Isolated cluster formation on CNT multi electrode array (MEA).
(a) A bright field image of a neuronal cluster on a CNT electrode. The electrode diameter is 30 µm and the inter electrode distance is 200 µm (b) A fluorescent microscope image of the cluster in (a), stained for cell nuclei (DAPI-blue), glia (GFAP-green) and neurons (TUJ1-red). (c) A bright field image of clusters on a MEA chip. Color coded lines show the Pearson correlation between the electrical activities of all cluster pairs above a threshold of 0.1. The electrically isolated clusters (red full circles) were distinguished from linked clusters (blue full circles) both functionally (no significant correlations to other clusters) and visually (no apparent extensions to other clusters).
They have developed a new kind of a lab-on-a-chip platform that may help neuroscientists understand one of the deepest mysteries of our brain — how neuronal networks communicate and work together. The researchers believe their tool can be also used to test new drugs. It might also advance artificial intelligence and aid scientists in rewiring artificial limbs to our brain.
The brain is composed of a daunting number of circuits interconnected with other countless circuits, so understanding of how they function has been close to impossible. But using engineered brain tissue in a Petri dish, Shein’s device allows researchers to see what’s happening to well-defined neural circuits under different conditions. The result is an active circuitry of neurons on a man-made chip. With it they can look for patterns in bigger networks of neurons, to see if there are any basic elements for information coding.
The researchers were also able to measure patterns from nerve activity, at nodes where a number of nerves converged into networks. What they detected appears to show that neural networks have a hierarchical structure — large networks are composed of smaller sub-networks. This observation, and a unique setup using electrodes and living nerves, allowed them to create hierarchical networks in a dish.
The brain’s circuits work like codes. They can see the patterns in the networks and simplify them, or control connectivity between cells to see how the neuronal network responds to various chemicals and conditions, the scientists report. One theory, proposed by Prof. Ben-Jacob, is that the human brain stores memories like a holograph of an image: small neural networks contain information about the whole brain, but only at a very low resolution.
So far the researchers are able to reveal that clusters of as few as 40 cells can serve as a minimal but sufficient functional network. This cluster is capable of sustaining neural network activity and communicating with other clusters. What this means exactly will be the next question.