INTRODUCTION TO SPECIAL ISSUE: UNDERSTANDING THE NATURE-NURTURE INTERACTIONS IN LANGUAGE AND LEARNING DIFFERENCES.

Dr. Bernice Wong, editor of the Learning Disability Quarterly, invited this special issue in response to the growing interest in the biological factors in language and learning differences. Many professionals in the field of learning disabilities do not have the necessary training to be critical consumers of such research, for example, in genetics and the various brain-imaging technologies. In addition, there is often a long delay between publication of genetics and brain-imaging research findings in peer-reviewed journals and the trickle-down of these findings to practitioners or researchers who specialize in areas other than the biological factors in language and language differences. Furthermore, some professionals who are enthusiastic about biological explanations of language and learning differences do not have first-hand experience in genetics or brain-imaging research and may embrace brain-based educational bandwagons naively and uncritically.

Therefore, I invited representatives of five biologically oriented research approaches to write articles for this special issue and gave them a threefold charge. First, I asked each to provide a tutorial on their major research tool for investigating biological influences on language and learning for readers in other fields who have not had training in genetics, neuroanatomy, brain imaging, electrophysiology, or cognitive neuroscience. Second, I asked each to provide a succinct summary of current research understandings in their respective fields regarding language and learning differences. Third, I asked each of them, as researchers with expertise in the biological bases of language and learning differences, to discuss some of their own recent research.

Although each contributor was given the charge of writing about his or her biological research, each addressed, without any solicitation, the issue of interactions between biological and environmental factors. Wendy Raskind, M.D., Ph.D, a medical geneticist, emphasized that even if a screening test materializes some day for biologically based reading disorder, it will probably identify those who are at-risk for reading problems rather than diagnose reading disability. It is still the case that quality of reading instruction plays a critical role in preventing and lessening the severity of reading disability. Christiana Leonard, Ph.D., a neuroanatomist, showed that not only physical properties of the brain but also socioeconomic indicators of environmental factors predict performance on reading and language measures. Todd Richards, Ph.D., a neurophysicist, stressed the importance of conducting functional imaging at a developmental stage when reading problems are treatable and preventable -- because not only are there brain differences between those who learn to read easily and those who struggle in learning to read, but the brain may also change in response to learning to read. Dennis Molfese, Ph.D., and Victoria Molfese, Ph.D., are developmental psychologists who have combined electrophysiological and behavioral methods in longitudinal studies to demonstrate that brain recordings of newborns can predict language and reading problems in the preschool and school age years, respectively. Their research tool may be used to identify at-risk children for very early intervention. Finally, James Booth, Ph.D., a cognitive neuroscientist associated with the pioneering program in learning disabilities at Northwestern University, makes the important point that none of the biological methods yields data interpretable without a model of cognition and language based on paradigms in which individuals process incoming information from the environment.

Thus, research on the biological factors in language and learning should not be equated with biological determinism. Nature is but one variable in the nature-nurture interaction equation. Understanding these biologically influenced constraints may lead to early identification of at-risk children for purposes of early intervention in which individually tailored environments are created to facilitate language development and learning. Just as concerning as those who too readily embrace biological explanations are those who categorically reject them because environmental interventions such as teaching result in learning -- just because development and learning are responsive to teaching does not mean that they are not influenced by biological factors.

An unexpected theme to emerge in these articles is the distinction between language disability and reading disability, which is receiving increasing research attention. One of the lessons of genetics research is that the same phenotype (expressed behavior) can have multiple underlying genotypes (sources of biological influence). Reading is no exception. Leonard's research is identifying differences in the neuroanatomical markers of children with language disability compared to reading disability. Molfese and Molfese are finding that different patterns of electrophysiological recordings in newborns are associated with low language ability and reading disability. Richards is restricting his brain-imaging research to students with reading disability without primary language disability at this point. So is Raskind. However, more research is needed, as both argued, from multiple disciplinary perspectives on poor reading in individuals with language disability and those without language disability (but probably subtle problems in metalinguistic judgment.)

The major goal of this special issue is to empower nonexperts on biological research methods to become critical consumers of the rapidly growing research literature on the biological bases of language and learning differences. Towards this end, readers may find the articles to be not only useful sources of current information but also a reference to return to when trying to make sense of a research article using a particular tool of biological research. I recommend that readers also read another special issue on the same topic that is forthcoming from the Journal of Learning Disabilities, guest edited by Jeff Gilger.

I thank each of the peer reviewers who provided valuable comments on these articles and are in their own right major contributors to the research on the biological bases of language and learning disabilities: Guinevere Eden, Ph.D.; Jack Fletcher, Ph.D.; Jeff Gilger, Ph.D.; Panagiotis G. Simos, Ph.D.; and Frank Wood, Ph.D. I also thank Reid Lyon for his leadership in this field and finally Bernice Wong for the opportunity to share this research on the contribution of nature to learning problems with the readers of the Learning Disability Quarterly. I am very grateful to each of the authors who produced these articles under tight time constraints and also read and commented on each other's articles.

NOTES

Grant No. P50 33812-05 from the National Institute of Child Health and Human Development supported preparation of this special issue on the biological bases of reading and language disorders.

Please address correspondence to: Virginia W. Berninger, 322 Miller, Box 353600, University of Washington, Seattle, WA 98195-3600.

VIRGINIA WISE BERNINGER, Ph.D., is professor, University of Washington.