Effects of beta-amyloid (25-35) on learning in the common snail.

The effects of neurotoxic beta-amyloid fragment (25-35) on the formation of behavioral sensitization and a conditioned defensive reflex to food were studied. Administration of beta-amyloid (25-35) to common snails before the start of training led to a significant reduction in sensitization of the defensive reaction, weakening of the formation of the conditioned defensive reflex to food, and impairment of memory. These impairments to behavioral plasticity may be mediated by changes in synaptic plasticity previously observed in the presence of beta-amyloid.