Ca3 hippocampus

Federal government websites often end in. The site is secure. The hippocampus, in the temporal lobe, is phylogenetically one ca3 hippocampus the oldest parts of the brain and forms part of the limbic system.

Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. On theoretical grounds, the architecture of CA3 circuits seems to be well adapted for the rapid storage and retrieval of associative memories. This is thought to require plastic changes in the strength of specific synaptic contacts.

Ca3 hippocampus

Federal government websites often end in. The site is secure. Human functional magnetic resonance imaging fMRI studies have long investigated the hippocampus without differentiating between its subfields, even though theoretical models and rodent studies suggest that subfields support different and potentially even opposite functions. The CA3 region of the hippocampus has been ascribed a pivotal role both in initially forming associations during encoding and in reconstructing a memory representation based on partial cues during retrieval. These functions have been related to pattern separation and pattern completion, respectively. In recent years, studies using high-resolution fMRI in humans have begun to separate different hippocampal subregions and identify the role of the CA3 subregion relative to the other subregions. However, some of these findings have been inconsistent with theoretical models and findings from electrophysiology. In this review, we describe selected recent studies and highlight how their results might help to define different processes and functions that are presumably carried out by the CA3 region, in particular regarding the seemingly opposing functions of pattern separation and pattern completion. We conclude with discussing limitations of functional imaging and briefly outline possible future developments of the field. The hippocampus is something of a lodestone for functional imaging studies in human memory research. However, in addition to methodological shortcomings inherent to functional magnetic resonance imaging fMRI such as the indirect relationship to neuronal activity and the relatively low signal-to-noise ratio SNR and significant susceptibility artifacts in this region Ojemann et al. Everything we know from in vitro and animal studies points in the opposite direction. Not only is the hippocampus histologically heterogeneous, but electrophysiological recordings in subfields of the rodent hippocampus suggest a functional dissociation, and circumscribed lesions produce dissociable deficits Lee and Kesner, a ; Lee et al. Some of the hippocampal subfields might even be involved in contrary operations, which could easily lead to null results or opposite conclusions across studies. Some studies in humans acknowledge a possible functional heterogeneity by considering the anterior and posterior hippocampus differentially e.

The number of glutamate receptors opened by synaptic stimulation in single hippocampal spines. Change institution.

From a behavioral perspective, the CA3a,b subregion of the hippocampus plays an important role in the encoding of new spatial information within short-term memory with a duration of seconds and minutes. This can easily be observed in tasks that require rapid encoding, novelty detection, one-trial short-term or working memory, and one-trial cued recall primarily for spatial information. These are tasks that have been assumed to reflect the operations of episodic memory and require interactions between CA3a,b and the dentate gyrus via mossy fiber inputs into the CA3a,b. The CA3a,b is also important for encoding of spatial information requiring multiple trials including the acquisition of arbitrary and relational associations. These tasks tend to be non-episodic and can be mediated by arbitrary and conjunctive operations. All these tasks are assumed to operate within an autoassociative network function of the CA3 region.

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Ca3 hippocampus

The hippocampus, in the temporal lobe, is phylogenetically one of the oldest parts of the brain and forms part of the limbic system. The hippocampus proper is defined by the dentate gyrus and Cornu Ammonis CA. The CA3 region has attracted major attention in recent years for its specific role in memory processes, susceptibility to seizures and neuro-degeneration. Internal connectivity in the CA3 subfield is more rich than in other hippocampal regions. This circuit is implicated in encoding spatial representations O'Keefe and Nadel, and episodic memories Scoville and Milner,

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Astori, S. They play a key role in operations and functions of the CA3 region, including the generation of physiological and pathological synchronous population activities. People also looked at. The BOLD response is a coarse signal when compared to single cell activity, both in time and in space. Finally, CA3a,b may, in cooperation with the dentate gyrus, play an important role in processing the geometry of the environment. In addition, neurophysiological and acetylcholinesterase and BDA an anterograde tracer results suggest that the output from dorsal CA3 to the medial septum via the fimbria was damaged without removing the input connections back to dorsal CA3a,b Hunsaker et al. CrossRef Medline Google Scholar. Li, X. Additional experimental evidence supporting the role of CA3a,b in rapid acquisition of novel information comes from a contextual fear-conditioning experiment with subregion-specific lesions Lee and Kesner a. Even when stepping from theoretical models to rodent studies, some discrepancies can be observed between model and data, which are likely due to both methodological difficulties as well as the challenge of operationalizing specific memory processes. Hippocampus 9 7—24 They are suggested to bind, or coordinate, activity of spatially dispersed neurons due to a single stimulus Gray et al. Madrid: Moya. Second, and inversely, depression may result if few vesicles are available for release Schikorski and Stevens, ; Shepherd and Harris,

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A specific role for recurrent synapses was established by genetically deleting NMDA receptor expression at recurrent synapses of CA3 pyramidal cells Nakazawa et al. If unpaired, the rat was to refrain from digging. Federal government websites often end in. Neuron 87 , — Activity-dependent regulation of inhibitory synapse development by Npas4. However, the rat should withhold displacing the object if it was not in its paired location No-Go. Samsonovich, A. Bazelot, M. New York: John Wiley. Cambridge and Dept. Active properties of neocortical pyramidal neuron dendrites. Google Scholar.