Subthalamic nucleus volumes are highly consistent but decrease age-dependently-a combined magnetic resonance imaging...

Area of Science:

• Neuroscience
• Neuroanatomy
• Medical Imaging

Background:

• The subthalamic nucleus (STN) is a primary target for deep brain stimulation (DBS) in Parkinson's disease.
• Existing knowledge on human STN volume and neuron count is debated, impacting DBS effectiveness.
• The tripartite hypothesis of STN functional subdivision lacks morphological evidence.

Purpose of the Study:

• To investigate human STN volumes and neuron counts using combined MRI and stereology.
• To explore potential age-related changes in STN morphology.
• To provide morphological basis for the STN tripartite hypothesis.

Main Methods:

• Utilized 3 Tesla MRI and stereological analysis on luxol-stained and HuC/D-stained human brain slices.
• Measured STN volumes from 25 hemispheres across 14 individuals (aged 65-96).
• Quantified neuron number, cell density, and regional variations within the STN.

Main Results:

• MRI-derived STN volumes (99 ± 6 mm³) were smaller but consistent compared to stereology (132 ± 20 mm³).
• Average neuron count was 431,088 ± 72,172; both volume and neuron count decreased with age.
• Neuron density varied across subregions, with higher density in the ventral STN compared to the dorsal STN.

Conclusions:

• Consistent STN volume measurements challenge previous findings of large size variations.
• Age-dependent reductions in STN volume and neuron number may affect DBS outcomes in elderly Parkinson's patients.
• Observed regional differences in STN subregions offer morphological support for the tripartite theory.