Search

Summary: Innate defensive responses, unlearned behaviors improving individuals’ chances of survival, have been found to involve the dopamine (DA) system. In the superior colliculus (SC), known for its role in defensive behaviors to visual threats, neurons expressing dopaminergic receptors of type 1 (Drd1+) and of type 2 (Drd2+) have been identified. We hypothesized that SC neurons expressing dopaminergic receptors may play a role in promoting innate defensive responses. Optogenetic activation of SC Drd2+ neurons, but not Drd1+ neurons, triggered defensive behaviors. Chemogenetic inhibition of SC Drd2+ neurons decreased looming-induced defensive behaviors, as well as pretreatment with the pharmacological Drd2+ agonist quinpirole, suggesting an essential role of Drd2 receptors in the regulation of innate defensive behavior. Input and output viral tracing revealed SC Drd2+ neurons mainly receive moderate inputs from the locus coeruleus (LC). Our results suggest a sophisticated regulatory role of DA and its receptor system in innate defensive behavior.

The driving ranges of electric vehicles (EVs) will decrease greatly with increased use of the vehicle heating system in a cold climate. Air conditioning heat pump (ACHP) systems, which convert energy stored in the ambient environment into heat, represent a promising approach for increasing the EV driving range. In this work, the performance of an ACHP system in an EV under extremely cold conditions is investigated experimentally. The requirements of an ACHP system for EVs at various ambient temperatures are determined using our capacity matching strategy. A prototype system designed based on these requirements is evaluated. Data collected from experiments performed at a full-scale facility under extreme temperature conditions are analyzed. The results show that the ACHP system proposed for EV applications can satisfy both the cooling and heating requirements for the passenger compartment. The system increased the driving range by 23% when compared with that of an EV using a positive-temperature-coefficient (PTC) heater at −10 °C.