Humans are creatures of habit. When we wake up, eat, exercise, and sleep at the same times every day, our bodies flourish. Break your daily habits, and it can throw off your internal mechanisms (metabolism, endocrine system, immune system). Some of your habits are great, such as your habit of washing your hands or eating veggies. Other habits are less so, such as the habit of snacking at the wrong times or making poor food choices.
According to new research out of Duke University Medical Center, there is one “master cell” responsible for controlling all your habits. The cell, known as the “fast-spiking interneuron” (or FSI), served as “master conductor of the widespread changes in outgoing neuron activity.”
The researchers trained mice to press a lever in exchange for receiving a tasty treat. The mice developed the habit of pressing the lever, a habit that continued even when no treat was dispensed. Even if they had a chance to eat all the treats they wanted beforehand, they still pressed that lever out of habit.
They then compared the brain activity of these lever-pressing mice to mice without the habit. Their focus was on the striatum, the part of the brain that sends stop and go signals throughout the neural pathways. The habit-driven mice had stronger pathways (both stop and go), and the go pathway always fired before the stop. The fast-spiking interneurons in the habit-driven mice’s brains tended to be more excitable.
When the mice were given a drug that reduced FSI activity, their brains reverted to pre-habit brain activity, with a balance between the stop and go neural pathways.
FSIs are one of the neurons responsible for transmitting messages between the neurons in specific brain regions. They’re fairly rare—just 1% of the cells in the striatum—they grow “long branch-like tendrils” that connect them to the 95% of neurons that trigger these two neural pathways. As the research indicated, this cell is “driving the changes” in the striatum’s neurons, making it the “master cell” that controls your habits.
According to the researchers, “Some harmful behaviors like compulsion and addiction in humans might involve corruption of the normally adaptive habit-learning mechanisms. Understanding the neurological mechanisms underlying our habits may inspire new ways to treat these conditions.”
1. Justin K. O’Hare, Haofang Li, Namsoo Kim, Erin Gaidis, Kristen Ade, Jeff Beck, Henry Yin and Nicole Calakos. “Striatal fast-spiking interneurons selectively modulate circuit output and are required for habitual behavior,” eLife, Sept. 5, 2017. DOI:#10.7554/eLife.26231.