Injuries to the brain and disorders like Alzheimer’s can impair our ability to develop new memories. Depending on the severity of the memory loss, this can make it difficult for a person to work or live alone. It may also be extremely traumatic.

“Loss of memory is arguably the most devastating occurrence that can accompany disease or damage,” Wake Forest School of Medicine neuroscientist Robert Hampson remarked in 2018. “Memory is at the core of who a person is… We lose our sense of self if we lose our memories.”

A new study implies that a DARPA-funded “memory prosthesis,” which Hampson is working on, could one day restore people’s ability to generate new memories by shocking their brains in just the right manner.

Crafting Memories

When we meet new information, like as learning a stranger’s name, neurons in the hippocampus engage, sending electrical impulses to other neurons. This pattern is then encoded in the brain, and when the information is needed later, the neurons fire in the same way.

If the hippocampus is injured by disease or injury, the neurons in the brain may have difficulties memorising the pattern, and you may forget your new acquaintance’s name before the end of your first chat.

Researchers at Wake Forest University and the University of Southern California (USC) are developing a memory prosthesis that utilizes electrodes to zap neurons in the hippocampus during memory formation.

The theory is that this will assist reinforce the pattern of electrical activity in the brain and increase the person’s capacity to recall information later — and it appears to work based on recent human testing.

“We’re seeing gains ranging from 11% to 54%”

– Robert Hampson

Perfect in every way

The researchers developed two versions of their memory prosthesis through previous research in both animals and humans: a “memory decoding model” (MDM) and a “multi-input, multi-output” (MIMO) model.

The MDM model basically examines the electrical activity in the hippocampus when a person correctly makes a memory and then derives an average pattern associated with successful memories. When the person is attempting to develop a new memory, it sends that pattern back into the brain via electrodes.

MIMO is a more advanced model. It is trained to analyse electrical activity in the CA3 region of the hippocampus, which receives new information, and then predicts the best pattern of electrical impulses in a different region (the CA1 region) for successful memory formation.

“The model’s input is live CA3 data recorded straight from a patient, and the model constantly predicts what the CA1 output should be,” Sampson explained to Freethink. “The output prediction is then used as a pattern to activate CA1.”

In a recent study, the researchers tested their memory prosthesis on 24 people who previously had electrodes implanted in their brains to aid doctors in their epilepsy research. Some of these folks suffered brain traumas as well as pre-existing memory loss.

The participants completed simple memory tests while their brain electrical activity was recorded during the study.

Each task began with the display of a picture on a screen. The image was shown again up to 30 seconds later, along with decoy images. The study participants were then asked to identify the image they had previously seen.

Each participant completed 100 to 150 of these tasks, allowing the researchers to tailor their MDM and MIMO models to each individual’s brain activity.

The participants repeated the memory tasks again a few days later. This time, some participants had their brains stimulated based on their personalised MDM or MIMO models, while others received random stimulation or no treatment at all.

The participants then completed “delayed recognition” activities at least 30 minutes later. They were asked to rank their familiarity with three images: one they’d been asked to remember previously, a previously seen decoy image, and a completely new one.

Participants who received MDM or MIMO stimulation outperformed those who received random or no stimulation on both types of activities. On average, the more advanced MIMO model produced the best outcomes, and persons with the worst recollections at the start of the trial improved the most.

“We’re seeing gains ranging from 11% to 54%,” Hampson told MIT Technology Review.

“An implant must either run continually or be intelligent enough to know when to switch itself on or off”

– Robert Hampson

Looking forward

The latest study indicates that properly guided brain stimulation can increase a person’s ability to form new memories, but we’re still a long way from having a device that can help people with dementia or catastrophic brain injuries regain lost memory function.

First, there are hardware challenges to solve.

According to Hampson, a device to treat memory loss would require electrodes that could be permanently implanted – today’s electrodes generate scar tissue around them, causing them to fail.

We also require more sophisticated electrodes. The ones used in the study could only record from and activate 40-100 neurons, according to USC researcher Dong Song, and a device to cure memory issues in the real world would need to be able to stimulate hundreds or thousands.

The models also require more testing.

Because they were already undergoing the dangerous electrode implantation surgery, testing them in people with epilepsy made the most logistical sense, but we don’t know how well they’d work in people who don’t have epilepsy.

“We… need to seek authorization and volunteers to test the procedures in Alzheimer’s and maybe stroke patients as well,” Hampson told Freethink.

Another problem for the researchers is determining how to govern the system to have the greatest impact – we don’t need to recall every new piece of information we meet, and our short-term memory can only hold so much.

“An implant must either run continually or be intelligent enough to know when to switch itself on or off,” Hampson explained.

Because the hippocampus isn’t the only area of the brain involved in memory formation, if a person’s memory problems are caused by injury elsewhere in the organ, they may require a different treatment.

Still, with further development, it’s likely that this new memory prosthesis will not only assist some people overcome memory problems, but may one day give everyone a better memory – get the device implanted, and your odds of forgetting a name will be minimized.

Info source – Freethink