“Surprisingly, this back-and-forth communication is even stronger during dream-like sleep than it is when animals are awake and running,” he said. “This means that splines play a critical role in coordinating information during sleep, perhaps helping to solidify awake experiences into enhanced long-term memories during this dream-like state.”

The new findings focus on a part of the brain called the retrosplenial cortex. This region helps us figure out when to turn left vs. right, and is also important for memory and imagining the future. Importantly, it is also one of the first brain regions to become impaired in the early stages of Alzheimer’s disease.

“We studied many different brain regions, and splines were consistently strongest in the retrosplenial cortex.” Ahmed said. “Given that the retrosplenial cortex is altered very early in Alzheimer’s disease, this means that we may be able to use spline rhythms in people as an early biomarker for Alzheimer’s. We are currently investigating this possibility in preclinical models of neurodegenerative diseases.”

The study’s other authors—all members of Ahmed’s lab at the U-M Department of Psychology—are Fang-Chi Yang, Sharena Rice, Vaughn Hetrick, Alcides Lorenzo Gonzalez, Danny Siu, Ellen Brennan, Tibin John and Allison Ahrens.