Behavioral and Electrophysiological Evidence for Gestational Age Effects in Healthy Preterm and Fullterm Infants Studied Two Weeks after Expected Due Date

We investigated the effects of gestational age at birth on behavioral and electrophysiological measures of 135 medically healthy infants, studied at 42 weeks postconception, and stratified into 3 groups--early-born preterms, 26-32 weeks (n = 55); middle-group preterms, 33-37 weeks (n = 43); and fullterms, 38-41 weeks (n = 37). Subjects were studied behaviorally with the Assessment of Preterm Infants' Behavior (APIB) and electrophysiologically with brain electrical activity mapping (BEAM). Fullterms showed significantly better behavioral function than both preterm groups. Less difference was found between the preterm groups. EEG spectral and photic evoked response were of significantly less amplitude for the preterms than the fullterms. Path analysis showed gestational age effects on behavioral (3 of 6) and electrophysiological (13 of 17) variables due to postnatal complications. We conclude that some differences attributable to gestational age at birth are explained by the cumulative effect of minor but unavoidable complications associated with premature birth. We speculate that remaining effects may result from developmentally inappropriate sensorimotor stimulation consequent to the premature experience of an extrauterine environment.     

Linguistic profiles of dyslexic and good readers

Linguistic profiles of 60 boys with average intelligence were examined at kindergarten, grade 2, and grade 4. The subjects were 7 dyslexic, 7 mildly dyslexic, 30 average, and 16 good readers, defined in terms of the discrepancy between standardized reading and intelligence scores. Across the three ages, reader groups did not differ in language comprehension, but did differ in confrontation and rapid automatized naming (RAN), three syntactic measures, and verbal memory. Group strengths and weaknesses were, with few exceptions apparent in kindergarten and maintained throughout. The kindergarten tasks which most effectively predicted reading group membership at grade 4 were giving letter sounds, and rapid naming; these predicted 4th grade reading group at close to 100 percent accuracy. The study, together with a further comparison of average and high IQ good readers, provides an interesting contrast between the role of RAN and Confrontation naming in reading. This work was supported in part by NIHCD grants RO1HD18761 to F. H. Duffy, RO1HD18654 to H. Als, and the Mental Retardation Grant P30HD18655 to C. F. Barlow.     

Prediction of dyslexia in kindergarten boys

This study followed 163 boys from kindergarten through fourth grade. A battery of neurospychological and preacademic tests and electrophysiological measures (BEAM) were administered in kindergarten, and reading tests at grade 4, in an attempt to delineate precursors of dyslexia. Three of the kindergarten tasks (giving sounds associated with letters, rapid naming of numbers, and finger localization) differentiated dyslexics from normal readers with 98 percent correct classification. The tasks primarily involve grapheme-phoneme associations, storage and retrieval of phonological information in long-term memory, and verbal labeling. Results are interpreted as confirming the role played by phonological processing tasks in the prediction of dyslexia. Preliminary BEAM results for visual evoked potential topography suggest a significant increment in the distribution of this potential in the left parietal and frontal region, and, for auditory evoked potential topography, a significant difference between the two groups in the right posterior hemisphere. This work was supported in part by NIHCD grants RO1HD18761 to F.H. Duffy, RO1HD18654 to H. Als, and the Mental Retardation Grant P30HD18655 to C.F. Barlow.