Combined sensors will shed light on the work of the brain

With the help of LEDs, the size of which is comparable to the size of neurons, researchers at the University of Michigan are discovering the secrets of the neural signaling pathways of the brain.

Scientists have developed and tested neural probes on mice that allow the most miniature implantable LEDs to be inserted into the brain tissue. These new probes make it possible to regulate and register the activity of many individual neurons, as well as to assess how changes in the activity of one neuron can affect the surrounding cells. The authors believe that experiments conducted using such probes could lead to a breakthrough in the understanding and treatment of neurological diseases such as Alzheimer's disease.

The work of the human brain is provided by a neural network consisting of about 100 billion nerve cells, and the study of the mechanisms that ensure the harmonious joint functioning of these cells is an extremely important task for specialists in this field.

In the brain of genetically modified rodents, the activity of neurons can be triggered and blocked using light waves. Usually, neuroscientists using this optogenetic technique illuminate the region of the brain they are interested in using implantable optical fibers and register the reaction caused using microelectrodes introduced independently of the light guides. This allows you to determine which regions of the brain are responsible for certain behavioral reactions. However, the described approach does not provide information about the interaction of neurons with each other.

A new sample of probes will help to cope with this task. Each 0.1 mm wide probe contains 12 LEDs and 32 electrodes. The size of miniature LEDs is comparable to the size of a neuron's body, which allows them to trigger or block the activity of individual cells. At the same time, microelectrodes register the level of electrical activity at the level of individual cells, which makes it possible to assess the effect of changes in the behavior of one neuron on the surrounding neural network of the brain.

In experiments on mice, the researchers used new probes to study the mechanisms of signal transmission in the brain of animals, namely in the hippocampus – the region of the brain responsible for short- and long-term memory.

The experimental results, which proved the concept, showed that the superficial and deep neurons of the hippocampus generate brain waves of various types when stimulated. The role of these waves in the formation of memories will be studied in further experiments.

Article by Fan Wu et al. Monolithically Integrated µLEDs on Silicon Neural Probes for High-Resolution Optogenetic Studies in Behaving Animals is published in the journal Neuron.

Evgeniya Ryabtseva

Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the University of Michigan – Mapping the brain: Probes with tiny LEDs shed light on neural pathways.