The most powerful substance in the human brain for neuronal communication is glutamate. It is by far the most abundant, and it's implicated in all kinds of operations. Among the most amazing is the slow restructuring of neural networks due to learning and memory acquisition, a process called synaptic plasticity. Glutamate is also of deep clinical interest: After stroke or brain injury and in neurodegenerative disease, glutamate can accumulate to toxic levels outside of neurons and damage or kill them.

In a paper the authors described how glutamate is released from neural synapses after the neuron fires and the results are published in Nature Communications.

"With this paper, we uncover how signals are transmitted across synapses to turn on the switch for plasticity," the senior author says. "We demonstrate that glutamate is first released near AMPA-type glutamate receptors, to relay the signal from one neuron to the next, and then near NMDA-type receptors immediately after the first signal to activate the switch for synaptic plasticity."

Mechanistically, glutamate release lead to maximal membrane depolarization through AMPA receptors, alleviating the pore-blocking magnesium leading to greater activation of NMDA receptors. Together, these results suggest that release sites are likely organized to activate NMDA receptors efficiently.

https://social.mbl.edu/turning-on-the-switch-for-plasticity-in-the-human-brain

https://www.nature.com/articles/s41467-021-21004-x

http://sciencemission.com/site/index.php?page=news&type=view&id=publications%2Fasynchronous-release&filter=22