Noradrenaline involvement in the memory-enhancing effects of exposure to a complex rhythm stimulus following discriminated passive avoidance training in the young chick.
Previous research in our laboratory has demonstrated a significant memory-enhancing effect of exposure to a complex rhythm stimulus following weakly-reinforced passive avoidance learning in chicks. The aim of this study was to explore whether noradrenaline mediates this process. Chicks were trained on a strongly-reinforced single-trial passive avoidance task involving discrimination between two coloured beads. Intracerebral administration of the protein synthesis blocker, anisomycin, revealed that a phase of memory formation sensitive to arousal levels was extended by approximately 35 min following exposure to the complex rhythm stimulus. Administration of 2,4-dinitrophenol showed that this extension occurred during phase B of intermediate-term memory. Finally, a higher dose of the beta-adrenergic receptor antagonist, propranolol, was required to inhibit long-term memory in the presence of the auditory stimulus than in its absence. These findings suggest that the memory-enhancing effects of the complex rhythm stimulus may be mediated by noradrenaline, possibly via an increase in physiological arousal.
Toukhsati
S R
SR
Psychology Department, Monash University, Caulfield East 3145, Vic., Australia. samia.toukhsati@med.monash.edu.au
Rickard
N S
NS
Perini
E
E
Ng
K T
KT
Gibbs
M E
ME
D019297:2,4-Dinitrophenol / Q000494:pharmacology; D000161:Acoustic Stimulation; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D001143:Arousal / Q000187:drug effects / Q000502:physiology; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology*; D002645:Chickens; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology; D004193:Discrimination Learning / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology*; D046709:Pattern Recognition, Physiological / Q000502:physiology*; D010775:Photic Stimulation; D011433:Propranolol / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
D000319:Adrenergic beta-Antagonists; D011500:Protein Synthesis Inhibitors; D014475:Uncoupling Agents; D000841:Anisomycin; D011433:Propranolol; D019297:2,4-Dinitrophenol; D009638:Norepinephrine