You drive to the supermarket as if in a dream, guiding your car without really thinking about it, piloting from memory. Details like the path to the market's address that can be recalled as facts and knowledge, which are associated with times, places, and events are called "declarative memories." They are often unavailable to people who have suffered traumatic brain injuries.
It is those kinds of memories—and the brain functions that enable them—that the Pentagon's Defense Advanced Research Projects Agency (DARPA) is now exploring through its newly launched Restoring Active Memory (RAM) program. To do so, the agency will develop an implantable, wireless neural interface device that aims to bridge the gaps that interfere with a person's memory functions and effectively restore their abilities. If it's successful, this would lead to a potentially game-changing neural prosthesis in the form of a brain chip. Such a procedure has already brought positive results in lab rats. The research into how well it might work for humans is expected to take four years.
"We are going to start with very simple and high-impact areas of memory function," said Dr. Justin Sanchez, RAM's program manager, "and get that established first."
Understanding the fundamental neural circuits involved in memory formation is the first step according to Sanchez. Next, the program aims to develop new computational models that'll allow medical officers to interface with those circuits, to sense and interpret the signals between them.
"Once we have developed the next generation's devices to interface with the brain, we need to think about encoding," explained Sanchez. "This is the process by which we send neural signals back to those neural circuits to restore that function."
There are few, if any, effective existing therapies for those afflicted with memory deficits due to traumatic brain injuries, a problem that's affected around 270,000 military personnel since 2000 and impacts an estimated 1.7 million U.S. civilians each year. Bridging the gaps in an injured person's brain is no easy matter, but it's conceptually feasible, says Sanchez, if you think of it as a disconnect in a circuit.
"Let's say we record on one side of the circuit and understand the neural signaling that the brain was trying to send to the other side of the gap," said Sanchez. "We can interpret that information and use it to help send signals to the other side of the gap, so that we can continue to flow that information in the brain and continue the possibility of formation of those memories."
DARPA has set up significant milestones for UCLA and the University of Pennsylvania, the two Universities leading the RAM program, such as finding biomarkers involved in memory recall, evaluating the effectiveness of computational models that interpret the neural signals, inferring how long these signals have to be sent to the brain, as well as resolving the hardware challenges of creating a small biocompatible device that handles all this processing.
Epileptic patients who have their brain stimulated through implanted brain electrodes as part of their treatment could be the first set of patients to receive the neural prosthesis, once the device is approved by the FDA.
While it's impossible to insert or manipulate memories, according to the scientists, implanting a neural prosthesis could have unexpected effects. One of the big questions being ironed out at DARPA's RAM program are the kind of side effects a patient might experience.
"These could involve alterations in cognitive and emotional function, including a change in personality," says neuroethicst James Giordano of Georgetown University Medical Center, who currently serves on DARPA's Neuroethics, Legal, and Social Issues' Advisory Panel. "Of course, these could be mitigated by adapting the function of the technology and/or ceasing its operation, and also involve other forms of management."
With $40 million being distributed between the universities and agencies involved in RAM, DARPA is hopeful that the program will come up with a memory recovery solution for those suffering from brain injuries or other types of dysfunction.
"How is someone going to have a livelihood if they can't remember how to do simple tasks?" asks Rick Weiss, director of strategic communications at DARPA, discussing the lives of injured military personnel."We are obligated to try to restore these individuals back to their full function if it is within our power."
[Image: Flickr user John Mettraux]