Pierre Paul Broca (1824–1880) was a French doctor best known for his work on the region of the brain responsible for producing language. In 1861, Broca began his work on language and the brain with an autopsy of the brain of one of his patients, Mr Leborgne , who, while being able to understand speech, was unable to speak. Broca discovered damage to the left side of the brain, which he argued was responsible for language production. This area soon became known as ‘Broca’s area’. The discovery of Broca's area revolutionised the understanding of language processing, speech production, and comprehension, as well as the effects that damage to this area may cause. It also popularised the principle of localisation of function, which suggests that psychological functions can be associated with particular regions of the brain.