title: Post-training re-exposure to fear conditioned stimuli enhances memory consolidation and biases rats toward the use of dorsolateral striatum-dependent response learning.
abstract: In a dual-solution task that can be acquired using either hippocampus-dependent "place" or dorsolateral striatum-dependent "response" learning, emotional arousal induced by unconditioned stimuli (e.g. anxiogenic drug injections or predator odor exposure) biases rats toward response learning. In the present experiments emotionally-arousing conditioned stimuli were used to modulate the relative use of multiple memory systems. In Experiment 1, adult male Long-Evans rats initially received three standard fear-conditioning trials in which a tone (2 kHz, 75 dB) was paired with a brief electrical shock (1 mA, 2s). On day 2, the rats were trained in a dual-solution plus-maze task to swim from the same start arm (South) to a hidden escape platform always located in the same goal arm (East). Immediately following training, rats received post-training re-exposure to the fear-conditioned stimuli (i.e. tone and context) without shock. On day 3, the relative use of place or response learning was assessed on a probe trial in which rats were started from the opposite start arm (North). Post-training re-exposure to fear-conditioned stimuli produced preferential use of a response strategy. In Experiment 2, different rats received fear conditioning and were then trained in a single-solution task that required the use of response learning. Immediately following training, rats received post-training re-exposure to the fear-conditioned stimuli without shock. Re-exposure to fear-conditioned stimuli enhanced memory consolidation in the response learning task. Thus, re-exposure to fear-conditioned stimuli biases rats toward the use of dorsolateral striatum-dependent response learning and enhances memory consolidation of response learning.
authors.affiliation: Department of Psychology & Institute for Neuroscience, Texas A&M University, College Station, TX 77843-4235, United States.
authors.forename: Kah-Chung
authors.initials: KC
authors.lastname: Leong
authors.affiliation: Department of Psychology & Institute for Neuroscience, Texas A&M University, College Station, TX 77843-4235, United States.
authors.forename: Jarid
authors.initials: J
authors.lastname: Goodman
authors.affiliation: Department of Psychology & Institute for Neuroscience, Texas A&M University, College Station, TX 77843-4235, United States. Electronic address: markpackard@tamu.edu.
authors.forename: Mark G
authors.initials: MG
authors.lastname: Packard
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001307:Auditory Perception / Q000502:physiology; D003213:Conditioning, Psychological; D003342:Corpus Striatum / Q000502:physiology; D004597:Electroshock; D005239:Fear / Q000502:physiology; D006624:Hippocampus / Q000502:physiology; D008297:Male; D018782:Maze Learning / Q000502:physiology; D000069077:Memory Consolidation / Q000502:physiology; D011581:Psychological Tests; D020318:Rats, Long-Evans; D013550:Swimming
keywords: Anxiety; Fear; Hippocampus; Memory; Stress; Striatum