Science News has more on how a zap of electric current, placed just so, can increase your ability to make and maintain new memories:
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.”
The amygdala’s key roles in emotional responses and fear-associated learning have been well-studied. So the Emory scientists made sure that amygdala stimulation at low levels of current (0.5 milliamps) did not result in emotional responses, an elevated heart rate, or other signs of arousal. Study participants reported that they did not notice the stimulation at any point in the study.
The researchers avoided direct stimulation of the hippocampus, figuring that would be too close to the machinery of memory itself, like introducing a live wire into a computer’s motherboard.
Study participants first viewed 160 neutral objects (emotional faces were excluded, for example) and were asked to judge whether the objects belonged indoors or outdoors. For half of the images, participants received stimulation for one second after each image disappeared from the screen. They were quizzed on half the stimulated images and half the unstimulated images immediately, and the other half the next day. 40 new images were used as decoys. The effect of stimulation on immediate recognition was not statistically strong. However, the next day, the effects on stimulated images were clear.
“This makes sense because the amygdala is thought to be important for memory consolidation — making sure important events stick over time,” Manns says.
79 percent of the participants (11 out of 14) showed an improvement on overnight memory tests, while the remaining 21 percent showed no improvement or impairment. When compared to no stimulation, the increase in number of images accurately recognized ranged from around 8 percent up to several hundred percent.
Some of the patients had impaired memory as a result of their epilepsy; the patients in whom a greater effect was seen generally had poorer baseline memory performance. For instance, one patient essentially forgot all of the control images, but maintained good memory for the stimulated images. However, a substantial effect was also observed in people who had an average memory to start with.
“The average was like having a ‘B’-level memory performance move up to an ‘A’,” Willie says.