Densities and 3D distribution of synapses using FIB/SEM imaging in the mouse hippocampus and neocortex

Synapses have been identified, segmented and quantified in the adult mouse hippocampus and neocortex using 3D electron microscopy (FIB-SEM). Three animals have been used for the hippocampus (ID2, ID4 and ID28) and three animals for the neocortex (ID5, ID24 and ID25). In the hippocampus we have studied three layers in the CA1 area (stratum oriens, stratum radiatum and stratum lacunosum-moleculare). In the neocortex we have studied the following layers of the somatosensory cortex (S1HL): L1, L2, L3, L4, L5a, L5b and L6. Data obtained include the total densities of synapses, the number of excitatory (asymmetric) and inhibitory (symmetric) synapses, their sizes (measured as the Feret’s diameter and synaptic apposition surfaces) and their spatial distribution.