Scientists know which general areas of the brain are responsible for memory storage: the hippocampus, the cerebellum, and the neocortex. But until now, exactly where memories hide in those areas has remained a mystery. New research suggests that memories are stored in the space between two nerve cells, or neurons. That space, called a synapse, consists of two membranes that play a vital role in learning and memory.
In a paper published in the Proceedings of the National Academy of Sciences (PNAS), a team of biophysicists, physical chemists, and materials scientists in Tennessee share that synapses are more than just an information highway. Generally, synapses are understood to be a space in which two neurons pass information to each other; when one neuron transmits information in the form of neurotransmitters, a 20-nanometer synaptic cleft forms between the neuron and its recipient. In this space are two membranes: one that helps the first neuron send out information and one that helps the second neuron receive information.
A computer illustration of a neuron.
Credit: Nicolas P. Rougier/Wikimedia Commons
Each membrane contains a lipid bilayer responsible for synaptic plasticity, or the brain’s ability to learn new information. Because of this, the scientists at Oak Ridge National Laboratory and the University of Tennessee wondered if memories were stored in those lipid bilayers, which have long been suspected to help the brain adapt to new information.
The scientists tested this concept by applying electrical stimulation to a lipid bilayer model in the lab. The electrical stimulation (which mimicked the process by which neurons pass information to one another) triggered the long-term changes inherent to synaptic plasticity. These changes lasted more than 24 hours without further stimulation, suggesting that the lipid bilayer doesn’t just play a role in memory storage—it’s responsible for it.
Further research will be necessary to solidify the neuronal lipid bilayer’s role in memory storage. If the lipid bilayer is responsible for memory, it’ll revolutionize how we study and potentially treat disorders like amnesia and dementia. It could boost scientists’ efforts to model computers’ memory capabilities after the human brain in an approach called neuromorphic computing.