A research team led by Tuomas Tallinen (Department of Physics and Nanoscience Center, University of Jyvaskyla), Jun Young Chung and Lakshminarayanan Mahadevan (Paulson School of Engineering and Applied Sciences, Harvard University) is studying the folded structure of the human brain. Their findings published in Nature Physics indicate that the convoluted structure can be attributed to mechanical compression. A 3D-printed model was used by the researchers to support their theory.
This new view on the physical rather than the biological or biochemical origin of brain folds was introduced already in 1975, but until recently, evidence to back up these theories was lacking, given the ethical concerns related to experiments on the human brain.
To tackle this problem and provide supporting evidence for this theory, Tallinen, Mahadevan et al. created a 3D-printed brain model from soft gels, based on an MRI scan of a developing fetal human brain.
Their model brain was composed of different layers of gel, which were engineered to grow in size once they came into contact with a liquid solvent, thereby imitating the growth of an actual cortex. The different expansion levels of these layers resulted in mechanical compression forces, leading to the formation of folds similar to those in fetal brains. In addition, the research team performed numerical simulations for their study, leading to the same characteristic convolution patterns.
When concluding their experiment, the authors suggest that the size, shape, placement and orientation of the cortical folds are a result of mechanical instability and therefore there is an important physical aspect to neurodevelopment. This could have a significant impact on the way certain neurological disorders are treated and diagnosed in future.