Glutamate receptor antagonist infusions into the basolateral and medial amygdala reveal differential contributions to olfactory vs. context fear conditioning and expression.
The basolateral amygdala's involvement in fear acquisition and expression to visual and auditory stimuli is well known. The involvement of the basolateral and other amygdala areas in fear acquisition and expression to stimuli of other modalities is less certain. We evaluated the contribution of the basolateral and medial amygdala to olfactory and to context fear and fear conditioning by infusing into these areas the NMDA receptor antagonist AP5, the AMPA/kainate receptor antagonist NBQX, or vehicle prior to either odor-shock pairings or fear-potentiated startle testing. Pre-training AP5 infusions into the basolateral amygdala disrupted fear conditioning to the odor but not the context conditioned stimulus (CS). Pre-test NBQX infusions disrupted fear-potentiated startle to the odor but not context CS. Neither compound blocked fear conditioning when infused into the medial amygdala prior to training, but pre-test NBQX infusions did block fear-potentiated startle. The results confirm and extend recent findings suggesting a role for the basolateral amygdala in olfactory fear and fear conditioning, reveal an unexpected dissociation of the basolateral amygdala's involvement in discrete cue versus context fear and fear conditioning, and implicate for the first time the medial amygdala in fear-potentiated startle.
Walker
David L
DL
Emory University School of Medicine, Department of Psychiatry and Behavioral Sciences, Atlanta, Georgia 30329, USA. dlwalke@emory.edu
Paschall
Gayla Y
GY
Davis
Michael
M
D015763:2-Amino-5-phosphonovalerate / Q000008:administration & dosage; D000679:Amygdala / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001245:Association Learning / Q000187:drug effects / Q000502:physiology*; D003214:Conditioning, Classical / Q000187:drug effects / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage; D005239:Fear / Q000187:drug effects / Q000502:physiology; D008297:Male; D008845:Microinjections; D051381:Rats; D017207:Rats, Sprague-Dawley; D017470:Receptors, Glutamate / Q000187:drug effects / Q000378:metabolism*; D013216:Reflex, Startle / Q000187:drug effects / Q000502:physiology*; D012903:Smell / Q000187:drug effects / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D017470:Receptors, Glutamate; D015763:2-Amino-5-phosphonovalerate