The medial septum/diagonal band of Broca complex (MSDB) is a key structure that modulates hippocampal rhythmogenesis. Cholinergic neurons of the MSDB play a central role in generating and pacing theta-band oscillations in the hippocampal formation during exploration, novelty detection, and memory encoding. How precisely cholinergic neurons affect hippocampal network dynamics in vivo, however, h...

Abstract The hippocampal mossy fiber synapse is a key of the trisynaptic circuit. Post-tetanic potentiation (PTP) most powerful form plasticity at this synaptic connection. It widely believed that PTP an entirely presynaptic phenomenon, implying induction input-specific, and requires neither activity multiple inputs nor stimulation postsynaptic neurons. To directly test cooperativity associativ...

Allopregnanolone (ALLO), synthesized by pyramidal neurons, is a potent positive allosteric modulator of the action of GABA at GABA(A) receptors expressing specific neurosteroid binding sites. In the brain, ALLO is synthesized from progesterone by the sequential action of two enzymes: 5alpha-reductase type I (5alpha-RI) and 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD). In the cortex, hippoca...

The closely related synaptic vesicle membrane proteins synaptophysin and synaptoporin are abundant in the hippocampal formation of the adult rat. But the prenatal hippocampal formation contains only synaptophysin, which is first detected at embryonic day 17 (E17) in perikarya and axons of the pyramidal neurons. At E21 synaptophysin immunoreactivity extends into the apical dendrites of these cel...

Nicotinic acetylcholine receptors (nAChRs) are expressed in the hippocampus, and their functional roles are beginning to be delineated. The effect of nAChR activation on the activity of both interneurons and pyramidal neurons in the CA1 region was studied in rat hippocampal slices. In CA1 stratum radiatum with muscarinic receptors inhibited, local pressure application of acetylcholine (ACh) eli...

Abstract: Pyramidal neurons in the intact brain are bombarded by synaptic inputs that cause tonic depolarization, shunting, and noisy fluctuations in membrane potential; by comparison, pyramidal neurons in acute slices experience little background input. Such differences in operating conditions can compromise extrapolation of in vitro data to explain neuronal operation in vivo. For instance, py...

BACKGROUND Pretreatment with 17beta-estradiol (E2) is profoundly neuroprotective in young animals subjected to focal and global ischemia. However, whether E2 retains its neuroprotective efficacy in aging animals, especially when administered after brain insult, is largely unknown. METHODOLOGY/PRINCIPAL FINDINGS We examined the neuroprotective effects of E2 and two agonists that bind to non-cl...

We tested the hypothesis that differential sensitivity to ethanol of synaptic GABA(A) somatic and dendritic inhibitory postsynaptic currents (IPSCs) in hippocampal CA1 pyramidal neurons could be due to differences in the extent of GABA(B) receptor activity at GABAergic synapses in these two hippocampal subfields. Our present results show that dendritic (distally evoked) GABA IPSCs contain a lar...

Previous studies have demonstrated that dye coupling between neurons can be reduced by maneuvers that reduce intracellular pH. However, it is apparent that marked extracellular alkaline- as well as acid-going pH shifts can occur in the mammalian CNS. In light of the fact that an applied change in extracellular pH may produce a damped change in intracellular pH in the same direction, in this stu...

Previous neurophysiological and behavioral studies relate hippocampal functions to place learning and memory, and encoding of task (or context)-specific information. Encoding of both task-specific information and own location is essential for episodic memory and for animals to navigate to reward-related places. It is suggested that different neural circuits with different assemblies of differen...