How to Fires Up our Synapses

Processing of sensory impressions and information depends very much on how the synapses in our brain work. A team around chemist Robert Ahrends from the University of Vienna and neuroscientist Michael R. Kreutz from Leibniz Institute for Neurobiology in Magdeburg now showed how lipid and protein regulation impact brain’s processing of a beautiful and stimulating environment. The lipids located in the membranes of the synapses are central to signal transmission, the researchers report in “Cell Reports“.

“We usually enjoy a beautiful environment, socializing, a cosy apartment, good restaurants, a park – all this inspires us,” says Robert Ahrends from the Institute of Analytical Chemistry of the University of Vienna and former group leader at ISAS in Dortmund. Previous studies have already shown that such an enriched environment can sometimes have a positive effect on child development or even on the human ability to regenerate, e.g. after a stroke, however the reason for these observations “was not yet clarified at the molecular level“.

Stimulating sensory perceptions are ultimately formed via the activity or regulation of synapses, i.e. those connecting units between our neurons that transfer information from one nerve cell to another. To clarify the underlying molecular principles, the researchers offered the rodents, their model organisms, an enriched environment based on plenty of room to move, a running wheel and other toys.

With the help of post-genomic analysis strategies (multiomics) and using state-of-the-art mass spectrometry and microscopy as well as bioinformatics for data analysis, they investigated the regulation of synapses in the hippocampus of the rodents, more precisely the interaction of the proteins and especially lipids (fats) located in the synaptic membranes.

80 percent of the brain cells are only supporting cells. We have therefore focused on the synapses as central sites of signal transmission and isolated them,” says neuroscientist Michael Kreutz. The team gathered quantitative and qualitative information about the network of molecules regulated at synapses and examined their lipid metabolism, also under the influence of an enriched environment.
The analyses revealed that 178 proteins and 20 lipids were significantly regulated depending on whether the rodents had spent time in an enriched environment or an uncomfortable one.

Source: https://chemie.univie.ac.at/

Artificial Synapses Made from Nanowires

Scientists from Jülich together with colleagues from Aachen and Turin have produced a memristive element made from nanowires that functions in much the same way as a biological nerve cell. The component is able to both save and process information, as well as receive numerous signals in parallel. The resistive switching cell made from oxide crystal nanowires is thus proving to be the ideal candidate for use in building bioinspired “neuromorphic” processors, able to take over the diverse functions of biological synapses and neurons.

Image captured by an electron microscope of a single nanowire memristor (highlighted in colour to distinguish it from other nanowires in the background image). Blue: silver electrode, orange: nanowire, yellow: platinum electrode. Blue bubbles are dispersed over the nanowire. They are made up of silver ions and form a bridge between the electrodes which increases the resistance.

Computers have learned a lot in recent years. Thanks to rapid progress in artificial intelligence they are now able to drive cars, translate texts, defeat world champions at chess, and much more besides. In doing so, one of the greatest challenges lies in the attempt to artificially reproduce the signal processing in the human brain. In neural networks, data are stored and processed to a high degree in parallel. Traditional computers on the other hand rapidly work through tasks in succession and clearly distinguish between the storing and processing of information. As a rule, neural networks can only be simulated in a very cumbersome and inefficient way using conventional hardware.

Systems with neuromorphic chips that imitate the way the human brain works offer significant advantages. Experts in the field describe this type of bioinspired computer as being able to work in a decentralised way, having at its disposal a multitude of processors, which, like neurons in the brain, are connected to each other by networks. If a processor breaks down, another can take over its function. What is more, just like in the brain, where practice leads to improved signal transfer, a bioinspired processor should have the capacity to learn.

With today’s semiconductor technology, these functions are to some extent already achievable. These systems are however suitable for particular applications and require a lot of space and energy,” says Dr. Ilia Valov from Forschungszentrum Jülich. “Our nanowire devices made from zinc oxide crystals can inherently process and even store information, as well as being extremely small and energy efficient,” explains the researcher from Jülich’s Peter Grünberg Institute.

Source: http://www.fz-juelich.de/