Direct Amygdala Stimulation Can Enhance Human Memory

Everyone has memories that they would enjoy remembering more clearly if possible. Someday, a process similar to this type of amygdala stimulation will be used by a lot more people to recall events from the past that shaped what kind of people they became.

Direct electrical stimulation of the human amygdala, a region of the brain known to regulate memory and emotional behaviors, can enhance next-day recognition of images when applied immediately after the images are viewed, neuroscientists have found.

The findings are the first example of electrical brain stimulation in humans giving a time-specific boost to memory lasting more than a few minutes, the scientists say. Patients’ recognition only increased for stimulated images, and not for control images presented in between the stimulated images. The experiments were conducted at Emory University Hospital in 14 epilepsy patients undergoing intracranial monitoring, an invasive procedure for the diagnosis of seizure origin, during which electrodes are introduced into the brain.

“We were able to tag specific memories to be better remembered later,” says co-first author Cory Inman, PhD, postdoctoral fellow in the Department of Neurosurgery. “One day, this could be incorporated into a device aimed at helping patients with severe memory impairments, like those with traumatic brain injuries or mild cognitive impairment associated with various neurodegenerative diseases. However, right now, this is more of a scientific finding than a therapeutic one.”

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“We see this as a platform for the further study of memory enhancement,” says senior author Jon T. Willie, MD, PhD, assistant professor of neurosurgery and neurology at Emory University School of Medicine.

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New Research into Sleep’s Benefits to Memory

The research says that adequate sleep is helpful for using what’s learned from memories more efficiently.

Researchers at the University of York have shed new light on sleep’s vital role in helping us make the most of our memory.

Sleep, they show, helps us to use our memory in the most flexible and adaptable manner possible by strengthening new and old versions of the same memory to similar extents.

The researchers also demonstrate that when a memory is retrieved — when we remember something — it is updated with new information present at the time of remembering. The brain appears not to ‘overwrite’ the old version of the memory, but instead generates and stores multiple (new and old) versions of the same experience.

The results of the research, carried out at York’s Sleep, Language and Memory (SLAM) Laboratory, are presented in the journal Cortex today.

Lead researcher Dr Scott Cairney of York’s Department of Psychology said: “Previous studies have shown sleep’s importance for memory. Our research takes this a step further by demonstrating that sleep strengthens both old and new versions of an experience, helping us to use our memories adaptively.

“In this way, sleep is allowing us to use our memory in the most efficient way possible, enabling us to update our knowledge of the world and to adapt our memories for future experiences.”

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Corresponding author Professor Gareth Gaskell of York’s Department of Psychology said: “Our study reveals that sleep has a protective effect on memory and facilitates the adaptive updating of memories.

“For the sleep group, we found that sleep strengthened both their memory of the original location as well as the new location. In this way, we were able to demonstrate that sleep benefits all the multiple representations of the same experience in our brain.”

The researchers point out that although this process helps us by allowing our memories to adapt to changes in the world around us, it can also hinder us by incorporating incorrect information into our memory stores.