Auditory lexical decision, categorical perception, and FM direction discrimination differentially engage left and right auditory cortex

• Published in: Neuropsychologia Vol. 42; no. 2; pp. 183 - 200
• Main Authors: Poeppel, David, Guillemin, Andre, Thompson, Jennifer, Fritz, Jonathan, Bavelier, Daphne, Braun, Allen R
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2004; Elsevier Science
• Subjects: Acoustic Stimulation; Adult; Anatomical correlates of behavior; Auditory Cortex - anatomy & histology; Auditory Cortex - diagnostic imaging; Auditory Cortex - physiology; Auditory Perception - physiology; Behavioral psychophysiology; Biological and medical sciences; Blood Flow Velocity; Brain Mapping; Cerebrovascular Circulation; Dose-Response Relationship, Radiation; Female; Functional Laterality - physiology; Fundamental and applied biological sciences. Psychology; Hemispheric asymmetry; Humans; Language; Magnetic Resonance Imaging; Male; Neuropsychological Tests; Phonetics; Pitch Discrimination - physiology; Production and perception of spoken language; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Reaction Time; Semantics; Spectral; Speech perception; Temporal; Time Factors; Tomography, Emission-Computed; Verbal Behavior - physiology; Word recognition; Hemispheric asymmetry; Word recognition; Spectral; Temporal; Speech perception; Human; Frequency modulation; Word; Central nervous system; Cognition; Verbal perception; Experimental study; Auditory cortex; Encephalon; Hearing; Acoustic stimulus; Language; Topography; Lexical decision; Speech; Perception; Auditory pathway; Recognition
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2003.07.010

Recent neuroimaging and neuropsychological data suggest that speech perception is supported in bilaterally auditory areas. We evaluate this issue building on well-known behavioral effects. While undergoing positron emission tomography (PET), subjects performed standard auditory tasks: direction discrimination of frequency-modulated (FM) tones, categorical perception (CP) of consonant–vowel (CV) syllables, and word/non-word judgments (lexical decision, LD). Compared to rest, the three conditions led to bilateral activation of the auditory cortices. However, lateralization patterns differed as a function of stimulus type: the LD task generated stronger responses in the left, the FM task a stronger response in the right hemisphere. Contrasts between either words or syllables versus FM were associated with significantly greater activity bilaterally in superior temporal gyrus (STG) ventro-lateral to Heschl’s gyrus. These activations extended into the superior temporal sulcus (STS) and the middle temporal gyrus (MTG) and were greater in the left. The same areas were more active in the LD than the CP task. In contrast, the FM task was associated with significantly greater activity in the right lateral–posterior STG and lateral MTG. The findings argue for a view in which speech perception is mediated bilaterally in the auditory cortices and that the well-documented lateralization is likely associated with processes subsequent to the auditory analysis of speech.