Neuroscience

In the split second that you accidentally touch the hot handle of a cast iron skillet, pain and a sense of danger rush in. Sensory signals travel from the pain receptors in your finger, up through your spinal cord, and into your brainstem. Once there, a special group of neurons relays those pain signals to a higher brain area called the amygdala, where they trigger your emotional fear response and help you remember to avoid hot skillets in the future. Researchers assumed this process must be mediated by fast-acting neurotransmitters, but Salk scientists found that this was not the case. Associate Professor Sung Han, postdoctoral researcher Dong-Il Kim, and colleagues created two new tools to study larger, slower molecules called neuropeptides. These allowed the scientists to study their role in the danger circuit in live mice for the first time. Their findings revealed that neuropeptides, not fast neurotransmitters like glutamate, were the main messenger in this danger circuit—and more than one neuropeptide is involved. Their findings may explain why existing medications that target only one neuropeptide are often ineffective, and could inspire the development of new treatments for fear-related conditions like anxiety and post-traumatic stress disorder.

A new study has provided an unprecedented look at how gene regulation evolves during human brain development, showing how the 3D structure of chromatin—DNA and proteins—plays a critical role. This work offers new insights into how early brain development shapes lifelong mental health. The study was a collaboration between Professor Joseph Ecker’s lab at Salk and colleagues at UC Los Angeles, UC San Francisco, UC San Diego, and Seoul National University. The team created the first map of DNA modification in the hippocampus and prefrontal cortex—two regions of the brain critical to learning, memory, and emotional regulation, and also frequently involved in disorders like autism and schizophrenia. The researchers hope the data resource, which they’ve made publicly available through an online platform, will be a valuable tool scientists can use to connect genetic variants associated with these conditions to the genes, cells, and developmental periods that are most sensitive to their effects.