Atropine-induced, state-dependent learning for spatial information, but not for visual cues.

This study investigates state-dependent learning employing atropine. The reaction of rats to (1) the presentation of novel stimuli, (2) habituation to intermittent presentations of the same stimulus at the same local, (3) spatial change at the site of stimulus presentation, and (4) a visual stimulus change, was investigated in the straight alleyway test, controlling for the possible development of behavioral and/or pharmacological tolerance. Our findings reveal that rats habituated to stimulus presentation at a specific location, when under an atropine effect, do react to stimulus presentation at another location, or to a different stimulus, when under an atropine effect, indicating that this drug does not interfere with the acquisition of spatial or visual information. Differently, however, rats habituated to stimulus presentation at a specific location in the absence of an atropine effect are unable to react to spatial change when under the atropine effect, but do react to a visual stimulus change. This suggests that atropine interferes either with the retrieval of previously acquired spatial information or with the comparison of previously acquired spatial information with current information, but does not interfere with visual recognition. These findings reveal that atropine interferes with the use of spatial information acquired in the absence of a drug effect.