Peter Chaisit-Charles: The patient Peter Chaisit-Charles had a suspected tumour in his brain. For the last four years he has suffered from epilepsy, with his lesion causing abnormal electrical activity in the brain. Recently it started to affect his short term memory too. The tumour was growing in the left temporal lobe – the area of the brain that controls our speech and language functions. If the tumour had continued to grow, Peter could have lost part of his ability to talk.