![]() ![]() And the more the STN was engaged – or the more that part of the brain responded to the unexpected sound – the more it affected the subjects’ working memory and the more they lost hold of what they were trying to keep in mind. The results show, the researchers write, that unexpected events manifest the same brain signature as outright stopping of the body. The STN is part of the brain’s stopping system and is a particular focus of this study. The volunteers’ brain activity was recorded, as well as their accuracy in recalling the letters they’d been shown.Ī reconstruction of deep brain stimulation electrodes that have been surgically placed into the most common target structure for treatment of Parkinson’s disease, the subthalamic nucleus (orange). On a minority of trials, this sound was replaced by a birdsong segment – which is not startling like a “bang!” but is unexpected and surprising, like a cell phone chirping suddenly. Most of the time, while they were maintaining the letters in mind, and before the recall test, they were played a simple, single-frequency tone. On each trial, they were asked to hold in mind a string of letters, and then tested for recall. (The STN is the main target for therapeutic deep brain stimulation in Parkinson’s disease.)Īll the volunteers were given a working memory task. The study analyzes signals from the scalp in 20 healthy subjects as well as signals from electrode implants in the STN of seven people with Parkinson’s disease. Specifically, it may be important, Aron said, for a “broad stop.” A broad stop is the sort of whole-body jolt we experience when, for example, we’re just about to exit an elevator and suddenly see that there’s another person standing right there on the other side of the doors. Courtesy Jan WesselĮarlier research by Aron and colleagues had shown that the STN is engaged when action stopping is required. Jan Wessel, now at the University of Iowa. This is a small lens-shaped cluster of densely packed neurons in the midbrain and is part of the basal ganglia system. ![]() The current study focuses particularly on one part of the brain’s stopping system – the subthalamic nucleus (STN). The same brain system that is implicated in “over-stopping” motor activity in these patients, Aron said, might also be keeping them over-focused. ![]() Parkinson’s patients may also present as the “opposite of distractible,” often with a thought stream so stable that it can seem hard to interrupt. The disease can cause muscle tremors as well as slowed-down movement and facial expression. The findings may give insights into Parkinson’s disease, said Aron, a professor of psychology in the UC San Diego Division of Social Sciences, and Wessel, now an assistant professor of psychology and neurology at the University of Iowa. The researchers suggest that the same brain system that is involved in interrupting, or stopping, movement in our bodies also interrupts cognition – which, in the example of the phone ringing, derails your train of thought. Published in Nature Communications, the study comes from the lab of neuroscientist Adam Aron at the University of California San Diego, together with collaborators at Oxford University in the UK, and was led by first author Jan Wessel, while a post-doctoral scholar in the Aron Lab. Have you had the experience of being just on the verge of saying something when the phone rang? Did you then forget what it is you were going to say? A study of the brain’s electrical activity offers a new explanation of how that happens. The study analyzes signals from the scalp in healthy volunteers as well as signals from electrode implants in the brains of people with Parkinson’s disease. ![]()
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