Synaptic
transmission.
(August 28, 2015) A
German-French team has developed a light-sensitive switch that regulates a
protein implicated in the neurobiology of synaptic plasticity. The agent
promises to shed new light on the phenomenology of learning, memory and
neurodegeneration.
Learning is made possible by the fact that the functional
connections between nerve cells in the brain are subject to constant
remodeling. As a result of activation-dependent modification of these links
(‘synaptic plasticity’), circuits that are repeatedly stimulated “learn” to
transmit signals ever more efficiently. This process is thought to provide the
molecular basis for learning and memory, allowing the information encoded in
such networks to be recalled and exploited in novel situations. The primary
targets for modification are the specialized receptor proteins in nerve-cell
membranes that mediate the transmission of electrical signals between
individual neurons. A team of researchers led by Dirk Trauner, Professor of
Chemical Biology and Genetics at LMU, in collaboration with colleagues at the
Institut Pasteur in Paris, has now synthesized a light-dependent switch that
enables them to control the activity of a particular class of receptors which
is crucial for the formation and storage of memories. The compound provides a
powerful new tool for researchers interested in probing the mechanisms that
underlie short- and long-term memory. The results appear in the online journal
“Nature Communications”.
Individual nerve cells generally use chemical messengers to
communicate with each other. These so-called neurotransmitters are released by
specialized structures called synapses at the end of the signal-transmitting
fiber (the axon) and diffuse across the synaptic cleft – the narrow gap that
separates nerve cells from each other. The chemical then binds to receptors on
the “post-synaptic” neuron. How the post-synaptic cell reacts is dependent on
the nature of the neurotransmitter and the corresponding receptor. “In this
context, the so-called NMDA receptor is very special,” says Laura Laprell, a
PhD student in Trauner’s group and joint first author of the new study. “It is
primarily responsible for the fact that we have the capacity to form memories
and the ability to learn.”