Mapping and Deciphering Neural Codes of NMDA Receptor-Dependent Fear Memory Engrams in the Hippocampus
(A) Spike rasters of simultaneously recorded 243 CA1 units from a control mouse in response to the conditioned tone and foot-shock during training. (B) A representative unit only responded to CS during learning. (C) A representative unit responded only to CS-paired foot shock during learning. (D) A representative unit responded to both CS and tone-paired US, but not to CS during recall. (E) A representative unit responded to CS and US during pairing as well as to recall tone. Within each panel, upper subplot is peri-event raster; each short vertical tick presents a spike. Spike activities are aligned at the time when stimuli were delivered. Lower subplot shows histogram calculated with 100 msec temporal windows.