The Science of Love

NIMH Laboratory of Brain and Cognition An fMRI scan investigating areas of the brain used in working memory - Similar types of scans were carried out by Dr Fisher in her research

On the other hand there is no doubt that Helen Fisher writes with a light, breezy touch and that she presents a comprehensive account of the various emotions that interact with romantic love. So far as the underlying chemistry is concerned, that too is presented in a clear manner. But it is not chemistry that will reveal the working of the mind. No more than fifty different types of molecule have so far been recognised to function as neurotransmitters in the human body. Let me remind you what these chemicals do. The connection between one nerve cell and the next is a salt water-filled fibre that stops just short of the nerve cell it is going to innervate. A tiny electric current, generated in the first cell, passes along the fibre until it reaches the gap between nerve fibre and the recipient cell. At this point a chemical substance, the aptly named neurotransmitter, is released.

Neurotransmitter molecules bind to the membrane of the recipient cell, causing it to respond in a particular manner. Within the brain, the outcome is generally to transmit current to a further nerve cell, and so on. There are over a trillion discrete fibers that connect the hundred billion nerve cells in our brain to each other; many nerve cells are linked to more than a thousand other cells. The result is an immensely complicated neural network. No two brains, not even those of identical twins, have exactly the same cell-to-cell connections. With a trillion fibres and just fifty types of neurotransmitter to choose from, it is clear that the vast majority of fibres use the same neurotransmitter. So it is not chemicals like dopamine or norepinephrine that distinguish one set of fibres from another. The discrimination between thoughts of love and every other emotion must reside in the precise pathways – among a myriad of possibilities – that are followed when a new feeling, a novel thought, arises in the brain.

So it is not chemistry but biophysics - or an innovative discipline yet to be developed - that will elucidate the basis of emotions like love and hate, calm and anger, pleasure and sorrow, joy and despair. In the meantime we can do no more than applaud the author's attempts, and look enviously across the Atlantic: what fun it must be for a love-struck psychology student at Stony Brook to have the opportunity of engaging in Helen Fisher's research projects.

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