University of Texas Scientists Discovered Episodic Memory Neurons
Scientists at the University of Texas Southwestern Medical Center have discovered about a hundred neurons involved in the formation of episodic memory in the hippocampus and entorhinal cortex of the human brain. The results, published in the journal NeuroImage, will help develop new treatments for mental disorders and traumatic brain injury.
The study of the memory mechanism involved 27 patients with epilepsy, who were implanted with electrodes during the surgical treatment of an intractable form of epilepsy. Volunteers performed memorization tasks, which made it possible to determine the activity of the involved nerve cells. A total of 103 neurons were identified, the frequency of which was associated with the successful formation of episodic memory – memory of personal experience, including memory of the place and time of events.
As the authors of the work write, these neurons have important properties. For example, they exhibit the same pattern of activity when a person memorizes information and when he tries to extract this information from memory. This activity may be related to schizophrenia, where, due to hippocampal dysfunction, sufferers are often unable to distinguish delusions or hallucinations from actual memories.
The results complement an important memory formation model called Separate Phases at Encoding And Retrieval (SPEAR), based on rodent experiments. This model explains how the brain manages to distinguish between old and new memory when retrieving information. Scientists have shown that the peak activity of neurons is tied to the phase of theta waves in the hippocampus, but this phase shifted between memory coding and recollection.