Intro | Broca's Area | Wernicke's Area
Part 1: Image-Mapped Tutorial
Part 2: Matching Self-Test
Part 3: Multiple-Choice Self-Test
Wernicke's Area was identified in 1874 with the discovery that a lesion in this region of the left parietal and temporal lobes results in an inability to comprehend language. With this second report of language disruption following damage to the left hemisphere, this side of the brain emerged as the "dominant" hemisphere. The more quiet or "dumb" right hemisphere was labeled "nondominant". In more recent years, with increased understanding of the right hemisphere's contributions to mental processes, this dominant / nondominant distinction has evolved into a more accurate picture in which both hemispheres make unique, but necessary contributions to most behaviors.
| Advanced |
Wernicke's aphasia is often referred to as fluent aphasia; fluent, even grammatical speech is possible, but much of what is said is confused and makes little sense. Anomia, or difficulty with finding the proper word to use, is also common with fluent aphasia. In addition to describing fluent aphasia, Wernicke introduced the concept of disconnection symptoms that result from the severing of connections between two cerebral processing areas. Wernicke speculated that if fibers connecting Broca's and Wernicke's areas (called arcuate fasiculus) were damaged, a speech deficit would occur in which speech sounds, articulation, and comprehension would be retained but speech would be disrupted. This so-called conduction aphasia would result from the inability to judge the appropriateness of on-going speech. Another classic symptom of conduction aphasia is the inability to repeat what others say. Wernicke's speculations have proven accurate in most cases.
Disruption of the ability to comprehend spoken language is most frequently associated with damage to the first temporal gyrus. Disruption of the ability to comprehend written language (dyslexia) is most frequently associated with damage to the adjacent posterior parietal cortex and the disconnection of visual areas in occipital lobe from Wernicke's area. It is speculated that temporal cortex, composing Wernicke's area, contains sound images of the words used to represent objects and concepts. Recent studies of language processing in the normal nervous system using PET (positron-emission test) imaging, have indicated that only occipital cortex is activated during the passive reading of words. Reading the name of an object and thinking of or stating the use of the object activates much of frontal cortex including Broca's area.