Adaptive functional reorganization in amyotrophic lateral sclerosis: coexisting degenerative and compensatory changes

Area of Science:

• Neuroscience
• Neurology
• Neuroimaging

Background:

• Amyotrophic lateral sclerosis (ALS) involves significant functional brain changes alongside structural degeneration.
• This study focuses on functional adaptation in ALS patients with distinct motor neuron dysfunction patterns.

Purpose of the Study:

• To evaluate functional adaptation in ALS patients with lower motor neuron predominant (LMNp) and upper motor neuron predominant (UMNp) dysfunction.
• To investigate brain activation and connectivity patterns during motor tasks in different ALS subtypes.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to study 17 LMNp ALS patients, 14 UMNp ALS patients, and 14 controls.
• Activation patterns during motor task preparation were analyzed, along with connectivity using the supplementary motor area (SMA), cerebellum, and striatum as seed regions.

Main Results:

• UMNp patients showed increased cerebellar activation and decreased dorsolateral prefrontal cortex and SMA activation compared to controls.
• UMNp patients exhibited increased cerebello-striatal connectivity but decreased SMA-striatal and SMA-cerebellar connectivity.
• A positive correlation was found between clinical variables and striato-cerebellar connectivity in UMNp patients.

Conclusions:

• Increased cerebello-striatal connectivity in ALS suggests compensatory processes despite SMA-network dysfunction.
• The findings highlight a combination of neurodegenerative and adaptive changes in the brain circuitry of ALS patients.