Hippocampal formation

The hippocampal formation includes DG, the hippocampus proper including CA1 -CA4 sectors (Lorente de No 1934) and the subiculum (van Hoesen 1982). Based on previous publications on postischemic cell proliferation in the rodent brain (e.g., Liu et al. 1998 Nakatomi et al. 2002), at first we focused our attention on DG and hippocampus proper. 

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The hippocampus, which got its name from the Greek word for seahorse, due to its form, is a nucleus in the depth of the temporal lobe. The hippocampus is important for the integration of sensory information, for spatial orientation and for memory formation. The hippocampal formation contains the CA (cornu ammonis) regions, the dentate gyms and the subiculum. 

Sa Ml, Madeira MD, Ruela C, Volk B, Mota-Miranda A, Paula-Barbosa MM (2004) Dendritic changes in the hippocampal formation of AIDS patients a quantitative Golgi study. Acta Neuropathol 107(2) 97-110... 

Isaacson LG, Taylor DH. 1989. Maternal exposure to 1,1,2-trichloroethylene affects myelin in the hippocampal formation of the developing rat. Brain Res 488 403-407. 

Kohler, C., and Steinbusch. H.W.M. Identification of serotonin and non-serotonin-containing neurons of the mid-brain raphe projecting to the entorhinal area and the hippocampal formation. A combined immunohistochemical and fluorescent retrograde tracing study in the rat brain. Neuroscience 7 951-975. 1982. 

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Drake C, Patterson T, Simmons M, Chavkin C, Milner T. Kappa opioid receptor-like immunoreactivity in guinea pig brain ultrastructural localization in presynaptic terminals in hippocampal formation. J Comp Neurol 1996 370 377-395. 

Herman, J., Patel, P., Akil, H. and Watson, S. Localization and regulation of glucocorticoid and mineralocorticoid receptor messenger RNAs in the hippocampal formation of the rat. Mol. Endocrinol. 3 1886-1894,1989. 

Hyman, B. T.,VanHoesen,G. W.,Damasio,A. R. and Barnes, C. L. Alzheimer s disease cell-specific pathology isolates the hippocampal formation. Science 225 1168-1170,1984. 

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Some intracellular signal transduction molecules are reduced in schizophrenia. The release of neurotransmitters is regulated by a family of proteins that coordinate vesicular trafficking (see Ch. 9). Of these, the expression of complexin I and II appears to be decreased in prefrontal cortex and subfields of the hippocampal formation, and the ratio of complexin I to complexin II is elevated in the hippocampus [35], SNAP-25 (Synaptosomal Associated Protein, kDa 25) has inconsistently been found to be down-regulated in both these regions. Synapsin expression is also reduced, but more robust decrements have been observed in bipolar disorder (Ch. 55). 

Kar S, Baccichet A, Quirion R, Poirier J. 1993b. Entorhinal cortex lesion induces differential responses in [ I] insulinlike growth factor I, [ I] insulin-like growth factor II and [ I] insulin receptor binding sites in the rat hippocampal formation. Neuroscience 55 69-80. 

Kar S, Seto D, Dore S, Hanisch U-K, Quirion R. 1997a. Insulin-like growth factors-I and -II differentially regulate endogenous acetylcholine release from the rat hippocampal formation. Proc Natl Acad Sci USA 94 14054-14059. 

Lee TH, Kato H, Pan LH, Ryu JH, Kogure K, Itoyama Y. 1998. Localization of nerve growth factor, trkA and P75 immu-noreactivity in the hippocampal formation and basal forebrain of adult rats. Neuroscience 83 335-349. 

Temporal lobe brain structures, in particular the hippocampal formation, appear to play a pivotal yet transient role in the formation of new explicit memories. This chapter focuses on possible neurochemical mechanisms underlying the encoding of new information in the hippocampus and the modulation of memory function by different neurotransmitter systems in the brain. 

Figure 1. A. SimpMed diagram of the rodent hippocampal formation illustrating the major glutamatergic circuitry. The principal neuronal helds granule cells (GC) of the dentate gyrus and pyramidal cells of CAl and CA3 in Ammon s horn are shown. The main excitatory connections are also indicated the perforant path from entorhinal cortex to the granule cells, from there the mossy hbre (mf) axonal projections to CA3 and then the Schaffer collaterals (Sch) from CA3 to ipsilateral CAl and commissural (Comm) to contralateral CAl cells. Evoked responses in (B) were obtained by stimulating the afferent pathway from entorhinal cortex, the medial perforant path (Med), and recording the granule cell (GC) response in the hilus of the dentate gyrus.

Basal forebrain cholinergic nuclei project to all cerebral cortical areas and the amygdala (nbM), hippocampal formation, cingulate, and hypothalamus (medial septal nucleus and vertical limb of the diagonal band), and the olfac-... 

FIGURE 1.6 Modes of cell m igration to the cerebral cortex. Schematic drawing of the cerebral cortical wall of the rodent at about embryonic day 13.5. The arrows indicate the main routes of cell migration. Abbreviations CP, cortical plate Hi, hippocampal formation IZ, intermediate zone LGE, lateral ganglionic eminence MGE, medial ganglionic eminence MZ, marginal zone POC, primary olfactory cortex V, lateral ventricle VZ, ventricular zone Adapted from (de Carlos et al. (1996). 

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