August 28, 2015

Light-activated learning

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.”