Simulation of the maternal odor preference's learning and exposure to the conditioned maternal odor in P5–P8 aPC pyramidal cells. (A) Protocol for classical conditioning of maternal odor preference in the nest. A delayed pairing procedure was used in which the CS (maternal odor) onset preceded the UCS (maternal care, NE action) by 2 sec. CS and UCS overlapped for 1 sec, after which the CS was terminated. The CS–UCS pairing was presented seven times with 1 sec intervals. Learning was tested by the presentation of CS during 3 sec. After the test, CS alone was presented again during 10 sec. After a 2-sec interval learning was tested again by the presentation of CS during 3 sec. During this period, the pyramidal cells of the aPC had properties compatible with the P5–P8 age. (B) Number of cumulative aPC pyramidal cell spikes during the CS–UCS pairing and CS presentation, collected at every 100 msec of simulation. (C) Number of active aPC pyramidal cells during the CS–UCS pairing and CS presentation, collected at every 100 msec of simulation. (D) Synaptic weight gain of Pyr–Pyr (black curve) and Mt–Pyr (blue curve) synapses during CS–UCS pairing and CS presentation. Excitatory mitral inputs fire at the respiratory rhythm (2 Hz). Bin 0.5 msec.
