Norepinephrine is an endogenous neurotransmitter distributed throughout the mammalian brain. In higher cortical structures such as the hippocampus, norepinephrine, via beta adrenergic receptor (AR) activation, has been shown to reinforce the cognitive processes of attention and memory. In this study, we investigated the effect of beta1AR activation on hippocampal cornu ammonis 3 (CA3) network a...

Gamma frequency (30-80 Hz) oscillations are implicated in memory processing. Such rhythmic activity can be generated intrinsically in the CA3 region of the hippocampus from where it can propagate to the CA1 area. To uncover the synaptic mechanisms underlying the intrahippocampal spread of gamma oscillations, we recorded local field potentials, as well as action potentials and synaptic currents ...

Theories of associative memory suggest that successful memory storage and recall depend on a balance between two complementary processes: pattern separation (to minimize interference) and pattern completion (to retrieve a memory when presented with partial or degraded input cues). Putative attractor circuitry in the hippocampal CA3 region is thought to be the final arbiter between these two pro...

The concentration level of extracellular L-glutamate released from region CA3 of mouse hippocampal slices under tetraethylammonium (TEA) chloride and KCl stimulation was measured with independent methods, i.e., a capillary-based enzyme sensor, a patch sensor, and an enzyme-based imaging method. The L-glutamate level was compared with those at regions CA1 and DG. It was found that the enhanced c...

Contextual learning involves associating cues with an environment and relating them to past experience. Previous data indicate functional specialization within the hippocampal circuit: the dentate gyrus (DG) is crucial for discriminating similar contexts, whereas CA3 is required for associative encoding and recall. Here, we used Arc/H1a catFISH imaging to address the contribution of the largely...

Aging is associated with cognitive decline in both humans and animals and of all brain regions, the hippocampus appears to be particularly vulnerable to senescence. Age-related spatial learning deficits result from alterations in hippocampal connectivity and plasticity. These changes are differentially expressed in each of the hippocampal fields known as cornu ammonis 1 (CA1), cornu ammonis 3 (...

We propose a mechanism to explain both retrospective and prospective recall activity found in experimental data from hippocampal regions CA3 and CA1. Our model of temporal context dependent episodic memory replicates reverse recall in CA1, as recently recorded and published [Foster, D., & Wilson, M. (2006). Reverse replay of behavioural sequences in hippocampal place cells during the awake stat...

Protein synthesis is involved in the consolidation of short-term memory into long-term memory. Previous electrophysiological data concerning LTP in CA3 suggest that protein synthesis in that region might also be necessary for short-term memory. We tested this hypothesis by locally injecting the protein synthesis inhibitor anisomycin in hippocampal area CA1 or CA3 immediately after contextual fe...

Intracerebroventricular kainate administration in rat, a model of temporal lobe epilepsy (TLE), causes degeneration of the hippocampal CA3 pyramidal and dentate hilar neurons. This leads to a robust but aberrant sprouting of the granule cell axons (mossy fibers) into the dentate supragranular layer and the CA3 stratum oriens. Because this plasticity is linked to an increased seizure susceptibil...

Alzheimer's disease is the most common neurodegenerative disorder in the elderly. Amnestic mild cognitive impairment (MCI) is a relatively newly defined clinical entity that requires memory decline while activities of daily living remain intact. Most amnestic MCI patients develop Alzheimer's disease. Using an innovative surface-based hippocampal analytic technique we analysed the structural mag...