General Description of Our Research Program: The efforts of the Human Development Lab focus on two programs of research investigating the development of sensory processing (auditory and somatosensory) and cognitive abilities in children during the period of 5 years to 18 years of age utilizing electroencephalography (EEG) and event-related potentials (ERPs) methodologies as well as traditional behavioral measures obtained from a variety of neuropsychological assessments.

In our research on sensory processing abilities, we are examining sensory registration and sensory gating in children with and without sensory processing disorders.  This work is a result of our interests in conducting treatment effectiveness studies in clinical populations served by occupational therapists and other applied health professionals.  The purpose of the present effort is to better understand the experimental conditions that produce the most reliable electrophysiological measures of sensory registration and sensory gating of the auditory system in normal adults and children 4 to 10 years of age.  With our refined Sensory Gating (P50) ERP paradigm we have shown that children with sensory processing disorders display deficiencies in their ability to gate repetitive sensory (auditory) information and are exploring the interrelationships of the ERP measures with behavioral manifestations of sensory processing deficits. 

In our research on the cognitive development in children and adolescents, we are using a variety of ERP paradigms (e.g., ERN, CNV, Novelty-Oddball) to measure the changes in the functioning of the prefrontal cortex which are critical for the development of higher order cognitive abilities, specifically executive functions.  An emphasis of this research is to understand more about the changes in brain function during adolescence and how those changes impact function in everyday activities.  Current methodological efforts are focusing on the reliability and stability of the various components of ERP paradigms when recorded from children, adolescents, and young adults, and to determine if reliability improves when controlling for specific state and trait characteristics of the participants. A unique aspect of this work is our demonstration of the usefulness of multivariate statistical techniques as a means of understanding individual differences. 

Project Title:  Reliability of Cognitive ERPs in Children and Adults

Summary Statement:  Investigates the reliability and stability of the various components of event related potential (ERP) paradigms when recorded from children and young adults and determines if reliability improves when controlling for specific variance elements.

Full Abstract:  The long term goals of this program of research are to contribute to the increasing amount of evidence for continued development of the brain into early adulthood.   Electroencephalographic (EEG) measures and neuropsychological assessments are being employed to investigate the interrelationships of maturation of specific brain regions and the development of cognitive and emotional processes in children and adolescents.  The results obtained from this study will be applied to the development of a model that will elucidate interrelationships of variables representing stimulus-response mechanisms, trait, and state characteristics of an individual and their associated changes in various ERP measurements observed during periodic assessments in typically developing children using a longitudinal design.

The goal of the proposed research is to investigate the reliability and stability of the various components of event related potentials (ERPs).

Three specific aims will be examined; 1) Determine the split-half reliability for ERP components derived from a single test session to estimate the theoretical limit of measurement error for the ERP components of cognitive ERP paradigms; 2) Evaluate the test-retest reliability of ERP measures to access the degree of stability of individual traits such as maturation and gender that may impact ERP measures; 3) Assess whether the variance attributed to extraneous parameters that are a consequence of processing EEG data (e.g., number of trials in an averaged ERP) might be statistically removed from the overall variance of the ERP measure prior to the calculation of reliability measures and hence, result in increased reliability measures.

The research design entails obtaining multiple channel EEG recordings from 30 participants in each of 3 age groups (8-yr olds, 12-yr olds and young adults) while performing 3 ERP paradigms:  the Novelty Auditory Oddball (an auditory discrimination task), Contingent Negative Variation (a sustained attention task), and the Error-Related Negativity (error-monitoring in simple visual discrimination task). Each participant will complete these EEG/ERP tasks in each of two visits separated by a 1-2 week period. Split-half and test-retest reliability coefficients will then be determined for the principle components of these ERP paradigms. To validate the existence of a variance component related to the process of generating the averaged waveform from which ERP measures are extracted, partial correlations will be performed in order to remove the effects of number of trials in waveform from the ERP component measure of each participant and the standardized residuals will be saved.  Split-half and test-retest will then be recomputed using the standardized residuals instead of the original ERP measures.  These new reliability coefficients are expected to be higher than those not accounting for variance due to waveform processing. 

Health related impacts include understanding changes in the brain in relation to normal, adaptive behaviors in adolescence.  But in addition these changes in the brain may also serve to generate the onset of abnormal forms of psychopathologic behaviors that may develop in adolescence, such as violence, depression, psychosis, substance abuse.

Funded by: National Institute of Health  for period of 4/01/05 to 3/31/07.

Project Title:  Sensory Gating Mediated by Attention

Summary Statement:  Investigates the whether manipulations of attention levels during EEG/ERP sensory gating paradigms differentially affects adults and children and to determine the split-half and test-retest reliability measures of sensory gating in children and adults.

Full Abstract:  The long term goals of this program of research on sensory gating in children is based on building a multivariate model that will help elucidate which factors contribute to measuring stable sensory gating in children and testing the model to determine if it functions similarly for children and adults.  The model states that measures of sensory gating may vary from individual to individual because the outcome represents an interaction of stimulus presentation protocols, such as stimulus intensity, number of trials, and task instructions, with several trait and state variables of the participant including but not limited to maturation of prefrontal cortex and executive function (attention), alpha7 nicotinic acetylcholine receptor gene (gene abnormalities), and stress level at electroencephalography (EEG) testing (noradrenergic tone). The proposed project will contribute to the understanding the role of attention in this model of sensory gating. 

The three specific aims of the project are:  1) To determine if the manipulation of attention will differentially effect sensory gating in adults and children; 2) To demonstrate that the developmental nature of attention coincides with changes in levels of sensory gating in children; 3) To determine the split-half and test-retest reliability measures of sensory gating in children and adults.

The research design entails assessing 40 young adults and 40 children, ages 6 to 12 years, during two visits.  EEG data will be collected using 3 variations of the Sensory Gating event-related potential (ERP) paradigm which manipulate the focus of attention. One version will be used twice, once on each visit, in order to obtain test-retest reliability measures.  To investigate maturation of attention in children and its relationship to changes in sensory gating performance, several behavioral measures of attention will be obtained.

The health related impact of the project is a better understanding of the variability in sensory gating measures observed in children.  Such knowledge will lead to more reliable and objective measures of the brain's ability and inability to gate sensory information which will allow valid early identification of neurodevelopmental disorders such as in schizophrenia and autism.  Improved measures of sensory gating may lead to productive and cost efficient studies assessing treatment effectiveness.

Funded by:  National Institute of Health (NIH) for the period of 9/01/06 to 8/31/08.

Project Title:  Validating Sensory Processing Disorders through Concomitant Neurophysiological Neuropsychological, Psychophysiological, and Neurobiological Measures

Summary Statement:  Investigates the relationship of stress (cortisol levels) and genetic markers for alpha-7 receptors sites in EEG/ERP measures of sensory gating in children with and without sensory processing disorders.

Full Abstract:  Sensory gating, the brain’s ability to suppress repeated, irrelevant sensory input and to selectively regulate the sensitivity to sensory stimuli, is an essential brain mechanism and protective function of the central nervous system. Previous electrophysiological studies on sensory gating by us and others have shown that most adults and children without disabilities display sensory gating to repetitive auditory stimulation.  However our recent research shows that, as a group, children with sensory processing disorders (SPD) demonstrate significantly less auditory sensory gating than an age-matched peer group of children without disorders.  In addition children with SPD did not show a relationship between sensory gating and age that was observed in their matched peer group.  Our recent electrophysiological data further illustrates that children with sensory processing disorders separate into two subtypes, one that is hypersensitive and one that is hyposensitive to auditory stimuli.

The proposed project focuses on the task of validating the diagnosis of sensory processing disorders through a series of inter-related data gathering activities on each child in either of two groups, children with SPD and children without disorders.  First, we propose to further refine our present ERP techniques to produce even more reliable electrophysiological measures of brain processing of auditory stimuli in both the sensory gating and the sensory registration paradigm.  Further work with these paradigms will allow us to refine our classification procedures that are suggestive of the presumed subtypes of hypersensitivity and hyposensitivity and at the same time, validate, through replication, our previous findings.  Second, we will obtain behavioral measures to provide indices of sensory function in everyday activities using the Sensory Profile (Dunn, 1999) and the Sensory Responsivity Scale (SENSor) assessment and inventory (Miller, in preparation).  To these measures, we will add several neuropsychological measures of cognitive and executive functioning such as IQ, maze solving, perceptual motor speed and digit span recall.  The addition of these cognitive and executive functioning measures may provide a demonstration of the dissociation between the two groups where they match on cognitive measures but differ on sensory measures.  Furthermore, the inter-relationship of these behavioral measures and their relationship to the sensory gating and sensory registration neurophysiological measures will also be explored.  Third, the project will begin to explore how domains other than neurophysiology (i.e., ERP measures) and neuropsychological (i.e., the behavioral measures of sensory and cognitive abilities) might contribute to the understanding and defining of sensory processing disorders.  For each child, we propose to collect measures from the psychophysiology domain (i.e., cortisol levels as an indicator of anxiety or stress) and neurobiological domains (i.e., DNA sampling for the nicotinic alpha 7 receptors as an indicator of genetic predisposition). 

By examining the inter-relationship of measures from the domains of neurophysiology, neuropsychological, psychophysiology, and neurobiological obtained within a single study of both children with and without sensory processing disorders, we will have a better understanding of: (1) the underlying brain mechanisms of sensory processing disorders; (2) how to reliably diagnose sensory processing disorders, and (3) how to better develop potential strategies for treatment and accessing their effects through well designed treatment efficacy studies.

Funded by: Wallace Research Foundation for the period of 1/1/06 to 12/31/06.