scholarly journals Mapping electromagnetic networks to haemodynamic networks in the human brain

2021 ◽  
Author(s):  
Golia Shafiei ◽  
Sylvain Baillet ◽  
Bratislav Misic
Keyword(s):  
Frequency Band ◽  
Single Frequency ◽  
Functional Networks ◽  
Network Architectures ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Neural Communication ◽  
Cortical Hierarchy ◽  
Connectivity Patterns ◽  
The Relationship

AbstractWhole-brain neural communication is typically estimated from statistical associations among electromagnetic or haemodynamic time-series. The relationship between functional network architectures recovered from these two types of neural activity remains unknown. Here we map electromagnetic networks (measured using magnetoencephalography; MEG) to haemodynamic networks (measured using functional magnetic resonance imaging; fMRI). We find that the relationship between the two modalities is regionally heterogeneous and systematically follows the cortical hierarchy, with close correspondence in unimodal cortex and poor correspondence in transmodal cortex, potentially reflecting patterns of laminar differentiation, recurrent subcortical input and neurovascular coupling. Correspondence between the two is largely driven by slower rhythms, particularly the delta (2-4 Hz) and beta (15-29 Hz) frequency band. Moreover, haemodynamic connectivity cannot be explained by electromagnetic activity in a single frequency band, but rather arises from the mixing of multiple neurophysiological rhythms. Collectively, these findings demonstrate highly organized but only partly overlapping patterns of connectivity in MEG and fMRI functional networks, opening fundamentally new avenues for studying the relationship between cortical micro-architecture and multi-modal connectivity patterns.

scholarly journals Cerebral functional networks during sleep in young and older individuals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Véronique Daneault ◽  
Pierre Orban ◽  
Nicolas Martin ◽  
Christian Dansereau ◽  
Jonathan Godbout ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Brain Plasticity ◽  
Network Connectivity ◽  
Sleep Stages ◽  
Functional Networks ◽  
Older Individuals ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Age Related ◽  
Light Sleep

AbstractEven though sleep modification is a hallmark of the aging process, age-related changes in functional connectivity using functional Magnetic Resonance Imaging (fMRI) during sleep, remain unknown. Here, we combined electroencephalography and fMRI to examine functional connectivity differences between wakefulness and light sleep stages (N1 and N2 stages) in 16 young (23.1 ± 3.3y; 7 women), and 14 older individuals (59.6 ± 5.7y; 8 women). Results revealed extended, distributed (inter-between) and local (intra-within) decreases in network connectivity during sleep both in young and older individuals. However, compared to the young participants, older individuals showed lower decreases in connectivity or even increases in connectivity between thalamus/basal ganglia and several cerebral regions as well as between frontal regions of various networks. These findings reflect a reduced ability of the older brain to disconnect during sleep that may impede optimal disengagement for loss of responsiveness, enhanced lighter and fragmented sleep, and contribute to age effects on sleep-dependent brain plasticity.

scholarly journals Transcranial direct current stimulation alters functional network structure in humans

2018 ◽  
Author(s):  
M. Ruttorf ◽  
S. Kristensen ◽  
L.R. Schad ◽  
J. Almeida
Keyword(s):  
Neuronal Activity ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Network Architecture ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Direct Current Stimulation ◽  
Brain States ◽  
The Relationship ◽  
Central Tool

AbstractTranscranial direct current stimulation (tDCS) is routinely used in basic and clinical research, but its efficacy has been challenged on a methodological and statistical basis recently. The arguments against tDCS derive from insufficient understanding of how this technique interacts with brain processes physiologically. Because of its potential as a central tool in neuroscience, it is important to clarify whether and how tDCS affects neuronal activity. Here, we investigate influences of offline tDCS on network architecture measured by functional magnetic resonance imaging. Our results reveal a tDCS-induced reorganisation of a functionally-defined network that is dependent on whether we are exciting or inhibiting a node within this network, confirming in a functioning brain, and in a bias free and independent fashion that tDCS influences neuronal activity. Moreover, our results suggest that network-specific connectivity has an important role in defining the effects of tDCS and the relationship between brain states and behaviour.

scholarly journals Brain Activation of Patients With Obsessive-Compulsive Disorder During a Mental Rotation Task: A Functional MRI Study

2021 ◽  
Vol 12 ◽  
Author(s):  
Sanghoon Oh ◽  
Wi Hoon Jung ◽  
Taekwan Kim ◽  
Geumsook Shim ◽  
Jun Soo Kwon
Keyword(s):  
Magnetic Resonance Imaging ◽  
Cognitive Function ◽  
Neural Activity ◽  
Symptom Severity ◽  
Brain Activation ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Obsessive Compulsive ◽  
Compulsive Disorder ◽  
The Relationship

Functional neuroimaging studies have implicated alterations in frontostriatal and frontoparietal circuits in obsessive-compulsive disorder (OCD) during various tasks. To date, however, brain activation for visuospatial function in conjunction with symptoms in OCD has not been comprehensively evaluated. To elucidate the relationship between neural activity, cognitive function, and obsessive-compulsive symptoms, we investigated regional brain activation during the performance of a visuospatial task in patients with OCD using functional magnetic resonance imaging (fMRI). Seventeen medication-free patients with OCD and 21 age-, sex-, and IQ-matched healthy controls participated in this study. Functional magnetic resonance imaging data were obtained while the subjects performed a mental rotation (MR) task. Brain activation during the task was compared between the two groups using a two-sample t-test. Voxel-wise whole-brain multiple regression analyses were also performed to examine the relationship between obsessive-compulsive symptom severity and neural activity during the task. The two groups did not differ in MR task performance. Both groups also showed similar task-related activation patterns in frontoparietal regions with no significant differences. Activation in the right dorsolateral prefrontal cortex in patients with OCD during the MR task was positively associated with their total Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) scores. This study identified the specific brain areas associated with the interaction between symptom severity and visuospatial cognitive function during an MR task in medication-free patients with OCD. These findings may serve as potential neuromodulation targets for OCD treatment.

scholarly journals Network variants are similar between task and rest states

2020 ◽  
Author(s):  
Brian T. Kraus ◽  
Diana Perez ◽  
Zach Ladwig ◽  
Benjamin A. Seitzman ◽  
Ally Dworetsky ◽  
...  
Keyword(s):  
Resting State ◽  
Resting State Fmri ◽  
Functional Networks ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Brain Organization ◽  
Precision Data ◽  
Specific Effects ◽  
Multiple Tasks ◽  
Over Time

AbstractRecent work has demonstrated that individual-specific variations in functional networks (that we call “network variants”) can be identified in individuals using functional magnetic resonance imaging (fMRI). These network variants exhibit reliability over time with resting-state fMRI data. These properties have suggested that network variants may be trait-like markers of individual differences in brain organization. Another test of this conclusion would be to examine if network variants are stable between task and rest states. Here, we use precision data from the Midnight Scan Club (MSC) to demonstrate that (1) task data can be used to identify network variants reliably, (2) these network variants show substantial spatial overlap with those observed in rest, although state-specific effects are present, (3) network variants assign to similar canonical functional networks in different states, and (4) single tasks or a combination of multiple tasks produce similar network variants to rest. Together, these findings further reinforce the trait-like nature of network variants and demonstrate the utility of using task data to define network variants.

scholarly journals Creativity in art and science: are there two cultures?

2012 ◽  
Vol 14 (1) ◽  
pp. 49-54 ◽  
Keyword(s):  
Creative Process ◽  
Word Association ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Neural Basis ◽  
Two Cultures ◽  
Brain Circuits ◽  
The Arts ◽  
The Relationship ◽  
Key Questions

The study of creativity is characterized by a variety of key questions, such as the nature of the creative process, whether there are multiple types of creativity, the relationship between high levels of creativity ("Big C") and everyday creativity ("little c"), and the neural basis of creativity. Herein we examine the question of the relationship between creativity in the arts and the sciences, and use functional magnetic resonance imaging to explore the neural basis of creativity in a group of "Big C" individuals from both domains using a word association protocol. The findings give no support for the notion that the artists and scientists represent "two cultures. " Rather, they suggest that very gifted artists and scientists have association cortices that respond in similar ways. Both groups display a preponderance of activation in brain circuits involved in higher-order socioaffective processing and Random Episodic Silent Thought /the default mode.

scholarly journals Simulating Local Deformations in the Human Cortex Due to Blood Flow-Induced Changes in Mechanical Tissue Properties: Impact on Functional Magnetic Resonance Imaging

2021 ◽  
Vol 15 ◽  
Author(s):  
Mahsa Zoraghi ◽  
Nico Scherf ◽  
Carsten Jaeger ◽  
Ingolf Sack ◽  
Sebastian Hirsch ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Brain Tissue ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Tissue Properties ◽  
The Relationship ◽  
The Brain

Investigating human brain tissue is challenging due to the complexity and the manifold interactions between structures across different scales. Increasing evidence suggests that brain function and microstructural features including biomechanical features are related. More importantly, the relationship between tissue mechanics and its influence on brain imaging results remains poorly understood. As an important example, the study of the brain tissue response to blood flow could have important theoretical and experimental consequences for functional magnetic resonance imaging (fMRI) at high spatial resolutions. Computational simulations, using realistic mechanical models can predict and characterize the brain tissue behavior and give us insights into the consequent potential biases or limitations of in vivo, high-resolution fMRI. In this manuscript, we used a two dimensional biomechanical simulation of an exemplary human gyrus to investigate the relationship between mechanical tissue properties and the respective changes induced by focal blood flow changes. The model is based on the changes in the brain’s stiffness and volume due to the vasodilation evoked by neural activity. Modeling an exemplary gyrus from a brain atlas we assessed the influence of different potential mechanisms: (i) a local increase in tissue stiffness (at the level of a single anatomical layer), (ii) an increase in local volume, and (iii) a combination of both effects. Our simulation results showed considerable tissue displacement because of these temporary changes in mechanical properties. We found that the local volume increase causes more deformation and consequently higher displacement of the gyrus. These displacements introduced considerable artifacts in our simulated fMRI measurements. Our results underline the necessity to consider and characterize the tissue displacement which could be responsible for fMRI artifacts.

scholarly journals Association between uncontrolled eating and caudate responses to reward cues

2019 ◽  
Author(s):  
Patrícia Bado ◽  
Jorge Moll ◽  
Bruno P. Nazar ◽  
Ricardo de Oliveira-Souza ◽  
Raquel da Costa ◽  
...  
Keyword(s):  
Eating Behaviors ◽  
Reward System ◽  
Normal Weight ◽  
Reward Sensitivity ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Fmri Study ◽  
Trait Impulsivity ◽  
Uncontrolled Eating ◽  
The Relationship

Reward sensitivity has been hypothesized to play a significant role in a range of eating behaviors, including overeating. Previous functional magnetic resonance imaging (fMRI) findings in overweight individuals indicate heightened responses to food, but also to other reward types, suggesting generalized overactivity of the reward system. The current fMRI study investigated the relationship between general reward sensitivity and eating behavior in normal-weight individuals, while controlling for trait impulsivity. Participants were young adults, some demonstrating ADHD symptoms, allowing for a range of impulsivity profiles. A classical conditioning task was used to measure striatal responses to monetary reward stimuli. Uncontrolled eating scores from the Three Eating Factor Questionnaire were positively correlated with caudate responses to reward predicting cues. This association was not explained by self-reported impulsivity. The current findings provide support for heightened reward anticipation as a neural phenotype contributing to overeating.

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