Brain communication systems

Performing everyday activities like walking in the park, smelling flowers and remembering the way back home requires a complex brain communication system. This is achieved by billions of brain cells called neurons, which transmit information to other neurons via a structure called a synapse.

At the synapse, a presynaptic neuron passes chemicals called neurotransmitters to a receiving postsynaptic neuron. Excitatory neurotransmitters activate the postsynaptic neuron to transmit the impulse, or 'message', to other neurons, while inhibitory neurotransmitters dampen nerve impulses.

Recently, scientists discovered that cells called astrocytes help to regulate information transfer between neurons by contacting both pre- and postsynaptic structures at a tripartite synapse. Astrocytes release neurotransmitter-like molecules called gliotransmitters, which control synapse development and influence neuron activity.

Different gliotransmitters affect brain functions ranging from forming memories to falling asleep. The EU-funded SYNTWOGLIOTS (In the brain, at the level of a single synapse an individual astrocyte releases several gliotransmitters) project aimed to see whether individual astrocytes can release several gliotransmitters at the same synapse to control multiple facets of the nervous system.

First, researchers showed that synapses require astrocytes to function properly. Using microscopy, they confirmed that astrocytes interact with pre- and post-neuronal elements of the synapse in living brain cells.

Having shown that contact with astrocytes was necessary for synapse development and for modulating neural impulses, researchers looked at gliotransmitters from individual astrocytes. They found that two different gliotransmitters were released by the same cell in the hippocampus, an area of the brain important for memory.

Since astrocytes connect with thousands of synapses across the brain, changes in gliotransmitter levels may contribute to neurodegenerative disorders like Alzheimer's, Parkinson's and Huntington's diseases.