Immature excitatory neurons in the amygdala come of age during puberty

The human amygdala is critical for emotional learning, valence coding, and complex social interactions, all of which mature throughout childhood, puberty, and adolescence. Across these ages, the amygdala paralaminar nucleus (PL) undergoes significant structural changes including increased numbers of mature neurons. The PL contains a large population of immature excitatory neurons at birth, some of which may continue to be born from local progenitors. These progenitors disappear rapidly in infancy, but the immature neurons persist throughout childhood and adolescent ages, indicating that they develop on a protracted timeline. Many of these late -maturing neurons settle locally within the PL, though a small subset appear to migrate into neighboring amygdala subnuclei. Despite its prominent growth during postnatal life and possible contributions to multiple amygdala circuits, the function of the PL remains unknown. PL maturation occurs predominately during late childhood and into puberty when sex hormone levels change. Sex hormones can promote developmental pro-cesses such as neuron migration, dendritic outgrowth, and synaptic plasticity, which appear to be ongoing in late-maturing PL neurons. Collectively, we describe how the growth of late-maturing neurons occurs in the right time and place to be relevant for amygdala functions and neuropsychiatric conditions.

Automated summary

The human amygdala plays a crucial role in emotional learning, valence coding, and complex social interactions, and it continues to mature throughout childhood, puberty, and adolescence. The amygdala paralaminar nucleus (PL), which undergoes structural changes and increased numbers of mature neurons, contains a large population of immature excitatory neurons at birth. These immature neurons persist throughout childhood and adolescence, suggesting a protracted developmental timeline. While the function of the PL remains unknown, its maturation primarily occurs during late childhood and puberty, coinciding with changes in sex hormone levels. This suggests that sex hormones may play a role in the maturation and development of PL neurons, which could be relevant for amygdala functions and neuropsychiatric conditions.