Peter H. Wolff - US grants

This proposal examines the hypothesis that impaired serial order control for coordinated action is an underlying functional deficit common to reading impairment and the non-reading behavioral correlates of specific reading retardation. Under a neuropsychological frame of reference, various measures of coordinated unimanual and bimanual action, motor speech, and expressive language are examined, with particular emphasis on the interaction between rate and timing precision or rate and serial order control as the dimensions which may best characterize the disorder. Emphasis on the motor system implies no causal relationship between movement disturbances and reading retardation. On the other hand, the motor system is well suited for the objective analysis and decomposition of temporal variables in complex behavior that are shared by speech, expressive language, and skilled action. The study focuses on adolescents and adults with specific reading disabilities to examine which aspects of serial order control may be developmentally invariant. It compares male and female adolescents with specific reading disability; and it uses a matched "pathological" control group of adolescents with specific learning disabilities who are reading at grade level to test whether the presumed deficit of serial order control is particular to reading retardation or common to various learning disabilities.

The Fragile-X syndrome is one of the most common forms of mental retardation with a well-defined genetic etiology. The clinical management and educational guidance of affected individuals, as well as genetic counselling for family members depend critically on informed knowledge about the intellectual potential and psychological performance profiles of affected individuals. Although the syndrome has been described primarily in males, identified female carriers of the Fragile-X may show mild forms of developmental disability, but almost nothing is known at present about their intellectual potential and behavioral characteristics. The project will examine the behavioral features of institutionalized and non-institutionalized males with the Fragile-X site, and of obligate female carriers with and without the Fragile-X, as well as unaffected controls who either are or are not retarded, and who are selected specifically for each subgroup. All subjects will be examined by an extensive neuropsychological protocol that emphasizes component aspects of language function, motor coordination, and spatial abilities, as well as for patterns of social communication. Affected individuals are identified by currently accepted methods of karyotyping for the Fragile-X, and these will be complemented by more fined molecular linkage techniques once the latter are operational. Individuals with a confirmed Fragile-X, and genetic relatives as well as unrelated controls, will be examined by behavioral measures to test the level of overall intellectual potential and different profiles of performance deficits. Results from such studies will be compared between affected males who are or are not institutionalized, affected females and unaffected obligate female carriers. The purposes of the study are two-fold: to provide a detailed description of the behavioral characteristics in affected individuals; and to explore the potential of the syndrome as a prototype for investigations on the behavior genetics of mental retardation.

psychomotor function; reading disorder; developmental genetics; child psychology; gender difference; mathematical model; eye movements; human population genetics; questionnaires; psychological tests;