Mayim Bialik plays scientist Amy Farrah Fowler in hit CBS sitcom The Big Bang Theory and she is smart in real life, with a Ph.D. in neuroscience.

Bialik, who is the author of the new book Girling Up, explains what is going on in our brains when we get nostalgic for things like movies and shows we loved as kids– one of them includes her popular '90s sitcom, Blossom.

She said in an interview with Tech Insider, "My name is Mayim Bialik, and I play Amy Farrah Fowler on "The Big Bang Theory. I'm often recognized for my role in "Blossom," the '90s sitcom where I was playing the lead character from the years that I was 14 to 19."

The 41-year old CBS Star explained the science behind nostalgia. "And there actually is kind of a neuroscience reason why we are nostalgic for things. Obviously, our brains store everything we experience as memories. And sometimes we store them consciously, and sometimes they're stored more unconsciously."

The American actress noted, "But one of the reasons that we have such a fondness for certain things is that memories are better encoded when they are paired with a very strong emotional response."

She continued, "So if something tragic or sad happens, you will often remember it in a very persistent way, and if something makes you feel good or makes you laugh a lot, which I think maybe people experienced with "Blossom," you sometimes will get a stronger sense of memory and connection from something that has a positive emotion associated with it."

Mayim Bialik
Mayim Bialik as Amy Farah Fowler in The Big Bang Theory CBS

She, however, cautioned there are negative experiences too. "I should add that sometimes experiences that are negative can be so powerful that you don't remember them at all. That's a whole different chemical process."

The actress who plays Amy in The Big Bang Theory went on to share her own experience with fans' nostalgia. "Depending on where I am, and I guess the age of the person coming up to me, a lot of people tend to know me from "Big Bang Theory." It's a show that has tens of millions of people watching it every week, so statistically speaking, many people who also like me on "Blossom" are probably watching "Big Bang Theory," Mayim told the outlet.

"But once in a while, I'll get someone who says "I don't watch 'Big Bang Theory,' but I really loved you on Blossom. Often I'll get young women, young enough to be my daughter, saying "my mom loved you on 'Blossom,' but I'm too young to have seen it, so I love you on Big Bang Theory. That makes me feel old," she cheekily added.