Something to talk about
Language distinguishes humans from the other hominids (chimpanzees, gorillas, and orangutans). We can point out three major aspects of language: writing, reading and speaking, which is the easiest to explain, from a nonscientific point of view.
Interestingly, languages have some points in common in every culture: every person learns it at an early stage of life and every language presents its own syntax (subject, verb and complement: what varies is the order) and grammar (every language has rules).
Towards the end of the 19th century, Paul Broca and Carl Wernicke found the two, most important areas of human brain linked to the ability to speak.
Both studied a pathology generally called aphasia (inability to speak). It has to be pointed out that aphasia can mean either the inability to understand heard words or to speak. And that made a huge difference.
The two aphasias, in fact, depends on which of the two areas has been damaged: Wernicke's or Broca's area.
Both areas are in the left brain in right handed people. In 70% percent of left handed humans, they are on the same side, while the remaining 30% is divided into a 15% who has them on the right and a 15% in both hemispheres.
Wernicke's area is in the posterior temporal lobe and surrounds the primary auditory area. That is quite obvious, because of the links between listening and speaking.
Words reach A1 and, then, Wernicke's area, which contains sound images of heard words. Hence, thanks to this area, we can comprehend the words we hear.
The information is sent to the Broca's area by the arcuate fasciculus. Broca's area is situated in the left inferior frontal region and creates those programmes for moving the organs we use to articulate words (mouth, tongue, etc.).
It has to be said that there are other parts of our brain, which are involved in speaking: the supplementary language area and some zones of motor and somatosensory cortex.
For what concerns aphasias, according to the different functions of the damaged regions, we can explain the three different types: a damage of the Wernicke's area will result in a receptive aphasia (the patient can't understand any language) and one of the Broca's area in an expressive aphasia (the patient understand what heard but won't be able to repeat it or to reply).
A problem with the auxiliary areas causes a problem of speech arrest: the patient is likely to develop a variable inability to conclude phrases.
