Joan Stiles - US grants

The purpose of this study is to expand upon a finding from a previous study in this laboratory which indicated that children with focal right cerebral hemisphere injury have difficulty with spatial construction tasks. The earlier study documented in a very general way impairment within a special cognitive domain. This project will examine the early development of spatial cognition in toddlers with right hemisphere injury at a much more detailed level of analysis. The specific aims of this project are: To define more precisely the spatial deficit identified previously; to observe whether and how the form of the deficit changes with development; and to determine if children who have difficulty with spatial construction are also delayed in the acquisition of the linguistic terms for those relations. The methodology proposed here is an adaptation of a spontaneous play task in which children are given toys and simply allowed to play. The play sessions are videotaped. The tapes serve as the basis for micro-analysis of spatial construction strategies. Data from normal 1-4 year old children, recently collected in this laboratory, indicate that developmental change in the childrens' representation of space can be analyzed along a number of different dimensions. With development children: Construct more kinds of relations and combine different relations within a single spatial grouping; build in more directions in space; use multiple spatial loci; the products of the construction process are more elaborate; and the procedures used to achieve particular groupings are more complex. We want to use these same indices of developmental change can be used to assess spatial deficit in right hemisphere damaged children. Finally, we want to examine childrens' comprehension of spatial terms, like in, on, and next to, to assess the relationship between language and thought in children with a specific conceptual disorder. Do we see delay in the acquisition of spatial terms, or can the children acquire the terms based on partial knowledge of their meaning.

The purpose of this project is to study the development of a range of spatial cognitive skills in 6-month to 4-year-old children with either right or left hemisphere focal brain injury to determine the extent to which spatial deficits can be documented in children with injuury to the right side of the brain. The project extends and elaborates the findings of an earlier study assessing children's block play, which identified, for the first time, a spatial constructive deficit in 2- and 3-year-olds with focal right hemisphere injury. The specific aims of this project are: First, to define more precisely the spatial constructive deficit identified previously, using tasks similar to the block play tasks used in the earlier study, but applying much more detail analytic measures; second, to examine drawing as a different kind of spatial constructive task to determine whether the deficit is specific to the organization of objects in space, or more general; and third, to extend the range of spatial cognitive assessment to the study of spatial perception. For all of the tasks, children will be followed longitudinally so that we can observe possible changes in behavior that might reflect functional recovery or development. Different methods will be used to assess spatial cognitive ability for the different tasks. The first involves a spontaneous block play task in which children are given small sets of toys and encouraged to play. Their play activities are videotaped, and later analyzed in detail for the kinds of spatial relations generated. The method for the drawing tasks in similar, except that children are asked to draw pictures of common objects, then both the pictures and the ways in which the children generated the pictures are assessed in detail. Spatial perception will be assessed differently according to the age of the children. Children under one year of age will be tested using versions of standard preference for novelty and object localization paradigms. Match-to-sample tasks will be used with 2- to 4-year-old children.

DESCRIPTION: The proposed research, a five-year prospective longitudinal study, aims to examine the early development of spatial analysis, which is considered to involve the ability to specify the parts, configuration, and the integration of parts and configurations. The specific aims are: 1) to define patterns of deficit associated with early injury; 2) to look at reaction time studies for spatial analysis in real time; 3) to examine longitudinal patterns of development in these skills after early focal injury; 4) to look at cross-domain spatial processing; and 4) to extend previous work by applying an fMRI protocol for examining patterns of neural activation in spatial analytic processing. Three cognitive-behavioral studies and one fMRI study are proposed. The studies aims to extend the previous findings from the applicants showing left and right-sided early-acquired brain lesions in children to have similar pattern of spatial analysis deficits to adults with later-acquired left or right lesions. The new information from the proposed research would concern description of extra spatial analysis tasks by brain region, with a view to comparing construction and perception of space information, and the examination of differences in neural organization following early focal injury.

Previous studies of spatial development within the context of the Center have been limited and focused on spatial analytic processing in a subset of population groups. In this phase of the Center we will expand our study of spatial processing to systematically examine the relations between the various levels of spatial processing. Performance on spatial cognitive tasks may require different levels of spatial processing. Therefore, we need to define and study spatial processes ranging from the most basic attentional mechanisms to aspects of complex planning, and to compare profiles of deficit and normal processing across these levels of processing. The focal lesion populations will be used as the basis for generating specific hypotheses about possible associations and dissociations in spatial processing as they are related to lesions in particular brain regions. The focal lesion population constitutes a core population within the Center in that they are the group for whom we have the best descriptions of neurological deficit, and the group for whom we can make the strongest predictions about performance profiles within the area of spatial processing. The provide a means of defining how spatial processes can come apart. In this sense, the focal lesion population provides a window on normal development. If profiles of impairment reflect normal points of cleavage in the spatial analytic system, then based on our findings,, it should be possible to design studies which in the performance of normally developing children is made to echo the profiles of children with early injury. The study of the focal lesion population provides the opportunity to create cycles of confirmatory testing which can help to define the nature or normal processing and as well as to specify patterns of impairment. All of this work can be extended to the study of population with less well defined lesions. Four subdomains of spatial processing will be examined: will be initiated through a new collaboration with Eric Courchesne at UCSD. Dr Courchesne has an international reputation for studies of attention in normal and impaired populations. He has proposed a series of studies focused on basic mechanisms of attention. These studies are important to our understanding of performance in other spatial domains. Our studies of spatial cognition will include both an extension of our work in spatial analysis as well as a new study of mental rotation. Tasks of spatial memory will include a new memory for location task and the memory task using the Rey Osterreith Complex Figure. Finally, will begin to examine the development of executive functioning.

Over the past ten years, we have made significant progress in addressing key questions concerning deficit and development after early stroke. We found evidence of subtle early impairment and subsequent development in each domain examines. However, the profiles of impairment and development differed across domains. Deficits of language acquisition are initially pervasive in that they are observed following injury to widely distributed brain areas. Spatial analytic deficits exhibit more specific patterns of brain-behavior association, similar to those observed among adults with injury to comparable brain regions. We have to look for ways to resolve the apparent disparity in our cross-domain findings. The model that best fit our data focuses on redefining the nature of early plasticity. Recent animal studies provide strong evidence that plasticity plays a central role in brain development. Brain organization is to a large extent defined by the changes in patterns of connectivity that occur as a result of input to the maturing system. Early injury constitutes a perturbation of normal development. Specific neural resources are lost, and there is consequent impairment of the system. However, it is also a developing system and therefore a system with an exuberance of resources the fate of which are determined in large measure by input. Thus, the magnitude and duration of the initial impairment may well depend on a range of factors such as the timing of insult, extent and location of injury, and specificity of the neural substrate for athe function under consideration. In the next phase of the injury, and specificity of the neural substrate for the function under consideration. In the next phase of the project, we will extend our investigation of the long-term effects of early injury on development. We have made considerable headway in defining developmental profiles in the preschool and early school-age period. Less is known about change in the later school years. One goal for the next phase will be the focused examination of development within and across these domains. We will also initiate a full-scale study of two other important domains, spatial attention and executive functioning. We have initiated a collaboration with Eric Courchesne at UCSD who has an international reputation for studies of attention of normal and impaired populations. He has proposed studies focused on the basic mechanisms of attention which are important to our understanding of performances in other domains. Finally, we will begin to examine the development of executive functioning ina the FL population. Planning is key to a wide range of problem solving activities. Limitations on the initiation or flexibility of planning skills could have serious consequences for the development of children with early injury.

[unreadable] DESCRIPTION (provided by applicant): Although there has been substantial work documenting behavioral change in spatial cognitive processing, little is known about the development of the neural systems that mediate these functions. Recent advances in fMRI now make it possible to ask critical questions concerning the relations between behavioral change and change in the associated brain systems: What does it mean to say that particular brain regions mediate, or to come to mediate, certain types of processing? How do patterns of neural commitment emerge in development? Specifically, to what extent does the development of the neural systems reflect the profiles of change observed in behavioral data? The major goals of this proposal focus on documenting the relationship between developmental change in a basic aspect of spatial cognitive functioning, visual pattern processing, and change in the brain system, the ventral occipital temporal lobe system, that mediates these functions. Three series of studies are proposed. The first is focuses on mapping developmental change in the functional organization of the ventral visual system, exploring the neural organization of category specific information along the ventral surface of the temporal lobe. The second is directed toward examining change in the patterns of hemispheric lateralization for the basic cognitive processes involved in spatial pattern analysis, focusing on the separable process of configural, or global, and featural, or local, level processing. Third examines regulation of information exchange across the cerebral hemispheres, looking at the exchange of information related to global and local level processes. In addition, because all of these studies use functional Magnetic Resonance Imaging (fMRI) to address questions of brain organization in pediatric populations, this project will also investigate two methodological questions: (1) Are there changes with development in the BOLD response. Arterial spin labeling (ASL) measures will be employed to address this question; (2) Are there age-related change in brain morphology as it relates to anatomical normalization?

DESCRIPTION (provided by applicant): An international team of researchers proposes to examine the development of face processing from infancy through adolescence. We will investigate how infants' and children's face processing expertise is tuned by their experience with different classes of faces early in development. Children from infancy through adolescence and from different countries will be tested to determine how their experience with faces of different race, gender, age, and species affect their ability to classify faces into different categories and to recognize the identity of individual faces. We will test the hypothesis that while the human visual system may be biased at birth to favor face-like stimuli, much of our face processing ability is acquired through experience with thousands of faces over the course of development. Differential degrees of exposure to different categories of faces (race, gender, age, and species) will impact on how humans classify faces into different face categories and how they recognize individual faces within these general categories. Analogous to phonetic development, at early stages of face expertise acquisition, infants and children may process a broad range of faces from different races, genders, ages, and species with equal facility. As children mature and are selectively exposed to a limited number of face categories (one's own species, race, gender, and age group), their face expertise becomes more specialized. As they become increasingly more skilled at processing faces with which they have extensive experience (expertise), they lose their natural ability to process faces from face categories with which they have limited experience. This research program will provide much needed information to form a comprehensive picture of the development of face processing abilities and to delineate the role of experience in the formation of face expertise. Our research should facilitate the development of a general theory of face processing in children and adults. The methods we refine for this project should be of use for clinical studies and assessments that involve children with atypical trajectories in the development of face processing including cases of autism and developmental prosopagnosia.