In other words, after we reach our mid-30s, our brain synapses become less diverse and regions become more similar.
The study was a collaboration between researchers from KTH and University of Edinburgh.
This first-ever catalog of synapses across the lifespan contributes to our understanding of how the brain works. Synapses are believed to be the storage place for memories and they direct the flow of information when we think and act, Fransén says. They also are implicated in many diseases of the brain.

“Knowing which synapses change with old age could for instance give clues to why we forget certain things but not others,” he says.

Using information from the experiments on how regions develop, Fransén constructed a model of synapses found in the brain region called the hippocampus, which is where memories are formed. He found that at a young age, synapse compositions are not so different from each other, but during maturation they become increasingly more varied. After a plateau during adulthood (from about 20 to 35 years), the number of synapse variants decreases again.

The model showed that in the adult brain, when separate inputs are sent in, different inputs produce different outputs. Conversely, in the young or aged brain, the outputs become more similar.

“One can speculate that the wealth of differences in composition between brain regions and ages is related to an evolutionary adaptation in which the demands of the child, youth, the adult and the elderly are all different,” he says. “The development of our synapses shows a continuous change throughout life.”