Deep brain stimulation (DBS) is an established treatment for neurological disorders such as Parkinson's disease. The technique uses a surgically implanted electrode to deliver electrical stimulation directly into a specific area of the brain, such as the motor cortex, in order to increase neural activity in the targeted region. Researchers have recently begun exploring other applications for DBS, such as the treatment of cognitive and mood disorders. Though the treatment has been effective in treating certain disorders, studies explaining how the treatment works have been scarce.

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A team of researchers led by Paul W. Frankland and colleagues at The Hospital for Sick Children in Toronto, Canada, have sought to uncover the mechanisms that allow DBS to translate into neurological changes (J. Neurosci. 31, 13469–13484; 2011). They hypothesized that DBS might influence cognitive ability if applied to the hippocampus, the center of learning and memory in the brain. In a set of mice, DBS was used to stimulate to the entorhinal cortex, a region of the brain that provides direct input into memory-related circuitry in the hippocampus.

They found that stimulation of the entorhinal cortex led to increased production of new neurons in the hippocampus, demonstrating that the effects of DBS may spread farther than the targeted brain region. Furthermore, these new neurons were quickly integrated into existing memory circuits, suggesting that they might functionally contribute to memory processes.

The scientists tested whether this neuronal growth spurt led to an enhancement in the mice's memory ability. Based on the location of the new cells, they investigated whether spatial memory ability would be enhanced in the stimulated mice. They found that mice who had received DBS were significantly better at navigating to a designated target than those that had not received the treatment. This suggests not only that DBS stimulates growth of new neurons in the brain, but also that these new neurons can translate into enhanced cognitive abilities.

The results of this study show that DBS can enhance cognitive abilities by increasing the production of new neurons in the brain. The treatment, which has already been used in thousands of human patients, may therefore provide therapeutic benefits. Frankland told the Society for Neuroscience, “These new findings have important clinical implications as they inform potential treatments for humans with memory disorders.”