Upper Motor Neurons in Primary Lateral Sclerosis represent a critical neuronal population whose degeneration defines this rare neurodegenerative disorder. This page provides detailed information about their structure, function, and role in disease processes.[1]
Corticospinal neurons degenerate in PLS affecting voluntary movement.
| Property | Value |
|---|---|
| Category | Motor Cortex |
| Location | Primary motor cortex, layer 5 |
| Cell Type | Pyramidal neurons (upper motor neurons) |
| Projection | Corticospinal tract |
Excessive glutamate signaling leads to calcium overload in upper motor neurons. Impaired glutamate transporters (SLC1A2) reduce glutamate reuptake, while increased NMDA receptor (GRIN1) activity promotes excitotoxic cell death.[2]
Upper motor neurons in PLS exhibit:
Activated microglia release pro-inflammatory cytokines:
This chronic neuroinflammation contributes to corticospinal tract degeneration.
While less prominent than in ALS, abnormal protein aggregation has been observed:
Impaired transport along corticospinal axons:
| Gene/Protein | Role in UMN Degeneration |
|---|---|
| ALS2 (ALS2) | Alsin - axonal transport |
| SPG7 (SPG7) | Mitochondrial function |
| BSCL2 (BSCL2) | Lipid droplet metabolism |
| REEP5 (REEP5) | ER morphology |
| Ighmbp2 (IGHMBP2) | DNA binding, transcription |
| LMNA (LMNA) | Nuclear envelope integrity |
| DCTN1 (DCTN1) | Axonal transport (dynactin) |
| KIF5A (KIF5A) | Axonal transport (kinesin) |
| SOD1 (SOD1) | Oxidative stress response |
| GRIN1 (GRIN1) | Glutamate receptor |
| TARDBP (TDP-43) | RNA processing |
The study of Upper Motor Neurons in Primary Lateral Sclerosis 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.
Turner MR. Primary lateral sclerosis. 2004. ↩︎
Eisen A, Weber M. The motor cortex and amyotrophic lateral sclerosis. 2001. ↩︎