Visual acuity in the water maze: sensitivity to muscarinic receptor blockade in rats and mice

A visual acuity task performed in the water maze in rats [Behav. Brain Res. 119 (2001) 77] was used to reveal the sensitivity of the visual system to muscarinic receptor blockade. Intraperitoneal injection of 0.2 mg/kg scopolamine had no effect, but 2 mg/kg severely compromised visual acuity, but did not affect the swim strategy to solve the task. Spatial learning in a reference memory version of the water maze, however, was impaired by 0.2 mg/kg scopolamine. It was also confirmed that the same visual acuity task is applicable to C57BL6/J mice. The visual deficit induced by 2 mg/kg scopolamine was less severe compared to rats, possibly due to a change in swim strategy in the drug condition. The effect of scopolamine on spatial reference memory in mice was not tested in this study. These data suggest that it may be possible to dissociate drug-induced effects on memory from changes in sensory perception. (C) 2003 Elsevier B.V. All rights reserved.