Will Self: PsychoGeography

In Fantastic Voyage, an absurd 1966 sci-fi film that made a tremendous impact on me as a child, a top scientist is shot and receives a devastating brain injury. Rather than resort to more orthodox surgical techniques, the decision is made to miniaturise a submarine full of expert medics, and inject them into the boffin's bloodstream. Here, the nano-sub powers up the gooey conduits of arteries, attacked by savage antibodies, until the clot is reached and zapped with a laser.

At least part of what riveted me to Fantastic Voyage was the idea of being shot up with an itsy-bitsy Raquel Welch, but I also think its extreme inversion of our way of perceiving space was even more significant. It's a truism that objects in the mouth appear far larger to that sensitive "organ" than they are in reality, yet here was an ensemble cast of Hollywood actors caroming about someone's circulatory system, with him none the wiser. We depend more than we realise on the integrity of our bodies as a way of defining our place in the world; that's why a child is able to contemplate violent discorporation with such equanimity: he truly doesn't know where he is.

Nor do you know where you are when you undergo surgery. The pre-med shot is a woozy trip down a tiled tunnel towards the furry black hole of the general anaesthetic. Oblivion scrambles up the space-time continuum, so that you emerge younger than you were when you went under, gently weeping atop blue remembered hills. It could be that it's this peculiarity of hospitalisation that has made me the geo-weirdo I so manifestly am. For I was born with an inguinal hernia, and - according to my mother - spent the first six weeks of my life in a "little cage" in the Charing Cross Hospital, being fed through a tube.

Christ knows what sort of trauma this induced: maybe it caused the strabismus with which I'm also afflicted. In order to correct this I used to go for regular sessions at University College Hospital, where they made me look at magic-lantern slides of bunnies hopping over hedges; or rather, not. Apparently the non-hopping meant I had no binocular vision, and hence no true depth perception. When I was about eight they operated at Ormond Street and "tied up" the muscles of my lazy left eye. This didn't help me to catch balls any better, but it did mean that I no longer stared into the sky at a crazy angle, as if expecting a googly from God.

A more traumatic instance of psycho-surgery came in my early twenties, when I repaired to the Royal Free Hospital in Hampstead to have my tonsils removed. In the bed next to me was a sergeant major from the SAS (or so he claimed), who'd been shot in the neck by a sniper on the Falls Road in Belfast. This bit of his tale must've had some veracity, because when I moaned about the hideous pain in my throat, the nurse admonished me: "You should've seen him, when he came in. He had a swelling on his neck bigger than his head!" The SAS man and I got on surprisingly well, and we conducted clandestine operations together, sneaking around the great, concrete ziggurat of the hospital in search of liquor and smokes to consume in its hideous atria.

But this is all mere persiflage; leading up to the very point of my nub: the last surgery I had was on my mouth, the roof to be specific. Lying down in a dental chair, on the 17th floor of Guy's Tower by London Bridge, a very jolly-hockey-sticks surgeon cut a neat, conical section out of the roof of my mouth. I was fully conscious at the time, so I had none of that odd dislocation of space and time. It occurred to me that early, wildcat surgery must at least have had this advantage: you knew exactly where you were, even if you were in excruciating pain. "This might hurt a little when the anaesthetic wears off," explained Joyce Grenfell as she ushered me out.

A little? By the time I reached home I was a puling wreck. Not only was I in pain, but the deadly truism was in full force. The incision in the roof of my mouth wasn't a centimetre across - it was a mile wide. It was a vast pit gouged out of the living earth of my body, up the terraced sides of which swarmed many many thousands of cruelly exploited peasants, such as you see in photographs by Sebastiao Salgado. In some grotesque inversion of Fantastic Voyage, the entire world, actual size, was being forced into a hole in my poor, vulnerable mouth. Naturally, Raquel Welch was nowhere in sight.

Will Self's new novel, 'The Book of Dave', is published by Viking at £17.99