Cortical interneurons: a significant neuronal population and its correlation with neurological disorders

Cortical interneurons, although fewer numerically compared to pyramidal cells are essential for keeping the brain’s circuits balanced. They regulate when pyramidal neurons fire, help synchronize oscillations, and allow the cortex to adapt. Their development begins in the ganglionic eminences and continues for a long period, even after birth. In humans, this process is more complicated than in rodents because it also involves cortical progenitors and outer radial glia. This extended timeline may explain both their diversity and their sensitivity to problems during development. Recent advances with transcriptomics and human-derived models have revealed both similarities with other mammals and features unique to our species like additional interneuron subtypes such as the rosehip cell. Problems in interneuron development - whether caused by genetic mutations, molecular errors, or environmental influences - are now seen as a shared mechanism in several brain disorders, including autism, schizophrenia, and epilepsy. Among the many interneuron classes, those expressing parvalbumin and somatostatin seem to be especially affected. From an evolutionary perspective, the expansion of interneuron numbers and connections may have contributed to the advanced processing ability of the human cortex. These observations underline the dual role of interneurons as both a developmental vulnerability and a potential therapeutic target