Lukas Frey, Sophia Kirscht, Judith Ebert, Tijana Hanauske, Thomas Deller, Stephan W. Schwarzacher, Tassilo Jungenitz
The development of early postnatally-born hippocampal granule cells (pbGCs) can be studied in organotypic entorhino-hippocampal slice cultures (OTCs) in which local dentate gyrus (DG) and entorhinal projections are established within the first 10 days in vitro . Thus, pbGCs develop within an existing neural network, comparable to the adult situation in vivo. In this study, we analyzed the development of small dendritic protrusions (SDPs) on complete reconstructions of dendritic trees from retrovirally (RV) labeled pbGC born at postnatal day 4–5 during the phase of early spinogenesis in OTCs. We found SDPs with head (spines) and without head (other protrusions) as early as 12 days post RV injection (dpi) in all parts of the growing dendritic tree of pbGCs. At 14 – 20 dpi, while dendritic reorganization was still ongoing, SDP density as well as spine tip size increased moderately. At 16 dpi, spines with larger, bulbous heads appeared. Interestingly, the percentage of spines stayed constant at 60% of all SDPs over time. While spines were evenly distributed in all parts of the dendritic tree with no preference for any layer, other SDPs were more abundant at proximal parts of the dendritic tree within the granule cell layer (GCL). Our findings support the idea that SDPs appear early in dendritic development and are associated with dendritic growth rather than the establishment of specific synaptic connectivity. The uniform distribution of spines across the dendritic tree during the phase of dendritic maturation and reorganization suggests that early spinogenesis may be guided in part by intrinsic cellular programs, while not excluding a contribution of layer-specific cues.
Jairo A. Rozo, Leonardo Palacios-Sánchez, Andrés M. Pérez-Acosta
Santiago Ramón y Cajal is widely recognized as the father of modern neuroscience. However, his life has many extraordinary facets, and he is even considered a polymath. Among his many activities, his artistic endeavors stand out, and this article focuses on exploring the origins of Cajal’s passion for the arts. The Aragonese scholar cultivated drawing, painting, literature, chess, and, notably, photography with equal intensity and passion. This article shows Cajal’s artistic dimension, exploring the origins and evolution of his passion for drawing, painting, and photography. We demonstrate that his profound visual capacity and the technical skill developed through his art were not unrelated to his scientific work. On the contrary, they became the fundamental support for his ability to innovate and document the delicate structures of the nervous system through beautiful drawings and photographs that allowed him to show humanity the “butterflies of the soul,” the name he gave to the elegant cells he saw in nervous tissue. His inclination for drawing was evident from childhood, and despite serious conflicts with his father, who desperately wanted him to become a doctor, he managed to take painting courses and perfect his technique. His work as a painter, writer, and photographer is presented, leaving the door open for future explorations into the life of a great man who continues to amaze almost a century after his passing.
O. Kabenova, R. Zhulduzbayev, I. Brak, B. Kerimkulov, R. Siugzdaite, A. Kustubayeva
Brain maturation during childhood and adolescence involves complex structural changes that vary among individuals. Characterizing these trajectories is essential for understanding normative development and identifying deviations associated with neurological conditions. We analyzed structural magnetic resonance imaging data from 179 healthy participants aged 7–20 years. Cortical thickness, regional surface area, and regional brain volumes were assessed to characterize age-related morphometric patterns and sex differences. These features were also used to predict chronological age. Ten regression algorithms spanning regularized linear, Bayesian, kernel-based, and gradient-boosting approaches were evaluated using repeated age-stratified five-fold cross-validation. Total gray matter volume decreased with age, whereas white matter volume increased, reflecting ongoing myelination and brain maturation. The caudate nuclei and nucleus accumbens showed age-related volume reductions, while cerebellar and brainstem volumes increased, suggesting continued maturation of motor and sensory systems. No significant age-related associations were observed for cortical surface area. In contrast, cortical thickness showed widespread age-related decreases, including in the superior temporal sulcus, anterior cingulate cortex, and prefrontal cortex, consistent with functional specialization. Males had significantly larger cortical, subcortical, and white matter volumes, as well as larger surface areas across multiple cortical regions. However, cortical thickness did not differ significantly by sex. A stacking ensemble achieved the best age-prediction performance, with an age-bias-corrected mean absolute error of 1.41 years. Despite the observed morphological sex differences, the corrected brain-age gap did not differ significantly between sexes. These findings provide a region-specific reference for normative brain development in a Central Asian pediatric and adolescent sample and establish a preliminary framework for predicting age from standard brain morphometric measures. Independent replication in larger and more diverse samples is required to assess the generalizability of these findings.
Sayaka Hashimoto, Takuya Okada, Kazuko Keino-Masu, Ken Miya, Masayuki Masu
The medial habenula (MHb), a medial subdivision of the habenula located in the dorsal diencephalon, sends axons towards the interpeduncular nucleus (IPN) through the fasciculus retroflexus. Upon reaching the IPN, MHb axons cross the midline multiple times. Although heparan sulfate proteoglycans have previously been shown to play a role in MHb axon guidance, the role of heparan sulfate 6-O-endosulfatases, Sulfatase 1 (Sulf1) and Sulfatase 2 (Sulf2), has to date not been investigated. We thus examined MHb axon trajectories in Sulf1 and Sulf2 knockout mice and found that Sulf1/2 double knockout (DKO) mice showed several types of pathfinding errors after reaching the ventral surface of the brain. The abnormalities included aberrant anterior extension into the mammillary body, abnormal lateral projection on the brain surface, and reduced midline crossing within the IPN. Furthermore, the DKO mice exhibited altered outcomes in social conflict in a tube test assay: they showed a higher win rate against wild-type mice. This behavioral phenotype may reflect functional impairment of the MHb-IPN circuit resulting from its developmental abnormalities. Taken together, these findings suggest that Sulf1/2 are required for proper MHb-IPN circuit formation during development, which is in turn critical for its normal function in adulthood.
