Brain News – Researchers at the University of California, San Diego, explored how information is processed in the human brain by connecting different functional brain regions during activities. The study is published in PLOS Biology.
The Study
The study combined diffusion MRI data from the Human Connectome Project with histological cross-sections of the corpus callosum, the major tract that connects the right and left sides of the brain. The Human Connectome maps the strength of all connections in the brain, without giving away the number of axons involved in them. On the other hand, charting the histological cross-sections provides a rough estimate of the number of axons packed in a given volume.
By combining connection strengths with the axon densities, the researchers gained an estimate of the number of axons existing in the cerebral cortex. This helped them to understand better the far-reaching wiring of the brain and its link to brain functions.
The Findings
The analysis shows that even though crucial long-distance connections exist between the far-reaching regions of the brain, the actual number of these connections is low. This has led the researchers to infer that longer functional connections in the human brain are made in multiple steps.
For instance, the lengthy brain wirings in the arcuate fasciculus tract or the cortical areas actually involve millions of axons but fewer long functional connections. In such cases, the human brain processes information in neuronal relays.
One of the lead researchers, Burke Rosen, elaborates, “Our finding implies that [sometimes brain] integration is accomplished either via linkage of the dense local connections or by rare, extraordinarily privileged long-range axons.”
Towards New Measures
The researchers are enthusiastic that this study can help devise new models of cognition that improve brain wiring between the distal regions of the human brain.
To Know More You May Relate To
Rosen, B. Q., & Halgren, E. (2022). An estimation of the absolute number of axons indicates that human cortical areas are sparsely connected. PLoS biology, 20(3), e3001575. https://doi.org/10.1371/journal.pbio.3001575