# Organization and hierarchy of the human functional brain network lead to a chain-like core

## TL;DR

This study reveals that the human brain's functional network during rest is organized into a hierarchical, chain-like structure with a central core, highlighting the importance of occipital and cerebellar regions.

## Contribution

It introduces a novel analysis of resting-state fMRI data showing the brain's hierarchical chain-like network architecture using maximum spanning tree methodology.

## Key findings

- Brain regions form a hierarchical chain-like structure.
- Occipital cortex is central in the network.
- Cerebellar regions form a closed core.

## Abstract

The brain is a paradigmatic example of a complex system as its functionality emerges as a global property of local mesoscopic and microscopic interactions. Complex network theory allows to elicit the functional architecture of the brain in terms of links (correlations) between nodes (grey matter regions) and to extract information out of the noise. Here we present the analysis of functional magnetic resonance imaging data from forty healthy humans during the resting condition for the investigation of the basal scaffold of the functional brain network organization. We show how brain regions tend to coordinate by forming a highly hierarchical chain-like structure of homogeneously clustered anatomical areas. A maximum spanning tree approach revealed the centrality of the occipital cortex and the peculiar aggregation of cerebellar regions to form a closed core. We also report the hierarchy of network segregation and the level of clusters integration as a function of the connectivity strength between brain regions.