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The study targeted a specific area of the brain using a combination of MRI brain scans and noninvasive brain stimulation, which improved the brain’s ability to make new memories. The study authors used MRI to measure participants’ brain activity while they played a memory game after receiving the stimulation, and found that their brain improvement lasted for 24 hours after receiving the stimulation.
Previous research has shown it is possible to improve memory with stimulation, but this study identified how the brain changed its level of excitability increased to improve memory. This increase in activity means that stimulation enhanced excitability, and that’s important because excitability is a marker for good memory formation.
Being able to manipulate the memory network in this very specific way certainly holds promise in the ability to intervene in disorders of memory, which occur for a variety of reasons. The study found that while the brain network was undergoing stimulation and forming a new memory, the excitability in the subject’s brain network increased dramatically.
After receiving TMS for several consecutive days, study participants would play a memory game to assess how much their associative memory had improved. There are different kinds of memory, the study focused on associative contextual memory, which is thought to be created in a specific posterior network of the hippocampus. This type of memory is an arbitrary collection of little pieces that the brain binds together to create a coherent association that can be recalled later.
That’s the kind of memory that the hippocampus and this network of regions is thought to do, and that’s exactly the kind of memory tested in the experiment to determine how TMS influenced this network’s ability to do that kind of memory formation. The study included 32 Chicago subjects (16 in the experimental group, 16 in the control group) between the ages of 18 and 35 who had normal, healthy memory and cognitive abilities.
Participants underwent an MRI scan of their brain before receiving stimulation. To precisely identify where the study participant’s hippocampal network was located, the scientists used a sterotactic positioning system a navigator tool consisting of a forehead sensor, camera and a pinpoint tool to localize the position of the physical head as it related to participant’s brain scan from the MRI.
Participants then received 20 minutes of repetitive TMS to the stimulation target in their brain via a magnetic stimulating coil for five consecutive days. The TMS feels like a mild tapping at 20 beats per second. Researchers tested the memory of study participants by asking them to look at several images and try to associate them or remember their location.