The effects of abnormally high or low stress on learning are well established. The Barnes maze and Morris water maze are two commonly-used tests of spatial memory, of which the water maze is considered more stressful; however, until now this has not been demonstrated empirically. In the present study, mice matched for performance on commonly-used anxiety tasks were trained on either the Barnes maze or water maze or received no cognitive testing. Water-maze training induced greater increases in plasma corticosterone than did Barnes maze training, assessed 30 min. after the final session. Importantly, spatial learning was inversely correlated with corticosterone levels in the water maze but not the Barnes maze, suggesting that performance on the water maze may be more affected by test-induced stress even within wild-type subjects of the same age and gender. These findings are important when considering the appropriate cognitive tasks for any experiment in which stress responses may differ systematically across groups.
KeywordsAnxiety; stress; corticosterone; Barnes maze; Morris water maze; Elevated plus maze; Light-dark activity; social dominance; behaviour The Barnes maze [3] and Morris water maze [19] are similar tasks in that they both measure the ability of a mouse to learn and remember the location of a target zone using a configuration of distal visual cues located around the testing area [11,23]. Both tasks rely on hippocampaldependent spatial reference memory and on the inherent tendencies of the subjects to escape from an aversive environment [2,27]. It has been suggested that the Barnes maze is less anxiogenic [13,21]; however, we know of no data that support this assumption.Innate anxiety and cognitive ability differ considerably among mouse strains [5,13,18] highlighting the fact that the selection of a background strain and the choice of behavioural Corresponding author: Fiona Harrison, PhD, Vanderbilt University, Division of Diabetes, Endocrinology & Metabolism, 7465 Medical Research Building IV, 2213 Garland Avenue, Nashville, TN, 37232-0475, Fiona.Harrison@Vanderbilt.edu, Phone: 615-936-1660, FAX: 615-936-1667. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The subjects were thirty 7-week-old male, C57BL/6J mice obtained from Jackson Laboratory (Bar Harbor, ME, USA; stock #000664) and left undisturbed for 1 week before testing began. Mice were housed five per cage until 1 day before testing in the Barnes or water maze, when mice were singly housed to eliminate any additional stress that may arise from test order within the cage as other mice are r...