Today we have Dr. Mark Mattson, an adjunct professor of neuroscience at Johns Hopkins School of Medicine who is making his third appearance on STEM-Talk. Today’s interview focuses on Mark’s research into glutamate and comes on the heels of the publication of Mark’s new book, “Sculptor and Destroyer: Tales of Glutamate – The Brain’s Most Important Neurotransmitter.” Today Mark explains how more than 90 percent of the neurons in the brain deploy the little-known molecule glutamate as their neurotransmitter. Glutamate controls the structure and function of the brain’s neuronal networks and mediates many of our human capabilities, such as learning, memory, creativity, and imagination. But there’s also a dark side to glutamate. Mark shares how it can play a causal role in the development of disorders such as autism, schizophrenia, and epilepsy as well as diseases such as Alzheimer’s, Parkinson’s, and ALS. Mark is affectionally known as the godfather of intermittent fasting and his first appearance on STEM-Talk focused on the many ways that fasting optimizes healthspan and even lifespan. His second STEM-Talk interview followed the publication of his book, “The Intermittent Fasting Revolution: The Science of Optimizing Health and Enhancing Performance.” Show Notes: [00:04:05] Dawn welcomes Mark back to STEM-Talk for his third appearance. Dawn mentions that our previous two episodes with mark focused on intermittent fasting, and that Mark is considered the godfather of intermittent fasting. Dawn goes on to mention that the National Institutes of Health has described Mark as “one of the world’s top experts on the potential cognitive and physical health benefits of intermittent fasting.” [00:05:05] Ken mentions that in our previous STEM-TALK interview Mark shared that he was working on a new book about glutamate. Ken adds that Mark considers his research on glutamate to be his most important work. Ken asks why Mark feels as though this research is his most important, given his substantial contributions in other areas. [00:05:49] Dawn mentions that Mark’s research hasn’t been limited to just glutamate and intermittent fasting. Mark has contributed to a broad range of topics including brain evolution, cognition, the impact of diet and lifestyle on brain health, as well as the pathogenesis and treatment of various neurological conditions. Dawn asks Mark to talk about his motivation to understand how the pieces of the “brain puzzle” fit together, which is the core motivation for his pursuing a broad scope of research. [00:07:22] Ken asks about Mark’s postdoc work, where he discovered that glutamate sculpts the formation of hippocampal neuronal networks during development. [00:09:33] Ken mentions that while Mark was at the University of Kentucky, he discovered that the amyloid beta peptide which accumulates in the brain during Alzheimer’s disease renders neurons vulnerable to excitotoxicity. Ken goes on to say that since this, and the previously mentioned discovery, neurologists have shown that neuronal network hyperexcitability occurs early in Alzheimer’s and may contribute to neuronal degeneration. Ken asks Mark to talk about the significance of these two discoveries. [00:13:39] Dawn asks Mark to talk about the significance of glutamate as a molecule and how it controls the formation of nerve cell networks as the brain develops in utero. [00:17:50] Ken asks Mark why he thinks that glutamate rarely comes up in discussions of neurotransmitters, despite its importance of its functions. [00:19:58] Ken asks Mark to expound on the “dark side” of glutamate. [00:26:04] Dawn mentions that we may never know where in the universe glutamate originated, and while it might have been here on Earth, it perhaps originated somewhere else in the universe. Dawn asks Mark to expand on that notion. [00:28:33] Ken shifts to the history of glutamate research, explaining that up until the 1940’s