Cortical Auditory Signal Processing in Poor Readers

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 96; no. 11; pp. 6483 - 6488
• Main Authors: Nagarajan, Srikantan, Mahncke, Henry, Salz, Talya, Tallal, Paula, Roberts, Timothy, Merzenich, Michael M.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 25.05.1999; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: Acoustic Stimulation; Adult; Auditory cortex; Auditory Cortex - physiology; Auditory Cortex - physiopathology; Auditory signals; Behavioral neuroscience; Biological Sciences; Biology; Cerebral Cortex - physiology; Cerebral Cortex - physiopathology; Control groups; Dyslexia; Dyslexia - physiopathology; Ears & hearing; Electroencephalography; Evoked Potentials, Auditory - physiology; Female; Frequency ranges; Humans; Magnetic fields; Magnetoencephalography; Male; Mental stimulation; Neurology; Neurons - physiology; Reaction Time; Reading; Reference Values; Sensors; Waveforms
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.96.11.6483

Magnetoencephalographic responses recorded from auditory cortex evoked by brief and rapidly successive stimuli differed between adults with poor vs. good reading abilities in four important ways. First, the response amplitude evoked by short-duration acoustic stimuli was stronger in the post-stimulus time range of 150-200 ms in poor readers than in normal readers. Second, response amplitude to rapidly successive and brief stimuli that were identical or that differed significantly in frequency were substantially weaker in poor readers compared with controls, for interstimulus intervals of 100 or 200 ms, but not for an interstimulus interval of 500 ms. Third, this neurological deficit closely paralleled subjects' ability to distinguish between and to reconstruct the order of presentation of those stimulus sequences. Fourth, the average distributed response coherence evoked by rapidly successive stimuli was significantly weaker in the β - and γ -band frequency ranges (20-60 Hz) in poor readers, compared with controls. These results provide direct electrophysiological evidence supporting the hypothesis that reading disabilities are correlated with the abnormal neural representation of brief and rapidly successive sensory inputs, manifested in this study at the entry level of the cortical auditory/aural speech representational system(s).