Figure 7.

Results of olfactory learning manipulated by postsynaptic facilitation. A, As the postsynaptic facilitation mechanism was effective in both LN-PN and LN-LN, the trace of LFP and the rastergram of all PNs obtained from learning cycle 2 (left panel) and cycle 8 (right panel) are exhibited. It was noticed that, after experiencing several learning cycles, the firing activities became more synchronous across PNs (comparing cycle 8 with cycle 2 here). B, Corresponding to A, the level of synchronization across active PNs (PN 10-PN 28) was further evaluated by cross-covariance analysis. After several cycles of learning, the PNs' firing patterns became more synchronous indicated by larger values of maximum cross-covariance (top, red distribution) and overall shorter time lag to the main peak (bottom, red distribution). C, Changes of synaptic strength distribution during the first three cycles of learning of odor A in the model with postsynaptic facilitation in LN-PN and LN-LN. D, The total spike number in PNs along learning cycles modified by postsynaptic facilitation in LN-PN and LN-LN. Decrease of total spike number (mostly the first 3 or 4 cycles) was observed.