The Subicular Complex

Hippocampal intrinsic afferents to the subiculum originate from other hippocampal regions. The CAl neurons send a dense projection to the subiculum and the CAS pyramidal cells project to all parts of the subicular complex through the Schaffer collateral pathway (Swanson et al., 1978). The extrahippocampal projections to the subiculum mainly originate from the raphe nuclei (Conrad et al., 1974), locus coeruleus... 

In the primate hippocampus the D5 receptor was found to be frequently coexpressed with the Di receptor in pyramidal neurons. However, while the Di receptor is prominent in dendrites and dendritic spines, the D5 receptor is mostly localized in the dendritic shaft (Bergson et al., 1995b). In the human brain, D5 mRNA is present in the hippocampus and subicular complex. 

The clue to this transition seems to be found in the sense of olfaction. Early in the course of AD, degeneration occurs in the entorhinal cortex-hippocampal-subicular complex (Price and Morris, 1999). The olfactory bulb, particularly the anterior olfactory nucleus, shows numerous neurofibrillary tangles (NFTs). Odor identification deficits during life may be associated with NFTs in the hippocampus (Wilson et al., 2007). 

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