scholarly journals A comprehensive neural simulation of slow-wave sleep and highly responsive wakefulness dynamics

2021 ◽  
Author(s):  
Jennifer S Goldman ◽  
Lionel Kusch ◽  
Bahar Hazal Yalcinkaya ◽  
Damien Depannemaecker ◽  
Trang-Anh Estelle Nghiem ◽  
...  
Keyword(s):  
Open Access ◽  
Human Brain ◽  
Slow Wave Sleep ◽  
Spatial Scales ◽  
Mean Field ◽  
Brain Regions ◽  
Inhibitory Neurons ◽  
Neural Dynamics ◽  
Healthy Human ◽  
Brain States

Hallmarks of neural dynamics during healthy human brain states span spatial scales from neuromodulators acting on microscopic ion channels to macroscopic changes in communication between brain regions. Developing a scale-integrated understanding of neural dynamics has therefore remained challenging. Here, we perform the integration across scales using mean-field modeling of Adaptive Exponential (AdEx) neurons, explicitly incorporating intrinsic properties of excitatory and inhibitory neurons. We report that when AdEx mean-field neural populations are connected via structural tracts defined by the human connectome, macroscopic dynamics resembling human brain activity emerge. Importantly, the model can qualitatively and quantitatively account for properties of empirical spontaneous and stimulus-evoked dynamics in the space, time, phase, and frequency domains. Remarkably, the model also reproduces brain-wide enhanced responsiveness and capacity to encode information particularly during wake-like states, as quantified using the perturbational complexity index. The model was run using The Virtual Brain (TVB) simulator, and is open-access in EBRAINS. This approach not only provides a scale-integrated understanding of brain states and their underlying mechanisms, but also open access tools to investigate brain responsiveness, toward producing a more unified, formal understanding of experimental data from conscious and unconscious states, as well as their associated pathologies.

scholarly journals The functional organization of human epileptic hippocampus

2016 ◽  
Vol 115 (6) ◽  
pp. 3140-3145 ◽  
Author(s):  
Petr Klimes ◽  
Juliano J. Duque ◽  
Ben Brinkmann ◽  
Jamie Van Gompel ◽  
Matt Stead ◽  
...  
Keyword(s):  
Spatial Scale ◽  
Local Field ◽  
Medial Temporal Lobe ◽  
Slow Wave Sleep ◽  
Functional Organization ◽  
Spectral Power ◽  
Spatial Scales ◽  
Field Potential ◽  
Brain Regions ◽  
Behavioral State

The function and connectivity of human brain is disrupted in epilepsy. We previously reported that the region of epileptic brain generating focal seizures, i.e., the seizure onset zone (SOZ), is functionally isolated from surrounding brain regions in focal neocortical epilepsy. The modulatory effect of behavioral state on the spatial and spectral scales over which the reduced functional connectivity occurs, however, is unclear. Here we use simultaneous sleep staging from scalp EEG with intracranial EEG recordings from medial temporal lobe to investigate how behavioral state modulates the spatial and spectral scales of local field potential synchrony in focal epileptic hippocampus. The local field spectral power and linear correlation between adjacent electrodes provide measures of neuronal population synchrony at different spatial scales, ∼1 and 10 mm, respectively. Our results show increased connectivity inside the SOZ and low connectivity between electrodes in SOZ and outside the SOZ. During slow-wave sleep, we observed decreased connectivity for ripple and fast ripple frequency bands within the SOZ at the 10 mm spatial scale, while the local synchrony remained high at the 1 mm spatial scale. Further study of these phenomena may prove useful for SOZ localization and help understand seizure generation, and the functional deficits seen in epileptic eloquent cortex.

scholarly journals Conservative and disruptive modes of adolescent change in brain functional connectivity

2019 ◽  
Author(s):  
František Váša ◽  
Rafael Romero-Garcia ◽  
Manfred G. Kitzbichler ◽  
Jakob Seidlitz ◽  
Kirstie J. Whitaker ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Human Brain ◽  
Developmental Change ◽  
Aerobic Glycolysis ◽  
Brain Regions ◽  
Association Cortex ◽  
Brain Organization ◽  
Healthy Human ◽  
Age Related ◽  
Strongly Connected

AbstractAdolescent changes in human brain function are not entirely understood. Here we used multi-echo functional magnetic resonance imaging (fMRI) to measure developmental change in functional connectivity (FC) of resting-state oscillations between pairs of 330 cortical regions and 16 subcortical regions in N=298 healthy adolescents. Participants were aged 14-26 years and were scanned on two or more occasions at least 6 months apart. We found two distinct modes of age-related change in FC: “conservative” and “disruptive”. Conservative development was characteristic of primary cortex, which was strongly connected at 14 years and became even more connected in the period 14-26 years. Disruptive development was characteristic of association cortex, hippocampus and amygdala, which were not strongly connected at 14 years but became more strongly connected during adolescence. We defined the maturational index (MI) as the signed coefficient of the linear relationship between baseline FC (at 14 years,FC14) and adolescent change in FC (∆FC14−26). Disruptive systems (with negative MI) were functionally specialised for social cognition and autobiographical memory and were significantly co-located with prior maps of aerobic glycolysis (AG), AG-related gene expression, post-natal expansion of cortical surface area, and adolescent shrinkage of cortical depth. We conclude that human brain organization is disrupted during adolescence by the emergence of strong functional connectivity of subcortical nuclei and association cortical areas, representing metabolically expensive re-modelling of synaptic connectivity between brain regions that were not strongly connected in childhood. We suggest that this re-modelling process may support emergence of social skills and self-awareness during healthy human adolescence.

scholarly journals Voluntary movement initiation is not coupled to optimal sensorimotor oscillatory phases

2019 ◽  
Author(s):  
Sara J Hussain ◽  
Mary K Vollmer ◽  
Romain Quentin ◽  
Iñaki Iturrate ◽  
Leonardo G. Cohen
Keyword(s):  
Human Brain ◽  
Voluntary Movement ◽  
List Type ◽  
Voluntary Movements ◽  
Movement Initiation ◽  
Healthy Human ◽  
Strongly Coupled ◽  
Motor Behaviors ◽  
Brain States ◽  
Time Point

AbstractSuccessful initiation of a voluntary movement requires transmission of descending motor commands from the primary motor cortex (M1) to the spinal cord and effector muscles. M1 activity alternates between brief excitatory and inhibitory brain states in the form of oscillatory phases that correlate with single neuron spiking rates and population-level neuronal activity. The influence of these brief brain states on fundamental motor behaviors, like movement initiation, is not known. Here, we asked if voluntary movement initiation occurs during specific oscillatory phases of sensorimotor rhythms using a combination of transcranial magnetic stimulation (TMS), electroencephalography (EEG), and behavioral testing. To address this, we empirically determined the time point at which M1 released the motor command required to produce a simple finger movement during a self-paced movement initiation task. We then probabilistically modeled the oscillatory phase at this time point in the mu (8-12 Hz) and beta (13-30 Hz) ranges, and at each frequency between 8 and 50 Hz, determining each subject’s preferred movement initiation phase for each frequency. After pooling the identified phases across subjects, we identified no significant clustering of preferred movement initiation phases within mu or beta frequencies, or at any other frequency between 8 and 50 Hz. These results demonstrate that movements were not preferentially initiated during optimal oscillatory phases at any frequency. Thus, we conclude that initiation of self-paced voluntary movements is not strongly coupled to optimal sensorimotor oscillatory phases in the healthy human brain. It remains to be determined if more complex aspects of motor behavior like action selection occur during optimal oscillatory phases.Key points summaryMotor cortical activity alternates between periods of excitation and inhibition, but the influence of these brain states on fundamental motor behaviors like movement initiation is unknown.We examined whether self-paced voluntary movements are preferentially initiated during optimal sensorimotor oscillatory phases.Our results showed no evidence that voluntary movements were predominantly initiated during optimal phases across a range of frequencies.We conclude that initiation of voluntary, self-paced movements is not strongly coupled to optimal sensorimotor oscillatory phases in the healthy human brain.

scholarly journals Global Signal Topography of the Human Brain: A Novel Framework of Functional Connectivity for Psychological and Pathological Investigations

2021 ◽  
Vol 15 ◽  
Author(s):  
Yujia Ao ◽  
Yujie Ouyang ◽  
Chengxiao Yang ◽  
Yifeng Wang
Keyword(s):  
Human Brain ◽  
Spatial Information ◽  
Brain Regions ◽  
Intrinsic Structure ◽  
Global Signal ◽  
Neural Information ◽  
Sensory Cortices ◽  
Brain States ◽  
Global And Local ◽  
Local Brain

The global signal (GS), which was once regarded as a nuisance of functional magnetic resonance imaging, has been proven to convey valuable neural information. This raised the following question: what is a GS represented in local brain regions? In order to answer this question, the GS topography was developed to measure the correlation between global and local signals. It was observed that the GS topography has an intrinsic structure characterized by higher GS correlation in sensory cortices and lower GS correlation in higher-order cortices. The GS topography could be modulated by individual factors, attention-demanding tasks, and conscious states. Furthermore, abnormal GS topography has been uncovered in patients with schizophrenia, major depressive disorder, bipolar disorder, and epilepsy. These findings provide a novel insight into understanding how the GS and local brain signals coactivate to organize information in the human brain under various brain states. Future directions were further discussed, including the local-global confusion embedded in the GS correlation, the integration of spatial information conveyed by the GS, and temporal information recruited by the connection analysis. Overall, a unified psychopathological framework is needed for understanding the GS topography.

Kinetic analysis of muscarinic receptors in human brain and salivary gland in vivo

1995 ◽  
Vol 268 (6) ◽  
pp. R1491-R1499
Author(s):  
Y. Hiramatsu ◽  
W. C. Eckelman ◽  
J. A. Carrasquillo ◽  
R. S. Miletich ◽  
I. H. Valdez ◽  
...  
Keyword(s):  
Human Brain ◽  
Muscarinic Acetylcholine Receptor ◽  
Brain Regions ◽  
Binding Potential ◽  
Pharmacokinetic Analysis ◽  
Parotid Glands ◽  
Planar Imaging ◽  
In Vivo Evaluation ◽  
Healthy Human

Previous studies in rats have suggested that the muscarinic acetylcholine receptor (mAChR) antagonist (S)-3-quinuclidinyl-(S)-4-[123I]iodobenzilate [(SS)-IQNB] may be useful for the in vivo evaluation of mAChRs in humans as a control for the higher-affinity compound (RR)-IQNB. We have directly tested this hypothesis and examined the distribution of mAChRs in brain regions and parotid glands of healthy human volunteers in vivo using (RR)- and (SS)-IQNB (relatively high- and low-affinity antagonists, respectively), planar imaging, and pharmacokinetic analysis. This is the first in vivo study of mAChRs in humans that has employed stereoisomeric ligands and metabolic analysis to determine specific receptor binding. We observed that (SS)-IQNB showed much faster clearance from blood than (RR)-IQNB and different metabolite profiles. Also, the transport kinetics of the enantiomers were different. The estimated binding potential (approximately Bmax/Kd) of (RR)-IQNB was highest in two cortical regions, intermediate in parotid gland, and lowest in cerebellum. The aggregate results show that in humans (SS)-IQNB does not act as an ideal general probe to measure the nonspecific IQNB distribution. However, (RR)-IQNB does appear to have value when used for studies of human brain mAChRs.

scholarly journals A High-Resolution In Vivo Atlas of the Human Brain’s Benzodiazepine Binding Site of GABAA Receptors

2020 ◽  
Author(s):  
Martin Nørgaard ◽  
Vincent Beliveau ◽  
Melanie Ganz ◽  
Claus Svarer ◽  
Lars H Pinborg ◽  
...  
Keyword(s):  
High Resolution ◽  
Human Brain ◽  
Mrna Expression ◽  
Brain Regions ◽  
Mrna Levels ◽  
Gamma Aminobutyric Acid ◽  
Healthy Human ◽  
Brain Functions ◽  
The Brain

ABSTRACTGamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human brain and plays a key role in several brain functions and neuropsychiatric disorders such as anxiety, epilepsy, and depression. The binding of benzodiazepines to the benzodiazepine receptor sites (BZR) located on GABAA receptors (GABAARs) potentiates the inhibitory effect of GABA leading to the anxiolytic, anticonvulsant and sedative effects used for treatment of those disorders. However, the function of GABAARs and the expression of BZR protein is determined by the GABAAR subunit stoichiometry (19 genes coding for individual subunits), and it remains to be established how the pentamer composition varies between brain regions and individuals.Here, we present a quantitative high-resolution in vivo atlas of the human brain BZRs, generated on the basis of [11C]flumazenil Positron Emission Tomography (PET) data. Next, based on autoradiography data, we transform the PET-generated atlas from binding values into BZR protein density. Finally, we examine the brain regional association with mRNA expression for the 19 subunits in the GABAAR, including an estimation of the minimally required expression of mRNA levels for each subunit to translate into BZR protein.This represents the first publicly available quantitative high-resolution in vivo atlas of the spatial distribution of BZR densities in the healthy human brain. The atlas provides a unique neuroscientific tool as well as novel insights into the association between mRNA expression for individual subunits in the GABAAR and the BZR density at each location in the brain.

Network maps of the human brain's rich club

2013 ◽  
Vol 1 (2) ◽  
pp. 248-250 ◽  
Author(s):  
OLAF SPORNS ◽  
MARTIJN P. VAN DEN HEUVEL
Keyword(s):  
Human Brain ◽  
Degree Sequence ◽  
Brain Regions ◽  
Imaging Data ◽  
Healthy Human ◽  
Rich Club ◽  
Human Volunteers ◽  
Global Brain ◽  
High Degree ◽  
The Brain

Does the human brain have a central connective core, and, if so, how costly is it?Noninvasive imaging data allow the construction of network maps of the human brain, recording its structural and functional connectivity. A number of studies have reported on various characteristic network attributes, such as a tendency toward local clustering, high global efficiency, the prevalence of specific network motifs, and a pronounced community structure with several anatomically and functionally defined modules and interconnecting hub regions (Bullmore & Sporns, 2009; van den Heuvel & Hulshoff Pol, 2010; Sporns, 2011). Hubs are of particular interest in studies of the brain since they may play crucial roles in integrative processes and global brain communication, thought to be essential for many aspects of higher brain function. Indeed, hubs have been shown to correspond to brain regions that exhibit complex physiological responses and maintain widespread and diverse connection profiles with other parts of the brain. We asked if, in addition to being highly connected, brain hubs would also exhibit a strong tendency to be mutually interconnected, forming what has been called a “rich club” (Colizza et al., 2006). Rich club organization is present in a network if sets of high-degree nodes exhibit denser mutual connections than predicted on the basis of the degree sequence alone. We investigated rich club organization in the human brain in datasets that recorded weighted projections among different anatomical regions of the cerebral cortex, recorded from several cohorts of healthy human volunteers (van den Heuvel & Sporns, 2011; van den Heuvel et al., 2012).

scholarly journals Distance-based functional criticality in the human brain: intelligence and emotional intelligence

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Lili Jiang ◽  
Kaini Qiao ◽  
Chunlin Li
Keyword(s):  
Emotional Intelligence ◽  
Human Brain ◽  
Spatial Scales ◽  
Average Distance ◽  
Age Groups ◽  
Brain Regions ◽  
Brain Dynamics ◽  
Individual Behaviors ◽  
Key Factor ◽  
Organizational Principles

Abstract Background Anatomical distance has been identified as a key factor in the organizational principles of the human brain. On the other hand, criticality was proposed to accommodate the multiscale properties of human brain dynamics, and functional criticality based on resting-state functional magnetic resonance imaging (rfMRI) is a sensitive neuroimaging marker for human brain dynamics. Hence, to explore the effects of anatomical distance of the human brain on behaviors in terms of functional criticality, we proposed a revised algorithm of functional criticality called the distance-based vertex-wise index of functional criticality, and assessed this algorithm compared with the original neighborhood-based functional criticality. Results We recruited two groups of healthy participants, including young adults and middle-aged participants, for a total of 60 datasets including rfMRI and intelligence as well as emotional intelligence to study how human brain functional criticalities at different spatial scales contribute to individual behaviors. Furthermore, we defined the average distance between the particular behavioral map and vertices with significant functional connectivity as connectivity distance. Our results demonstrated that intelligence and emotional intelligence mapped to different brain regions at different ages. Additionally, intelligence was related to a wider distance range compared to emotional intelligence. Conclusions For different age groups, our findings not only provided a linkage between intelligence/emotional intelligence and functional criticality but also quantitatively characterized individual behaviors in terms of anatomical distance.

scholarly journals Is There a Brain Microbiome?

2021 ◽  
Vol 16 ◽  
pp. 263310552110187
Author(s):  
Christopher D Link
Keyword(s):  
Animal Models ◽  
Human Brain ◽  
Neurodegenerative Diseases ◽  
Ground Truth ◽  
Healthy Human ◽  
Strong Motivation ◽  
The Many ◽  
The Brain

Numerous studies have identified microbial sequences or epitopes in pathological and non-pathological human brain samples. It has not been resolved if these observations are artifactual, or truly represent population of the brain by microbes. Given the tempting speculation that resident microbes could play a role in the many neuropsychiatric and neurodegenerative diseases that currently lack clear etiologies, there is a strong motivation to determine the “ground truth” of microbial existence in living brains. Here I argue that the evidence for the presence of microbes in diseased brains is quite strong, but a compelling demonstration of resident microbes in the healthy human brain remains to be done. Dedicated animal models studies may be required to determine if there is indeed a “brain microbiome.”

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