Fig. 7.

Postsynaptic expression of HCN1 channels within dendritic spines in ERC layer II. (A–F) HCN1 channels were visualized with immunoperoxidase immunolabeling in perisynaptic and extrasynaptic portions of the plasmalemma adjacent to excitatory synapses within dendritic spines in ERC layer II. HCN1 channels were seen in close proximity to the SER spine apparatus (pseudocolored pink) (A, B, C, E, F). HCN1 channels were also observed in spine necks, especially in the narrow “bottleneck” (A, E). All dendritic spines receive axospinous Type I asymmetric glutamatergic-like synapses; synapses are between black arrows. Color-coded arrowheads point to HCN1 (red) immunoreactivity. Profiles are pseudocolored for clarity. Ax, axon; Sp, dendritic spine; Mit, mitochondria. Scale bars, 200 nm.