Role of different types of cortical projections neurons in value-based action selection

Abstract

Decision making with considering what or where is valuable is essential process to survive the world. Value-based decision making consists of two major steps of valuation and action selection. Previous study showed that advanced neural signals for action selection appear first in the secondary motor cortex among multiple regions in rats performing a dynamic foraging task. To further explore neural circuit process underlying value-based action selection, neural activity was investigated targeting two different types of projections neurons, namely intratelencephalic (IT) and pyramidal tract (PT) neurons, which project primarily to other cortical and subcortical structures, respectively, in the secondary motor cortex of mice performing a dynamic foraging task in head-fixed system. It was found that deep-layer IT and PT neurons exhibit the earlier advanced action selection signals than superficial-layer neurons. Deep-layer IT and PT neurons also convey chosen value and outcome signals, which would allow updating of value of the chosen target. However, value for contralateral-side is first signaled in deep-layer IT neurons preceding action selection. Unilateral activation of deep-layer IT neurons reduced the rate of selecting high-value contralateral side. These results suggest that deep-layer IT neurons of the secondary motor cortex may play a primary role in value-dependent action selection. These results also suggest different neural circuit processes underlying perceptual decision making, in which PT neurons are important for action selection, and value-based decision making.