COGNITIVE NEUROSCIENCE AND NEUROPSYCHOLOGYVowel categorization induces departure of M100 latency from acoustic predictionRoberts, Timothy P. L.CA; Flagg, Elissa J.; Gage, Nicole M.1Author Information Department of Medical Imaging, University of Toronto, 150 College St., Toronto, Ontario, M5S 3E2, Canada 1Mail Code 5100, 3151 Social Sciences Plaza A, University of California, Irvine, CA 92697-5100, USA CACorresponding Author: firstname.lastname@example.org Received 16 April 2004; accepted 26 May 2004 NeuroReport: July 19th, 2004 - Volume 15 - Issue 10 - p 1679-1682 doi: 10.1097/01.wnr.0000134928.96937.10 Buy SDC Metrics Abstract MEG studies have shown that the timing (latency) of the evoked response that peaks ∼100 ms post-stimulus onset (M100) decreases as frequency increases for sinusoidal tones. We investigated M100 latency using a continuum of synthesized vowel stimuli in which the dominant formant frequency increases from 250 Hz (perceived /u/) to 750 Hz (perceived /a/) in 50 Hz steps. While M100 latency did vary inversely with formant frequency overall, frequency modulation was flattened within each vowel category. However, for mid-continuum ambiguous tokens (i.e. those with increased reaction time/decreased accuracy in the concurrent behavioral identification task), M100 reverted to formant frequency differences, agreeing with previous findings of frequency-dependence. A theory is proposed in which phonological categorization emerges from specific spatial distribution of frequency-tuned neurons. © 2004 Lippincott Williams & Wilkins, Inc.