Some regions of the adult brain stay as malleable as a baby’s brain, so we can grow new connections, strengthen existing connections, and even create new neurons, allowing all of us to be lifelong learners. We didn’t always think that. Until five or six years ago, the prevailing notion was that we were born with all of the brain cells we were ever going to get, and they steadily eroded in a depressing journey through adulthood to old age.
We do lose synaptic connections with age. Some estimates of neural loss alone are close to 30,000 neurons per day. But the adult brain also continues creating neurons within the regions normally involved in learning. These new neurons show the same plasticity as those of newborns.
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成人大腦內有些區域能夠維持像嬰兒大腦般的可塑性，所以我們的大腦可以建立新的神經連繫, 強化現存的連繫, 甚至產生新的神經元, 讓每個人都可以終身學習。以前，大家不會有這種想法，甚至5-6年前， 大家還相信人腦細胞自出生就已經有定數，隨著每個人的成長至衰老，腦細胞衹會慢慢被損耗及減少。
其實，隨著年齡漸長，腦神經細胞的突觸連接的確會減少，有估計顯示，單是神經元的損耗，每天就有接近30,000個。但是，在成人大腦的學習區域，會不斷有新的神經元產生，而這些神經元擁有與新生嬰兒腦袋般的可塑性。