The findings, published in the March 16 issue of Neuron, pull together a growing body of evidence from the field. The study shows definitively that interactions between the PICK1 protein and another group of proteins known as AMPA receptors are critical for specific neurons, called Purkinje cells, in the lower back part of the brain to become de-sensitized to certain molecular signals.
Desensitization to molecular signals from neighboring neurons - a process known as long-term depression, or LTD - is thought to be responsible for several forms of motor learning, one of which is known as the vestibulo-ocular reflex. The vestibulo-ocular reflex coordinates eye movements with head movements, allowing us to perform activities such as reading in a moving automobile.
"We've long known that LTD underlies responses like the vestibulo-ocular reflex. This study gets at the heart of how LTD occurs, specifically how PICK1 controls the Purkinje cell's response to the signaling molecule, glutamate," says Richard L. Huganir, Ph.D., a Howard Hughes Medical Institute investigator and chair of the Solomon H. Snyder Department of Neuroscience at Hopkins.
The first critical step in establishing LTD happens when Purkinje cells swallow up surface proteins called AMPA receptors. Without AMPA receptors on the surface, these cells no longer are able to respond to signals from neighboring neurons. Researchers had known that PICK1 somehow was involved in the swallowing and removal of AMPA receptors, but only in this most recent study did they reveal how.
The investigators used individual nerve cells as well as brain slices from three different populations of genetically
Contact: Audrey Huang
Johns Hopkins Medical Institutions