After-effects of 10 Hz tACS over the prefrontal cortex on phonological word decisions

Introduction Previous work in the language domain has shown that 10 Hz rTMS of the left or right posterior inferior frontal gyrus (pIFG) in the prefrontal cortex impaired phonological decision-making, arguing for a causal contribution of the bilateral pIFG to phonological processing. However, the neurophysiological correlates of these effects are unclear. The present study addressed the question whether neural activity in the prefrontal cortex could be modulated by 10 Hz tACS and how this would affect phonological decisions. Methods In three sessions, 24 healthy participants received tACS at 10 Hz or 16.18 Hz (control frequency) or sham stimulation over the bilateral prefrontal cortex before task processing. Resting state EEG was recorded before and after tACS. We also recorded EEG during task processing. Results Relative to sham stimulation, 10 Hz tACS significantly facilitated phonological response speed. This effect was task-specific as tACS did not affect a simple control task. Moreover, 10 Hz tACS significantly increased theta power during phonological decisions. The individual increase in theta power was positively correlated with the behavioral facilitation after 10 Hz tACS. Conclusion Our results show a facilitation of phonological decisions after 10 Hz tACS over the bilateral prefrontal cortex. This might indicate that 10 Hz tACS increased task-related activity in the stimulated area to a level that was optimal for phonological performance. The significant correlation with the individual increase in theta power suggests that the behavioral facilitation might be related to increased theta power during language processing

Сравнение молекулярно-генетических методов выявления мутаций в гене CALR при миелопролиферативных заболеваниях

Molecular genetic detection of CALR gene somatic mutations is required for myeloproliferative neoplasms diagnosis and treatment according to the novel WHO clinical recommendations. CALR mutations are found in approximately 25–35 % cases of essential thrombocythemia and primary myelofibrosis and they are associated with benign clinical outcome. In this study we have compared sensitivity and selectivity of seve ral different options of CALR mutation molecular genetic detection in blood samples of 379 CMD patients and 17 healthy donors. Among methods compared in our study there have been conventional polymerase chain reaction with electrophoretic detection, real-time quantitative polymerase chain reaction, direct Sanger sequencing of polymerase chain reaction fragments and polymerase chain reaction high resolution melting curve analysis. By means of melting curve analysis CALR mutations have been found in 97 (25.5 %) patients, whereas in the cases of Sanger sequencing and polymerase chain reaction there have been 87 (23.0 %) and 84 (22.1 %) CALR mutation positive patients respectively.Молекулярно-генетические исследования для определения соматических мутаций в гене кальретикулина (CALR) включены в клинические рекомендации Всемирной организации здравоохранения в качестве одних из основных диагностических критериев миелопролиферативных заболеваний. Примерно в 25–35 % случаев эссенциальной тромбоцитемии и первичного миелофиброза бывают выявлены мутации в гене CALR, наличие которых ассоциировано с благоприятным прогнозом течения заболевания. В нашем исследовании выполнено сравнение результатов молекулярно-генетических методов для определения мутаций в гене CALR. Проведен анализ образцов периферической крови 379 пациентов с хроническими миелопролиферативными заболеваниями и 17 образцов крови здоровых доноров. Наличие мутаций в гене CALR определяли методом полимеразной цепной реакции с электрофоретической детекцией и количественной полимеразной цепной реакции в реальном времени, методом секвенирования по Сэнгеру и анализом кривых плавления. Мутации в гене CALR определены у 97 (25,5 %) пациентов методом анализа кривых плавления. Из них у 87 (23,0 %) пациентов мутации в гене найдены методом секвенирования по Сэнгеру. С помощью полимеразной цепной реакции мутации в гене CALR были обнаружены у 84 (22,1 %) пациентов

Offline 20 Hz transcranial alternating current stimulation over the right inferior frontal gyrus increases theta activity during a motor response inhibition task

Lyzhko E, Peter SE, Nees F, Siniatchkin M, Moliadze V. Offline 20 Hz transcranial alternating current stimulation over the right inferior frontal gyrus increases theta activity during a motor response inhibition task. Neurophysiologie Clinique. 2023;53(3): 102887.Objectives: Previous studies have shown that the right inferior frontal gyrus (rIFG) and the pre-supplementary motor area (preSMA) play an important role in motor inhibitory control. The aim of the study was to use theta frequency transcranial alternating current stimulation (tACS) to modulate brain activity in the rIFG and preSMA and to test the effects of stimulation using a motor response inhibition task.Methods: In four sessions, 20 healthy participants received tACS at 6 Hz over preSMA or rIFG, or 20 Hz over rIFG (to test frequency specificity), or sham stimulation before task processing. After each type of stimulation, the participants performed the Go/NoGo task with simultaneous elec-troencephalogram (EEG) recording.Results: By stimulating rIFG and preSMA with 6 Hz tACS, we were not able to modulate either behavioral performance nor the EEG correlate. Interestingly, 20 Hz tACS over the rIFG signifi-cantly increased theta activity, however without behavioral effects. This increased theta activ-ity did not coincide with the stimulation area and was localized in the fronto-central and centro-parietal areas

Comparison of molecular genetic methods of detection of mutations in the CALR gene in myeloproliferative disorders

Molecular genetic detection of CALR gene somatic mutations is required for myeloproliferative neoplasms diagnosis and treatment according to the novel WHO clinical recommendations. CALR mutations are found in approximately 25–35 % cases of essential thrombocythemia and primary myelofibrosis and they are associated with benign clinical outcome. In this study we have compared sensitivity and selectivity of seve ral different options of CALR mutation molecular genetic detection in blood samples of 379 CMD patients and 17 healthy donors. Among methods compared in our study there have been conventional polymerase chain reaction with electrophoretic detection, real-time quantitative polymerase chain reaction, direct Sanger sequencing of polymerase chain reaction fragments and polymerase chain reaction high resolution melting curve analysis. By means of melting curve analysis CALR mutations have been found in 97 (25.5 %) patients, whereas in the cases of Sanger sequencing and polymerase chain reaction there have been 87 (23.0 %) and 84 (22.1 %) CALR mutation positive patients respectively

Emotional processing in Parkinson's disease and anxiety: an EEG study of visual affective word processing

A general problem in the design of an EEG-BCI system is the poor quality and low robustness of the extracted features, affecting overall performance. However, BCI systems that are applicable in real-time and outside clinical settings require high performance. Therefore, we have to improve the current methods for feature extraction. In this work, we investigated EEG source reconstruction techniques to enhance the extracted features based on a linearly constrained minimum variance (LCMV) beamformer. Beamformers allow for easy incorporation of anatomical data and are applicable in real-time. A 32-channel EEG-BCI system was designed for a two-class motor imagery (MI) paradigm. We optimized a synchronous system for two untrained subjects and investigated two aspects. First, we investigated the effect of using beamformers calculated on the basis of three different head models: a template 3-layered boundary element method (BEM) head model, a 3-layered personalized BEM head model and a personalized 5-layered finite difference method (FDM) head model including white and gray matter, CSF, scalp and skull tissue. Second, we investigated the influence of how the regions of interest, areas of expected MI activity, were constructed. On the one hand, they were chosen around electrodes C3 and C4, as hand MI activity theoretically is expected here. On the other hand, they were constructed based on the actual activated regions identified by an fMRI scan. Subsequently, an asynchronous system was derived for one of the subjects and an optimal balance between speed and accuracy was found. Lastly, a real-time application was made. These systems were evaluated by their accuracy, defined as the percentage of correct left and right classifications. From the real-time application, the information transfer rate (ITR) was also determined. An accuracy of 86.60 ± 4.40% was achieved for subject 1 and 78.71 ± 0.73% for subject 2. This gives an average accuracy of 82.66 ± 2.57%. We found that the use of a personalized FDM model improved the accuracy of the system, on average 24.22% with respect to the template BEM model and on average 5.15% with respect to the personalized BEM model. Including fMRI spatial priors did not improve accuracy. Personal fine- tuning largely resolved the robustness problems arising due to the differences in head geometry and neurophysiology between subjects. A real-time average accuracy of 64.26% was reached and the maximum ITR was 6.71 bits/min. We conclude that beamformers calculated with a personalized FDM model have great potential to ameliorate feature extraction and, as a consequence, to improve the performance of real-time BCI systems