Credit: Markku Lahdesmaki/Corbis

Platitudes are burbled to me, which I ignore, grabbing my plastic hammer again before my sister can take it. My mother sits back and finds her place in her cloth-eared book.

As I clumsily hold the toy hammer in my right hand, I look down at it. How much longer will I know the truth? How long can I hold on to my precious memories before they are lost and I become an empty vessel like my beaker, only to be refilled with the same contents? I must try to hold on to my past, my life.

There is one memory above all that I still cling to. More than the memories of my work, my beautiful wife, my three children and five grandchildren. Oh Lord. I can't even remember their names. One was John. Or Jonny. Or was that my younger brother? He had fair hair … or was that my daughter? An involuntary whimper escapes from my mouth.

My mother looks up briefly from her book. I try to calm myself, but it is not easy. Where memories should stand there are only holes. How frightening, to know that your life is being stolen from you and there is nothing you can do to hold on to it.

But I'm getting distracted again. One memory remains imprinted in my mind as though burnt with a branding iron. This memory is too strong to be rubbed out like a mistake. Perhaps the trauma of it has reached too deeply into my brain: the memory of my death, 18 months ago.

The familiar antiseptic odour of the large room. Frustrated, I swivelled on the lab stool that squeaked. The latest results weren't right. The GFAP stains had failed and the whole batch of biopsies was barely readable. I readjusted the microscope, suppressing a yawn.

This should have been an ideal candidate for the double-blind trial – a patient who had developed epilepsy due to trauma five years before his death. The trial was my latest attempt to track down consciousness within the brain.

We were examining patients whose brains were measurably impaired, preventing them from being consciously aware of such ordinary actions as seeing movement, yet still able to carry out those actions unconsciously.

Rather than study living patients, my research group studied the neural structures after their deaths. Large-scale biopsies of key regions of the brains were prepared, sliced into layers less than the thickness of a single cell, stained, scanned into the computer, then image processing and extrapolation software derived their original three-dimensional neural connectivity.

This patient had been especially interesting. Apparently, in addition to blind-sight, his symptoms during each fit resembled a near-death experience: the classic tunnel with white light at the end, a feeling of weightlessness and calm. He maintained consciousness each time while experiencing this effect.

The biopsy of his parietal lobes should have been an excellent additional sample for the trial. Now it was ruined, damn it, all because of a faulty batch of stain.

Sighing, I released the slide and walked to the medical waste disposal, threw it away. My watch said 19:22 - already over an hour later than I'd promised my wife. I took off the old lab coat, grabbed my jacket. Locking the lab doors, I took the stairs two at a time as usual, palmed my swipe card on the security door and left the building.

It had been raining. Streetlights reflected their orange glows from the wet tarmac. My car flashed its lights at me as I disarmed it. Then the reassuring clunk of the door as I pulled it shut.

I barely remember the first part of the drive home. My mind was still on the failed biopsies. How many weeks behind were we now? Twin dazzling lights directly in front of my face. Maybe my airbag deployed. A horrible, deafening noise that seemed to come from inside my body. An instant of excruciating pain.