Four-day-old Vantress × Arbor Acre chicks were first trained to key-peck for heat reinforcement and then tested for passive avoidance learning following an intraperitoneal injection of atropine sulfate or saline. Chicks injected with 1.0 mg/kg of atropine responded more quickly than saline-injected chicks when their key-peck responses were punished with aversive wing-shocks. These findings, therefore, are consistent with the view that cholinergic mechanisms are involved in inhibitory behavior in the young domestic chick.
Behavioral and Neural Biology, Vol. 31, No. 4, April 1981, 471-475.