Immature neurons in the primate amygdala: Changes with early development and disrupted early environment

Area of Science:

• Neuroscience
• Developmental Biology
• Primate Research

Background:

• The amygdala paralaminar nucleus (PL) in primates contains immature neurons.
• Understanding neuronal development in the PL is crucial for comprehending brain maturation.

Purpose of the Study:

• To investigate the developmental changes in PL neurons from infancy to adolescence in macaques.
• To examine the impact of early-life maternal separation stress on PL neuronal development in infant macaques.

Main Methods:

• Comparative analysis of PL neurons in infant and adolescent maternally-reared macaques.
• Assessment of PL neurons in infant macaques exposed to maternal separation versus controls.
• Quantification of immature and mature neurons, soma volumes, and TBR1 mRNA expression.

Main Results:

• Adolescent macaques showed fewer immature neurons, more mature neurons, and larger immature soma volumes in the PL compared to infants.
• Total neuron counts decreased in adolescent PL, suggesting migration out of the nucleus.
• Maternal separation did not alter neuron counts but correlated immature neuron soma volume with mature neuron counts and TBR1 mRNA levels in infants.

Conclusions:

• Immature neurons in the primate amygdala paralaminar nucleus gradually mature by adolescence.
• Early-life maternal separation stress may disrupt normal neuronal maturation pathways in the PL, as indicated by altered TBR1 mRNA expression and neuron maturation correlations.