“What a loss, to spend that much time with someone only to find out that she’s a stranger.”
Joel (Jim Carrey) decides to have brain surgery to erase his ex-girlfriend, Clementine (Kate Winslet) from his memories when he finds out that she had the same procedure.
He just wants to make amends. Unfortunately, he shows up at the bookstore where Clementine works and discovers that she’s dating a younger guy named Patrick (Elijah Wood). Joel’s friends begrudgingly tell him that Clem had a weird procedure and Joel, sad and alone with Valentine’s Day coming up, desperately seeks the help of the neurosurgeon who performed it, Dr. Howard Mierzwiak (Tom Wilkinson).
The problem is not with Joel, but with his mind. One Psychology Today article explains that the assault of memories we have after a breakup is actually normal. These memories are being processed from the vantage point that our brain no longer has the same reasons for holding on to the memories as it once did. Instead of planning a wedding, we’re trying to remember what it is about this person that made us think we wanted to marry them in the first place!
Dr. Mierzwiak tells Joel when he comes in for the surgery that, “Technically, the procedure is brain damage.” This is due to the elimination of the memories that Joel associates with Clementine; some of them are long-term, some short-term, but all erasure means destroying neural pathways that link Joel with Clementine.
Of course, that doesn’t stop human chemistry. One idea presented in Eternal Sunshine of the Spotless Mind is that vanishing neurons do not delegate human attraction. Certain relationships like the one between Joel and Clementine, and the one between Dr. Mierzwiak and his colleague, Mary (Kirsten Dunst) may find a way, even without the memory that this has already happened to them.