Прехирургическое картирование речевых зон коры головного мозга с помощью фМРТ: актуальное состояние и тенденции

Presurgical brain mapping of language-eloquent cortex aims to minimize its injury during neurosurgery in patients with brain tumors and drug-resistant epilepsy, and thereby, to preserve their quality of life. Two main goals of language mapping are to identify the localization and lateralization of brain regions involved in language. Gold standards for them are the intraoperative mapping and Wada test, respectively; however, due to some limitations of these techniques, non-invasive preliminary language mapping becomes reasonable. During the last years, fMRI has been widely applied for such purposes. Our literature review focuses on innovations and actual tendencies which spread in the field of language mapping via fMRI in the last decade. State-of-the-art knowledge on brain organization of language, which underpins brain mapping of language processing via fMRI, is briefly described in the article. Contemporary studies of fMRI validity in localization and lateralization of language brain regions are considered. Strategies of presurgical language mapping, such as application of tractography in addition to fMRI, combined analysis of fMRI tasks as well as resting-state fMRI are also discussed. Well-established fMRI tasks for brain mapping of language production and comprehension, as well as new experimental developments in this field, are listed and described.Прехирургическое картирование областей мозга, критически важных для осуществления речевых функций, направлено на минимизацию повреждения этих областей во время нейрохирургического вмешательства у пациентов с опухолями головного мозга и фармакорезистентной эпилепсией и тем самым на сохранение качества их жизни. Две основных задачи картирования речи – это определение локализации и латерализации речевых зон, “золотыми стандартами” для решения которых являются интраоперационное картирование (ИОК) и проба Вада соответственно. Однако ряд ограничений этих методов обусловливает целесообразность неинвазивного предварительного картирования речи, для которого в последние годы наиболее широко используется функциональная МРТ (фМРТ). Проведенный обзор литературы сосредоточен на нововведениях и актуальных тенденциях, которые получили распространение в области фМРТ-картирования речи за последнее десятилетие. В статье кратко изложено текущее состояние представлений о мозговой организации речевых функций, лежащих в основе картирования речи с применением фМРТ. Рассматриваются современные исследования валидности результатов фМРТ, касающихся локализации и латерализации речевых областей. Отдельно обсуждаются такие тактики прехирургического картирования речи, как дополнение фМРТ-данных результатами трактографии, комбинированный анализ фМРТ-проб и использование фМРТ покоя. Перечисляются и описываются устоявшиеся фМРТ-пробы для картирования зон, связанных с порождением и восприятием речи, и новые экспериментальные разработки в этой области

Macro- And microstructural changes in cosmonauts' brains after long-duration spaceflight

Long-duration spaceflight causes widespread physiological changes, although its effect on brain structure remains poorly understood. In this work, we acquired diffusion magnetic resonance imaging to investigate alterations of white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF) compositions in each voxel, before, shortly after, and 7 months after long-duration spaceflight. We found increased WM in the cerebellum after spaceflight, providing the first clear evidence of sensorimotor neuroplasticity. At the region of interest level, this increase persisted 7 months after return to Earth. We also observe a widespread redistribution of CSF, with concomitant changes in the voxel fractions of adjacent GM. We show that these GM changes are the result of morphological changes rather than net tissue loss, which remained unclear from previous studies. Our study provides evidence of spaceflight-induced neuroplasticity to adapt motor strategies in space and evidence of fluid shift- induced mechanical changes in the brain. © 2020The Authors, some rights reserved.Peer reviewe

Erratum to: Cortical reorganization in an astronaut’s brain after long-duration spaceflight (Brain Struct Funct, DOI 10.1007/s00429-015-1054-3)

peer reviewe

The effect of prolonged spaceflight on cerebrospinal fluid and perivascular spaces of astronauts and cosmonauts

peer reviewedLong-duration spaceflight induces changes to the brain and cerebrospinal fluid compartments and visual acuity problems known as spaceflight-associated neuro-ocular syndrome (SANS). The clinical relevance of these changes and whether they equally affect crews of different space agencies remain unknown. We used MRI to analyze the alterations occurring in the perivascular spaces (PVS) in NASA and European Space Agency astronauts and Roscosmos cosmonauts after a 6-mo spaceflight on the International Space Station (ISS). We found increased volume of basal ganglia PVS and white matter PVS (WM-PVS) after spaceflight, which was more prominent in the NASA crew than the Roscosmos crew. Moreover, both crews demonstrated a similar degree of lateral ventricle enlargement and decreased subarachnoid space at the vertex, which was correlated with WM-PVS enlargement. As all crews experienced the same environment aboard the ISS, the differences in WM-PVS enlargement may have been due to, among other factors, differences in the use of countermeasures and high-resistive exercise regimes, which can influence brain fluid redistribution. Moreover, NASA astronauts who developed SANS had greater pre- and postflight WM-PVS volumes than those unaffected. These results provide evidence for a potential link between WM-PVS fluid and SANS. Copyright © 2022 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY)

Brain Tissue-Volume Changes in Cosmonauts

[No abstract available

Alterations of functional brain connectivity after long-duration spaceflight as revealed by fMRI

The present study reports alterations of task-based functional brain connectivity in a group of 11 cosmonauts after a long-duration spaceflight, compared to a healthy control group not involved in the space program. To elicit the postural and locomotor sensorimotor mechanisms that are usually most significantly impaired when space travelers return to Earth, a plantar stimulation paradigm was used in a block design fMRI study. The motor control system activated by the plantar stimulation involved the pre-central and post-central gyri, SMA, SII/operculum, and, to a lesser degree, the insular cortex and cerebellum. While no post-flight alterations were observed in terms of activation, the network-based statistics approach revealed task-specific functional connectivity modifications within a broader set of regions involving the activation sites along with other parts of the sensorimotor neural network and the visual, proprioceptive, and vestibular systems. The most notable findings included a post-flight increase in the stimulation-specific connectivity of the right posterior supramarginal gyrus with the rest of the brain; a strengthening of connections between the left and right insulae; decreased connectivity of the vestibular nuclei, right inferior parietal cortex (BA40) and cerebellum with areas associated with motor, visual, vestibular, and proprioception functions; and decreased coupling of the cerebellum with the visual cortex and the right inferior parietal cortex. The severity of space motion sickness symptoms was found to correlate with a post-to pre-flight difference in connectivity between the right supramarginal gyrus and the left anterior insula. Due to the complex nature and rapid dynamics of adaptation to gravity alterations, the post-flight findings might be attributed to both the long-term microgravity exposure and to the readaptation to Earth's gravity that took place between the landing and post-flight MRI session. Nevertheless, the results have implications for the multisensory reweighting and gravitational motor system theories, generating hypotheses to be tested in future research