital areas. Low frequency (1 Hz) rTMS showed to have no major effect on basic EEG band power, however we found a notable shift of frontal alpha power asymmetry towards the right hemisphere, which correlated with the clinical outcome. Our study results suggest that two widely used rTMS protocols strongly differ in their electrophysiological mechanisms. Low frequency stimulation finesse on frontal alpha power asymmetry shift, whereas high frequency protocol acts on wider electrophysiological changes in the brain.
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