New insight into how brain makes memories

Researchers have gained fresh insights into the changes at molecular and cellular level in the brain while forming memories.

The findings can help people with Alzheimer's get back their memories, the researchers said.

Every time we make a memory, somewhere in our brain a tiny filament reaches out from one neuron and forms an electrochemical connection to a neighbouring neuron.

The filaments that make these new connections are called dendritic spines and, in a series of experiments, the researchers report that a specific signalling protein, Asef2, plays a critical role in spine formation.

This is significant because Asef2 has been linked to autism and the co-occurrence of alcohol dependency and depression.

"Alterations in dendritic spines are associated with many neurological and developmental disorders, such as autism, Alzheimer's disease and Down Syndrome," said lead researcher Donna Webb, an associate professor at Vanderbilt University.

"However, the formation and maintenance of spines is a very complex process that we are just beginning to understand," Webb said.

Neuron cell bodies produce two kinds of long fibres that weave through the brain: dendrites and axons.

Axons transmit electrochemical signals from the cell body of one neuron to the dendrites of another neuron.

When one of the dendritic filaments makes contact with one of the axons, it begins to adhere and to develop into a spine.

The axon and spine form the two halves of a synaptic junction. New connections like this form the basis for memory formation and storage.

Autism has been associated with immature spines, which do not connect properly with axons to form new synaptic junctions.

However, a reduction in spines is characteristic of the early stages of Alzheimer's disease. This may help explain why individuals with Alzheimer's have trouble forming new memories.

"Once we figure out the mechanisms involved, then we may be able to find drugs that can restore spine formation in people who have lost it, which could give them back their ability to remember," said Webb.

The findings were published in Journal of Biological Chemistry.