Neural Mechanism of Mammalian Vocalization

Re: comment on Dr. Holstege's presentation


On Tue Dec 8, S.M. Brudzynski wrote
>Dr. Holstege. I enjoyed reading your presentation. The description of speech mechanisms provides further clarification on the distinction between speech and human vocalization. I think that you agree that, under physiological conditions, vocalizations are initiated in the limbic structures and speech in the neocortex. Thus, patinets with motor aphasia can still vocalize. The problem of interpretation may arise in some patients with cortical lesions or congenital dysfunctions. Would their vocalization-like vocal utterances be regarded as attempts to produce abnormal speech or as vocalizations. This rather academic question has clinical relevance and important diagnostic value not only in brain damaged cases but also in the interpretation of the vocal outcome during focal epileptic seizures.
Dear Dr. Brudzynski,
Thank you for reading my presentation. In respect to your question, I would like to repeat that, in my view, speech is a combination of vocalization and motor cortical modulation. Therefore, all speech is produced by the limbic system as well as by the motor cortex, instructed by Broca's area. Thus, speech is not produced by the motor cortex alone. All vocal utterances by humans consist of a combination of motor cortex and limbic system activity. When of these two components the motor cortex is deficient, the limbic system remains, i.e. only the vocalization part remains. However, the individual had the intention, possibly by means of its prefrontal cortex (?), to produce speech, for which the individual had to initiate activity of the limbic system as well as of the motor cortex. Thus, in patients with cortical lesions only the vocalization part remains intact, producing the vocalization like utterances. However, the individuals had the intent to produce both components of speech.
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