Every three or four weeks a face would appear at the glass panel of my office door. It was a pale, cartoon face and belonged to Philip. He never made appointments. Nor did he knock on the door. He just stood there looking in until I noticed and beckoned him through. He would stay for half an hour or so, standing all the while and bobbing slightly like a puppet, then leave without announcement, sometimes mid-sentence. Our conversations were fractured. "Do you think my internal organs are made of Lego?" he would say, or, "I'm visible now, am I?" There were long pauses, minutes on end, as he scanned the walls for shifting hieroglyphics or attended to his voices, of which there were several. One was critical and abusive; one gave a commentary on his actions ("He's filling the kettle") in counterpoint with another that tried to redirect his behaviour ("Don't fill the kettle"). The devil was in there too, growling deep oaths in a mysterious language. When Phil went, he left traces in my brain, like a tune when the record stops. I felt infected. Was I moving like a puppet? Was that my cartoon face in the mirror? Was I visible?
If Phil's head was pandemonium, Jeff's, by comparison, was a vacuum jar. He sat like a corpse at the kitchen table as his wife prepared coffee. "You're a bit low at the moment, aren't you love?" she said, but he was beyond melancholy. We were handed mugs of coffee and left to it. For the next hour I entered the void of Jeff's frontal lobes, probing with puzzles and neuropsychological exercises: "Tell me as many words as you can think of beginning with the letter 'A.'" "Ant," he said. I always found it hard working with depressed people. They might feel a photon brighter for their hour of cognitive therapy but I would leave the session feeling soaked to the bones with their despair. Depression has a physical presence. Jeff's impoverished emotional state was due to brain damage rather than mood disorder. It was a sense of absence that permeated the room. He was a black hole. The longer I spent in his company the emptier I felt.
When I interacted with Philip, my eyes widened slightly; I felt myself paying closer attention to the walls; my thoughts became looser at the joints. By contrast, I only had to think of Jeff to feel a sense of inertia. Thoughts are embodied and our bodies are socially embedded. To remember an event is partly to simulate bodily states that were active at the time. This applies not just to the visceral reconstructions of Proustian reminiscence when an odour or a melody fuels the limbic brain and transports us to another place and time. A voluntary train of thought or the reading of a text will also cause subtle reconfigurations of physiology as our biological machinery simulates previous experience. Words infuse the body as well as the mind. These simulations are compartmentalised and partial, but our reactions are sometimes disproportionate. I have memories that can make me shudder and thoughts that steal up in the dead of night and grip my gut. Certain forms of brain damage can induce heightened somatic and emotional responses to the most innocuous stimuli. One man tells me that, after surviving a viral infection of the brain, he could "feel" words. Reading a description of a wintry scene would leave him ice cold and shivering.
The human frame is designed for social mimicry, much of it quite involuntary, and patterns we detect in another person's mental life and behaviour find an automatic resonance in our own. The evidence is there from the first few hours of life when a baby will mirror its mother's facial expressions. You see it in the "postural synchrony" of friends gossiping over coffee; or in our prime minister aping the presidential cowboy strut at White House press conferences. Mimicry serves important functions, and brains have circuits specialised for the purpose. So-called "mirror neurons" in the frontal cortex are activated not only in response to actions generated by oneself (reaching for an object, say) but also in response to the perception of similar actions performed by other individuals. One might think of mirror neurons as a kind of bridge between minds. Through observation of others, conscious and unconscious, we extend our own knowledge and behavioural repertoire. Mimicry is a learning mechanism. It creates channels for empathy and co-operation, and provides a semaphore for communication of allegiance, deference and status. (The PM's funny walk is ambiguous. It signals deference to the president, but at the same time is an assertion of Blair's own status. The two of them seem to be engaged in a funny walks arms race, the cowboy strut becoming slightly more exaggerated at each successive encounter.)
Jeff has no spark, partly, perhaps, because he is blind to the spark in others. His mirror neurons are shattered. He is disconnected from the social grid. (Philip, on the other hand, sees reflections and connections everywhere.) Yet the last time I saw Jeff, he surprised me by suddenly bursting into life. A little boy toddled into the room. Jeff swept him into his arms and kissed his cheek. "My son," he said, "My son." I had never seen him so alive. It wasn't his son, as a matter of fact. But I didn't let on.
