title: Resting state fMRI: A review on methods in resting state connectivity analysis and resting state networks.
abstract: The inquisitiveness about what happens in the brain has been there since the beginning of humankind. Functional magnetic resonance imaging is a prominent tool which helps in the non-invasive examination, localisation as well as lateralisation of brain functions such as language, memory, etc. In recent years, there is an apparent shift in the focus of neuroscience research to studies dealing with a brain at 'resting state'. Here the spotlight is on the intrinsic activity within the brain, in the absence of any sensory or cognitive stimulus. The analyses of functional brain connectivity in the state of rest have revealed different resting state networks, which depict specific functions and varied spatial topology. However, different statistical methods have been introduced to study resting state functional magnetic resonance imaging connectivity, yet producing consistent results. In this article, we introduce the concept of resting state functional magnetic resonance imaging in detail, then discuss three most widely used methods for analysis, describe a few of the resting state networks featuring the brain regions, associated cognitive functions and clinical applications of resting state functional magnetic resonance imaging. This review aims to highlight the utility and importance of studying resting state functional magnetic resonance imaging connectivity, underlining its complementary nature to the task-based functional magnetic resonance imaging.
authors.affiliation: 1 Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Science and Technology, India.
authors.forename: K A
authors.initials: KA
authors.lastname: Smitha
authors.affiliation: 1 Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Science and Technology, India.
authors.forename: K
authors.initials: K
authors.lastname: Akhil Raja
authors.affiliation: 1 Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Science and Technology, India.
authors.forename: K M
authors.initials: KM
authors.lastname: Arun
authors.affiliation: 2 Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, India.
authors.forename: P G
authors.initials: PG
authors.lastname: Rajesh
authors.affiliation: 1 Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Science and Technology, India.
authors.forename: Bejoy
authors.initials: B
authors.lastname: Thomas
authors.affiliation: 1 Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Science and Technology, India.
authors.forename: T R
authors.initials: TR
authors.lastname: Kapilamoorthy
authors.affiliation: 1 Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Science and Technology, India.
authors.forename: Chandrasekharan
authors.initials: C
authors.lastname: Kesavadas
mesh_terms: D001931:Brain Mapping / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D012146:Rest / Q000502:physiology
keywords: Graph analysis; independent component analysis; resting state functional connectivity; seed-based analysis