A team of neuroscientists at the New York University School of Medicine has found a link between chronic pain and overactive pyramidal neurons during sleep periods. In their study, published in the journal Nature Neuroscience, the group conducted experiments with injured mice experiencing chronic pain.

Prior research has shown that there is often a link between chronic pain and insomnia. After experiencing a neural injury of some sort, many patients are left with some degree of lasting pain. This tends to result in poor sleep and sometimes insomnia. Once that happens, the pain becomes worse, and over time becomes chronic. But why this happens has been a mystery. In this new effort, the team in New York conducted experiments with mice hoping to find the answer.

The work involved inducing chronic pain in mice by damaging two of the three branches that make up a group of sciatic nerves. Doing so led to skin sensitivity in the legs. The researchers scanned the brains of each of the mice before and after the damage. They observed that pyramidal neurons in the part of the cerebral cortex responsible for sensation processing in the skin became more active. And over the course of several weeks, the activity increased, peaking during non-REM sleep.

Approximately 9,000 people are admitted to Norwegian hospitals with stroke each year. About half of these patients feel exhausted afterwards, and many patients sleep more during the day than before the stroke. These after-effects are challenging and significantly affect patients’ everyday life.

However, we still have a limited understanding of which factors lead to increased fatigue and daytime sleep after stroke. Our research group therefore wanted to investigate whether cognitive and emotional complaints are related to increased fatigue and sleep during the day.

Our results were recently published in an article in the journal Frontiers in Neurology.

Here is an important reason to stay in touch with friends and family: social isolation causes memory and learning deficits and other behavioral changes. Many brain studies have focused on the effects social deprivation has on neurons, but little is known about the consequences for the most abundant brain cell, the astrocyte.

Researchers at Baylor College of Medicine working with animal models report in the journal Neuron that during social isolation, astrocytes become hyperactive, which in turn suppresses brain circuit function and memory formation. Importantly, inhibiting astrocyte hyperactivity reversed the cognitive deficits associated with social deprivation.

“One thing we have learned during the COVID pandemic is that social isolation can influence cognitive functions, as previous studies suggested,” said co-first author, Yi-Ting Cheng, graduate student in Dr. Benjamin Deneen’s lab at Baylor. “This motivated co-first author Dr. Junsung Woo and me to further investigate the effects of social isolation in the brain, specifically in astrocytes.”