title: A field model of learning: 2. Long-term memory in the crab Chasmagnathus granulatus.
abstract: In the previous companion paper, the possibility of learning by Chasmagnathus in field conditions was demonstrated. Here, we study long-term memory inquiring to what extent an internal representation could be maintained in a complex environment. Two 45-min training sessions, each of 15 visual danger stimulus presentations with 3-min intertrials, were given at a 24-h interval. Throughout the first training session and during the first 22.5 min of re-training on day 2, crabs kept the same hiding response level but then, during the second phase of re-training, the re-emerging increased up to the point that 32% of surface crabs ignored the stimulus. Each session was followed by a 22.5-min testing without stimulation. At testing on day 2 after re-training, crabs showed a change in the usual exploring strategy. Results reveal long persistency in responding despite a rest interval of 24 h followed by a gradual decrease in response until it vanishes. The statistical analysis was performed by comparing performances at day 2 (Rescorla in Am Psychol 43:151-160, 1988) and then confirmed through comparisons between day 1 and day 2. However, it is not possible to identify separate and taxonomically well-defined learnings but rather a tangled collection of processes that influence each other blurring some of the diagnostic features of each learning.
authors.affiliation: Laboratorio de Neurobiología de la Memoria, Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IFIByNE-CONICET, Pabellón II, Ciudad Universitaria (C1428EHA), Buenos Aires, Argentina.
authors.forename: María del Valle
authors.initials: Mdel V
authors.lastname: Fathala
authors.forename: María Cecilia
authors.initials: MC
authors.lastname: Kunert
authors.forename: Héctor
authors.initials: H
authors.lastname: Maldonado
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D003386:Brachyura / Q000502:physiology*; D003213:Conditioning, Psychological / Q000502:physiology; D017753:Ecosystem; D004780:Environment, Controlled; D005010:Ethology / Q000379:methods*; D005106:Exploratory Behavior / Q000502:physiology; D007858:Learning / Q000502:physiology*; D008570:Memory, Short-Term / Q000502:physiology*; D023421:Models, Animal; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D013045:Species Specificity; D013663:Teaching; D013997:Time Factors