Amplitude and frequency feature extraction of neural activity in mouse ventrolateral striatum under different motivational states using fiber photometric system

In this paper, we focused on the motivation of mice and aimed to extract neural activity features of D2 medium spiny neurons (D2-MSNs) in the ventrolateral striatum of mice under different motivational states. Motivated behavior is defined as the activation of goal-directed behavior, and this enables actions such as ingestion, sleeping and reproduction, which are essential for living. In human society, motivation allows us to participate in society, improving our quality of life. Loss of motivation has been causing problems such as withdrawal from society. If the symptom is heavy, it can even threaten our lives, and treatment is necessary. The mechanisms which lead to loss of motivation are yet to be understood, and an effective treatment does not exist. To solve these problems, we decided to find features in the neural activity which affect motivation, because understanding the mechanism may contribute to the establishment of treatment. In the experiment, the neural activity was recorded using gene-encoded ratio metric calcium ion (Ca²⁺) indicator and by constructing a fiber photometric system, which enabled recording of neural activity at specific brain region for specific type of neurons. While the recording took place, mice performed food-incentive leverpressing tasks, which were used to define motivational states. The experimental results show that both the amplitude and frequency components of Ca²⁺ fluctuation have features which are good predictors of motivational states.