Fiddling with objects, tapping feet, and shifting while we are lost in thought are near universal behaviors for humans, but apparently not uniquely human. Not only have neuroscientists seen thinking mice fidgeting in a most human-like way, but they have also observed how active seemingly irrelevant areas of mouse brains become when confronted with an intellectual challenge. While it is all exceptionally cute, the imaging team warn it complicates attempts to observe thinking brains in action.
Dr Anne Churchland of Cold Spring Harbor Laboratory leads a lab devoted to wide-field imaging of neuron activity in mouse brains. "You can see activity in a big part of the brain all at the same time," she said in a statement. "We usually just measure neurons in one small part of the brain at a time, and don't usually get a whole big-picture view like this."
Churchland trained thirsty mice to grab handles to initiate trials and then lick one of two spouts in response to visual or auditory stimuli, receiving a water reward if they chose correctly. She expected neuro-imaging would reveal the parts of the brain that control handle grabbing and licking to be activated, along with those for higher-level processing. In Nature Neuroscience, Churchland and her colleagues report they saw much more widespread activity, for example patterns associated with movements of the hind limbs, twitching nose and whiskers, and even dilating pupils.
"We think of all these together as making up a movement landscape. We were always aware of a few of these movements, but the landscape is turning out to be much richer than we had realized," Churchland said.
Churchland is particularly interested in identifying these movements' purpose. At this stage, she and her colleagues are still not sure, but they are particularly interested in the idea all this movement actual helps decision-making. “Maybe the movements are part of the process of thinking and deciding," Churchland said.
If so, it has implications for human thought-processing as well. If movements of the body help people think, it’s possible that confining ourselves to chairs while we think is a particularly bad choice, limiting the range of movements we can make. The person who gets annoyed at you for clicking your pen or clucking your tongue may be undermining your chance of reaching the best conclusion.
Churchland notes people with attention deficit hyperactivity disorder (ADHD) fidget much more than others. Frequently they are disciplined and stigmatized for it. Yet they, and the mice, may be our best opportunities to understand why more subtle movements are important to almost everyone.
“Maybe [those with ADHD] need to move more because activating their cognitive machinery requires more movements compared to the average person,” Churchland said.
