Sometimes just hearing a few notes of a song is enough to transport us back in time, to a moment long forgotten. Our brain is actually able to reconstruct entire memories from small fragments. How does it work?
The human brain consists of billions Neurons who work collectively. Neurons are like the building blocks of thought and each can serve multiple purposes. For example, different memories are encoded by different patterns of activity within the same neurons. The process is similar to the way your smartphone screen can display different images with the same pixels, or how the same LEGO bricks can be used to build different objects.
Neuroresearch
How neurons achieve this has been a rapidly evolving area of research in recent decades, and sophisticated models of neural networks are now widely used in digital computers.
Surprisingly, this type of computation is not unique to neurons: the same computation principles can also occur in other biological and even purely physical processes.
A new study
A new study led by researchers at Caltech, the University of Chicago and the University of Maynooth in Ireland has shown how neural network-like capabilities are inherent in the natural dynamics of molecules as they self-direct and assemble into structures. The phenomenon is similar to the way neurons work together to retrieve and reassemble memories, and can therefore be considered a form of “associative retrieval.”
The self-organization process
To understand what happens in this test tube full of molecules, imagine a large swimming pool with hundreds of LEGO pieces. LEGO pieces can be assembled in different ways, so you can build a car, a castle or a caterpillar from the same bricks.
The idea of how self-assembly achieves associative remembering is this: if you give the pool mix a “seed” of a design – for example, a few pieces already assembled to create a wheel and a windshield – the rest could Assemble components yourself to produce the desired end product (in this case a car)? This is an example of a successful associative memory process.
The results of the study
In this study, the team designed 917 different molecules, or “molecule tiles,” that can combine to form three different two-dimensional shapes: the letters H, A, or M. The team added three trillion of these molecules in relatively equal amounts of each of the 917 variations in a test tube and observed that the pieces actually assembled themselves to form numerous small Hs, A's and M's. Although some of the letters were not so partially formed, there were no random hybrids of two or three letters. This was an important initial result of the study.
The future of research
The project builds on several decades of work in Winfree's laboratory. “The exciting thing about DNA nanotechnology is that it is truly the only molecular design technology today that makes it possible to explore sophisticated theories of molecular computation at the large-N limit—here are almost a thousand different types of molecules all working together,” explains Constantine Evans, lead author of the study.
synthetic
Research into the way neurons encode memories has led to a fascinating discovery: molecules can also self-assemble into structures, similar to a neural network. This study showed that molecules can self-assemble into specific structures, a process that can be viewed as a form of “associative recall.”
For better understanding
What is associative memory?
Associative retrieval is a process by which memories are retrieved. In the context of this study, it refers to how molecules can self-assemble to form specific structures, a process similar to the way neurons work together to retrieve and reassemble memories.
What is a Neural Network?
A neural network is a collection of interconnected neurons that work together to process information. In the human brain, neural networks are responsible for many functions, including the encoding of memories.
What is self-organization?
Self-organization is a process in which molecules combine to form complex structures without external intervention. In this study, researchers observed that molecules can self-assemble to form specific structures, a process similar to the way neurons work together to retrieve and reassemble memories.
What are the implications of this study?
This study could have significant implications for understanding how memories are encoded and retrieved. It could also pave the way for new advances in the field of nanotechnology.
What is the next step in this research?
The researchers plan to continue their work by exploring other types of biomolecular processes, such as multicomponent condensates and genetic regulatory networks.
References
Caption: Molecular tiles in a solution self-organize into three shapes – H, A or M – depending on the concentration of common tiles that form a “seed” or seed point of a particular shape. Photo credit: Olivier Wyart
“Pattern recognition in the nucleation kinetics of nonequilibrium self-assembly.” In addition to Evans, Murugan and Winfree, Jackson O'Brien from the University of Chicago is co-author. Funding was provided by the National Science Foundation, the Evans Foundation for Molecular Medicine, the European Research Council, Science Foundation Ireland and the Carver Mead New Adventures Fund.
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