Post-training intracranial self-stimulation facilitates a hippocampus-dependent task

• Published in: Behavioural brain research Vol. 160; no. 1; pp. 141 - 147
• Main Authors: Soriano-Mas, Carles, Redolar-Ripoll, Diego, Aldavert-Vera, Laura, Morgado-Bernal, Ignacio, Segura-Torres, Pilar
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 07.05.2005; Elsevier Science
• Subjects: Animal; Animals; Avoidance Learning - physiology; Avoidance Learning - radiation effects; Behavior, Animal - radiation effects; Biological and medical sciences; Delayed spatial alternation T-maze task; Electric Stimulation - methods; Explicit memory; Flexible expression of memory; Fundamental and applied biological sciences. Psychology; Hippocampus; Hippocampus - physiology; Hippocampus - radiation effects; Intracranial self-stimulation; Lateral hypothalamus; Learning. Memory; Male; Maze Learning - physiology; Maze Learning - radiation effects; Memory; Memory - physiology; Memory facilitation; Motor Activity - physiology; Practice (Psychology); Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Wistar; Retention (Psychology) - physiology; Retention (Psychology) - radiation effects; Self Stimulation; Space Perception - physiology; Space Perception - radiation effects; Stereotaxic Techniques; Time Factors; Memory facilitation; Delayed spatial alternation T-maze task; Lateral hypothalamus; Intracranial self-stimulation; Explicit memory; Flexible expression of memory; Hippocampus; Facilitation; Physical training; Rat; Rodentia; Central nervous system; Cognition; Encephalon; Vertebrata; Mammalia; Animal; Self stimulation
• ISSN: 0166-4328; 1872-7549
• DOI: 10.1016/j.bbr.2004.11.025

Previous research has shown that post-training intracranial self-stimulation facilitates implicit or procedural memory. To know whether it can also facilitate explicit memory, post-training intracranial self-stimulation was given to Wistar rats immediately after every daily session of a delayed spatial alternation task that seems to depend on the integrity of the hippocampal memory system. We tested the effects of intracranial self-stimulation in three consecutive learning phases which tried to make the task progressively more difficult: 10 s delay (D10 phase), 30 s delay (D30 phase), and inverting the starting position of the animals to make their response more dependent on allocentric cues (INV phase). Every phase finished when each rat achieved a fixed learning criterion. Intracranial self-stimulation facilitated the flexible expression of the learned response (INV phase). That is, when the starting position was randomly inverted, only the rats that received intracranial self-stimulation maintained the performance level acquired in the previous training phases. Changing the starting position reduced the correct performance of the non-treated subjects, which need more training sessions to achieve the learning criterion and made less correct responses than treated rats. These findings show that post-training intracranial self-stimulation can facilitate hippocampus-dependent memories.