The Workings of Working Memory

Synaptic Communication

How do we keep thoughts in our mind? It seems a simple question until we remind ourselves of the brain as a dynamic labyrinth of neurons constantly firing and receiving electrical signals. But researchers from the University of Wisconsin-Madison believe they’ve figured out how working memory holds a piece of information. The holder of a thought, they have discovered, is a molecular sensor that controls nerve cell communication keeping a message present and active even long after its delivery.

“The sensor could play a role in keeping a thought ‘on line’ until it is either lost or burned into longer-lasting forms of memory,” says the study lead Dr. Edwin Chapman, a professor at the UW School of Medicine and Public Health.

Most communication between synapses occurs instantaneously–an electrical impulse spurs calcium in the sending cell to release a burst of neurotransmitter into the receiving cell. This process takes just milliseconds to play out.

The Wisconsin scientists focused instead on a second, slower, asynchronous communication phase, in which residual levels of calcium continue to cause the release of neurotransmitters over several seconds.

“We knew that different calcium sensors controlled these two distinct phases of synaptic transmission,” says Chapman, based in the Department of Neuroscience.

The team theorized that slow transmission, with its maintenance of a communication state for a longer time period, might be the key to the retention of thoughts in working memory. They found that they were able to change the speed of slow release with higher and lower levels of a protein called Doc2 without impacting fast release.

“Doc2 took its time responding to calcium, unlike synaptotagmin, which responded immediately,” Chapman says.

The research could eventually produce practical results providing insight into conditions such as autism and schizophrenia. “Defects in release mechanisms are seen in many nerve diseases,” says Chapman.


Tags: , ,

Leave a Reply

You must be logged in to post a comment.