Work Begins on Brain Stimulator to Correct Memory

Can deep brain stimulation affect how well and what we remember?

An x-ray shows EEG-recording electrodes under the skull of an epilepsy patient.

For some of the approximately 10 million people worldwide with traumatic brain injury (TBI), forming and holding onto new memories can be one of the hardest things theyll do in a day. Now imagine a device implanted in the brain that can help them encode memories by means of small electric shocks.

Initial steps toward such a memory neuroprosthetic are being taken at the University of Pennsylvania, where researchers have started tests on brain surgery patients to try to locate, and influence, the processes that control memory formation.

When people suffer brain injuries, several things happen. Neurons might be damaged from the initial impact or from bruising or swelling in the brain afterward. The axons that connect brain regions might be severely jarred during impact, in some cases literally separating from neurons.

The brain is a complex network of neurons that all have to communicate with each other, says Matthew Kirschen, a pediatric neurologist at the Childrens Hospital of Philadelphia, who is not involved in the Penn research. All you need is a little disruption in axonal process and memory is impaired.

The Pennsylvania team is one of several in the United States that were funded last year by DARPA, the Pentagon research agency, to design and build stimulators that could influence cognition by constantly recording brain function and zapping particular brain areas with low doses of electricity (see Military Funds Brain-Computer Interfaces to Control Feelings).

The Penn team, led by cognitive neuroscientist Michael Kahana, has already begun analyzing brain recordings from patients with severe epilepsy. As part of their treatment, these patients receive a small mesh of electrodes under their skulls, which they wear for two to seven weeks. The electrodes collect EEG recordings that are used to calculate where in their brains their seizures are originating, in preparation for surgery to remove the malfunctioning tissue.

While they undergo this treatment, some patients are also volunteering to let Kahana study them as they play memory games on a computer. The EEG electrodes record the average electrical activity of tens of thousands of neurons at once; Kahana says some of the brain waves measured this way are correlated with memory function.

The link between EEG oscillations and memories isnt clear, but the Penn researchers suspect that certain frequencies could offer a marker for how well a person will remember things. These include so-called theta oscillationsa type of neuronal activity in the hippocampus, one brain region thats active in creating new memories. They are the ones [I] think are the most important for memory formation, and theyre often present in the hippocampus, says Josh Jacobs, an assistant professor at Drexel Universitys School of Biomedical Engineering, Science, and Health Systems, who is working on the project.

Read the rest here:
Work Begins on Brain Stimulator to Correct Memory