Exposure to novelty enhances retrieval of very remote memory in rats.
Rats were trained in a one-trial step-down inhibitory avoidance task at the age of 3 months and tested for retention 1 day later, or 3, 6, 9, 12, 15, and 19 months later, i.e., when the animals were 3, 6, 9, 12, 15, 18, or 22 months of age. Retrieval performance declined with time and was undetectable in the last two age groups. Exposure to an unrelated novel environment (a square box lined with black plastic) 1 h before retention testing enhanced retrieval at all ages, regardless of the decline in the level of test session performance. The effect cannot be explained by an anxiogenic effect of the novelty box, or by an influence of novelty on locomotion or exploration, or by a nonspecific influence of exposure to novelty on step-down latency in the inhibitory avoidance apparatus.
Izquierdo
Luciana A
LA
Departamento de Bioquímica, Centro de Memória, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, 90035-003 Porto Alegre, RS, Brazil. izquier@terra.com.br
Barros
Daniela M
DM
Medina
Jorge H
JH
Izquierdo
Ivan
I
D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D001522:Behavior, Animal; D005106:Exploratory Behavior / Q000502:physiology*; D008124:Locomotion / Q000502:physiology; D008297:Male; D008568:Memory / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012153:Retention, Psychology / Q000502:physiology; D013997:Time Factors