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Recently, the laboratory of Sami El-Boustani, an assistant professor at the University of Geneva, has studied the role played by motivation in perception (感知) and decision-making. “We wanted to observe how sensory information sent by cortical neurons (大脑皮层神经元) is changed by the degree of motivation and to what extent the latter can have an effect on learning and performance in a decision-making task,” explains Sami El-Boustani.

The research team developed a behavioral pattern involving mice in a controlled water consumption condition. Researchers first trained these mice to respond to the stimulation of two whiskers (鼠须) (A and B) and to produce an action — licking a spout (舔壶嘴)— only for whisker A in order to obtain a drop of water. Following this training, these mice reacted mainly to the stimulation of whisker A. Finally, the researchers conducted these experiments at decreasing levels of thirst in order to vary the motivation of the mice to participate in the task.

In a state of great thirst, mice licked the spout randomly with great motivation. In a state of medium thirst, the choice of their action became ideal. They mainly licked the spout when whisker A was stimulated. Finally, when they were not very thirsty, their performance in the task dropped again. By observing the activity of neuronal populations responsible for perceptual decision-making in these mice, researchers discovered that high-motivation leads to the strong stimulation of cortical neurons, which causes a loss of accuracy in the perception of the stimulation. In contrast, in the low-motivation state, the accuracy of the sensory information was recovered, but the strength of the signal was too low for it to be sent correctly.

These results reveal that the level of motivation does not only impact decision-making but also the perception of sensory information, which leads to the decision. Researchers observed that mice understood the rule very quickly but could only express this learning much later, depending on a changed perception linked to their level of motivation. The research on the role of motivation in learning opens the way to new adaptive methods that aim to maintain the best level of motivation during learning.