A study published in Frontiers in Computational Neuroscience has revealed that the human brain’s structures operate in up to 11 dimensions. Conducted by the Blue Brain Project, scientists discovered fascinating new details about the complexity of the human brain.
“We found a world that we had never imagined,” explained neuroscientist Henry Markram, director of Blue Brain Project and professor at the EPFL in Lausanne, Switzerland.
A universe of multidimensional structures inside the brain
Image Credit: Blue Brain Project.
The image attempts to illustrate something that cannot be imaged — a universe of multi-dimensional structures and spaces. On the left is a digital copy of a part of the neocortex, the most evolved part of the brain. On the right are shapes of different sizes and geometries in an attempt to represent structures ranging from 1 dimension to 7 dimensions and beyond. The “black-hole” in the middle is used to symbolize a complex of multi-dimensional spaces, or cavities. Researchers at Blue Brain Project report groups of neurons bound into such cavities provide the missing link between neural structure and function, in their new study published in Frontiers in Computational Neuroscience.
“There are tens of millions of these objects even in a small speck of the brain, up through seven dimensions. In some networks, we even found structures with up to eleven dimensions,” Markram added.
By studying the human brain, researchers discovered that traditional mathematical views were not applicable and ineffective.
“The mathematics usually applied to study networks cannot detect the high-dimensional structures and spaces that we now see clearly,” Markram revealed.
Instead, scientists decided to give algebraic topology a go.
Algebraic topology is a branch of mathematics that uses tools from abstract algebra to study topological spaces.
Scientists from the Blue Brain Project were assisted by mathematicians Kathryn Hess from EPFL and Ran Levi from Aberdeen University in applying this discipline in their new study.
“Algebraic topology is like a telescope and microscope at the same time. It can zoom into networks to find hidden structures – the trees in the forest – and see the empty spaces – the clearings – all at the same time,” explained professor Hess.
The Human Brain can create structures in up to 11 dimensions
The scientists discovered that the structures inside the brain are created when a group of neurons – cells that transmit signals in the brain – form something referred to as a clique. Each neuron is connected to every other neuron in the group in a unique way, creating a new object. The more neurons there are in a clique, the higher the ‘dimension’ of the object.
Algebraic topography allowed the scientists to model the structures within a virtual brain, created with the help of computers. They then carried out experiments on real brain tissue, in order to verify their results.
By adding stimuli into the virtual brain, the researchers found that cliques of progressively HIGHER dimensions assembled. Furthermore, in between the cliques, scientists discovered cavities.
“The appearance of high-dimensional cavities when the brain is processing information means that the neurons in the network react to stimuli in an extremely organized manner,” explained Levi.
“It is as if the brain reacts to a stimulus by building then razing a tower of multi-dimensional blocks, starting with rods (1D), then planks (2D), then cubes (3D), and then more complex geometries with 4D, 5D, etc.”
“The progression of activity through the brain resembles a multi-dimensional sandcastle that materializes out of the sand and then disintegrates,” he added.
The new data about the human brain offers unprecedented insight into how the human brain processes information.
However, the scientists have said that it still remains unclear as to how the cliques and cavities form in their highly specific ways.
The new study may eventually help scientists uncover one of the greatest mysteries of neuroscience: where does the brain ‘store’ its memories.
“They may be ‘hiding’ in high-dimensional cavities,” Markram concluded.