This study examined whether saline acts as an aversive stimulus for planarians and how it influences learning and memory. Using saline as an unconditioned stimulus, we first tested conditioned place avoidance. Saline did not support conditioned place avoidance acquisition; instead, it disrupted habituation to initially preferred tactile and visual stimuli. Further experiments assessed the establishment of conditioned place preference using food as the reinforcer with visual cues. Following training, exposure to saline impaired the expression of conditioned place preference for both light and dark contexts, indicating that the disruptive effect of exposure to saline extends beyond habituation. These findings suggest that saline interferes with the expression of learned behaviors through state-dependent retrieval failure caused by physiological changes induced by saline exposure. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Tazumi et al. (Mon,) studied this question.