Miodrag Stokić

Background/Aim. Neurofeedback (NFB) training of sensorimotor rhythm (SMR) contributes to improving cognitive performance and increasing attention. SMR power is increased when a person is focused and task-oriented. The shorter reaction time (RT) of the P300 auditory evoked potentials (AEPs) is associated with better attention. Hence, the increase in SMR power after NFB SMR training should decrease the RT in a cognitive task. The aim of the study was to examine the ability of healthy individuals to modulate the SMR of electroencephalographic (EEG) activity between 12 and 15 Hz during 20-day NFB training sessions. In addition, the effect of NFB SMR training on RT was investigated. Methods. Participants were divided into experimental and control groups, with 24 subjects (12 males and 12 females) in each group, aged between 25 and 40 years. Participants in the experimental group were trained with authentic NFB SMR training, while in the control group, false (placebo) training was applied. AEPs were registered on five occasions: before NFB training, after 5, 10, and 20 training sessions, and one month after the last training. Results. The results showed that a series of 20 NFB SMR training sessions increased the amplitudes of the SMR. RT in the experimental group was significantly shortened, while in the control group, it was not observed. Moreover, the increase in the power of the EEG signal o f t he S MR showed a negative correlation with RT, but only in a subgroup of male subjects. Conclusion. The obtained results indicate the effects of NFB training on the improvement of the attention process expressed by RT.

Background/Aim. This study aimed to investigate the effect of sensorimotor rhythm (SMR) (12-15 Hz) neurofeedback (NFB) training on auditory cognition measured by achievement on the QuickSIN test, changes in the amplitudes and latencies of evoked potentials in auditory oddball discrimination task and changes in the spectral power of the sensorimotor rhythm. Methods. Each of 16 healthy participants aged 25-40 years (8 male) had 20 daily sessions of SMR neurofeedback training. Auditory cognitive functions and electrophysiological correlates of cognitive processing were recorded 5 times: before NFB, after 5, 10, and 20 sessions, and one month after the last session. Results. The results showed a statistically significant decrease in N200 and P300 latencies at Fz, Cz, and Pz regions, improvement on the QuickSIN test and increase in EEG SMR rhythm spectral power in Cz region as a result of NFB SMR training. No significant effect of NFB training on the amplitude of N100, N200 and P300 on Fz, Cz and Pz was found. Conclusion.The obtained results suggest that sensorimotor rhythm training (SMR) neurofeedback (NFB) affects auditory perception in terms of shorter latencies of evoked potentials and better performance on QuickSIN test.

Auditory processing in children diagnosed with speech and language impairment (SLI) is atypical and characterized by reduced brain activation compared to typically developing (TD) children. In typical speech and language development processes, frontal, temporal, and posterior regions are engaged during single-word listening, while for non-word listening, it is highly unlikely that perceiving or speaking them is not followed by frequent neurones’ activation enough to form stable network connections. This study aimed to investigate the electrophysiological cortical activity of alpha rhythm while listening words and non-words in children with SLI compared to TD children. The participants were 50 children with SLI, aged 4 to 6, and 50 age-related TD children. Groups were divided into 2 subgroups: first subgroup – children aged 4.0 to 5.0 years old (E = 25, C = 25) and second subgroup – children aged 5.0 to 6.0 years old (E = 25, C = 25). The younger children’s group did not show statistically significant differences in alpha spectral power in word or non-word listening. In contrast, in the older age group for word and non-word listening, differences were present in the prefrontal, temporal, and parieto-occipital regions bilaterally. Children with SLI showed a certain lack of alpha desynchronization in word and non-word listening compared with TD children. Non-word perception arouses more brain regions because of the unknown presence of the word stimuli. The lack of adequate alpha desynchronization is consistent with established difficulties in lexical and phonological processing at the behavioral level in children with SLI.

Background/Aim. Neurofeedback (NFB) is a therapeutic method based on monitoring the electroencephalogram (EEG) and providing feedback on the brain activity of sub-jects. The aim of the pilot study was to investigate the effect of lower-beta or sensorimotor rhythm (SMR) (12?15 Hz) NFB training on amplitudes and latencies of late auditory event-related potentials (aERP) components N100, N200, P300 in Go-No go task of auditory discrimination. Methods. Each of 9 healthy participants aged 25?40 years (4 male) had 20 daily sessions of SMR neurofeedback training. The aERP was recorded 5 times: before NFB, after 5, 10, and 20 sessions, and one m onth after the last session. Results. The results showed a statistically significant decrease in N100, N200, and P300 latencies at Fz, Cz, and Pz regions. No significant effect of NFB training on amplitudes of components N100, N200 and N300 was found. Conclusion. The obtained results suggest that NFB training exerts its effect on the processes of auditory cognition.

Introduction/Objective Numerous studies on surface electromyographic (sEMG) signals in response to different respiratory parameters, particularly on sternocleidomastoid (SCM) muscles and diaphragm (DIA), indicated the promising advantages of their simultaneous monitoring with possible applications in the analysis of their correlation. This motivated a detailed statistical analysis of the average power (P-AV) on sEMG signals during prolonged breath-holding, simultaneously measured in the SCM and DIA areas. Methods The physiological breath-holding method was applied to 30 healthy volunteers, with sEMG of SCM and DIA regions measured before, during, and after the breath-holding exercise. All the subjects were sitting in an upward position, with nostrils closed by the right index finger and thumb during breath-hold. To synchronize the records, the user would press a special switch using the other hand at the beginning and at the end of breath-holding experiment. The average power of sEMG (P-AV) was measured for each 500 ms signal window. Results The P-AV remains constant before and 3 seconds after the exercise. During the ending of breathholding, at least one region had the P-AV afflux of a minimum of 91%. Student'st-test between SCM signals shows a significant difference of p < 0.001, while the DIA lacks it. Although the results showed that SCM is the dominant region in 76.67% of cases, the exclusive P-AV afflux in the DIA region was detected in precisely five cases (16.67% of the total namber of participants). Conclusions Our research concludes that there is the necessity of simultaneous measurement of SCM and DIA to observe dominant changes in sEMG during breath-holding. The physiological response of the respiratory center can be observed by approximately doubling P-AV in one of SCM or DIA regions.

Reliable diagnosis of depressive disorder is essential for both optimal treatment and prevention of fatal outcomes. This study aimed to elucidate the effectiveness of two non-linear measures, Higuchi’s Fractal Dimension (HFD) and Sample Entropy (SampEn), in detecting depressive disorders when applied on EEG. HFD and SampEn of EEG signals were used as features for seven machine learning algorithms including Multilayer Perceptron, Logistic Regression, Support Vector Machines with the linear and polynomial kernel, Decision Tree, Random Forest, and Naïve Bayes classifier, discriminating EEG between healthy control subjects and patients diagnosed with depression. This study confirmed earlier observations that both non-linear measures can discriminate EEG signals of patients from healthy control subjects. The results suggest that good classification is possible even with a small number of principal components. Average accuracy among classifiers ranged from 90.24 to 97.56%. Among the two measures, SampEn had better performance. Using HFD and SampEn and a variety of machine learning techniques we can accurately discriminate patients diagnosed with depression vs controls which can serve as a highly sensitive, clinically relevant marker for the diagnosis of depressive disorders.

Objectives: Biomarkers of major depressive disorder (MDD), its phases and forms have long been sought. Objectives were to examine whether the complexity of EEG activity, measured by Higuchi's fractal dimension (HFD) and sample entropy (SampEn), differs between healthy subjects, patients in remission, and in episode phase of the recurrent depression and whether the changes are differentially distributed between hemispheres and cortical regions.Methods: Resting state EEG with eyes closed was recorded from 22 patients suffering from recurrent depression (11 in remission, 11 in the episode), and 20 age and sex‐matched healthy control subjects. Artifact‐free EEG epochs were analyzed by in‐house developed programs running HFD and SampEn algorithms.Results: Depressed patients had higher HFD and SampEn complexity compared to healthy subjects. The complexity was higher in patients who were in remission than in those in the acute episode. Altered complexity was present in the frontal and centro‐parietal regions when compared to control group. The complexity in frontal and parietal regions differed between the two phases of depressive disorder.Conclusions: Complexity measures of EEG distinguish between the healthy controls, patients in remission and episode. Further studies are needed to establish whether these measures carry a potential to aid clinically relevant decisions about depression.

Introduction/Objective. Antenatal maternal anxiety (AMA) can have negative impact on child’s pre- and postnatal development. The aim was to examine the effect of AMA on changes in fetal blood flow throw middle cerebral artery (MCA) after acoustic stimulation, birth outcome, and early child development. Methods. Forty-three women in the third trimester of pregnancy and their children were enrolled in a longitudinal prospective study. The AMA (state and trait) was assessed using Spielberger’s questionnaire. The MCA blood flow was assessed using Doppler ultrasound before and after defined acoustic stimulus. The data regarding neonatal body weight, Apgar score, first step and word appearance, estimated speech-language (ESLD), sensory-motor (ESMD), and social-emotional (ESED) development at the age of three were collected. Results. Fetuses from mothers with high state and trait anxiety had slower reaction time and higher relative pulsatility index after defined auditory stimulation. There are more preterm deliveries, lower scores on ESLD, ESMD, and ESED in mothers with high STAI-T compared to low. There is a negative correlation between reaction time, relative pulsatility index, STAI-T and ESLD. Conclusion. High levels of antenatal maternal trait anxiety could have a negative effect on both, fetal reactivity to sound stimulation and early child development

Biomarkers of Major Depressive Disorder(MDD), its phases and forms have long been sought. Research indicates that the complexity measures of the cortical electrical activity (EEG) might be candidates for this role. To examine whether the complexity of EEG activity, measured by Higuchi fractal dimension (HFD) and sample entropy (SampEn), differs between healthy subjects, patients in remission and episode phase of the recurrent depression and whether the changes are differentially distributed between hemispheres and cortical regions. Resting state EEG with eyes closed was recorded from 26 patients suffering from recurrent depression and 20 age and sex-matched healthy control subjects. Artefact-free EEG epochs were analyzed by in-house developed programs running HFD and SampEn algorithms. Depressed patients had higher HFD and SampEn complexity compared to healthy subjects. Surprisingly, the complexity was even higher in patients who were in remission than in those in the episode. Altered complexity was present in the frontal and centro-parietal regions when compared to the control group. The complexity in frontal and parietal regions differed between the two phases of depressive disorder. SampEn manifested higher sensitivity than HFD in some cortical areas. Complexity measures of EEG distinguish between the three groups. Further studies are needed to establish whether these measures carry the potential to aid clinically relevant decisions about depression.

This study investigated the correlation between maternal anxiety and blood flow changes through the fetal middle cerebral artery (MCA) after defined acoustic stimulation in 43 normotensive (C) and 40 gestational hypertensive (GH) subjects. Neonatal outcomes (gestational age at birth, Apgar score, birth weight) in the C and GH groups were analyzed. State (STAI‐S) and trait (STAI‐T) anxiety was assessed using Spielberger's questionnaire. The MCA blood flow was assessed once between 28 and 41 weeks of gestation using color Doppler ultrasound before and after application of defined acoustic stimulus. Relative size of the Pulsatility index (Pi) change (RePi) was calculated. The general hypotheses were: (1) women in GH group would have higher anxiety; (2) higher anxiety correlates with higher RePi change and poorer neonatal outcome; (3) fetuses from the GH group would have poorer neonatal outcome. Subjects from the GH group had higher STAI‐T and RePi compared to the C group. A positive correlation between RePi and STAI‐S, STAI‐T, and systolic/diastolic blood pressure was found in both groups. There were more preterm deliveries in the GH group compared to the C group. A significant effect of STAI‐T on body weight was observed in the C and GH group. There was a predictive effect of STAI‐T and RePi on the C group, and STAI‐S, STAI‐T, diastolic blood pressure, and RePi on the GH group in terms of neonatal body weight. This study demonstrates an association between antenatal anxiety in GH women and increased fetal cerebral circulation in response to defined auditory stimulation.