The role of motivation in the performance of conditioned reflex switching of a maze skill in response to substitution of food reward quality in ants of the species Myrmica rubra

Abstract

The characteristics of learning in ants - active Myrmica rubra foragers - were studied in a maze at different levels of colony carbohydrate food need with reinforcement consisting of carbohydrate (sugar syrup) or protein (pupae of Lasius niger ants). Measures of the maze skill during learning reinforced with syrup were somewhat worse than those during learning reinforced with pupae, especially in terms of time-based measures. Ants were able to modify the acquired conditioned reflex reaction when the quality of reinforcement changed. At high levels of food need (" hungry" colony), substitution of syrup with larvae and vice versa was followed by transformation of the previously formed skill; this occurred at both experimental periods (training and testing). At low levels of motivation ("sated colony"), the optimized maze habit formed with protein reinforcement was replaced in the test with carbohydrate reinforcement by a "stochastic," unoptimized behavior with a dominance of investigative activity. These experiments demonstrated that conditioned reflex switching can occur in higher social insects - ants - in which the different forms depend on the level of colony need for food and, respectively, on the level of social food-related motivation of forager ants. The special importance of using the switch activating the corresponding motivational system before changing the reinforcement food quality is emphasized.