Neuroscientists know that neurons communicate with each other through the tiny spaces between them, in a process known as synaptic transmission (where synapses are the connections between neurons). Information travels from cell to cell via neurotransmitters such as glutamate, dopamine, or serotonin, which activate receptors on the receiving neuron to transmit excitatory or inhibitory messages.
However, beyond this basic outline, the details of how neurons communicate, a crucial brain function in our bodies, are unknown. Now, new research by scientists at the University of Maryland School of Medicine (USA) has managed to see for the first time the details about the architecture of this process.
These complicated molecular machines – synapses – are found in the brain everywhere: around 100 trillion of them because they are miniscule in size. Each is independent and precisely tuned to transmit more or less strong signals between cells. To visualize the characteristics of this sub-microscopic scale, the experts turned to an innovative technology known as single-molecule imaging , which can locate and follow the movement of individual protein molecules within the confines of a single synapse, even at living cells.
The scientists identified an unexpected and precise pattern in the neurotransmission process: “ We are seeing things that have never been seen before. This represents a totally new area of research. For many years, we’ve had a list of the many types of molecules found in synapses, but that didn’t get us very far in understanding how these molecules fit together, or how the process actually works structurally. Now by using single-molecule imaging, we have finally been able to reveal the architectural structure of the core of the synapse ”, explains Thomas Blanpied, leader of the work.
Why are synapses so efficient? Experts have found that at each synapse, key proteins are arranged very precisely across the space between cells: “Neurons work more effectively than we imagined. The proteins in two different neurons are aligned with incredible precision, almost forming a column that runs between the two cells. This proximity optimizes the power of the transmission and also suggests new ways in which this transmission can be modified ”, clarifies Blanpied.
Understanding the synaptic architecture will help clarify how communication works within the brain or, in the case of psychiatric or neurological illness (brain diseases such as depression, schizophrenia, or Alzheimer’s disease), how it stops working.
The study has been published in the journal Nature.
