Pyramidal Neurons

Pyramidal Neurons

Introduction

<table class="infobox infobox-cell">
<tr>
<th class="infobox-header" colspan="2">Pyramidal Neurons</th>
</tr>
<tr>
<td class="label">Taxonomy</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology (CL)</td>
<td>[CL:0000598](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000598)</td>
</tr>
<tr>
<td class="label">Database</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology</td>
<td>[CL:0000598](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000598)</td>
</tr>
<tr>
<td class="label">Cell Ontology</td>
<td>[CL:1001571](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_1001571)</td>
</tr>
<tr>
<td class="label">Cell Ontology</td>
<td>[CL:4023041](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_4023041)</td>
</tr>
<tr>
<td class="label">Layer</td>
<td>Type</td>
</tr>
<tr>
<td class="label">L2/3</td>
<td>Intratelencephalic</td>
</tr>
<tr>
<td class="label">L5 PT</td>
<td>Extratelencephalic</td>
</tr>
<tr>
<td class="label">L6 CT</td>
<td>Corticothalamic</td>
</tr>
</table>

Pyramidal Neurons

Introduction

<table class="infobox infobox-cell">
<tr>
<th class="infobox-header" colspan="2">Pyramidal Neurons</th>
</tr>
<tr>
<td class="label">Taxonomy</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology (CL)</td>
<td>[CL:0000598](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000598)</td>
</tr>
<tr>
<td class="label">Database</td>
<td>ID</td>
</tr>
<tr>
<td class="label">Cell Ontology</td>
<td>[CL:0000598](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000598)</td>
</tr>
<tr>
<td class="label">Cell Ontology</td>
<td>[CL:1001571](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_1001571)</td>
</tr>
<tr>
<td class="label">Cell Ontology</td>
<td>[CL:4023041](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_4023041)</td>
</tr>
<tr>
<td class="label">Layer</td>
<td>Type</td>
</tr>
<tr>
<td class="label">L2/3</td>
<td>Intratelencephalic</td>
</tr>
<tr>
<td class="label">L5 PT</td>
<td>Extratelencephalic</td>
</tr>
<tr>
<td class="label">L6 CT</td>
<td>Corticothalamic</td>
</tr>
</table>

Pyramidal [Neurons](/entities/neurons) is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes. [@spruston2008]

Overview

Pyramidal neurons are the principal excitatory neurons in the cerebral [cortex](/brain-regions/cortex) and [hippocampus](/brain-regions/hippocampus). They are characterized by their triangular-shaped cell bodies (soma) and long apical dendrites. These neurons are the primary projection neurons, sending axons to distant brain regions and forming the major output of the cortical column. Pyramidal neurons constitute approximately 70-80% of cortical neurons in the mouse brain and represent the dominant excitatory cell type in the mammalian neocortex. [@defelipe2023]

<!-- taxonomy-enrichment --> [@greig2023]

<!-- multi-taxonomy-enrichment -->

Multi-Taxonomy Classification

Taxonomy Database Cross-References

Morphology & Electrophysiology

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

PanglaoDB Marker Cross-References

• Unknown (PanglaoDB):

External Database Links

• [Cell Ontology (CL:0000598)](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000598)
• [OBO Foundry (CL:0000598)](http://purl.obolibrary.org/obo/CL_0000598)
• [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/)
• [PanglaoDB](https://panglaodb.se/)

Taxonomy & Classification

External Database Links

• [Cell Ontology (CL:0000598)](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000598)
• [OBO Foundry (CL:0000598)](http://purl.obolibrary.org/obo/CL_0000120)
• [Allen Brain Cell Atlas](https://portal.brain-map.org/atlases-and-data/bkp/abc-atlas)
• [CellxGene Census](https://cellxgene.cziscience.com/)

Key Characteristics

• Cell Body: Triangular/pyramidal shape, 10-20 μm diameter
• Dendrites: Single prominent apical dendrite, 4-8 basal dendrites, extensive dendritic arborization
• Axon: Long projection axon with extensive collateral branches
• Neurotransmitter: Glutamate (excitatory)
• Markers: CTIP2, SATB2, TBR1, NeuroD1, Cux1, Cux2
• Action Potential: Regular spiking, adapting

Subtypes

By Cortical Layer

By Region

• [Cortical Pyramidal Neurons](/cell-types/cortical-pyramidal-neurons)
• [Hippocampal CA1 Pyramidal Neurons](/cell-types/hippocampal-ca1-pyramidal-neurons)
• [CA3 Pyramidal Cells](/cell-types/ca3-pyramidal-cells)
• [Layer 5 Pyramidal Neurons](/cell-types/layer-5-pyramidal-neurons)

Function

Dendritic Integration

Pyramidal neurons integrate thousands of synaptic inputs across their elaborate dendritic trees. The apical dendrite extends radially through multiple cortical layers, receiving inputs from various neuronal types:

• Proximal dendrites: Local interneuron inputs, thalamocortical afferents
• Middle dendrites: Feedback connections from higher cortical areas
• Distal dendrites: Feedforward inputs, feedback from layer 1 interneurons

Action Potential Generation

Pyramidal neurons exhibit several key electrophysiological properties:

The axon initial segment (AIS), rich in voltage-gated Na+ channels (Nav1.2, Nav1.6), is the primary site of action potential initiation. [@kole2024]

Network Function

Pyramidal neurons form the core of cortical information processing:

• Feedforward processing: L2/3 → L4 → L2/3 → L5 → L6 pathways
• Feedback processing: Higher to lower cortical area connections
• Recurrent excitation: Extensive lateral connections within cortical columns
• Output generation: Subcortical projections to striatum, thalamus, brainstem

Involvement in Neurodegeneration

Alzheimer's Disease

Pyramidal neurons show multiple pathological changes in AD:

• Neuronal loss: Selective vulnerability of CA1 and subiculum pyramidal neurons, with 40-70% loss in severe AD [@gomezisla2024]
• [Tau](/proteins/tau) pathology: NFT accumulation begins in layer Pre-α (transentorhinal cortex), spreading through hierarchical cortical networks
• Dendritic degeneration: Loss of [dendritic spines](/cell-types/dendritic-spines) (30-50% reduction) precedes cell death
• Synaptic dysfunction: Impaired glutamate recycling, NMDAR dysfunction, excitotoxicity
• Hyperexcitability: Early network hyperactivity in [entorhinal cortex](/brain-regions/entorhinal-cortex) and hippocampus
• Electrophysiological changes: Reduced firing rates, impaired place cell stability

Parkinson's Disease

Cortical pyramidal involvement in PD:

• Cortical atrophy: Reduced pyramidal neuron density in motor and prefrontal cortices
• Executive dysfunction: L5 pyramidal neuron deficits contribute to impaired working memory
• Cognitive decline: Pathological changes in frontal pyramidal neurons predict dementia
• Hyperexcitability: Reduced inhibition from fast-spiking interneurons

Amyotrophic Lateral Sclerosis

• Upper motor neuron degeneration: Cortical pyramidal neurons (Betz cells in L5) degenerate
• Corticospinal tract: Axonal degeneration from pyramidal neuron loss
• Excitotoxicity: Impaired glutamate transport, NMDAR hyperactivation
• [TDP-43](/mechanisms/tdp-43-proteinopathy) pathology: Inclusions in cortical pyramidal neurons in >95% of ALS cases

Huntington's Disease

• Cortical pyramidal loss: L2/3 and L5 pyramidal neuron degeneration
• Dendritic pathology: Reduced spine density, dendritic simplification
• Circuit dysfunction: Impaired corticostriatal connectivity

Related Pages

• [Cortical Neurons](/cell-types/cortical-neurons)
• [Prefrontal Cortex Neurons](/cell-types/prefrontal-cortical-neurons)
• [Hippocampal CA1 Pyramidal Neurons](/cell-types/hippocampal-ca1-pyramidal-neurons)
• [Layer 5 Pyramidal Neurons](/cell-types/layer-5-pyramidal-neurons)
• [Excitotoxicity](/mechanisms/excitotoxicity)

See Also

• [Motor Neurons](/cell-types/motor-neurons)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)
• [Dendritic Spines](/mechanisms/dendritic-spines)

Background

The study of Pyramidal 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.

External Links

• [NeuroMorpho.Org](https://neuromorpho.org/) - Neuronal morphology database
• [Allen Brain Atlas](https://portal.brain-map.org/) - Brain gene expression data
• [Allen Brain Map - Cell Types](https://celltypes.brain-map.org/) - Single-cell transcriptomics

Pathway Diagram

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

Pathway Diagram

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