Brain: New Map Identifies the Core

A research team has created a complete high-resolution map of how millions of neural fibers in the human cerebral cortex - the outer layer of the brain responsible for higher level thinking - connect and communicate. 18/07/2008

The map identifies a network core
that could be key to the workings
of both hemispheres; © Indiana
University

The team identified a single network core, or hub, that may be key to the workings of both hemispheres of the brain. The work provides a comprehensive map of brain connections (the brain "connectome") and describes a novel application of a non-invasive technique that can be used to continue mapping the trillions of neural connections in the brain at greater resolution.

In the study, the scientists used diffusion magnetic resonance imaging (MRI) technology, which is a non-invasive scanning technique that estimates fiber connection trajectories based on gradient maps of the diffusion of water molecules through brain tissue. A highly sensitive variant of the method, called diffusion spectrum imaging (DSI), can depict the orientation of multiple fibers that cross a single location. The study applies this technique to the entire human cortex, resulting in maps of millions of neural fibers running throughout this part of the brain.

The investigators then carried out a computational analysis trying to identify regions of the brain that played a more central role in the connectivity, serving as hubs in the cortical network. They found a single highly and densely connected structural core in the brain of all participants in the medial posterior portion of the cortex, straddling both hemispheres.

Following, the researchers asked whether the structural connections of the brain shape its dynamic activity. The study examined the brains of five human participants who were imaged using both functional magnetic resonance imaging (fMRI) technology and DSI techniques to compare how closely the brain activity observed in the fMRI mapped to the underlying fiber networks.

According to the scientists, it turned out they were quite closely related: they say they measured a significant correlation between brain anatomy and brain dynamics.

COMPAMED.de; Source: Indiana University