Study sheds light on how ‘dopamine neurons’ contribute to memory formation in humans
Source: Cedars-Sinai Medical Center
Summary: Researchers shed light on how the human brain rapidly forms new memories, providing insights into potential new treatments for memory disorders.
Dopamine neurons degrade in neurodegenerative diseases such as Parkinson’s, which in addition to motor symptoms is often also accompanied by cognitive issues such as memory problems. A common treatment for patients with Parkinson’s, for instance, is to take medications that increase dopamine to a steady level. But those drugs do not facilitate the short bursts that help in the formation of memory. Researchers from the Cedars-Sinai Medical Center shed light on how the human brain rapidly forms new memories, providing insights into potential new treatments for memory disorders. The study found that dopamine neurons play a critical role in the formation of episodic memory, which allows people to remember such things as where they parked the car in the morning and what they had for dinner last night. The study findings were published in the journal Current Biology.
In the study, investigators observed the response of individual human dopamine neurons in patients undergoing deep brain stimulation surgery to treat Parkinson’s disease. The patients watched a sequence of images: Some had never been seen before and were thus “novel”; others were repeated and were therefore “familiar.” For each image, the patient pressed a button indicating whether it was novel or familiar. This allowed investigators to track the formation of new memories because an image was only novel once. Afterward, it formed a memory. This is an important new scientific discovery because it has so far remained unclear how the dopaminergic system contributes to episodic memory formation.
Project scientist, Jan Kaminski said, “What we discovered was that a subset of the dopaminergic neurons responded only when an image was novel, but not when it was familiar. In other words, it indicated if the image was new, but not if something was familiar.”
More Information: Jan Kamiński et al, “Novelty-Sensitive Dopaminergic Neurons in the Human Substantia Nigra Predict Success of Declarative Memory Formation”, Current Biology (2018). DOI: 10.1016/j.cub.2018.03.024