Mapping language function with task-based vs. resting-state functional MRI

Abstract

Background Use of functional MRI (fMRI) in pre-surgical planning is a non-invasive method for pre-operative functional mapping for patients with brain tumors, especially tumors located near eloquent cortex. Currently, this practice predominantly involves task-based fMRI (T-fMRI). Resting state fMRI (RS-fMRI) offers an alternative with several methodological advantages. Here, we compare group-level analyses of RS-fMRI vs. T-fMRI as methods for language localization. Purpose To contrast RS-fMRI vs. T-fMRI as techniques for localization of language function. Methods We analyzed data obtained in 35 patients who had both T-fMRI and RS-fMRI scans during the course of pre-surgical evaluation. The RS-fMRI data were analyzed using a previously trained resting-state network classifier. The T-fMRI data were analyzed using conventional techniques. Group-level results obtained by both methods were evaluated in terms of two outcome measures: (1) inter-subject variability of response magnitude and (2) sensitivity/specificity analysis of response topography, taking as ground truth previously reported maps of the language system based on intraoperative cortical mapping as well as meta-analytic maps of language task fMRI responses. Results Both fMRI methods localized major components of the language system (areas of Broca and Wernicke) although not with equal inter-subject consistency. Word-stem completion T-fMRI strongly activated Broca's area but also several task-general areas not specific to language. RS-fMRI provided a more specific representation of the language system. Conclusion We demonstrate several advantages of classifier-based mapping of language representation in the brain. Language T-fMRI activated task-general (i.e., not language-specific) functional systems in addition to areas of Broca and Wernicke. In contrast, classifier-based analysis of RS-fMRI data generated maps confined to language-specific regions of the brain.

Altered Spontaneous Neural Activity and Functional Connectivity in Parkinson’s Disease With Subthalamic Microlesion

“…Currently, resting state functional MRI (rs-fMRI) has been widely utilized to study brain activity and network changes among patients with neurological and mental illness ( Nathan et al, 2014 ; Poldrack and Farah, 2015 ; Tessitore et al, 2019 ; Ge et al, 2020 ). Compared to fMRI in the task state, rs-fMRI is simple ( Park et al, 2020 ), easy to perform and highly repeatable ( Smitha et al, 2019 ). In fact, there have been a few studies that have used rs-MRI in order to study alterations in the brain activity during microlesions ( Jech et al, 2012 ; Holiga et al, 2015 ).…”

Organizing Variables Affecting fMRI Estimates of Language Dominance in Patients with Brain Tumors

“…Language maps obtained with resting-state fMRI are less lateralized than those obtained with task-based fMRI [108,109]; although a few studies disagree with this finding [110]. A recent work [108] explained that the more symmetric language maps for resting-state fMRI were the result of more bilateral activations in the anterior (inferior frontal gyri) and posterior (temporal gyri) regions. Concurrently, task-based fMRI generated maps that displayed areas which are not specific to language (e.g., bilateral middle frontal gyrus and bilateral rostral cingulate zone) [108].…”

“…A recent work [108] explained that the more symmetric language maps for resting-state fMRI were the result of more bilateral activations in the anterior (inferior frontal gyri) and posterior (temporal gyri) regions. Concurrently, task-based fMRI generated maps that displayed areas which are not specific to language (e.g., bilateral middle frontal gyrus and bilateral rostral cingulate zone) [108]. The increased restriction to the critical language areas in resting-state fMRI as compared with task-based fMRI was confirmed by other studies also [110].…”

Advanced imaging techniques for neuro-oncologic tumor diagnosis, with an emphasis on PET-MRI imaging of malignant brain tumors

“…Task-based fMRI can be tailored to specific motor and language functions prescribed to delineate eloquent cortices in relation to tumor location. Resting-state fMRI evaluates neural networks at rest and can be a useful adjunct in cognitively impaired patients, especially for language mapping [ 96 , 97 ]. fMRI results must be interpreted with caution, as they can be limited by susceptibility, respiration, medications, motion, task uniformity, tumor vascularity leading to neurovascular uncoupling, and patient cooperation [ 98 – 100 ].…”