When crossing the street, which way do you first turn your head to check for oncoming traffic? This decision depends on the context of where you are. A group of scientists has been studying how animals use context when making decisions. And now, their latest findings have tied this ability to an unexpected brain region in mice, previously thought to primarily guide and plan movement.
This discovery, published today in Neuron, lends new insight into the brain’s remarkable ability to make decisions. Flexible decision making is a critical tool for making sense of our surroundings; it allows us to have different reactions to the same information by taking context into account.
«Context-dependent decision-making is a building block of higher cognitive function in humans,» said neuroscientist Michael Shadlen, MD, PhD, the paper’s co-senior author with Richard Axel, MD. «Observing this process in a motor area of the mouse brain, as we did with today’s study, puts us a step closer to understanding cognitive function at the level of brain cells and circuits.»
«If someone is standing uncomfortably close to me on a deserted street, I may try to run away, but if the same event occurred on a crowded subway car, I would feel no such danger,» said neuroscientist and first author Zheng (Herbert) Wu, PhD. «My decision to move or not move is dependent on the context of where I am; thus giving a reason behind the choices I make.»
To investigate how the brain achieves this context-dependent flexibility, the team surveyed several brain areas dedicated to processing and integrating sensory information, but found the critical area to be a part of the motor cortex called the ALM. Previous experiments suggested that the ALM has a relatively simple job: It guides movements of a mouse’s tongue and facial muscles.
Building on this understanding, the researchers designed a new experiment that required mice to make flexible decisions using their tongues and their olfactory system, which guides their sense of smell. In the experiment, a mouse first encountered a single odor. The mouse had to remember this odor, because after a brief pause, the researchers then puffed a second odor over the nostrils of the mouse. If both odors were the same, the mouse had to lick a tube to the left to get water. If the two odors were different, it had to lick a tube to the right.
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Materials provided by The Zuckerman Institute at Columbia University. Note: Content may be edited for style and length.