Clinical evidence of the motor speech center
Lesions in the area of the motor speech center are called Broca’s aphasia. Aphasia means as much as speechlessness. Broca’s aphasia results in characteristic symptoms that make it possible to distinguish it from Wernicke’s aphasia (see below).
Thus, although the affected persons can still understand what is spoken and read, they can only speak with considerable difficulty. Depending on the extent of the damage, the patient can no longer form individual words or speech production is completely absent. Typical symptoms of Broca’s aphasia include Speech production is significantly slowed down, strained and articulation is often unclear.
It should be noted that Broca’s aphasia is not caused by paralysis of muscles essential for speech production. The disturbances that the affected persons show when speaking are present in a similar form when writing.
- The formation of new, non-sensorial words (neologisms)
- Speaking short, choppy sentences (telegram style)
- The almost complete absence of grammatical syntax (agrammatism).
Anatomy of the sensory language center
The Wernicke area plays an immense role in language comprehension. This means that it plays a role not only in interpersonal communication but also in the thought processes of an individual, since these also largely run through linguistic formulations.
Clinical evidence of the sensory language center
A lesion in the Wernicke area with speech disorder is called sensory or Wernicke’s aphasia. In this case the understanding of speech is clearly disturbed. In contrast to patients with Broca’s aphasia, patients often speak fluently and a lot (logorrhea) and in normal sentence melody, but often with incomprehensible words.
Sentence structure and grammar also usually do not make sense anymore. They make use of semantic and phonematic paraphases. Semantic paraphasias describe a confusion of words from a similar group of meanings, for example table instead of chair.
Phonematic paraphasias are neologisms that allow the original meaning of a word to be guessed at (for example, bulb instead of flower), but in some cases do not allow the original word to be identified. In contrast to Broca’s aphasia, patients with Wernicke’s aphasia usually do not notice that something is wrong with their language, so they do not understand why their counterpart does not react adequately. A lesion of the secondary auditory cortex in the non-dominant hemisphere, on the other hand, does not lead to an impairment of speech understanding, since the Wernicke speech center is only present on one side, in the dominant hemisphere of the brain.
A disorder in the non-dominant hemisphere leads, among other things, to a loss of music understanding and recognition. Damage to the gyrus angularis, which connects the secondary auditory cortex with the visual cortex, usually causes disturbances in the speech center. The speech center is therefore a complex network that has its two main organs in the frontal and temporal lobes and is connected to other areas of the brain via numerous nerve fibers. Certainly, today the origin of language is still not understood in all its complexity.
