Fear conditioning enhances spontaneous AMPA receptor-mediated synaptic transmission in mouse hippocampal CA1 area.
AMPA receptor-mediated synaptic modifications in the amygdala have been reported to sustain cued fear conditioning. However, the hippocampal formation is also critically involved in fear learning. Therefore, we examined whether fear conditioning is also accompanied by changes in AMPA receptor-mediated synaptic transmission in the hippocampus. We focused on spontaneous miniature excitatory post-synaptic currents (mEPSCs). Young adult mice were trained using tone/footshock pairings and contextual/cued memories were tested 3-4 h and 1 day later. We found that the mEPSC frequency was significantly enhanced when recorded 3 h, but not 24 h, after fear conditioning training. Fear training induced a slight enhancement in the mEPSC amplitude at 3 h after training. The increased mEPSC frequency and amplitude were absent in animals that were only exposed to footshock or novelty or unpaired tone/footshock training. This implies that learning the association between context, tone and footshock transiently enhances hippocampal CA1 spontaneous synaptic transmission, which may contribute to the encoding of the fearful event.
Zhou
Ming
M
Swammerdam Institute for Life Sciences, Center for Neuroscience, Amsterdam, The Netherlands. m.zhou@uva.nl
Conboy
Lisa
L
Sandi
Carmen
C
Joëls
Marian
M
Krugers
Harm J
HJ
D000161:Acoustic Stimulation; D000818:Animals; D056547:CA1 Region, Hippocampal / Q000166:cytology / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D003463:Cues; D004597:Electroshock / Q000009:adverse effects; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D005239:Fear; D005786:Gene Expression Regulation / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018091:Receptors, AMPA / Q000235:genetics / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D018091:Receptors, AMPA