scholarly journals Whole brain mapping of somatosensory responses in awake marmosets investigated with ultra-high field fMRI

2020 ◽  
Author(s):  
Justine C. Cléry ◽  
Yuki Hori ◽  
David J. Schaeffer ◽  
Joseph S. Gati ◽  
J. Andrew Pruszynski ◽  
...  
Keyword(s):  
Brain Mapping ◽  
Tactile Stimulation ◽  
New World ◽  
Body Representation ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Whole Brain ◽  
Non Invasive ◽  
The Face ◽  
Somatosensory Responses

AbstractThe common marmoset (Callithrix jacchus) is a small-bodied New World primate that is becoming an important model to study brain functions. Despite several studies exploring the somatosensory system of marmosets, all results have come from anesthetized animals using invasive techniques and post-mortem analyses. Here we demonstrate the feasibility for getting high-quality and reproduceable sensorimotor mapping in awake marmosets with functional magnetic resonance imaging (fMRI). We acquired fMRI sequences in four animals while they received tactile stimulation (via air-puffs), delivered to the face, arm or leg. We found that the body representation progressed medially from the leg to the face in areas 3a, 3b, 1/2, and from caudal to rostral sites in areas S2 and PV. SI and SII exhibited a body representation in their functional connectivity pattern within the posterior and midcingulate and the thalamus. Interestingly, we also found a somatotopic body representation in two subcortical areas: the thalamus and, for the first time, in the putamen. These maps have similar organizations as those previously found in Old World macaque monkeys and humans, suggesting that these subcortical somatotopic organizations were already established before Old and New World primates diverged. Our results show the first whole brain mapping of somatosensory responses acquired in a non-invasive way in awake marmosets.Significant statementHere we used somatosensory stimulation combined with functional magnetic resonance imaging to map whole brain activation in awake marmosets. We used light tactile stimulation, consisting of air-puffs, delivered on the face, arm or leg. We found a topographic body representation in primary (SI) and secondary (SII) somatosensory regions, thalamus and putamen. We also revealed the existence of a body representation organization within the thalamus and the cingulate cortex by computing functional connectivity maps from seeds defined in SI/SII for face, arm and leg using resting-state fMRI data. This non-invasive approach will be essential for chronic studies by guiding invasive recording and manipulation techniques.

scholarly journals Increased sensitivity to strong perturbations in a whole-brain model of LSD

2021 ◽  
Author(s):  
Beatrice M. Jobst ◽  
Selen Atasoy ◽  
Adrián Ponce-Alvarez ◽  
Ana Sanjuán ◽  
Leor Roseman ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
External Perturbation ◽  
Brain Regions ◽  
Lysergic Acid ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Whole Brain ◽  
Response Diversity ◽  
Brain States ◽  
The Brain

AbstractLysergic acid diethylamide (LSD) is a potent psychedelic drug, which has seen a revival in clinical and pharmacological research within recent years. Human neuroimaging studies have shown fundamental changes in brain-wide functional connectivity and an expansion of dynamical brain states, thus raising the question about a mechanistic explanation of the dynamics underlying these alterations. Here, we applied a novel perturbational approach based on a whole-brain computational model, which opens up the possibility to externally perturb different brain regions in silico and investigate differences in dynamical stability of different brain states, i.e. the dynamical response of a certain brain region to an external perturbation. After adjusting the whole-brain model parameters to reflect the dynamics of functional magnetic resonance imaging (fMRI) BOLD signals recorded under the influence of LSD or placebo, perturbations of different brain areas were simulated by either promoting or disrupting synchronization in the regarding brain region. After perturbation offset, we quantified the recovery characteristics of the brain area to its basal dynamical state with the Perturbational Integration Latency Index (PILI) and used this measure to distinguish between the two brain states. We found significant changes in dynamical complexity with consistently higher PILI values after LSD intake on a global level, which indicates a shift of the brain’s global working point further away from a stable equilibrium as compared to normal conditions. On a local level, we found that the largest differences were measured within the limbic network, the visual network and the default mode network. Additionally, we found a higher variability of PILI values across different brain regions after LSD intake, indicating higher response diversity under LSD after an external perturbation. Our results provide important new insights into the brain-wide dynamical changes underlying the psychedelic state - here provoked by LSD intake - and underline possible future clinical applications of psychedelic drugs in particular psychiatric disorders.HighlightsNovel offline perturbational method applied on functional magnetic resonance imaging (fMRI) data under the effect of lysergic acid diethylamide (LSD)Shift of brain’s global working point to more complex dynamics after LSD intakeConsistently longer recovery time after model perturbation under LSD influenceStrongest effects in resting state networks relevant for psychedelic experienceHigher response diversity across brain regions under LSD influence after an external in silico perturbation

Language Functional Magnetic Resonance Imaging in Preoperative Assessment of Language Areas: Correlation with Direct Cortical Stimulation

Neurosurgery ◽  
2003 ◽  
Vol 52 (6) ◽  
pp. 1335-1347 ◽  
Author(s):  
Franck-Emmanuel Roux ◽  
Kader Boulanouar ◽  
Jean-Albert Lotterie ◽  
Mehdi Mejdoubi ◽  
James P. LeSage ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Left Hemisphere ◽  
Brain Mapping ◽  
Fmri Data ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Verb Generation ◽  
Language Areas

Abstract OBJECTIVE The aim of this study was to analyze the usefulness of preoperative language functional magnetic resonance imaging (fMRI), by correlating fMRI data with intraoperative cortical stimulation results for patients with brain tumors. METHODS Naming and verb generation tasks were used, separately or in combination, for 14 right-handed patients with tumors in the left hemisphere. fMRI data obtained were analyzed with SPM software, with two standard analysis thresholds (P < 0.005 and then P < 0.05). The fMRI data were then registered in a frameless stereotactic neuronavigational device and correlated with direct brain mapping results. We used a statistical model with the fMRI information as a predictor, spatially correlating each intraoperatively mapped cortical site with fMRI data integrated in the neuronavigational system (site-by-site correlation). Eight patients were also studied with language fMRI postoperatively, with the same acquisition protocol. RESULTS We observed high variability in signal extents and locations among patients with both tasks. The activated areas were located mainly in the left hemisphere in the middle and inferior frontal gyri (F2 and F3), the superior and middle temporal gyri (T1 and T2), and the supramarginal and angular gyri. A total of 426 cortical sites were tested for each task among the 14 patients. In frontal and temporoparietal areas, poor sensitivity of the fMRI technique was observed for the naming and verb generation tasks (22 and 36%, respectively) with P < 0.005 as the analysis threshold. Although not perfect, the specificity of the fMRI technique was good in all conditions (97% for the naming task and 98% for the verb generation task). Better correlation (sensitivity, 59%; specificity, 97%) was achieved by combining the two fMRI tasks. Variation of the analysis threshold to P < 0.05 increased the sensitivity to 66% while decreasing the specificity to 91%. Postoperative fMRI data (for the cortical brain areas studied intraoperatively) were in accordance with brain mapping results for six of eight patients. Complete agreement between pre- and postoperative fMRI studies and direct brain mapping results was observed for only three of eight patients. CONCLUSION With the paradigms and analysis thresholds used in this study, language fMRI data obtained with naming or verb generation tasks, before and after surgery, were imperfectly correlated with intraoperative brain mapping results. A better correlation could be obtained by combining the fMRI tasks. The overall results of this study demonstrated that language fMRI could not be used to make critical surgical decisions in the absence of direct brain mapping. Other acquisition protocols are required for evaluation of the potential role of language fMRI in the accurate detection of essential cortical language areas.

scholarly journals Measuring functional connectivity in stroke: Approaches and considerations

2017 ◽  
Vol 37 (8) ◽  
pp. 2665-2678 ◽  
Author(s):  
Joshua S Siegel ◽  
Gordon L Shulman ◽  
Maurizio Corbetta
Keyword(s):  
Functional Connectivity ◽  
Functional Organization ◽  
Brain Network ◽  
Global Changes ◽  
Brain Anatomy ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Non Invasive ◽  
Stroke Research ◽  
The Subject

Recent research has demonstrated the importance of global changes to the functional organization of brain network following stroke. Resting functional magnetic resonance imaging (R-fMRI) is a non-invasive tool that enables the measurement of functional connectivity (FC) across the entire brain while placing minimal demands on the subject. For these reasons, it is a uniquely appealing tool for studying the distant effects of stroke. However, R-fMRI studies rely on a number of premises that cannot be assumed without careful validation in the context of stroke. Here, we describe strategies to identify and mitigate confounds specific to R-fMRI research in cerebrovascular disease. Five main topics are discussed: (a) achieving adequate co-registration of lesioned brains, (b) identifying and removing hemodynamic lags in resting BOLD, (c) identifying other vascular disruptions that affect the resting BOLD signal, (d) selecting an appropriate control cohort, and (e) acquiring sufficient fMRI data to reliably identify FC changes. For each topic, we provide guidelines for steps to improve the interpretability and reproducibility of FC-stroke research. We include a table of confounds and approaches to identify and mitigate each. Our recommendations extend to any research using R-fMRI to study diseases that might alter cerebrovascular flow and dynamics or brain anatomy.

scholarly journals Laminar Specific fMRI Reveals Directed Interactions in Distributed Networks During Language Processing

2019 ◽  
Author(s):  
Daniel Sharoh ◽  
Tim van Mourik ◽  
Lauren J. Bains ◽  
Katrien Segaert ◽  
Kirsten Weber ◽  
...  
Keyword(s):  
Language Processing ◽  
Word Reading ◽  
Distributed Networks ◽  
Cognitive Tasks ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Top Down ◽  
Noninvasive Technique ◽  
Whole Brain ◽  
Critical Regions

AbstractLaminar resolution, functional magnetic resonance imaging (lfMRI) is a noninvasive technique with the potential to distinguish top-down and bottom-up signal contributions on the basis of laminar specific interactions between distal regions. Hitherto, lfMRI could not be demonstrated for either whole-brain distributed networks or for complex cognitive tasks. We show that lfMRI can reveal whole-brain directed networks during word reading. We identify distinct, language critical regions based on their association with the top-down signal stream and establish lfMRI for the noninvasive assessment of directed connectivity during task performance.

scholarly journals Individual Brain Charting, a high-resolution fMRI dataset for cognitive mapping

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Ana Luísa Pinho ◽  
Alexis Amadon ◽  
Torsten Ruest ◽  
Murielle Fabre ◽  
Elvis Dohmatob ◽  
...  
Keyword(s):  
High Resolution ◽  
Brain Mapping ◽  
Cognitive Functions ◽  
Cognitive Mapping ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Cognitive Mechanisms ◽  
Precise Mapping ◽  
Objective Basis ◽  
High Level

Abstract Functional Magnetic Resonance Imaging (fMRI) has furthered brain mapping on perceptual, motor, as well as higher-level cognitive functions. However, to date, no data collection has systematically addressed the functional mapping of cognitive mechanisms at a fine spatial scale. The Individual Brain Charting (IBC) project stands for a high-resolution multi-task fMRI dataset that intends to provide the objective basis toward a comprehensive functional atlas of the human brain. The data refer to a cohort of 12 participants performing many different tasks. The large amount of task-fMRI data on the same subjects yields a precise mapping of the underlying functions, free from both inter-subject and inter-site variability. The present article gives a detailed description of the first release of the IBC dataset. It comprises a dozen of tasks, addressing both low- and high- level cognitive functions. This openly available dataset is thus intended to become a reference for cognitive brain mapping.

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