Mapping and Deciphering Neural Codes of NMDA Receptor-Dependent Fear Memory Engrams in the Hippocampus
Figure 9
Activated ensemble CA1 units encoding simple or associative traces during reverberations, and their contributions to real-time ensemble trajectories described in MDA encoding subspaces.
(A) Spike raster of 56 CS-responding units corresponding to a CS trace reverberation (left). This particular reverberated CS ensemble trace is shown in MDA plot prior to spike training shuffle (left MDA plot); selective degradation of this CS trace after shuffling of these units’ spikes (middle MDA plot), but not affected by shuffling of randomly selected 56 non-responsive units (right MDA plot). (B) Spike raster of 49 US responsive units corresponding to a US trace reverberation. This reverberated trace is shown in MDA plot prior to shuffle (left MDA plot); selective degradation of this US trace after shuffling of these units’ spikes (middle MDA plot), but not affected by shuffling of randomly selected 49 non-responsive units (right MDA plot). (C) Spike raster of 44 responsive units corresponding to a US-to-CS associative trace reverberation. This reverberated associative trace is shown in MDA plot prior to shuffle (left MDA plot); selective degradation of this trace after shuffling of these units’ spikes (middle MDA plot), but not affected by shuffling of randomly selected 44 non-responsive units (right MDA plot). (D) Spike raster of 43 responsive units corresponding to a CS-to-US associative trace reverberation. This reverberated trace is shown in MDA plot prior to shuffle (left MDA plot); selective degradation of this trace after shuffling of these units’ spikes (middle MDA plot), but not affected by shuffling of randomly selected 49 non-responsive units (right MDA plot). Arrows show the moving direction of the trajectories.