Over the past century, neuroscientists have developed an understanding of numerous aspects of the brain including the workings of individual brain cells, communication between neighboring brain cells, and the impact specific cell clusters have on disease states. Despite these advances, little is known about the specific biochemical events within brain cells that give rise to consciousness such as thoughts, feelings, actions, perceptions and memories.

Now, neuroscientists in the Otto Laboratory at Rutgers University are delving into the molecular and genetic events within neurons that form some types of memories. Their research shows that some forms of learning activate a specific set of genes within neurons, producing proteins essential to both the formation of new memories and the strengthening of memories when recalled.

Forming new memories and/or recalling old ones turns on one gene and its protein product, the activity-regulated cytoskeletal protein (Arc), in a brain area called the hippocampus. This area is involved in many forms of learning. The researchers also determined that temporarily turning off this gene in the hippocampus blocks new learning, yet has no effect on previously established memories.

In related work led by Kartik Ramamoorthi, Massachusetts Institute of Technology researchers found that learning to relate an unpleasant event with the place where the event occurred activates another gene, Npas4, in the hippocampus' CA3 area. The results suggest that Npas4 activation initiates a cascade of intracellular biochemical events that, in turn, strengthen the connections between individual brain cells within the hippocampus and ultimately results in the formation of lasting memories.

Future work will focus on more fully characterizing the complex biochemical events that underlie new memory formation and how the alteration of these events contributes to several conditions including Alzheimer's disease.