Spatial learning strategies in the goldfish (Carassius auratus)

Abstract

Mammals and birds can use different spatial navigation strategies subserved by distinct learning and memory systems. A range of evidence suggests that, when animals are trained in a test environment where they can simultaneously rely on the spatial relationships among distal landmarks (place strategy) and on a single conspicuos local visual cue (cue strategy) to find a goal, they learn both place and cue strategies to solve the task. However, despite the importance of comparative studies for understanding the structure and function of spatial learning and memory systems in vertebrates, only a few studies have investigated spatial learning mechanisms in other vertebrate groups, such as fish. This experiment was designed to study the spatial strategies used by goldfish to find a goal in a plus maze. Goldfish were trained to find food in an arm placed in a constant room location and simultaneusly signaled by a single local visual cue (mixed place-cue procedure). Later probe trials were performed in order to to examine the relative importance of these sources of information and reveal learning and memory strategies used by the animals to solve the maze task. In these probe trials, either the two sources of information were dissociated in such a way that the goldfish needed to choose between place or guidance responses, or intramaze proximal cues or the extramaze distal landmarks were individually removed. The results suggest that fish, like mammals and birds, are able to solve a maze task using a place strategy ora guidance Strategy, and that these animals can switch from one strategy to another choosing and correctly performing the more adecuate of the two in each situation.