The objective of this research is to study the synaptic organization of efferent and intrinsic projections of the subicular complex in adult rats. Differences of synaptic organization within the sub-regions of the subicular complex (prosubiculum, subiculum proper, presubiculum, and parasubiculum) will be studied in order to define physiological differences related to the marked cytological differences in these sub-regions. Interdisciplinary neurophysiological, intracellular HRP tracing, and immunocytochemical techniques will be used together, and will provide information that none of the techniques could provide alone. The efferent projections from the subicular complex to the entorhinal cortex and amygdala will be examined, as well as circuitry intrinsic to these areas. The pathways will be studied by intracellular recording; intracellular injection of HRP to identify neurons and trace their axonal projections; and glutamic acid decarboxylase (GAD) immunocytochemistry to localize the somata and synaptic terminals of candidate inhibitory interneurons and their relationship to principal neurons. The proposed studies will (1) establish the entorhinal and amygdala targets of subicular efferent axons and the physiological action of subicular efferents on these targets, (2) provide quantitative information about differences in the degree of axonal branching to target areas of cells within different sub-regions of the subicular complex (by the use of intracellular tracing techniques), (3) indicate the localization and physiological properties of efferent cells within specific sub-regions of the subicular complex, and (4) clarify the synaptic relationship between principal neurons and GABAergic inhibitory interneurons. These studies will fill significant gaps in our knowledge about the synaptic organization of the subicular complex, a structure that is now widely recognized as the major source of hippocampal formation efferents.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS016721-05
Application #
3397087
Study Section
Neurology B Subcommittee 1 (NEUB)
Project Start
1981-07-01
Project End
1989-08-31
Budget Start
1987-09-01
Budget End
1988-08-31
Support Year
5
Fiscal Year
1987
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Type
Schools of Medicine
DUNS #
119132785
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Mello, L E; Tan, A M; Finch, D M et al. (1996) Fos-like immunoreactivity after status epilepticus and spontaneous seizures in rats. Epilepsy Res Suppl 12:205-13
Mello, L E; Kohman, C M; Tan, A M et al. (1996) Lack of Fos-like immunoreactivity after spontaneous seizures or reinduction of status epilepticus by pilocarpine in rats. Neurosci Lett 208:133-7
Handforth, A; Finch, D M; Peters, R et al. (1994) Interictal spiking increases 2-deoxy[14C]glucose uptake and c-fos-like reactivity. Ann Neurol 35:724-31
Gigg, J; Tan, A M; Finch, D M (1994) Glutamatergic hippocampal formation projections to prefrontal cortex in the rat are regulated by GABAergic inhibition and show convergence with glutamatergic projections from the limbic thalamus. Hippocampus 4:189-98
Mello, L E; Cavalheiro, E A; Tan, A M et al. (1993) Circuit mechanisms of seizures in the pilocarpine model of chronic epilepsy: cell loss and mossy fiber sprouting. Epilepsia 34:985-95
Gigg, J; Tan, A M; Finch, D M (1992) Glutamatergic excitatory responses of anterior cingulate neurons to stimulation of the mediodorsal thalamus and their regulation by GABA: an in vivo iontophoretic study. Cereb Cortex 2:477-84
Mello, L E; Cavalheiro, E A; Tan, A M et al. (1992) Granule cell dispersion in relation to mossy fiber sprouting, hippocampal cell loss, silent period and seizure frequency in the pilocarpine model of epilepsy. Epilepsy Res Suppl 9:51-9;discussion 59-60
Mello, L E; Tan, A M; Finch, D M (1992) Convergence of projections from the rat hippocampal formation, medial geniculate and basal forebrain onto single amygdaloid neurons: an in vivo extra- and intracellular electrophysiological study. Brain Res 587:24-40
Mello, L E; Tan, A M; Finch, D M (1992) GABAergic synaptic transmission in projections from the basal forebrain and hippocampal formation to the amygdala: an in vivo iontophoretic study. Brain Res 587:41-8
Lingenhohl, K; Finch, D M (1991) Morphological characterization of rat entorhinal neurons in vivo: soma-dendritic structure and axonal domains. Exp Brain Res 84:57-74

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