Dataset Information

Brain functional BOLD perturbation modelling for forward fMRI and inverse mapping.

ABSTRACT: To computationally separate dynamic brain functional BOLD responses from static background in a brain functional activity for forward fMRI signal analysis and inverse mapping.A brain functional activity is represented in terms of magnetic source by a perturbation model: ? = ?0 +??, with ?? for BOLD magnetic perturbations and ?0 for background. A brain fMRI experiment produces a timeseries of complex-valued images (T2* images), whereby we extract the BOLD phase signals (denoted by ?P) by a complex division. By solving an inverse problem, we reconstruct the BOLD ?? dataset from the ?P dataset, and the brain ? distribution from a (unwrapped) T2* phase image. Given a 4D dataset of task BOLD fMRI, we implement brain functional mapping by temporal correlation analysis.Through a high-field (7T) and high-resolution (0.5mm in plane) task fMRI experiment, we demonstrated in detail the BOLD perturbation model for fMRI phase signal separation (P + ?P) and reconstructing intrinsic brain magnetic source (? and ??). We also provided to a low-field (3T) and low-resolution (2mm) task fMRI experiment in support of single-subject fMRI study. Our experiments show that the ??-depicted functional map reveals bidirectional BOLD ? perturbations during the task performance.The BOLD perturbation model allows us to separate fMRI phase signal (by complex division) and to perform inverse mapping for pure BOLD ?? reconstruction for intrinsic functional ? mapping. The full brain ? reconstruction (from unwrapped fMRI phase) provides a new brain tissue image that allows to scrutinize the brain tissue idiosyncrasy for the pure BOLD ?? response through an automatic function/structure co-localization.

SUBMITTER: Chen Z

PROVIDER: S-EPMC5774799 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Brain functional BOLD perturbation modelling for forward fMRI and inverse mapping.

Chen Zikuan Z Robinson Jennifer J Calhoun Vince V

PloS one 20180119 1

<h4>Purpose</h4>To computationally separate dynamic brain functional BOLD responses from static background in a brain functional activity for forward fMRI signal analysis and inverse mapping.<h4>Methods</h4>A brain functional activity is represented in terms of magnetic source by a perturbation model: χ = χ0 +δχ, with δχ for BOLD magnetic perturbations and χ0 for background. A brain fMRI experiment produces a timeseries of complex-valued images (T2* images), whereby we extract the BOLD phase sig ...[more]

PMID: 29351339

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Project description:Blood Oxygenation Level Dependent functional MRI (BOLD fMRI) during electrical paw stimulation has been widely used in studies aimed at the understanding of the somatosensory network in rats. However, despite the well-established anatomical connections between cortical and subcortical structures of the sensorimotor system, most of these functional studies have been concentrated on the cortical effects of sensory electrical stimulation. BOLD fMRI study of the integration of a sensorimotor input across the sensorimotor network requires an appropriate methodology to elicit functional activation in cortical and subcortical areas owing to the regional differences in both neuronal and vascular architectures between these brain regions. Here, using a combination of low level anesthesia, long pulse duration of the electrical stimulation along with improved spatial and temporal signal to noise ratios, we provide a functional description of the main cortical and subcortical structures of the sensorimotor rat brain. With this calibrated fMRI protocol, unilateral non-noxious sensorimotor electrical hindpaw stimulation resulted in robust positive activations in the contralateral sensorimotor cortex and bilaterally in the sensorimotor thalamus nuclei, whereas negative activations were observed bilaterally in the dorsolateral caudate-putamen. These results demonstrate that, once the experimental setup allowing necessary spatial and temporal signal to noise ratios is reached, hemodynamic changes related to neuronal activity, as preserved by the combination of a soft anesthesia with a soft muscle relaxation, can be measured within the sensorimotor network. Moreover, the observed responses suggest that increasing pulse duration of the electrical stimulus adds a proprioceptive component to the sensory input that activates sensorimotor network in the brain, and that these activation patterns are similar to those induced by digits paw's movements. These findings may find application in fMRI studies of sensorimotor disorders within cortico-basal network in rodents.

Dataset Information

Brain functional BOLD perturbation modelling for forward fMRI and inverse mapping.

Publications

Brain functional BOLD perturbation modelling for forward fMRI and inverse mapping.

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