Hippocampus anatomy These limbic structures include the hippocampus, cingulate cortex, olfactory cortex, and amygdala. Paul MacLean once suggested, as part of his triune brain theory, that the limbic structures constitute the neural basis of emotion. While most neuroscientists no longer believe in the concept of a unified "limbic system", these regions are highly interconnected and do interact with one another. Starting at the dentate gyrus and working inward along the S-curve of the hippocampus means traversing a series of narrow zones. The first of these, the dentate gyrus (DG), is actually a separate structure, a tightly packed layer of small granule cells
Long-term potentiation is an atypical isoform of PKC that lacks a regulatory subunit and thus remains constitutively active. Unlike other kinases that mediate LTP, PKMζ is active not just in the first 30 minutes following LTP induction; rather, PKMζ becomes a requirement for LTP maintenance only during the late phase of LTP. PKMζ thus appears important for the persistence of memory and would be expected to be important in the maintenance of long-term memory. Indeed, administration of a PKMζ inhibitor into the hippocampus of the rat results in retrograde amnesia with intact short-term memory; PKMζ does not play a role in the