Will the problem of memory loss one day be forgotten? In the next few weeks the Pentagon’s research-and-development arm will announce a plan to fund the creation of a brain implant to help wounded soldiers recover their mental faculties. The research could also impact the millions of civilians affected by Alzheimer’s and other degenerative brain disorders.
We know in broad outline what it takes to lay down a memory. Throughout the years every single one of our experiences—from a major life event to the humdrum—has made and broken some of the vast network of connections that carry signals between the neurons in our brains: it is these patterns of connections that are central to our identity, our skills and how we think.
But traumatic brain injuries (TBI) can damage a person’s ability to retrieve memories, or to form or retain memories of new experiences. And since 2000, there have been almost a quarter million U.S. service personnel who have been diagnosed with TBI.
That’s why the U.S. Defense Advanced Research Projects Agency (DARPA) has launched the Restoring Active Memory (RAM) program. the RAM program will seek to find new methods for analysis and decoding of the neural networks to understand how to reverse damage caused by a brain injury. First, DARPA will try to create an implant that might bridge gaps in an injured brain, in order to help the injured overcome the loss of motor memories. Motor memories are those formed out of repetition—for example, when riding a bike or developing a one-handed tennis backhand.
Another target is declarative memories, which allow us to remember things such as specific moments of our lives, names of family members, what we ate for lunch, and so on. These commonly malfunction in sufferers from Alzheimer’s disease. To solve declarative memory problems, DARPA scientists plan to develop neuro-prosthetic devices that can directly interface with the hippocampus, one of the brain’s primary memory centers. Recent work suggests the hippocampus provides a kind of scaffold for thought, one that is essential if we are to make sense of our experiences.
For example, Robert Hampson and Sam Deadwyler of Wake Forest University in North Carolina, along with colleagues at the University of Southern California and University of Kentucky, studied the hippocampi of rodents and monkeys, and found that neurons in the hippocampus fire differently when they see blue or red, or a picture of food versus a face. Building from there, the researchers figured out how to extend short-term, working memory by stimulating the hippocampus.
Theodore Berger at the University of Southern California in Los Angeles, designed silicon chips to mimic the way neurons work.
Berger has also targeted the prefrontal cortex, a part of the brain that retrieves long-term memories forged by the hippocampus. Using implanted electrodes to stimulate a monkey’s prefrontal cortex, he and his team have been able to enhance the ability to remember an image.
Berger wants to restore the ability to create long-term memories by implanting chips like these in the brain in order to improve a person’s capacity to generate new memories and gain a strong hold on older ones. If it works as expected, it could even help Alzheimer’s patients retrieve memories that have been lost.
When it comes to soldiers, this kind of research has the potential to offer ways to erase memories or insert new ones, whether to make warriors more resilient or to forget a war crime. Of course, there are the obvious potential ethical issues here. When we tinker with memory, we are changing personal identity, and a faulty prosthetic memory could mean losing or altering a person’s sense of self. DARPA says that its RAM program is informed and advised by an outside panel of individuals with expertise in ethical, legal, and social issues.
The whole thing sounds like science fiction, but scientists studying memory do believe its a genuine possibility—eventually.
“It is possible that electrical stimulation of the brain could one day be used to help to improve or disrupt memory in general,” says professor Neil Burgess of the University College London Institute of Cognitive Neuroscience. “But it is clearly very early days for this type of approach.”
This research feeds into a wider initiative known as neuromorphics, where instead of thinking of brains as being like computers, the goal is to make computers more like brains.
DARPA’s SyNAPSE program—short for Systems of Neuromorphic Adaptive Plastic Scalable Electronics—is being carried out by IBM to redesign chips to emulate the ability of neurons to grow a thicket of synaptic connections. This is the feature of the brain that enables it to solve problems on the fly.
In another project, Kwabena Boahen at Stanford University has developed the Neurogrid circuit board, consisting of of 16 customized Neurocore chips. The board can simulate one million neurons and billions of synaptic connections on about the same amount of power it takes to run a tablet computer.
Boahen is working with other Stanford scientists to develop prosthetic limbs that would be controlled by a Neurocore-like implanted chip. “Long term, we may move from controlling a simple robotic arm to a prosthetic limb with human-like dexterity [controlled] directly with neural signals recorded from the motor cortex,” he says.
And the European Union’s Human Brain Project, led by professor Henry Markram at the École Polytechnique Fédérale de Lausanne on the shores of Lake Geneva, will spend one billion Euros to simulate the organ’s hundred billion or so neurons, in much greater detail than Neurogrid, over a decade or more. If that epic effort succeeds, extraordinary possibilities for brain repair will beckon.