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
Explicit memory Patient R.B. had bilateral lesions of the CA1 cell region along the whole length of the hippocampus. Adolph, Cahill and Schul completed a study showing that emotional arousal facilitates the encoding of material into long term declarative memory. They selected two subjects with bilateral damage to the amygdala, as well as six control subjects and six subjects with brain damage. All subjects were shown a series of twelve slides accompanied by a narrative. The slides varied in the degree to which they evoked emotion – slides 1 through 4 and slides 9 through 12 contain non-emotional content. Slides 5 through