Neuroscience of stuttering.

We disagree with William H. Perkins' comments (Letters, “Stuttering: a matter of bad timing,” 26 Oct., p [786][1]) pertaining to the Random Samples item “The stammering brain” (3 Aug., p 795). Perkins takes issue with the discovery by Anne Foundas at Tulane University and her colleagues that anatomical differences between stutterers and nonstutterers in the two brain regions associated with speech and language, Broca's area and Wernicke's area, might explicate the etiology of stuttering ([1][2]). Briefly, Perkins says these areas function at cognitive rates too slow to be considered a source of stuttering. Perkins cites George Miller's studies, decades ago, indicating that the human cognitive rate is 7 ± 2 thoughts per second, the same as the rate of syllable production, which is under voluntary control ([2][3]). Perkins maintains, “Any cause of stuttering has to account for why it can be involuntary and … how high-speed speech sounds can be produced with low-speed cognitive and linguistic equipment.” Certainly, Broca's area and Wernicke's area can process data more rapidly than 7 ± 2 items per second. Miller's review related to issues of absolute judgement and immediate memory when humans are in a stimulus- response setting or functioning in a communication system. He discussed how brains overcome the apparent 7 ± 2 limit, for instance, by making stimuli multidimensional, and he emphasized that such recoding powerfully increases the amount of information that can be processed. Our language, he commented, can repackage material into a few chunks rich in information ([2][3]). Without demonstration of an equivalency between how we process the stimulus input we memorize and how we process spontaneous thought for speech/language production, the 7 ± 2 limit lacks merit when applied to linguistic encoding of thoughts. Regardless, there is no neuroscientific data indicating that we think at the rate at which we talk, not to mention that there is no denotation of what a “thought” is. Foundas' discovery that abnormalities in the anatomic substrate of language might differ among stutterers raises the possibility that some have difficulty processing speech-motor control because of aberrancies in the frontal opercular areas (Broca's), others because of aberrancies near Wernicke's area. Their research has far-reaching implications: Perhaps stutters with anterior versus posterior gyral abnormalities differ in severity of their disorder, genetic background, or response to speech or pharmacologic therapy. 1. [↵][4]1. A. L. Foundas 2. et al. , Neurology 57, 207 (2001). [OpenUrl][5][Abstract/FREE Full Text][6] 2. [↵][7]1. G. Miller , The Psychology of Communication (Basic Books, New York, 1967). [1]: /lookup/doi/10.1126/science.294.5543.786b [2]: #ref-1 [3]: #ref-2 [4]: #xref-ref-1-1 "View reference 1 in text" [5]: {openurl}?query=rft.jtitle%253DNeurology%26rft.stitle%253DNeurology%26rft.aulast%253DFoundas%26rft.auinit1%253DA.%2BL.%26rft.volume%253D57%26rft.issue%253D2%26rft.spage%253D207%26rft.epage%253D215%26rft.atitle%253DAnomalous%2Banatomy%2Bof%2Bspeech-language%2Bareas%2Bin%2Badults%2Bwith%2Bpersistent%2Bdevelopmental%2Bstuttering%26rft_id%253Dinfo%253Apmid%252F11468304%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [6]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6OToibmV1cm9sb2d5IjtzOjU6InJlc2lkIjtzOjg6IjU3LzIvMjA3IjtzOjQ6ImF0b20iO3M6MjQ6Ii9zY2kvMjk1LzU1NTcvOTczLjIuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9 [7]: #xref-ref-2-1 "View reference 2 in text"