Identification of a pathway for intelligible speech in the left temporal lobe*

Sophie K. Scott1
, C. Catrin Blank3, Stuart Rosen2 and Richard J. S. Wise3

1 Institute of Cognitive Neuroscience and 2 Department of Phonetics and Linguistics, University College London,
3
MRC Clinical Sciences Centre, Cyclotron Unit, Hammersmith Hospital, London, UK

Correspondence to: Sophie K. Scott, Institute of Cognitive Neuroscience, University College London, London WC1N 3AR, UK E-mail: sophie.scott@ucl.ac.uk

*
the full text of this paper appears in Brain: A journal of neurology, Vol. 123, No. 12, 2400-2406, December 2000


Abstract
It has been proposed that the identification of sounds, including species-specific vocalizations, by primates depends on anterior projections from the primary auditory cortex, an auditory pathway analogous to the ventral route proposed for the visual identification of objects. We have identified a similar route in the human for understanding intelligible speech.
Using PET imaging to identify separable neural subsystems within the human auditory cortex, we used a variety of speech and speech-like stimuli with equivalent acoustic complexity but varying intelligibility. We have demonstrated that the left superior temporal sulcus responds to the presence of phonetic information, but its anterior part only responds if the stimulus is also intelligible. This novel observation demonstrates a left anterior temporal pathway for speech comprehension.

Keywords: PET; superior temporal sulcus; speech perception

Spectrograms of the sentence, "She cuts with her knife"

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Waveforms of the sentence, "She cuts with her knife"

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Spectrograms of the sentence, "They're buying some bread"

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Waveforms of the sentence, "They're buying some bread"

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