Auditory processing of different types of pseudo-words: an event-related fMRI study.
Imaging results on real word and pseudo-word processing have been heterogeneous, allowing only cautious claims about the neuroanatomical loci of lexico-semantic processing. In order to shed more light on this issue, we examined the impact of different structures of non-lexical stimuli on the outcome of comparisons between such items and matched real words. We anticipated that the degree to which a pseudo-word still resembles a particular real word template determines how word-like it is processed. To verify this idea, we tested different types of pseudo-words (either phonotactically legal and transparently or opaquely derived from real words or phonotactically illegal) in an event-related fMRI paradigm utilizing a lexical decision task. All types of pseudo-words elicited a stronger hemodynamic brain response than real words in the bilateral superior temporal gyri. Real words produced stronger brain activations than pseudo-words in the left posterior middle temporal and angular gyri, the rostral and caudal cingulate gyrus, the precuneus and the right inferior temporal gyrus. When contrasted to opaque pseudo-words transparent pseudo-words elicited a stronger brain response in a temporo-parietal region adjacent to the one observed for real words. Our results provide further support for the involvement of the left posterior middle temporal and angular gyri in lexical-semantic processing. The data also indicate that transparently derived pseudo-words are processed similarly to real words. In contrast, semantic operations are blocked when opaquely derived pseudo-words are processed.
Raettig
Tim
T
Max-Planck-Institute for Human Cognitive and Brain Sciences, Stephanstrasse 1a, D-04103 Leipzig, Germany. raettig@cbs.mpg.edu
Kotz
Sonja A
SA
D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D003627:Data Interpretation, Statistical; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009010:Monte Carlo Method; D011578:Psycholinguistics; D011597:Psychomotor Performance / Q000502:physiology; D013067:Speech Perception / Q000502:physiology; D013702:Temporal Lobe / Q000502:physiology