Comparing rewarding and reinforcing properties between 'bath salt' 3,4-methylenedioxypyrovalerone (MDPV) and cocaine using ultrasonic vocalizations in rats. - Simmons, Steven J.; Gregg, Ryan A.; Tran, Fionya H.; Mo, Lili; von Weltin, Eva; Barker, David J.; Gentile, Taylor A.; Watterson, Lucas R.; Rawls, Scott M.; Muschamp, John W. (Addiction Biology, 2018)