Variables affecting long-term memory of learning that a food is inedible in Aplysia..

Abstract

Long-term memory of learning that a food is inedible was studied in Aplysia. Seven days after a single training session, animals retained significant memory, as measured by a number of parameters. A 2nd experiment demonstrated savings 3 weeks after 2 training sessions. Long-term memory was also found after training procedures were altered to resemble those more likely to occur in nature, such as training for only 10 min or training with ad-lib access to inedible food, with no experimenter intervention. The effects were determined of bilaterally sectioning the esophageal nerves that innervate the gut. Denervation of the gut blocked the ability to learn that food is inedible but did not affect memory after the task had already been learned.

Cognition in Invertebrates

“…Susswein and colleagues have developed another promising composite paradigm using Aplysia feeding behavior (Susswein and Schwarz, 1983;Schwarz and Susswein, 1984, 1992Susswein et al, 1986;Schwarz et al, 1991;Chiel and Susswein, 1993;Botzer et al, 1998;Katzoff et al, 2002). Food touching the lips of Aplysia initiates biting, which causes food to enter the mouth.…”

Nitric oxide and histamine signal attempts to swallow: A component of learning that food is inedible inAplysia

“…During the learning, animals gradually stop responding to the food. Animals then remember that a food is edible or inedible for minutes to days Schwarz et al 1991;Botzer et al 1998). Learning with inedible food is dependent on the presence of background stimuli that maintain the arousal state of the animals, such as pheromones secreted by conspecifics or egg cordons in A. fasciata (Schwarz et al 1988(Schwarz et al , 1991.…”

“…When animals are maintained in isolation, preventing them from sensing pheromones released by conspecifics, the training is ineffective in causing long-term memory (Schwarz et al 1991). However, pre-arousing animals with food can restore the ability to learn in isolated animals (Schwarz and Susswein 1993).…”

“…Memory was shown in a test session that was identical to the initial training session Susswein et al 1986;Schwarz et al 1988Schwarz et al , 1991Botzer et al 1998). Memory was displayed by a decreased responsiveness during the first 5 min of the test session, with respect to the start of the original training session, and by a reduction from the training to the test session in the time to the criterion to stop the experiment Chiel and Susswein 1993;Botzer et al 1998).…”

“…Additional operant-like training paradigms also affect Aplysia feeding Susswein et al 1986;Schwarz et al 1988Schwarz et al , 1991Chiel and Susswein 1993;Botzer et al 1998;Katzoff et al 2002Katzoff et al , 2006Cohen-Armon et al 2004;Lyons et al 2005). In these paradigms Aplysia are exposed to a palatable food that is difficult or impossible to consume.…”