A. A. Savelov

Synergetic fMRI-EEG Brain Mapping in Alpha-Rhythm Voluntary Control Mode

For the first time in neurobiology-related issues, the synergistic spatial dynamics of EEG and fMRI (BOLD phenomenon) was studied during cognitive alpha biofeedback training in the operant conditioning mode (acoustic reinforcement of alpha-rhythm development and stability). Significant changes in alpha-rhythm intensity were found in T6 electrode area (Brodmann area 37). Brodmann areas related to solving alpha-training tasks and maximally involved in the formation of new neuronal network were middle and superior temporal gyri (areas 21, 22, and 37), fusiform gyrus, inferior frontal gyrus (areas 4, 6, and 46), anterior cingulate gyrus (areas 23 and 24), cuneus, and precuneus (area 7). Wide involvement of Brodmann areas is determined by psychological architecture of alpha-rhythm generating system control that includes complex cognitive activities: decision making, retrieval of long-term memory, evaluation of the reward and control efficiency during alpha-EEG biofeedback.

EEG-fMRI Study of Alpha-Stimulation Neurobiofeedback Training Course

fMRI-EEG dynamics of brain activity in volunteers was studied during the course of EEG alpha-stimulation training (20 sessions). Twenty-three healthy men (20-35 years) were subjected to 3-fold mapping in a feedback loop (EEG alpha-rhythm biofeedback with acoustic reinforcement). This procedure was performed at the beginning, middle, and end of the course. During the first neurofeedback training session, deactivation (p<0.001) was found in the right angular gyrus, supramarginal, and superior temporal gyri, Brodmann area 39, and cerebellum. Activation (p<0.001) was observed in the medial frontal and cingulate gyri, motor areas of both hemispheres, and Brodmann area 32. During final (third) neurofeedback training session, we observed strong deactivation (p<0.05 with FDR) of zones responsible for spatial thinking and motor functions: left medial frontal and left medial temporal gyri; right postcentral, lingual, and superior frontal gyri; insula and right side of the cerebellum; and precuneus and cuneus (Brodmann areas 6, 9, 7, 31, 8, 13, and 22). Changes in the alpha wave power were most pronounced in the primary and secondary somatosensory cortex of the left hemisphere (Brodmann areas 2L and 5L).

Dynamic Mapping of Brain and Cognitive Control of Virtual Gameplay (Study by Functional Magnetic Resonance Imaging)

Using functional magnetic resonance imaging technique, we performed online brain mapping of gamers, practiced to voluntary (cognitively) control their heart rate, the parameter that operated a competitive virtual gameplay in the adaptive feedback loop. With the default start picture, the regions of interest during the formation of optimal cognitive strategy were as follows: Brodmann areas 19, 37, 39 and 40, i.e. cerebellar structures (vermis, amygdala, pyramids, clivus). “Localization” concept of the contribution of the cerebellum to cognitive processes is discussed.

Neurovisualization of the dynamics of real and simulation biofeedback: functional magnetic resonance imaging study.

On-line brain mapping in subjects operating a competitive virtual gameplay was performed using functional magnetic resonance imaging. The interaction between the brain and visceral systems was studied on the model of real and simulated adaptive biofeedback. The immersion into a virtual story leads to a large-scale activation of cortical regions characterized by high values of voxels in the midtemporal, occipital, and frontal areas as well as in cingulate gyrus, cuneus, and precuneus (Brodmann areas 6, 7, 9, 10, 19, 24, 32, 39, 40, 45). The maximum increase in activity was observed during stage 2 of the game biofeedback, when the volumes of activated voxels increased several times in comparison with the starting phase. Qualitative characteristics of real and imitation game periods are discussed.

fMRI Responses in Healthy Individuals and in Patients with Mild Depression to Presentation of Pleasant and Unpleasant Images

Patients with mild depression and apparently healthy individuals were presented images and asked to sort them into “pleasant” and “unpleasant” subsets. In both groups, the main differences between brain activation patterns during presentation of pleasant and unpleasant images were localized in the motor regions (precentral and postcentral gyrus) and in the cerebellum (p<0.05 with FWE correction). Most likely, these clusters are associated with motion (pressing a button in accordance with the instruction). According to the data of intergroup contrasts, patients with depression had less pronounced activation of frontal structures (middle frontal gyrus and other areas, including the white matter) in response to both positive and negative images (p<0.001). In healthy subjects, the response of the temporo-occipital areas (lingual and fusiform gyrus) to unpleasant stimuli was more intensive than in patients (p<0.001). This can be due to differences in the semantic image processing. Thus, in case of mild depression, the response of the amygdaloid complex, the key structure in the development in affective disorder, was not always observed. At the same time, the response of frontal and temporo-occipital regions has a certain potential as a biomarker of mild depression, although the reliability of the obtained data requires additional confirmation.

Spontaneous Changes in Functional Connectivity of Independent Components of fMRI Signal in Healthy Volunteers at Rest and in Subjects with Mild Depression

Depression is associated with changes in the pattern of interaction of cerebral networks, which can reflect both existing symptoms and compensatory processes. The study is based on analysis of resting state fMRI data from 15 patients with mild depression and 19 conventionally healthy individuals. From fMRI signal recorded at rest for 4 min, the independent components were reconstructed. The intergroup differences and dynamics of functional connectivity from the first to the second recording were analyzed. Initially, depressive patients demonstrated weaker connectivity between cerebellar declive network (CN) and left central executive network (CEN) and also sensorimotor network (SMN); left CEN and primary visual network (PVN). During the second recording, the patients demonstrated more intensive reciprocal connection of the dorsal domain of default mode network (DMN) and auditory network (AN). In healthy subjects, positive correlations of the dorsal DMN and left CEN, right CEN and CN, and negative correlation of dorsal DMN and visuospatial network weakened from the first to second record. In the depression group, the interaction of AN with PVN, the right CEN with the anterior salience network and with ventral DMN weakened. At the same time, the connectivity between SMN and CN were strengthened. The results can be interpreted as spontaneous normalization of brain activity, but no direct evidence for their relation to the improvement of depression symptoms was found.

Quantitative Assessment of Normal Fetal Brain Myelination Using Fast Macromolecular Proton Fraction Mapping

BACKGROUND AND PURPOSE: Fast macromolecular proton fraction mapping is a recently emerged MRI method for quantitative myelin imaging. Our aim was to develop a clinically targeted technique for macromolecular proton fraction mapping of the fetal brain and test its capability to characterize normal prenatal myelination. MATERIALS AND METHODS: This prospective study included 41 pregnant women (gestational age range, 18–38 weeks) without abnormal findings on fetal brain MR imaging performed for clinical indications. A fast fetal brain macromolecular proton fraction mapping protocol was implemented on a clinical 1.5T MR imaging scanner without software modifications and was performed after a clinical examination with an additional scan time of <5 minutes. 3D macromolecular proton fraction maps were reconstructed from magnetization transfer-weighted, T1-weighted, and proton density–weighted images by the single-point method. Mean macromolecular proton fraction in the brain stem, cerebellum, and thalamus and frontal, temporal, and occipital WM was compared between structures and pregnancy trimesters using analysis of variance. Gestational age dependence of the macromolecular proton fraction was assessed using the Pearson correlation coefficient (r). RESULTS: The mean macromolecular proton fraction in the fetal brain structures varied between 2.3% and 4.3%, being 5-fold lower than macromolecular proton fraction in adult WM. The macromolecular proton fraction in the third trimester was higher compared with the second trimester in the brain stem, cerebellum, and thalamus. The highest macromolecular proton fraction was observed in the brain stem, followed by the thalamus, cerebellum, and cerebral WM. The macromolecular proton fraction in the brain stem, cerebellum, and thalamus strongly correlated with gestational age (r = 0.88, 0.80, and 0.73; P < .001). No significant correlations were found for cerebral WM regions. CONCLUSIONS: Myelin is the main factor determining macromolecular proton fraction in brain tissues. Macromolecular proton fraction mapping is sensitive to the earliest stages of the fetal brain myelination and can be implemented in a clinical setting.

Biocontrol Using fMRI Signals Recorded in Real Time: A New-Generation Neurotherapy

This review summarizes data on the therapeutic potential of biocontrol using fMRI signals recorded in real time (rt-fMRI), a novel technology allowing patients to learn voluntary control of activity in brain areas associated with impaired functions. Positive results have now been obtained using rt-fMRI biocontrol in poststroke states, Parkinson’s disease, pain syndrome, tinnitus, alcohol and nicotine abuse, major depressive episodes, arachnophobia, and misophobia, and possibly in schizophrenia, though it is essentially ineffective in antisocial personality disorder with criminal behavior. Nonetheless, the overall significance of results is poor because of suboptimal design, the lack of control groups, or small cohort sizes. This review considers the biological mechanisms underlying the technology, its current applications and potentials, and problems related to methods and methodology.

Experience in Continuous Neurobiocontrol Using fMRI Signals from the Primary Motor Cortex Using a 1.5-T MR Tomograph

Biocontrol based on fMRI signals from the motor area of the cortex is a potential approach to restoring motor functions in poststroke states and Parkinson’s disease. The region of interest in most studies is in the secondary motor areas and the strength of the magnetic field is 3 T. We report here our studies on biocontrol using the fMRI signal from an area of the primary motor cortex associated with the operation of the right hand obtained using a 1.5-T tomograph and settings optimal for obtaining optimal images at this magnetic field strength. Subjects were 16 healthy subjects who took part in 30-min fMRI recording including 1) individual localization of the region of interest (rhythmic fist clenching test) and attempts to control its activity using 2) imaginary movements and 3) any cognitive strategy of the participant’s choice. Attempts to carry out self-control in both cases led to activation of the precentral, anterior cingulate, superior frontal, and inferior parietal gyri and Brodmann zone 6. fMRI signal maps for these tasks did not show any statistically significant differences and the activation zones showed little if any overlap with the region of interest, evidencing lack of success of sessions. The limitations of the experiments are discussed, as are factors with adverse influences on the effectiveness of biocontrol.

Congenital medulloblastoma: Fetal and postnatal longitudinal observation with quantitative MRI

Congenital medulloblastoma is extremely rare. MRI appearance of this tumor in the fetal brain has not been described. A case of congenital medulloblastoma initially observed by antenatal MRI with postnatal follow-up and treatment is presented. A pregnant female underwent fetal MRI on the 31st gestational week for routine indications. Midline cerebellar lesion of ≤2 cm in size with minor T2 hypointensity and T1 hyperintensity was identified. Additionally, quantitative MRI including apparent diffusion coefficient (ADC) and fast macromolecular proton fraction (MPF) mapping was performed. The lesion showed a marked ADC decrease and MPF increase. MPF maps depicted the lesion most conspicuously. After term delivery, a male neonate presented with symptoms of increased intracranial pressure. Postnatal MRI identified obstructive hydrocephalus caused by a large posterior fossa mass. The child was treated by cerebrospinal fluid shunt placement. Follow-up quantitative MRI on the fifth month revealed tumor growth and vivid changes of its tissue contrast associated with brain maturation. The tumor appeared nearly isointense on T1- and T2-weighted images and slightly hypointense on the ADC map. MPF contrast showed the most remarkable change from hyper- to hypointensity due to brain myelination with stable MPF in the tumor. Subsequently, the child underwent partial tumor resection, and currently continues treatment with chemotherapy. The pathological diagnosis was desmoplastic/nodular medulloblastoma. The described case illustrates evolution of the tumor contrast in the course of fetal and postnatal brain development and highlights the added diagnostic value of MPF mapping in fetal and neonatal neuroimaging.