Hemispheric differences in processing tone frequency and amplitude modulations.

Transient frequency and amplitude modulations (FMs, AMs) of sound are requisite to speech recognition. We recorded whole-head magnetoencephalographic signals from seven subjects to binaural 620 ms 667 Hz tones, with 3, 30, or 300 ms FMs or AMs in the beginning or middle of the tone. Responses were significantly larger and earlier for FMs than AMs, for rapid than slow modulations, and for modulations at the beginning (BEG) than in the middle (MID) of the sound. BEG 3 ms FMs elicited strongest signals in the left and MID 3 ms FMs in the right hemisphere. Fast MID modulations produced significantly stronger responses in the right than left hemisphere. These differences may reflect different functions of the left and right hemisphere in speech perception.

[1]  P. Tallal,et al.  Neurobiological Basis of Speech: A Case for the Preeminence of Temporal Processing , 1993, Annals of the New York Academy of Sciences.

[2]  Zvi Wollberg,et al.  Responses of cells in the auditory cortex of awake squirrel monkeys to normal and reversed species-specific vocalizations , 1983, Hearing Research.

[3]  G. Ojemann.  Cortical organization of language , 1991, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[4]  P. Tallal,et al.  Defects of Non-Verbal Auditory Perception in Children with Developmental Aphasia , 1973, Nature.

[5]  Steven L. Miller,et al.  Speech and other central auditory processes: insights from cognitive neuroscience , 1995, Current Opinion in Neurobiology.

[6]  J. Mäkelä,et al.  Magnetic responses of the human auditory cortex to noise/square wave transitions. , 1988, Electroencephalography and clinical neurophysiology.

[7]  R A Cole,et al.  Segmenting speech into words. , 1980, The Journal of the Acoustical Society of America.

[8]  R. Zatorre,et al.  Pitch perception of complex tones and human temporal-lobe function. , 1988, The Journal of the Acoustical Society of America.

[9]  J. Mäkelä,et al.  Different analysis of frequency and amplitude modulations of a continuous tone in the human auditory cortex: A neuromagnetic study , 1987, Hearing Research.

[10]  Kourosh Saberi,et al.  A common neural code for frequency- and amplitude-modulated sounds , 1995, Nature.

[11]  Mitchell Steinschneider,et al.  Speech evoked activity in the auditory radiations and cortex of the awake monkey , 1982, Brain Research.