Dissociated theta phase synchronization in amygdalo- hippocampal circuits during various stages of fear memory.
The amygdala and the hippocampus are critically involved in the formation and retention of fear memories. However, their precise contribution to, and their interplay during, fear memory formation are not fully understood. In the present study we investigated network activities in the amygdalo-hippocampal system of freely behaving mice at different stages of fear memory consolidation and retention. Our data show enhanced theta phase synchronization in this pathway during the retrieval of fear memory at long-term (24 h post-training), but not short-term (2 min, 30 min and 2 h post-training) stages, following both contextual and auditory cued conditioning. However, retrieval of remotely conditioned fear (30 days post-training) failed to induce an increase in synchronization despite there still being memory retention. Thus, our data indicate that the amygdalo-hippocampal interaction reflects a dynamic interaction of ensemble activities related to various stages of fear memory consolidation and/or retention, and support the notion that recent and remote memories are organized through different network principles.
Narayanan
Rajeevan T
RT
Institut für Physiologie I, Westfälische Wilhelms-Universität Münster, Robert-Koch-Str 27a, Münster, Germany.
Seidenbecher
Thomas
T
Kluge
Christian
C
Bergado
Jorge
J
Stork
Oliver
O
Pape
Hans-Christian
HC
D000679:Amygdala / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D001362:Avoidance Learning; D001522:Behavior, Animal; D003214:Conditioning, Classical / Q000502:physiology; D005239:Fear; D046352:Freezing Reaction, Cataleptic; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009434:Neural Pathways / Q000502:physiology*; D013826:Theta Rhythm; D013997:Time Factors