Sensorimotor functional connectivity changes in amyotrophic lateral sclerosis

Area of Science:

• Neuroscience
• Neurology
• Medical Imaging

Background:

• Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons.
• Understanding brain functional changes in ALS is crucial for identifying compensatory mechanisms and disease progression markers.

Purpose of the Study:

• To investigate resting-state functional connectivity abnormalities in the sensorimotor cortex (SMC) of ALS patients.
• To determine the relationship between these functional changes and corticospinal tract (CST) damage assessed by diffusion tensor magnetic resonance imaging (DT MRI).

Main Methods:

• Resting-state functional magnetic resonance imaging (fMRI) was used to assess functional connectivity in 26 ALS patients and controls.
• Diffusion tensor magnetic resonance imaging (DT MRI) was employed to quantify corticospinal tract (CST) integrity.
• Functional connectivity patterns were compared between ALS patients and controls, and analyzed in relation to CST damage and disease severity.

Main Results:

• ALS patients showed increased functional connectivity between the left SMC and the right cingulate cortex, parahippocampal gyrus, and cerebellum-crus II compared to controls.
• In patients without CST damage, increased left SMC connectivity was more widespread, with additional right SMC connectivity to the parahippocampal gyrus.
• ALS patients with CST damage exhibited increased left SMC connectivity to the cingulate cortex and decreased right SMC connectivity to the cerebellum.
• Disease severity in ALS patients correlated with reduced SMC functional connectivity.

Conclusions:

• Functional brain changes, particularly in the SMC, are present in early-stage ALS.
• These alterations may represent compensatory mechanisms for early structural damage.
• The extent of functional connectivity changes appears to be influenced by the degree of CST damage and may decrease with disease progression.