Thanks for the Memories, Hippocampus and Entorhinal Cortex


Midterms and finals week have tested our brains beyond their broadest capabilities. Perhaps the greatest test of our mental stamina is when we cram thousands of facts into our brains in such a limited amount of hours. So what can we attribute this ability of cramming and memorizing a seemingly impossible amount of information that’s necessary to succeed in a competitive university? The way in which memories are formed is very complex and our understanding of memories continues to be challenged. The hippocampus is known to be integral in the formation of memories. However, new findings show that memories are not formed exclusively in the hippocampus. This research proves that the entorhinal cortex acts independently of the hippocampus to form memories about movement. This finding was groundbreaking because it suggests that the hippocampus and entorhinal cortex work separate of each other even though they are interrelated.

The basic formation of a memory works through synapses. Synapses are strengthened in order to change short term memories into long term ones. Neurotransmitters are released, ions pass through, and information is passed onto next neuron. The receptors that the neurotransmitters bind to are removed by proteins, including the STEP protein. Paul Lombroso, through Yale University of Medicine, found evidence that decreasing the level of STEP in mice with the Alzheimer’s mutation significantly reduced their cognitive deficits. This mutation speeds up the breakdown of Amyloid precursor protein (APP). Cognitive deficits, including loss of memory or disjointed memories, occur in neurodegenerative disorders such as Alzheimer’s Disease and Parkinson’s Disease as well as other neurological disorders such as schizophrenia. Lombroso’s research is now focused on designing a drug to reduce STEP activity.

The Brewer Lab for Human Memory Research at the UC San Diego School of Medicine uses functional and structural magnetic resonance imaging (MRI) to visualize brain activity in both healthy patients and patients with memory difficulties such as Alzheimer’s disease. Currently, the Brewer Lab is imaging the brains of patients with signs of early memory loss in order to more thoroughly understand the process of different neurodegenerative diseases. With the new information about the formation of memory in the hippocampus and entorhinal cortex, the understanding of neurodegenerative disorders can also advance.

In a 2014 study, Hales et al. found, through the Veterans Affairs San Diego Healthcare System, that lesions to the medial entorhinal cortex do not completely disrupt the process of memory formation in the hippocampus. This supports the idea that the hippocampus and entorhinal cortex work independently of each other although they are structurally connected.

The following video from the Massachusetts Institute of Technology outlines the new findings concerning the involvement of the entorhinal cortex in relation to the hippocampus in memory formation.