Brain cells deep in the skull steer reward decisions
A small brain region targeted in Parkinson’s treatment also plays a key role in how decisions are shaped by reward. A new study maps, for the first time, how distinct cell groups within it divide up that job.
The subthalamic nucleus is a small structure deep in the brain, part of the basal ganglia: a network involved in movement control and impulse regulation. It is a key target for deep brain stimulation in Parkinson’s disease. Its role in decision-making, however, has been less well understood.
Three cell groups, three functions
The study, published in eLife, had monkeys perform tasks requiring both sensory judgement and reward-based reasoning. Three distinct subpopulations of neurons in the subthalamic nucleus each played a different role: one was linked to forming the decision variable (the internal signal that tips a choice one way), another to adjusting the decision threshold, and a third to processes unrelated to the decision itself. Many cells also tracked outcomes, registering whether a choice was correct and what reward was expected.
This level of internal division of labour within the subthalamic nucleus during complex decisions had not previously been mapped in this detail.
Why this matters for aging and cognitive decline
The basal ganglia are vulnerable in aging and in neurodegenerative conditions including Parkinson’s disease and dementia. Understanding how these regions control decision-making helps clarify what goes wrong in cognitive decline at older ages. The study was conducted in monkeys and the findings are preliminary. Whether and how they translate to human clinical applications remains to be established.
Search terms for further research: subthalamic nucleus decision-making neurons, basal ganglia aging cognition, deep brain stimulation Parkinson mechanism