Earlier investigations in this laboratory demonstrated paired internal transverse arteries and veins associated with the rat cornu Ammonis (CA), mapped the vessels, and suggested segmental distribution and drainage patterns. Further studies of the smaller branches and capillaries were required to resolve the presence or absence of structurally segmented or isolated capillary beds common to vert...

Commentary What is the dentate gyrus (DG) good for? The answer may depend on whether or not you are interested in learning and memory, or epilepsy. While the actual circuitry is more complicated, the DG is the initial relay in the hippocampal circuit from the entorhinal cortex (EC). From there the DG projects to hippocampal sub-region Cornu Ammonis 3 (CA3), CA3 projects to hippocampal sub-regio...

Down syndrome (DS) is a high-incidence genetic pathology characterized by severe impairment of cognitive functions, including declarative memory. Impairment of hippocampus-dependent long-term memory in DS appears to be related to anatomo-functional alterations of the hippocampal trisynaptic circuit formed by the dentate gyrus (DG) granule cells - CA3 pyramidal neurons - CA1 pyramidal neurons. N...

We examined the generation, propagation and pharmacology of 4-aminopyridine (4-AP)-induced epileptiform activity (EA) in the intact interconnected limbic structure of the newborn (P0-7) rat in vitro. Whole-cell recordings of CA3 pyramidal cells and multisite field potential recordings in CA3, CA1, dentate gyrus, and lateral and medial entorhinal cortex revealed 4-AP-induced EA as early as P0-1....

This article introduces a new experimental paradigm for the study of temporal lobe epilepsy. This approach utilizes the isolated guinea pig brain in vitro preparation, which generates a pattern of hypersynchronous neuronal activity similar to the peculiar 8-30 Hz rhythm characterizing stereoelectroencephalographic hippocampal recordings in human temporal lobe epilepsy. The present report descri...

Hippocampal dentate granule cells directly excite and indirectly inhibit CA3 pyramidal cells via distinct presynaptic terminal specializations of their mossy fiber axons. This mossy fiber pathway contains the highest concentration of brain-derived neurotrophic factor (BDNF) in the CNS, yet whether BDNF is positioned to regulate the excitatory and/or inhibitory pathways is unknown. To localize B...

The mossy fiber to CA3 pyramidal cell synapse (mf-CA3) provides a major source of excitation to the hippocampus. Thus far, these glutamatergic synapses are well recognized for showing a presynaptic, NMDA receptor-independent form of LTP that is expressed as a long-lasting increase of transmitter release. Here, we show that in addition to this "classical" LTP, mf-CA3 synapses can undergo a form ...

The very different anatomical designs of the adjacent circuitries of the cortico-hippocampal pathway, along with their somewhat different synaptic plasticity mechanisms, suggest a nearly serial pathway of distinct memory circuits each contributing its own specialized processing operation to overall hippocampal function. Modeling and formal theoretical analysis of the prominent anatomical design...

The consolidation of memory is thought to occur via a hippocampal-neocortical dialog involving reactivation of memory patterns in the hippocampus during sharp-wave ripples. In this issue of Neuron, Nakashiba et al. demonstrate that CA3 output is required for consolidation of contextual fear memory. They also show that lack of CA3 output results in a decrease in ripple-related reactivation, prov...

The opiate-like peptide nociceptin/orphanin FQ (Noc) and its receptor [opiate receptor-like receptor (ORL-1)] are highly expressed in the hippocampus. Noc has inhibitory postsynaptic actions in CA1, CA3, and the dentate and seems to lack the disinhibitory, excitatory actions demonstrated for some opiate peptides in the hippocampus. The CA3 hippocampal region is important in the generation of hi...