The work comes from an excellent group such as Arturo Álvarez-Buylla, one of the most prominent scientists in the field of nervous system development, especially human brain development. He received the Prince of Asturias Award in 2011. The other senior author, Shaun Sorrells, a former postdoctoral researcher in Álvarez-Buylla's group, leads a young group. The study is excellent for its in-depth knowledge of the anatomy of the human brain at perinatal stages, the use of state-of-the-art techniques such as massive single-cell sequencing and the use of numerous cell population markers in immunohistochemistry. 

The authors have been studying the migration of immature progenitors and neurons in the human newborn and infant brain for years. Thus, they had published the existence of different streams of immature progenitors and inhibitory neurons in perinatal stages from the subventricular zone of the lateral ventricles to the olfactory bulb and medial prefrontal cortex (Sanai et al., 2011) and to the frontal lobe of the cortex (Paredes et al., 2016). In addition, they had also shown that there are progenitors and immature excitatory neurons in the paralimbic region of the amygdala of the newborn and young children and that at least the immature neurons persist until late in life and mature progressively (Sorrells et al., 2019). 

Now they have found immature inhibitory neurons in the entorhinal cortex in children's brains, at least until the age of 2-3 years (Nascimiento et al., 2024). The presence of these progenitors and immature neurons in various locations in the brains of infants and young children indicates that there is greater plasticity than was thought a few years ago, as the process of migration and maturation of these neurons may well be conditioned by external stimuli and experiences (as determined in animal models). 

The entorhinal cortex region is involved in the hippocampal circuitry involved in memory (spatial and episodic) and learning and is one of the first brain regions affected in Alzheimer's disease. The authors speculate that perhaps the fact that the development of these immature neurons in the entorhinal cortex is so delayed in time makes them more susceptible to neurodegeneration in Alzheimer's disease. However, we still know very little about how this disease is triggered, so it is difficult to draw conclusions linking these early neuronal populations in childhood and a neurodegenerative disease mostly associated with ageing. 
 

Although there is controversy about their existence, populations of neural stem cells and immature neurons in the human hippocampal dentate gyrus are altered in Alzheimer's disease (Moreno-Jiménez et al., 2019; Terreros-Roncal et al., 2021). 

All studies performed on human brains are limited in that they are purely descriptive and we cannot perform any cause-effect analysis. We depend on the advancement of human cell models such as cerebroids or the use of animals such as mice or non-primate monkeys.

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