"If we manage to understand the ways of communication between brain cells and the mechanisms that enable communication between different brain areas, we may be able to better understand the changes that occur in the brain in disease states, such as depression, anxiety and schizophrenia"
Will we ever be able to understand the communication going on between the 80 million neurons in our brain? Can we control it? Scientists all over the world are facing this challenge - and it seems that they will continue to face it - for many years. A new study recently carried out in the laboratory of Dr. Ofer Yizhar, in the Department of Neurobiology at the Weizmann Institute of Science, greatly advanced this long and complex journey towards its goal. in the article recently published in the scientific journal Nature Neuroscience Dr. Yizhar and the members of the research group he heads report on a method, which is designed to enable focused and controlled control over the communication between different areas of the brain.
"The question, how information is coded in the brain, is important in basic scientific research and medicine," says Dr. Yizhar. "If we succeed in understanding the ways of communication between brain cells and the mechanisms that enable communication between different brain areas, we may be able to better understand the changes that occur in the brain in disease states, such as depression, anxiety and schizophrenia. Today we do not understand how this communication works in practice, and this is the main reason why we currently do not have ways to effectively treat many brain diseases."
In order to control the activity of the connections, or the communication nodes between the different neurons, the scientists used optogenetic tools, and by means of them they were able to regulate the strength of the communication between distant brain regions. Optogenetics is a new field of research, which allows scientists to understand the operation of neural circuits in the brain. It combines genetic engineering of brain cells with lasers and optical fibers, through which it is possible to regulate the operation of the neural circuit.
The optogenetic tools developed by Dr. Yizhar allow scientists to enter the brain and influence the activity of connections between neurons. "We insert a gene that encodes a light-sensitive protein into a neuron," he says. "When we shine a light on the particular area of the brain where this protein is found, the protein is activated - and activates or silences the neuron. This way we can control the activity of the neurons". The light-sensitive genes are inserted into the cells using transgenic viruses, and the cells are illuminated using optical fibers. The scientists focused on the "communication cables" of the neurons, called axons, which connect distant areas of the brain. The neurons in the brain maintain connections with nearby neurons, and also with those located in very distant brain regions. Thus, for example, neurons in the amygdala (the part responsible for emotions such as fear, joy or surprise) send long axons to the prefrontal lobe, which is responsible for higher thinking functions. One of the ways to understand what information passes through the axon that connects distant parts of the brain is to temporarily silence this line of communication - and examine the result. Using this method it is possible to understand what happens when this communication channel is damaged, for example due to illness.
"In this study," says Dr. Yizhar, "we better understood the unique properties of the axon. We discovered that there are significant differences between the response of the neuron to optogenetic manipulations and the response of the axon that connects the same neuron to other brain regions. We hope that this research will allow us to control the activity of the axons that connect distant brain areas, and to understand how these communication mechanisms work.'
