18.14: Higher Mental Functions of the Brain: Language

Language is a system of communication that allows the expression of thoughts, ideas, and feelings. The brain processes language in both hemispheres.

Language formation and comprehension take place in the dominant hemisphere. The dominant hemisphere is responsible for understanding the meaning of spoken, written, or sign language, as well as the ability to communicate. For most people, the left hemisphere is the dominant one. The right hemisphere, then, gives tone and emotional context to the language.

Language processing in the left hemisphere happens in two areas. Wernicke's area, also known as the "language comprehension center," is located in the brain's left temporal lobe and is responsible for understanding language. This area interprets incoming speech from verbal, gestures, and written sources. Broca's area, also known as the "speech production center," is located in the brain's left frontal lobe and is responsible for producing language. It sends signals to the motor cortex that then initiates movements of muscles involved in speech.

The neural pathways involved in perceiving and vocalizing a specific word operate as follows:

• First, information about the word is conveyed to Wernicke's area.
  • If the word is written, Wernicke's area receives input about the word from the primary visual area.
  • If the word is spoken, Wernicke's area receives input about the word from the primary auditory area.
• Upon receiving the information, Wernicke's area translates the written or spoken word into the corresponding thought.
• Next, for the individual to respond to the spoken or written word or a gesture, Wernicke's area transmits information about the word to Broca's area.
• Broca's area then receives this input and develops a motor pattern to activate the necessary muscles for articulating the word.
• The motor pattern is conveyed from Broca's area to the primary motor area, which triggers the appropriate muscle contractions required for speech.
• Ultimately, the coordinated contraction of the speech muscles allows the word to be spoken.