Anterior hippocampal continuation

Major connections of the main olfactory system. Axons of MOB mitral/tufted cells (circles in the EPL and MCL, respectively) project as the LOT to synapse in a number of structures collectively referred to as primary olfactory cortex (POC). Centrifugal inputs to MOB include feedback projections from POC as well as inputs from subcortical forebrain and brainstem neuromodulatory cell groups. Abbreviations AON, anterior olfactory nucleus DP, dorsal peduncular cortex Ent, entorhinal cortex IG-AHC, indusium griseum-anterior hippocampal continuation LC, locus coeruleus NDB, nucleus of the diagonal band PeCo, periamygdaloid cortex PC, piriform cortex RN, raphe nuclei (dorsal and median raphe) TT, taenia tecta Tu, olfactory tubercle... 

MOB projects to several structures of the ipsilateral hemisphere, including the superficial plexiform layer of the anterior olfactory nucleus, piriform, periamygdaloid and lateral entorhinal cortices, taenia tecta, the anterior hippocampal continuation, in-dusium griseum and the olfactory tubercle (Figs. 14, 18, 19). Collectively, the regions directly innervated by the output of the MOB have been referred to as primary olfactory cortex (De Olmos et al. 1978). Most of these projections have been reported in several species (for review, cf. Shipley and Adamek, 1984). A recent study has also shown a... 

The anterior hippocampal continuation (AHC) has been described in detail elsewhere (Wyss and Sripanidkulchai, 1983 Adamek et al. 1984). It is located just ventral to the rostrum of the corpus callosum and dorsal to the taenia tecta. The AHC has also been called ttj (Switzer et al. 1985) and has been described in detail in the rat (Wyss and Sripanidkulchai, 1983). The inputs to AHC are similar to IG as are its efferent connections with the outstanding difference that IG does not project to the olfactory bulb while there is a modest projection from AHC to the olfactory bulb (Wyss and Sripanidkulchai, 1983 Scheibel and Scheibel, 1978 De Olmos et al. 1978). Other major efferent projections of the IG and AHC are to the mammillary bodies and anterior thalamic nuclei. 

Fig. 11. (continued) and its mRNA are coincident. This suggests that 5-HT7 receptors are mainly expressed at the level of cell bodies and dendrites. Abbreviations AD anterodorsal thalamic nucleus AHi amygdalohippocampal area AV anteroventral thalamic nucleus CA3 CA3 hippocampal field GP globus pallidus PVA paraventricular thalamic nucleus, anterior part Re reuniens thalamic nucleus SN substantia nigra SuG superficial grey layer of the superior colliculus SuM supramammillary nucleus. Scale bar 3 mm. 

In seven patients in whom stimulation sites were located within the hippocampal formation and gyrus, there was an evident antiepileptic response. Both CXP and secondary GTC seizures were abolished after 6 days of continuous stimulation and interictal EEG spikes were significantly reduced from days 4 to 11 of SAHCS. The most evident and fastest antiepileptic responses were found in five patients in whom the stimulation contacts were located at either the anterior pes hippocampus near the amygdala or at the anterior parahippocampal gyrus near the entorhinal cortex. Three patients did not respond, two of them when SAHCS was accidentally interrupted and the other patient when the stimulated contacts were located at the white matter lateral to the hippocampus. 

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