Cerebellar granule cells are generated postnatally in humans.

Area of Science:

• Neuroscience
• Developmental Biology
• Human Anatomy

Background:

• The precise timing of human cerebellar granule cell generation, whether prenatal or postnatal, remains unquantified.
• Understanding this developmental timeline is crucial for comprehending cerebellar function and its role in neuropsychiatric disorders.

Purpose of the Study:

• To determine the proportion of cerebellar granule cells generated prenatally versus postnatally in humans.
• To investigate age-related changes in granule cell and Purkinje cell numbers during the first year of life.

Main Methods:

• Utilized a design-based stereologic approach on postmortem human cerebellar samples.
• Analyzed cerebella from 14 children aged from the first postnatal day to 11 months.

Main Results:

• A significant age-related increase in total granule cells was observed, from 5.9 × 10^9 at 1 month to 37.6 × 10^9 at 10-11 months per cerebellar half.
• The total number of Purkinje cells showed no significant change during the same period.
• Approximately 85% of cerebellar granule cells are generated postnatally, with the granule cell to Purkinje cell ratio increasing substantially.

Conclusions:

• The human cerebellum undergoes substantial granule cell proliferation postnatally, indicating high functional plasticity in the first year of life.
• This early developmental plasticity suggests heightened sensitivity to environmental and internal factors.
• Findings have significant implications for understanding cerebellar involvement in neuropsychiatric conditions.