Lexical decision of nonwords and pseudowords in humans: a positron emission tomography study

In this functional positron emission tomography study brain activations during an auditory lexical decision task with two experimental conditions were investigated. First, the subjects had to discriminate between real words and nonwords; second, real words varied with pseudowords. Comparing each of these tasks to an auditory control condition we found bilateral activation of the superior temporal and inferior frontal gyrus, lateralized to the left in the pseudoword condition. The comparison of the lexical decision tasks revealed higher rCBF during the pseudo-/real word decisions within BA 47, adjacent to Broca's area, and the anterior cingulate. The data support the notion that the lexical decision during a nonword task is mainly based on a phonological discrimination process, whereas a pseudoword task more strongly requires lexical access resulting in activation of BA 47.

[1]  J. A. Frost,et al.  Determination of language dominance using functional MRI , 1996, Neurology.

[2]  Karl J. Friston,et al.  Hearing and saying. The functional neuro-anatomy of auditory word processing. , 1996, Brain : a journal of neurology.

[3]  K. Alho,et al.  Lateralized automatic auditory processing of phonetic versus musical information: A PET study , 2000, Human brain mapping.

[4]  J C Mazziotta,et al.  Improved signal-to-noise in PET activation studies using switched paradigms. , 1995, Journal of nuclear medicine : official publication, Society of Nuclear Medicine.

[5]  Klaus Willmes,et al.  Hemispheric lateralization at different levels of human auditory word processing: a functional magnetic resonance imaging study , 2000, Neuroscience Letters.

[6]  H. Herzog,et al.  Pharmacokinetics and radiation dose of oxygen-15 labelled butanol in rCBF studies in humans , 2004, European Journal of Nuclear Medicine.

[7]  Karl J. Friston,et al.  The cortical localization of the lexicons. Positron emission tomography evidence. , 1992, Brain : a journal of neurology.

[8]  M. Posner,et al.  The attention system of the human brain. , 1990, Annual review of neuroscience.

[9]  Karl J. Friston,et al.  Detecting Activations in PET and fMRI: Levels of Inference and Power , 1996, NeuroImage.

[10]  S. Scott,et al.  Identification of a pathway for intelligible speech in the left temporal lobe. , 2000, Brain : a journal of neurology.

[11]  H. Scheich,et al.  Phonetic Perception and the Temporal Cortex , 2002, NeuroImage.

[12]  E. T. Possing,et al.  Human temporal lobe activation by speech and nonspeech sounds. , 2000, Cerebral cortex.

[13]  C. Price.  The anatomy of language: contributions from functional neuroimaging , 2000, Journal of anatomy.

[14]  Stephen M. Rao,et al.  Human Brain Language Areas Identified by Functional Magnetic Resonance Imaging , 1997, The Journal of Neuroscience.

[15]  R J Wise,et al.  Separate neural subsystems within 'Wernicke's area'. , 2001, Brain : a journal of neurology.

[16]  W. Marslen-Wilson,et al.  The temporal structure of spoken language understanding , 1980, Cognition.

[17]  M. Torrens.  Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268 , 1990 .

[18]  Richard S. J. Frackowiak,et al.  The anatomy of phonological and semantic processing in normal subjects. , 1992, Brain : a journal of neurology.

[19]  R. Zatorre,et al.  Voice-selective areas in human auditory cortex , 2000, Nature.