The birth of a synaptic map of the brain may explain why aging causes changes in intelligence and behavior.

Photo Credit: Zhen Qiu, M?lissa Cizeron, and Seth Grant, an op-ed in the University of Edinburgh," and the University of Edinburgh's Science review notes that there are 100 trillion synapses in the neocortex of the human brain, each of which is a complex entity containing thousands of different signaling proteinsBeing able to understand the functions and changes of these different synapses is important for understanding the function of the brainFor the study, the scientists used mice as models to set out 10 time nodes (minimum 1 day, maximum 18 months) from birth to middle-aged age, and then observed what happens to synapsesFor observational purposes, the researchers used two structural proteins in synaptic neurons (SAP102 and PSD95) and labeled them fluorescentTheoretically, since the vast majority of central nervous system synapses usually carry these two proteins, they are labeled enough to be used to find the vast majority of synapsesBased on the expression of these two structural proteins, as well as the molecular and morphological characteristics of the synapses, the researchers divided the synapses of mice into three types, 37 subtypesSynapses of different types and subtypes also have their own preferred territory in different areas of the braindifferent synaptic signal proteins (Photo Source: References) The researchers found that these synapses also change dating over ageThese synaptic density changes vary slightly depending on the development of each brain regionFor example, the synaptic density of the brain stem reaches a peak earlier than the brainThis is also consistent with the important role played by the brain stem in the early developmentAs the mice grew older, the synaptic density of most brain regions decreased significantly from 3 months to 18 monthsTo better understand the impact of this change, the researchers focused on the hippocampus, a brain region closely related to learning and memoryInterestingly, these two types of proteins used to label synaptic structures changed differently over time (1 week, 3 months, 18 months - PSD95 changes are more pronounced, while SAP 102 levels are more stableThis also suggests that synapses in this area do change as they get olderThis may affect the activity and function of nerve activitysynapses in the hippocampus change with age (Picture source: References) The researchers conclude the paper by pointing out that this "census" of synapses helps us study synaptic changes and corresponding behavioral changes at different times and places in brain development Their work also brings important research tools for brain development, aging, and brain diseases References: 1? (2020), A brainvision atlas of the synapses of the across the mouse life span, Science, DOI: 10.1126/science.aba3163 .2 Kristina D Micheva et al., (2020), A synapse for the thes, science, DOI: 10.1126/science.