"Brainstorm" is like being caught in a Novocaine hurricane -- if you're not a numbskull when you walk in, you will be by the time you walk out. Talk about your brain drain.

As Natalie Wood's last film, it's not a pretty epitaph. The late actress looks puffy- eyed and drawn, a good 15 years older than costar Christopher Walken, who sounds like he swallowed a sponge. They're a mismatched young computer couple who, with Louise Fletcher and Cliff Robertson, build a thought recorder. It's a computer hooked up to brain-wave sensors that provides users with the likes of continuous loop orgasms and other out-of-pajama experiences.

Director Douglas Trumbull, whose leading lady died before he finished the film, is a visual wizard who, as a consequence, now gives his special effects top billing. Surprisingly, they're mundane, considering Trumbull's glittering creations for "Close Encounters of the Third Kind" and "Blade Runner." You can duplicate what you get here by squeezing your eyelids closed real tight: See the squiggly, wiggly lights?

At the same time, it's easy to understand why a technician turned director would fail his cast -- his fine first film "Silent Running" notwithstanding. Wood, for one, acts like a disoriented airline stewardess rather than the computer whiz she's supposed to be playing. Walken thinks he's a guest at a slumber party. Robertson plays the head of a computer corporation as if he were a tuna- boat captain. And Fletcher -- often 40 pounds heavier in one scene than in the next -- smokes and smokes and overacts until she has a heart attack. She's able, however, to record the attack and her subsequent trip to heaven on magnetic tape. Instead of Gabriel, she encounters a globular light show and a view of earth from what must be God's own space shuttle.

The object, for some reason, then becomes Walken's need to feel that tape. You get an exact playback: sight, sound, constriction of the blood vessels. Wood helps him experience it in a kind of low-energy "WarGames" computer-access scene, but makes him promise he won't die in the process. It's a pretty ghoulish business under the circumstances.

Only one scene was rewritten, says Trumbull, to finish the film without Wood. Still, it seems there wasn't an inch to spare for editing, as though nothing was pared away. And to beef it up, there's a slapstick scene in a robotics lab that approaches racism, with a black security guard doing "feets don't fail me now" pratfalls. There are also rollercoaster rides that date back to the early days of Cinerama masquerading as state-of- the-art cinematography. And occasionally the photographer turns his fisheye lens upside down.

For "Brainstorm," they were scraping the bottom of the stink tank. BRAINSTORM -- At the Circle MacArthur and the Springfield Mall.