Simultaneous functional MRI acquisition of distributed brain regions with high temporal resolution using a 2D-selective radiofrequency excitation

2014 ◽  
Vol 73 (2) ◽  
pp. 683-691 ◽  
Author(s):  
Jürgen Finsterbusch
Keyword(s):  
Functional Mri ◽  
Temporal Resolution ◽  
Brain Regions ◽  
High Temporal Resolution

scholarly journals High temporal resolution functional MRI using parallel echo volumar imaging

2008 ◽  
Vol 27 (4) ◽  
pp. 744-753 ◽  
Author(s):  
Cécile Rabrait ◽  
Philippe Ciuciu ◽  
Alejandro Ribés ◽  
Cyril Poupon ◽  
Patrick Le Roux ◽  
...  
Keyword(s):  
Functional Mri ◽  
Temporal Resolution ◽  
High Temporal Resolution

Cerebrovascular autoregulation as a neuroimaging tool

2006 ◽  
Vol 18 (2) ◽  
pp. 100-104 ◽  
Author(s):  
Jim Lagopoulos ◽  
Gin S. Malhi ◽  
Belinda Ivanovski ◽  
Catherine M. Cahill ◽  
Erhard W. Lang ◽  
...  
Keyword(s):  
Blood Flow ◽  
Spatial Resolution ◽  
Temporal Resolution ◽  
Cerebrovascular Disorders ◽  
Brain Regions ◽  
High Temporal Resolution ◽  
Cerebrovascular Autoregulation ◽  
Dynamic Representation ◽  
Flow Mechanisms ◽  
Resolution Measure

Functional transcranial Doppler (fTCD) sonography provides a high temporal resolution measure of blood flow and has over the years proved to be a valuable tool in the clinical evaluation of patients with cerebrovascular disorders. More recently, due to advances in physics and computing, it has become possible to derive indices of cerebrovascular autoregulation (CA) as well as cerebrovascular pressure reactivity (CR), using non-invasive techniques. These indices provide a dynamic representation of the brain's regulatory blood flow mechanisms not only in pathological states but also in health. However, whilst the temporal resolution of these regulatory indices is very good, spatially, the localization of brain regions remains very poor, thus limiting its brain mapping capacity. Functional MRI, on the contrary, is a brain-imaging technique that operates on similar blood flow principles; however, unlike fTCD, it provides high spatial resolution. Because both fTCD and fMRI determine blood flow-dependant imaging parameters, the coupling of fTCD with fMRI may provide greater insight into brain function by virtue of the combined enhanced temporal and spatial resolution that each technique affords. This review summarizes the fTCD technique with particular emphasis on the CA and CR indices and their relationship in traumatic brain injury as well as in health.

scholarly journals The neural dynamics of novel scene imagery

2018 ◽  
Author(s):  
Daniel N. Barry ◽  
Gareth R. Barnes ◽  
Ian A. Clark ◽  
Eleanor A. Maguire
Keyword(s):  
Prefrontal Cortex ◽  
Episodic Memory ◽  
Temporal Resolution ◽  
Memory Retrieval ◽  
Brain Regions ◽  
Ventromedial Prefrontal Cortex ◽  
Neural Dynamics ◽  
High Temporal Resolution ◽  
Memory Processing ◽  
Crucial Component

AbstractRetrieval of long-term episodic memories is characterised by synchronised neural activity between hippocampus and ventromedial prefrontal cortex (vmPFC), with additional evidence that vmPFC activity leads that of the hippocampus. It has been proposed that the mental generation of scene imagery is a crucial component of episodic memory processing. If this is the case, then a comparable interaction between the two brain regions should exist during the construction of novel scene imagery. To address this question, we leveraged the high temporal resolution of magnetoencephalography (MEG) to investigate the construction of novel mental imagery. We tasked male and female humans with imagining scenes and single isolated objects in response to one-word cues. We performed source level power, coherence and causality analyses to characterise the underlying inter-regional interactions. Both scene and object imagination resulted in theta power changes in the anterior hippocampus. However, higher theta coherence was observed between the hippocampus and vmPFC in the scene compared to the object condition. This inter-regional theta coherence also predicted whether or not imagined scenes were subsequently remembered. Dynamic causal modelling of this interaction revealed that vmPFC drove activity in hippocampus during novel scene construction. Additionally, theta power changes in the vmPFC preceded those observed in the hippocampus. These results constitute the first evidence in humans that episodic memory retrieval and scene imagination rely on similar vmPFC-hippocampus neural dynamics. Furthermore, they provide support for theories emphasising similarities between both cognitive processes, and perspectives that propose the vmPFC guides the construction of context-relevant representations in the hippocampus.Significance statementEpisodic memory retrieval is characterised by a dialogue between hippocampus and ventromedial prefrontal cortex (vmPFC). It has been proposed that the mental generation of scene imagery is a crucial component of episodic memory processing. An ensuing prediction would be of a comparable interaction between the two brain regions during the construction of novel scene imagery. Here, we leveraged the high temporal resolution of magnetoencephalography (MEG), and combined it with a scene imagination task. We found that a hippocampal-vmPFC dialogue existed, and that it took the form of vmPFC driving the hippocampus. We conclude that episodic memory and scene imagination share fundamental neural dynamics, and the process of constructing vivid, spatially coherent, contextually appropriate scene imagery is strongly modulated by vmPFC.

scholarly journals Frequency-resolved functional connectivity: Role of delay and the strength of connections

2020 ◽  
Author(s):  
Abolfazl Ziaeemehr ◽  
Alireza Valizadeh
Keyword(s):  
Functional Connectivity ◽  
Temporal Resolution ◽  
Computational Study ◽  
Brain Regions ◽  
Kuramoto Model ◽  
Functional Networks ◽  
High Temporal Resolution ◽  
Frequency Bands ◽  
The Brain

AbstractThe brain functional network extracted from the BOLD signals reveals the correlated activity of the different brain regions, which is hypothesized to underlie the integration of the information across functionally specialized areas. Functional networks are not static and change over time and in different brain states, enabling the nervous system to engage and disengage different local areas in specific tasks on demand. Due to the low temporal resolution, however, BOLD signals do not allow the exploration of spectral properties of the brain dynamics over different frequency bands which are known to be important in cognitive processes. Recent studies using imaging tools with a high temporal resolution has made it possible to explore the correlation between the regions at multiple frequency bands. These studies introduce the frequency as a new dimension over which the functional networks change, enabling brain networks to transmit multiplex of information at any time. In this computational study, we explore the functional connectivity at different frequency ranges and highlight the role of the distance between the nodes in their correlation. We run the generalized Kuramoto model with delayed interactions on top of the brain’s connectome and show that how the transmission delay and the strength of the connections, affect the correlation between the pair of nodes over different frequency bands.

scholarly journals Three-dimensional echo planar imaging with controlled aliasing: A sequence for high temporal resolution functional MRI

2015 ◽  
Vol 75 (6) ◽  
pp. 2350-2361 ◽  
Author(s):  
Mayur Narsude ◽  
Daniel Gallichan ◽  
Wietske van der Zwaag ◽  
Rolf Gruetter ◽  
José P. Marques
Keyword(s):  
Functional Mri ◽  
Temporal Resolution ◽  
Three Dimensional ◽  
Echo Planar Imaging ◽  
High Temporal Resolution ◽  
Planar Imaging ◽  
Echo Planar

scholarly journals Frequency-Resolved Functional Connectivity: Role of Delay and the Strength of Connections

2021 ◽  
Vol 15 ◽  
Author(s):  
Abolfazl Ziaeemehr ◽  
Alireza Valizadeh
Keyword(s):  
Functional Connectivity ◽  
Temporal Resolution ◽  
Computational Study ◽  
Brain Regions ◽  
Kuramoto Model ◽  
Functional Networks ◽  
High Temporal Resolution ◽  
Frequency Bands ◽  
The Brain

The brain functional network extracted from the BOLD signals reveals the correlated activity of the different brain regions, which is hypothesized to underlie the integration of the information across functionally specialized areas. Functional networks are not static and change over time and in different brain states, enabling the nervous system to engage and disengage different local areas in specific tasks on demand. Due to the low temporal resolution, however, BOLD signals do not allow the exploration of spectral properties of the brain dynamics over different frequency bands which are known to be important in cognitive processes. Recent studies using imaging tools with a high temporal resolution has made it possible to explore the correlation between the regions at multiple frequency bands. These studies introduce the frequency as a new dimension over which the functional networks change, enabling brain networks to transmit multiplex of information at any time. In this computational study, we explore the functional connectivity at different frequency ranges and highlight the role of the distance between the nodes in their correlation. We run the generalized Kuramoto model with delayed interactions on top of the brain's connectome and show that how the transmission delay and the strength of the connections, affect the correlation between the pair of nodes over different frequency bands.

Multidetector-row Computed Tomography in the Assessment of Coronary Artery Disease – New Techniques and Insights

2010 ◽  
Vol 6 (2) ◽  
pp. 43 ◽  
Author(s):  
Andreas H Mahnken ◽  
Keyword(s):  
Computed Tomography ◽  
Coronary Artery Disease ◽  
Coronary Artery ◽  
Data Acquisition ◽  
Temporal Resolution ◽  
High Temporal Resolution ◽  
Multidetector Row ◽  
Ct Scanners ◽  
Artery Disease ◽  
Cardiac Mdct

Over the last decade, cardiac computed tomography (CT) technology has experienced revolutionary changes and gained broad clinical acceptance in the work-up of patients suffering from coronary artery disease (CAD). Since cardiac multidetector-row CT (MDCT) was introduced in 1998, acquisition time, number of detector rows and spatial and temporal resolution have improved tremendously. Current developments in cardiac CT are focusing on low-dose cardiac scanning at ultra-high temporal resolution. Technically, there are two major approaches to achieving these goals: rapid data acquisition using dual-source CT scanners with high temporal resolution or volumetric data acquisition with 256/320-slice CT scanners. While each approach has specific advantages and disadvantages, both technologies foster the extension of cardiac MDCT beyond morphological imaging towards the functional assessment of CAD. This article examines current trends in the development of cardiac MDCT.

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