Event Related Potentials in Infants and Adults

Overview

This study will explore the development of visual perception and the brain activity that underlies it. It will examine electrical activity in the brain while people are processing characteristics of the visual environment, and how that processing might change with development. Infants who are within 2 weeks on either side of their 4-month birthday may be eligible for this study. A parent of the child also participates. Parents who join the study are asked basic questions about their family, such as its size and ethnic make-up, their infant's birth date, complications of pregnancy or delivery, and any health problems of the infant, such as congenital developmental disorders or visual abnormalities. Each family is seen at the clinic one time for a 45-minute visit. The infant is outfitted with an elastic net containing many small sensors that make contact with the scalp. He or she is then shown pictures on a computer screen. The sensors in the head net are connected to a computer that records the infant's brain activity while the infant watches the pictures on the screen. The head net is moistened with warm water before being applied, and is not uncomfortable to wear. Towels are available throughout the session to dry any excess moisture from the net.

The major objective of this research is to better understand the response of the brain to significant stimulation in early and later development. The proposed work is designed to examine infants', children's, and adults' (especially mothers') responses to salient features of the external environment. To do so, the present research studies the biological bases and behavioral significance of natural preferences and information processing. The primary research strategy to be used consists of analyzing behavioral and brain responses to visual patterns. In a laboratory procedure, subjects will explore patterns and their brain electrical activity will be measured simultaneously with an electronic analysis system. In specific, five experiments of visual attention in human infants, and 1 experiment in adults are proposed. In the first experiment with infants, babies are hypothesized to look longer at more saturated colors; in a second experiment, babies are hypothesized to look longer at gratings aligned along the vertical and horizontal orthogonals than along the obliques. Because saturated colors and orthogonal stimulation elicit greater activity in visual system neurons and greater amplitude evoked potentials than desaturated colors or oblique stimulation, respectively, these two experiments explore the hypothesis that the simple visual stimuli to which infants preferably attend are those that are particularly appropriate in stimulating the geniculostriate or primary visual system. In the third experiment, we plan to trace the ontogeny of the mature brain response to whole patterns as opposed to parts of patterns. In a fourth experiment, we intend to compare region-specific activity when the surface features of a familiarized visual target change to that when its location changes. In the fifth experiment, we examine individual differences in the power metrics associated with attention to visual stimuli in relation to individual differences in their corresponding behavior coded by observers. In an experiment with children and adults we will explore brain responses and their localization in to pictures of familiar and unfamiliar faces.