Novelty-Induced Arousal Enhances Memory for Cued Classical Fear Conditioning: Interactions between Peripheral Adrenergic and Brainstem Glutamatergic Systems

Autor/inn/en	King, Stanley O., II; Williams, Cedric L.
Titel	Novelty-Induced Arousal Enhances Memory for Cued Classical Fear Conditioning: Interactions between Peripheral Adrenergic and Brainstem Glutamatergic Systems
Quelle	In: Learning & Memory, 16 (2009) 10, S.625-634 (10 Seiten) PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	1072-0502
DOI	10.1101/lm.1513109
Schlagwörter	Animals; Stimuli; Classical Conditioning; Memory; Brain; Fear; Time Factors (Learning); Drug Use; Habituation; Motion + Suchen Sie Ihr Suchwort? Animal; Tier; Tiere; Anreizsystem; Gedächtnis; Gehirn; Furcht; Drug consumption; Substance abuse; Drogenkonsum; Bewegungsablauf
Abstract	Exposure to novel contexts produce heightened states of arousal and biochemical changes in the brain to consolidate memory. However, processes permitting simple exposure to unfamiliar contexts to elevate sympathetic output and to improve memory are poorly understood. This shortcoming was addressed by examining how novelty-induced changes in peripheral and/or central arousal modulates memory for Pavlovian fear conditioning. Male rats were either exposed to the conditioning chamber for 5-min or given no exposure 24 h before conditioning with five tone-shock (0.35 mA) pairings. Retention was assessed 48 h later in a different context. Non-pre-exposed animals exhibited significantly greater freezing during conditioned stimulus (CS) presentations than did pre-exposed animals (P less than 0.05). The improvement in retention produced by novelty was attenuated by pretraining a blockade of peripheral beta-adrenergic receptors with sotalol (6 mg/kg, i.p.). Study 2 revealed that novelty-induced increases in peripheral autonomic output are conveyed to the brain by visceral afferents that synapse upon brainstem neurons in the nucleus tractus solitarius (NTS). Blocking AMPA receptor activity in the NTS with CNQX (1.0 micrograms) significantly reduced freezing to the CS in non-pre-exposed animals (P less than 0.01). Study 3 showed that elevating epinephrine levels in habituated animals influences learning through mechanisms similar to those produced by novelty-induced arousal. Pre-exposed animals given epinephrine (0.1 mg/kg) froze significantly more than saline controls (P less than 0.01), and this effect was attenuated by intra-NTS infusion of CNQX. The findings demonstrate that novelty-induced arousal or increasing sympathetic activity with epinephrine in pre-exposed animals enhances memory through adrenergic mechanisms initiated in the periphery and transmitted centrally via the vagus/NTS complex. (As Provided).
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Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2017/4/10