The effects of androgens and the androgen antagonist, flutamide, on the density of dendritic spine synapses in the CA1 subfield of the hippocampus were studied in gonadectomized male and female rats. Treatment of orchidectomized male rats with dehydroepiandrosterone (DHEA; 2 d, 1 mg/d sc) increased the density of CA1 spine synapses observed 2 d later, by 106%, without significantly affecting ve...

Recent studies demonstrate that context-specific memory retrieval after extinction requires the hippocampus. However, the contribution of hippocampal subfields to the context-dependent expression of extinction is not known. In the present experiments, we examined the roles of areas CA1 and CA3 of the dorsal hippocampus in the context specificity of extinction. After pairing an auditory conditio...

This study was aimed at understanding the effect of intermittent hypobaric hypoxia preconditioning (IHHP) on neuroglobin (NGB) and Bcl-2 expression in the hippocampal CA1 region of rats following global cerebral ischemia-reperfusion. Wistar rats were randomly divided into sham, IHHP control, global cerebral ischemia-reperfusion (IR group), and IHHP+IR groups. The four-vessel occlusion rat model...

Acetylcholine (ACh), acting at muscarinic ACh receptors (mAChRs), modulates the excitability and synaptic connectivity of hippocampal pyramidal neurons. CA1 pyramidal neurons respond to transient ("phasic") mAChR activation with biphasic responses in which inhibition is followed by excitation, whereas prolonged ("tonic") mAChR activation increases CA1 neuron excitability. Both phasic and tonic ...

The role of interhemispheric connections along successive segments cortico-hippocampal circuits is poorly understood. We aimed to obtain a global picture spontaneous transfer activity during non-theta states across several nodes the bilateral circuit in anesthetized rats. Spatial discrimination techniques applied laminar field potentials (FP) CA1/Dentate Gyrus provided simultaneous left and rig...

Learning-related changes in strength in selected hippocampal synapses have been described recently. However, information is scarce regarding the spatial-temporal sequence of changes in synaptic weights taking place during the acquisition of a classical conditioning task and the contribution of both context (environmental details) and cues (conditioned and unconditioned stimuli: CS, US) to those...

Hippocampal information processing is often described as two-state, with a place cell state during movement and a reactivation state during stillness. Relatively little is known about how the network transitions between these different patterns of activity during exploration. Here we show that hippocampal network changes quickly and continuously as animals explore and become familiar with initi...

The mammalian hippocampus harbours neural circuitry that is crucial for associative learning and memory. The mechanisms that underlie the development and regulation of this complex circuitry are not fully understood. Our previous study established an essential role for the zinc finger protein Zbtb20 in the specification of CA1 field identity in the developing hippocampus. Here, we show that con...

In terms of its sub-regional differentiation, the hippocampal CA1 region receives cortical information directly via the perforant (temporoammonic) path (pp-CA1 synapse) and indirectly via the tri-synaptic pathway where the last relay station is the Schaffer collateral-CA1 synapse (Sc-CA1 synapse). Research to date on pp-CA1 synapses has been conducted predominantly in vitro and never in awake a...