Hippocampal CA4 Neurons

Hippocampal CA4 Neurons

Introduction

<table class="infobox infobox-cell">
<tr>
<th class="infobox-header" colspan="2">Hippocampal CA4 Neurons</th>
</tr>
<tr>
<td class="label">Taxonomy</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology (CL)</td>
<td>[CL:4023061](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_4023061)</td>
</tr>
<tr>
<td class="label">Database</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology</td>
<td>[CL:4023061](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_4023061)</td>
</tr>
</table>

Hippocampal Ca4 Neurons is an important cell type in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

Hippocampal CA4 Neurons

Introduction

<table class="infobox infobox-cell">
<tr>
<th class="infobox-header" colspan="2">Hippocampal CA4 Neurons</th>
</tr>
<tr>
<td class="label">Taxonomy</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology (CL)</td>
<td>[CL:4023061](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_4023061)</td>
</tr>
<tr>
<td class="label">Database</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology</td>
<td>[CL:4023061](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_4023061)</td>
</tr>
</table>

Hippocampal Ca4 Neurons is an important cell type in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

The CA4 region of the hippocampus is the most proximal subfield to the dentate gyrus, forming a critical node in the trisynaptic circuit. CA4 neurons receive input from the dentate gyrus mossy fibers and project to CA3 pyramidal neurons, playing essential roles in memory consolidation and pattern completion. [@hunsaker2008]

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Multi-Taxonomy Classification

Taxonomy Database Cross-References

Morphology & Electrophysiology

• Morphology: hippocampal CA4 neuron (source: Cell Ontology)
• Morphology can be inferred from Cell Ontology classification

External Database Links

• [Cell Ontology (CL:4023061)](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_4023061)
• [OBO Foundry (CL:4023061)](http://purl.obolibrary.org/obo/CL_4023061)
• [Allen Brain Cell Atlas](https://portal.brain-map.org/atlases-and-data/bkp/abc-atlas)
• [CellxGene Census](https://cellxgene.cziscience.com/)
• [Human Cell Atlas](https://www.humancellatlas.org/)

Taxonomy & Classification

External Database Links

• [Cell Ontology (CL:4023061)](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_4023061)
• [OBO Foundry (CL:4023061)](http://purl.obolibrary.org/obo/CL_4023061)
• [Allen Brain Cell Atlas](https://portal.brain-map.org/atlases-and-data/bkp/abc-atlas)
• [CellxGene Census](https://cellxgene.cziscience.com/)

Neuroanatomy

Location and Structure

CA4 is located in the hippocampal formation, bordered by the dentate gyrus hilus medially and the CA3 region laterally. The region contains:

• Pyramidal neurons: Principal excitatory neurons with triangular soma
• Interneurons: Various subtypes including basket cells, bistratified cells, and axo-axonic cells
• Astrocytes: Supporting glial cells crucial for metabolic support

Connectivity

• Input: Mossy fiber projections from dentate gyrus granule cells
• Output: CA3 pyramidal neurons via associational connections
• Local circuits: Reciprocal connections with dentate gyrus hilus neurons

Molecular Markers

Key markers for CA4 neurons include:

• Reelin: Secreted glycoprotein important for lamination
• Calbindin: Calcium-binding protein
• nNOS: Neuronal nitric oxide synthase
• Wnt2: Wingless-type MMTV integration site family member 2

Function in Memory Circuits

CA4 neurons contribute to:

Role in Neurodegenerative Diseases

Alzheimer's Disease

CA4 neurons are affected early in AD progression:

• Neurofibrillary tangles: CA4 shows tau pathology in early stages
• Synaptic loss: Mossy fiber synapses degenerate
• Hyperexcitability: Altered excitability contributes to seizures in AD
• Network dysfunction: Contributes to hippocampal circuit breakdown

Epilepsy

CA4 is particularly vulnerable in temporal lobe epilepsy:

• Mossy fiber sprouting: Aberrant connectivity
• Hyperexcitability: Loss of inhibitory control
• Cognitive comorbidity: Contributes to memory deficits

Therapeutic Implications

Drug Targets

• mTOR inhibitors: Reduce aberrant mossy fiber sprouting
• Anti-epileptics: Control hyperexcitability
• Neurotrophic factors: Support neuronal survival

Research Directions

• CA4 as early biomarker for AD progression
• Deep brain stimulation targeting CA3-CA4 circuit
• Gene therapy approaches for CA4 protection

Background

The study of Hippocampal Ca4 Neurons has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

See Also

External Links

Pathway Diagram

The following diagram shows the key molecular relationships involving Hippocampal CA4 Neurons discovered through SciDEX knowledge graph analysis: