Humans are social animals. Being able to communicate efficiently is essential in everyone’s life. Not by chance, during the evolution, we developed an even more complex language ability.
Speaking is an activity which might seem obvious. Nonetheless, the comprehension and production of a speech are very complex activities. Nature gave to our brain specific regions for these functions.
Being able to hear a speech doesn’t mean to be able to understand it.
For more information read also A journey into the Nervous System: the brain
As we have seen in a previous article, the human brain has many areas with very specific functions.
The areas which receive sounds are in the temporal lobe, more precisely in the superior posterior temporal left gyrus. Pulses from the cochlear nerve arrive there.
The primary auditory cortex, the part of the cerebral cortex which receives the stimuli for cochlear nerve, occupies Brodmann’s areas 41 and 42. These areas are, as we can see in the picture, near to the secondary auditory areas. The latter one has the function to associate a sound to his meaning, searching it into the memory of the person.
Moreover, nearby, there is a particular region: Wernicke’s area.
The Wernicke’s area
In an influential 1976 article called “Wernicke’s region: Where is it?” Bogen and Bogen defined the Wernicke area (commonly known as Wernicke’s area) unequivocally as “the area where a lesion will cause language comprehension deficit.”
In contrast, in recent decades the definition of “Wernicke’s area” become an anatomical rather than a functional one. It became a synonym of temporal superior posterior left gyrus (pSTG) and supramarginal gyrus (SMG).
Recent studies are changing our knowledge of this area.
For more information read also A journey into the Nervous System: the neurons
During studies about some aphasias (a deficit in the speech production) researchers have seen that the Brodmann’s area 22, in other words Wernicke’s area, has more functions in the production of the words than in the comprehension. Before a motor command is sent to the muscles, the speaker must momentarily activate knowledge about the sequence of consonant and vowel speech sounds (phonemes) that form the word to be spoken. Here Wernicke’s area seems to be involved.
Broca’s Area and the production of a speech
Producing words correctly is a complex process. There are many different areas which are interested in it.
Broca’s area is one of them and is considered to be the center of the spoken language.
This area occupies the 44 and 45 Brodmann’s areas. It is placed before the motor cortex, which sends commands to the face muscles. An injury at this level causes a deficit in the words’ production. In this region are stored motor patterns for each word we want to use.
Obviously, this area is not alone in this control. Even the supplementary motor cortex, placed in the frontal lobe, has similar functions.
All these connections form a very complex tangle with the aim of carrying out an activity which is apparently obvious: speaking.