Imagine your life on a computer screen. All the plot points are there -- the highs, lows, a wedding, perhaps a baby. Now highlight the last five years. Click delete.

That's the premise of "The Vow," a new film that opened this weekend starring Rachel McAdams as Paige, a woman who survives a terrifying auto accident but awakens from a coma with amnesia. She has no memory of the previous five years. Her new home, new hairstyle, new husband Leo (Channing Tatum). It's all a blank. What's worse, the last thing she does remember is being happily engaged -- to Jeremy (Scott Speedman), a hotshot attorney, eager to make up for past wrongs.

"I feel like I'm getting a free do-over in life," Paige says.

Inspired by true events, the movie is a love story at heart, but it's also the latest in a long line of films propelled by memory loss. Profound amnesia is rare, but you wouldn't think so given its frequent appearance on film and TV. "Memento," "50 First Dates," "The Bourne Identity," even the animated "Family Guy" and "Finding Nemo" have all tackled the issue. Many are satisfying -- and medically inaccurate.

"Most amnesiac conditions in films bear little relation to reality," writes Dr. Sallie Baxendale, a clinical neuropsychologist, in a 2004 review of amnesia movies in the British Medical Journal.

In reality, amnesia -- either retrograde (an inability to recall past events, as in "The Vow") or anterograde (new events) -- can be triggered by various causes, including neurosurgery, stroke, emotional trauma and, of course, a conk on the head.

To be as accurate as possible, "Vow" director Michael Sucsy researched memory loss. Like many patients, Paige speaks hoarsely upon emerging from her coma (breathing tubes irritate the throat); she suffers headaches; she hears sounds louder than normal.

But Sucsy drew the line at depicting other learning deficits (which are typical) or shaving her head (standard, as doctors drill a hole into the skull of those who suffer brain swelling).

"It's Hollywood, and we don't want Rachel McAdams with a shaved head," Sucsy said. "It's a movie -- not a documentary."

Hollywood's fascination with amnesia dates back to silent films such as "Garden of Lies" (1915), in which a bride loses her memory after a car crash on her wedding day. To cure her, a doctor enlists a man to pose as her husband, hoping to jar her memory.

Other Hollywood cures include hypnosis ("Spellbound," "Dead Again"), mysterious brews ("Cowboys & Aliens") and, of course, another conk on the head ("Tarzan the Tiger," Tom & Jerry's "Nit-Witty Kitty" and "Family Guy," to name a few) -- as if another brain injury, on top of the first, will help.

But science gets massaged on-screen.

"A startling number of 'bad' characters become 'good'" as a result of amnesia, Baxendale noted. Goldie Hawn morphs from spoiled socialite to domestic goddess (in "Overboard"). Assassins ("The Bourne Identity," "The Long Kiss Goodnight") rethink old ways.

Sci-fi flicks conveniently erase memory ("Total Recall," "Paycheck," the "Men in Black" films).

And screenwriters invent new diagnoses.

In "50 First Dates," Adam Sandler falls for Drew Barrymore, who has Goldfield Syndrome, a made-up condition in which new memories formed during the day vanish in sleep. Sandler "meets" her day after day, hoping to break through the neurological fog.

"Some viewers might envy Ms. Barrymore's ability to forget her romantic encounters with Mr. Sandler, but her affliction seems to be the result of a head injury," Baxendale noted.

Ouch, doc -- that's cold.