A joint project between researchers from the University of Birmingham and Ruhr-University has led to the discovery that, contrary to previous estimates, the human brain can recover episodic memories in just a tenth of a second, which is approximately one-third of the time it takes to blink, according to the Daily Mail. Using repetitive transcranial magnetic stimulation (rTMS), the team also found that this retrieval can be blocked when a patient is exposed to repeated magnetic stimulation.
There are two types of memorie – semantic and episodic. Episodic memories, which were the focus of the study, are individual memories of specific events that are unique to each person, such as the memory of your wedding day or first movie.
The team used electroencephalography (EEG) to monitor the brains of patients recalling episodic events in order to watch the retrieval process in real-time. They found that the process begins with a rapid reactivation of the parietal lobe, one of the brain's sensory areas, meaning retrieval begins with a reactivation of the areas of the brain that were involved in the formation of the memory rather than the memory cells themselves.
Upon further examination of the subjects, the team also found that when they endured magnetic stimulation from rTMS during the recall process, the previously observed EEG pattern was nowhere to be found, which suggests that a rapid response is integral for memory retrieval.
"Knowing that memory relies on very rapid reactivation of sensory information, and seeing that we can interfere with that, really improves our understanding of how our memory works," Gerd Waldhauser, who participated in the research, said in a press release. "It may help in understanding psychiatric conditions that involve the intrusion of unwanted memories. There are a number of instances where being able to intervene and target traumatic memories would be beneficial."
The findings were published in the Jan. 6 issue of The Journal of Neuroscience.
