Ageing of the human entorhinal cortex and subicular complex

Area of Science:

• Neuroscience
• Aging Research
• Brain Anatomy

Background:

• The entorhinal cortex (EC) and subicular complex (SC) are crucial for memory and cognition.
• Understanding age-dependent changes in these regions is vital for aging research.

Purpose of the Study:

• To investigate age-related neuronal and nuclear area modifications in the EC and SC.
• To quantify neuronal loss and cellular changes across the lifespan in specific layers.

Main Methods:

• Studied 30 human brains aged 14-86 years, excluding CNS impairment.
• Utilized Nissl, PAS, and hematoxylin-eosin staining on paraffin-embedded sections.
• Employed neuronal counting and Kariometry to analyze EC layers II, III, V, subiculum (S) pyramidal layer, and presubiculum (PS) layer II.

Main Results:

• EC layers showed a slight neuronal reduction up to 35 years, stabilizing until 75, then increasing slightly. Nuclear area decreased until 40-45 years, then increased until 75.
• Subiculum (S) pyramidal layer exhibited significant neuronal loss (30%) between 30-60 years. Nuclear area decreased in early years and increased significantly from 35 years onward.
• Presubiculum (PS) layer II demonstrated a consistent cell loss (32.9%) throughout life, with non-significant nuclear area changes.

Conclusions:

• Significant age-dependent neuronal loss occurs in the EC and SC, particularly after age 75.
• Nuclear area in these regions undergoes dynamic changes with age, showing initial decrease followed by increase.
• These findings highlight the structural impact of aging on memory-related brain structures.