Finding our way through the white and the grey

If you examine a man having a gaping wound in his head, reaching the bone, smashing his skull and breaking open the viscera of his skull, you should feel palpate his wound. You find that smash which is in his skull like the corrugations which appear on molten copper in the crucible, and something therein throbs and flutters under your fingers like the weak place in the crown of the head of a child when it has not become whole. Anonymous (c.1550 bce), in Ebers papyrus (cited in J. F. Nunn,...

Temporal lobe epilepsy emotions from nowhere

Epilepsy is a spontaneous electrical discharge that can start anywhere in the brain. Because of this, it is useful for natural experiments. Asking people with epilepsy to report their experiences during an attack and recording the electrical disturbance itself allow us to discover how each part of the brain produces our experience of the world. From such studies, we have learnt that damage to the limbic system can cause laughing and crying. A particular form of epilepsy, in which the electrical...

Closing the pain gate

In the spinal cord, where the pain nerves connect with other nerves, is the pain gate. Nerves dealing with touch sensation can switch off the connections between a pain nerve and the rest of the chain, which means that a pain signal arriving in the spinal cord cannot go any further and the pain sensation never arrives in the brain. We have all experienced the pain gate in action by rubbing it better. This contact with a painful area activates the touch nerves that block the pain nerves. This...