Enhanced generalization of auditory conditioned fear in juvenile mice.
Increased emotionality is a characteristic of human adolescence, but its animal models are limited. Here we report that generalization of auditory conditioned fear between a conditional stimulus (CS+) and a novel auditory stimulus is stronger in 4-5-wk-old mice (juveniles) than in their 9-10-wk-old counterparts (adults), whereas nonassociative sensitization induced by foot shock (US) and the ability to discriminate CS+ from an explicitly unpaired stimulus (CS-) are not dependent on age. These results suggest that aversive associations are less precise in juvenile mice and can more easily produce conditional responses to stimuli different from CS+. Yet, through the explicit unpairing of CS- from US during training, juveniles are able to overcome this greater fear generalization and learn that CS- is not associated with foot shock.
Ito
Wataru
W
Unit on Behavioral Genetics, Laboratory of Molecular Pathophysiology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA.
Pan
Bing-Xing
BX
Yang
Chao
C
Thakur
Siddarth
S
Morozov
Alexei
A
D000161:Acoustic Stimulation; D000367:Age Factors; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology; D001522:Behavior, Animal; D003214:Conditioning, Classical / Q000502:physiology*; D003463:Cues; D004597:Electroshock / Q000009:adverse effects; D005239:Fear; D046352:Freezing Reaction, Cataleptic; D005793:Generalization, Psychological / Q000502:physiology*; D008297:Male; D051379:Mice; D017288:Pain Threshold / Q000502:physiology; D011930:Reaction Time