The key to strong nerve cell connections, or synapses, may be found in the timing as the neurotransmitter acetylcholine is released in the brain’s hippocampus, according to a mouse study. Understanding the inner workings of neuron signaling could help scientists better understand the processes of learning and memory, and lead to new treatments for disorders such as schizophrenia and Alzheimer’s.
Neurons in the hippocampus (a brain region believed to play a vital role in learning and memory) communicate with each other at synapses by releasing various neurotransmitters, such as acetylcholine and glutamate, which trigger electrical signals in nearby neurons.
Neuroscientists have been working to pinpoint which cellular processes enable humans to learn from experience and save memories, and how certain conditions, such as schizophrenia and Alzheimer’s, affect these mechanisms.
Now, researchers from the National Institute of Environmental Health Sciences (NIEHS) believe they have discovered one such mechanism that synchronizes changes in the strength of synapses.
“We’ve demonstrated that when we stimulate the release of acetylcholine at just the right time in the hippocampus, we can induce a cellular change at synapses that use glutamate,” said Jerrel Yakel, Ph.D., a senior investigator in the NIEHS Laboratory of Neurobiology and co-author of the paper.
Prior research has confirmed that learning and memory is determined by the strengthening or weakening of synapses; signals that last less than a hundredth of a second release neurotransmitters that determine the electrical impulses of the adjoining neurons.
For the study, Yakel and co-author Zhenglin Gu, Ph.D., used molecular biology techniques to make some of the neurons in mouse brain cells produce a special light-sensitive protein, and then used a laser to trigger these neurons into releasing acetylcholine.
“A change of even a few hundredths of a second in the timing of acetylcholine release can make a difference,” said Gu. “No one had shown this was important until now.”
Yakel said the results of the study are a potentially important step in the study of disorders that distort learning and memory, such as Alzheimer’s disease and schizophrenia, conditions in which the acetylcholine system and hippocampus are key players.
The results of the study are published online in the journal Neuron.
Source: National Institutes of Health