A single kind of neuron deep within the brain serves as a “master controller” of habits, new research in mice indicates.
Some habits are helpful, such as automatically washing your hands before a meal or driving the same route to work every day. They accomplish an important task while freeing up valuable brain space. But other habits—like eating a cookie every day after work—seem to stick around even when the outcomes aren’t so good.
Researchers found that habit formation boosts the activity of the influential nerve cell, and that shutting it down with a drug is enough to break habits in sugar-seeking mice. Though rare, this cell exerts its control through a web of connections to more populous cells that are known to drive habitual behavior.
From earlier research by the same team, and which set them on the path for that “master controller”:
The team trained otherwise healthy mice to receive a tasty treat every time they pressed a lever. Many mice developed a lever-pressing habit, continuing to press the lever even when it no longer dispensed treats, and despite having had an opportunity to eat all the treats they wanted beforehand.
The team then compared the brain activity of mice who had developed a lever-pressing habit with those who hadn’t. They focused on an area deep within the brain called the striatum, which contains two sets of neural pathways: a “go” pathway, which incites an action, and a “stop” pathway, which inhibits action.
They found that both the go and stop pathways were stronger in habit-driven mice. Habit formation also shifted the relative timing of the two pathways, making the go pathway fire before the stop.
The reason so many behavioral traits are heritable is because they are strongly influenced by our physical nature, and our physical nature, in turn, is heritable.