Alterations of brain connectivity in brain disorders at rest studied by functional MRI

<p>Radu Mutihac</p>

Alterations of brain connectivity in brain disorders at rest studied by functional MRI

Radu Mutihac

University of Bucharest, Romania

: J Spine Neurosurg

Abstract

Studies of brain connectivity alterations using resting-state functional Magnetic Resonance Imaging (rsfMRI) and Diffusion Tensor Imaging (DTI) data have advanced our knowledge on the organization of large-scale structural and functional brain networks, which consist of spatially distributed, but functionally linked regions that continuously share information with each other. Brain’s energy is largely consumed at rest during spontaneous neuronal activity (~20%), while task-related increases in metabolism energy are minor (<5%). Spontaneous ultralow-frequency fluctuations in BOLD-based rsfMRI signals (<0.01 Hz) at the level of large-scale neural systems are not noise, but orderly and organized in a series of functional networks that permanently maintain a high level of temporal coherence among brain areas that are structurally segregated and functionally linked in Resting State Networks (RSNs). Some RSNs are functionally organized as dynamically competing systems both at rest and during tasks. The Default Mode Network (DMN), the most important RSN is even more active during rest and involved in realization of tasks like memory retrieval, emotional process and social cognition. Cortical connectivity at rest is reportedly altered in several neurological and psychiatric disorders. Most recently, human brain function has been imaged in fMRI and thereby accessing both sides of the mind-brain interface (subjective experience and objective observations) has simultaneously been performed. As such, functional neuroimaging moves onto new potential applications like reading the brain states, brain-computer interfaces, lie detection, also. The contribution aims to review and evaluate the most current approaches for early detection and classification of cognitive impairments and dementia, particularly among syndromes with relatively similar behavioral effects, based on alterations in brain connectivity at rest explored by rsfMRI and DTI.