Individual Brain Charting, a high-resolution fMRI dataset for cognitive mapping

Abstract

Functional Magnetic Resonance Imaging (fMRI) has furthered brain mapping on perceptual, motor, as well as higher-level cognitive functions. However, to date, no data collection has systematically addressed the functional mapping of cognitive mechanisms at a fine spatial scale. The Individual Brain Charting (IBC) project stands for a high-resolution multi-task fMRI dataset that intends to provide the objective basis toward a comprehensive functional atlas of the human brain. The data refer to a cohort of 12 participants performing many different tasks. The large amount of task-fMRI data on the same subjects yields a precise mapping of the underlying functions, free from both inter-subject and inter-site variability. The present article gives a detailed description of the first release of the IBC dataset. It comprises a dozen of tasks, addressing both low- and high- level cognitive functions. This openly available dataset is thus intended to become a reference for cognitive brain mapping.

Figure 1. Global quality indices of the acquired data: tSNR map and motion magnitude distribution.

(Left) The tSNR map displays the average of tSNR across all tasks and subjects. This shows values mostly between 30 and 60, with larger tSNR in cortical regions. (Right) Density of within-run motion parameters, pooled across subjects and tasks. Six distributions are plotted, for the six rigid-body parameter of head motion (translations and rotations are in mm and degrees, respectively). Each distribution is based on 73 k values, corresponding to all frame times for all acquisitions and subjects. Bold lines below indicate the 99% coverage of all distributions and show that motion parameters mostly remain confined to 1mm/1 degree across 99% of all acquired images.

Figure 2. Overview of information conveyed by activation maps resulting from a first-level analysis.

(top) Global effects of experimental subject condition, and phase-encoding direction. A per-voxel ANOVA breaks the variance of the set of brain maps into subject, experimental condition, and phase-encoding direction values. All maps are given in z-scale and thresholded at an FDR level of 0.05. (Bottom) Focusing on condition effect, the similarity between condition-related maps, averaged across subjects (left) is clearly related to the dissimilarity of the conditions, when these are characterized in terms of the Cognitive Atlas (right).

Figure 3. Group-level F-map, at a threshold of p<0.05 Bonferroni-corrected, representing the total area of the brain significantly covered by all tasks featuring the first release of the IBC dataset (FFX across tasks and subjects).

One can readily see that all the brain is covered, with higher values in sensory cortices and weaker values for the temporal and pre-frontal cortex as well as subcortical structures.