Different brain activation patterns in dyslexic children: evidence from EEG power and coherence patterns for the double-deficit theory of dyslexia.

AIMS QEEG and neuropsychological tests were used to investigate the underlying neural processes in dyslexia. METHODS A group of dyslexic children were compared with a matched control group from the Brain Resource International Database on measures of cognition and brain function (EEG and coherence). RESULTS The dyslexic group showed increased slow activity (Delta and Theta) in the frontal and right temporal regions of the brain. Beta-1 was specifically increased at F7. EEG coherence was increased in the frontal, central and temporal regions for all frequency bands. There was a symmetric increase in coherence for the lower frequency bands (Delta and Theta) and a specific right-temporocentral increase in coherence for the higher frequency bands (Alpha and Beta). Significant correlations were observed between subtests such as Rapid Naming Letters, Articulation, Spelling and Phoneme Deletion and EEG coherence profiles. DISCUSSION The results support the double-deficit theory of dyslexia and demonstrate that the differences between the dyslexia and control group might reflect compensatory mechanisms. INTEGRATIVE SIGNIFICANCE These findings point to a potential compensatory mechanism of brain function in dyslexia and helps to separate real dysfunction in dyslexia from acquired compensatory mechanisms.

[1]  B. Horwitz,et al.  Functional connectivity of the angular gyrus in normal reading and dyslexia. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[2]  M. Wolf,et al.  Naming-Speed Processes and Developmental Reading Disabilities , 2000, Journal of learning disabilities.

[3]  P. Skudlarski,et al.  Disruption of posterior brain systems for reading in children with developmental dyslexia , 2002, Biological Psychiatry.

[4]  Carsten Elbro,et al.  Predicting dyslexia from kindergarten : The importance of distinctness of phonological representations of lexical items , 1998 .

[5]  V. Mann,et al.  Phoneme Awareness and Future Reading Ability , 1993, Journal of learning disabilities.

[6]  T. Fernández,et al.  Electroencephalographic coherences discriminate between children with different pedagogical evaluation. , 1995, International journal of psychophysiology : official journal of the International Organization of Psychophysiology.

[7]  M. Adams.  Reading Acquisition. , 1993 .

[8]  E Donchin,et al.  A new method for off-line removal of ocular artifact. , 1983, Electroencephalography and clinical neurophysiology.

[9]  Mateo Obregón,et al.  Early naming deficits, developmental dyslexia, and a specific deficit hypothesis , 1992, Brain and Language.

[10]  B. Sklar,et al.  An EEG Experiment Aimed Toward Identifying Dyslexic Children , 1972, Nature.

[11]  H. Wimmer,et al.  Alpha and beta band power changes in normal and dyslexic children , 2001, Clinical Neurophysiology.

[12]  M. Habib,et al.  The neurological basis of developmental dyslexia: an overview and working hypothesis. , 2000, Brain : a journal of neurology.

[13]  Leanne M Williams,et al.  Standardized assessment of cognitive functioning during development and aging using an automated touchscreen battery. , 2006, Archives of clinical neuropsychology : the official journal of the National Academy of Neuropsychologists.

[14]  P. Accardo,et al.  Specific Reading Disability: A View of the Spectrum. , 1998 .

[15]  M. Shiota,et al.  Cognitive and neurophysiological evaluation of Japanese dyslexia , 2000, Brain and Development.

[16]  Torleiv Høien,et al.  Dyslexia: From Theory to Intervention , 2000 .

[17]  P. Tallal.  Experimental Studies of Language Learning Impairment: From Research to Remediation , 1999 .

[18]  B. Shaywitz,et al.  Dyslexia (Specific Reading Disability) , 2005, Biological Psychiatry.

[19]  Evian Gordon,et al.  Integrative Neuroscience in Psychiatry: The Role of a Standardized Database , 2003 .

[20]  E. Gordon,et al.  Integrative Neuroscience: The Role of a Standardized Database , 2005, Clinical EEG and neuroscience.

[21]  F. Manis,et al.  Naming Speed, Phonological Awareness, and Orthographic Knowledge in Second Graders , 2000, Journal of learning disabilities.

[22]  Joseph K. Torgesen,et al.  Prevention and Remediation of Severe Reading Disabilities: Keeping the End in Mind , 1997, Components of Effective Reading Intervention.

[23]  N. Geschwind,et al.  Developmental dyslexia: Four consecutive patients with cortical anomalies , 1985, Annals of neurology.

[24]  J. Fletcher,et al.  Specific reading disability (dyslexia): what have we learned in the past four decades? , 2004, Journal of child psychology and psychiatry, and allied disciplines.

[25]  L. Katz,et al.  Functional neuroimaging studies of reading and reading disability (developmental dyslexia). , 2000, Mental retardation and developmental disabilities research reviews.

[26]  L. Waites,et al.  Definition of dyslexia. , 1968, Canadian Medical Association journal.

[27]  Stephen R. Burgess,et al.  Changing relations between phonological processing abilities and word-level reading as children develop from beginning to skilled readers: a 5-year longitudinal study. , 1997, Developmental psychology.

[28]  D Liberati,et al.  EEG coherence in Alzheimer's disease. , 1998, Electroencephalography and clinical neurophysiology.

[29]  M. Eckert,et al.  Anatomical correlates of dyslexia: frontal and cerebellar findings. , 2003, Brain : a journal of neurology.

[30]  James L. McClelland,et al.  Understanding normal and impaired word reading: computational principles in quasi-regular domains. , 1996, Psychological review.

[31]  D. Tucker,et al.  EEG coherency. I: Statistics, reference electrode, volume conduction, Laplacians, cortical imaging, and interpretation at multiple scales. , 1997, Electroencephalography and clinical neurophysiology.

[32]  J. Victor,et al.  Power spectra and coherence in the EEG of a vegetative patient with severe asymmetric brain damage , 2000, Clinical Neurophysiology.

[33]  Dorothy V. M. Bishop,et al.  Cerebellar Abnormalities in Developmental Dyslexia: Cause, Correlate or Consequence? , 2002, Cortex.

[34]  Gerry Leisman,et al.  Aetiological factors in dyslexia: IV. Cerebral hemispheres are functionally equivalent. , 1980, The International journal of neuroscience.

[35]  N. Brunswick,et al.  Trait and state EEG indices of information processing in developmental dyslexia. , 2000, International journal of psychophysiology : official journal of the International Organization of Psychophysiology.

[36]  E. Gordon,et al.  PRELIMINARY VALIDITY OF “INTEGNEUROTM”: A NEW COMPUTERIZED BATTERY OF NEUROCOGNITIVE TESTS , 2005, The International journal of neuroscience.

[37]  Sabine Weiss,et al.  The contribution of EEG coherence to the investigation of language , 2003, Brain and Language.