Rick O. Gilmore

Spatio-temporal tuning of coherent motion evoked responses in 4-6 month old infants and adults

Motion cues provide a rich source of information about translations of the observer through the environment as well as the movements of objects and surfaces. While the direction of motion can be extracted locally these local measurements are, in general, insufficient for determining object and surface motions. To study the development of local and global motion processing mechanisms, we recorded Visual Evoked Potentials (VEPs) in response to dynamic random dot displays that alternated between coherent rotational motion and random motion at 0.8 Hz. We compared the spatio-temporal tuning of the evoked response in 4-6 months old infants to that of adults by recording over a range of dot displacements and temporal update rates. Responses recorded at the frequency of the coherent motion modulation were tuned for displacement at the occipital midline in both adults in infants. Responses at lateral electrodes were tuned for speed in adults, but not in infants. Infant responses were maximal at a larger range of spatial displacement than that of adults. In contrast, responses recorded at the dot-update rate showed a more similar parametric displacement tuning and scalp topography in infants and adults. Taken together, our results suggest that while local motion processing is relatively mature at 4-6 months, global integration mechanisms exhibit significant immaturities at this age.

Stability in young infants' discrimination of optic flow.

Although considerable progress has been made in understanding how adults perceive their direction of self-motion, or heading, from optic flow, little is known about how these perceptual processes develop in infants. In 3 experiments, the authors explored how well 3- to 6-month-old infants could discriminate between optic flow patterns that simulated changes in heading direction. The results suggest that (a) prior to the onset of locomotion, the majority of infants discriminate between optic flow displays that simulate only large (> 22 deg.) changes in heading, (b) there is minimal development in sensitivity between 3 and 6 months, and (c) optic flow alone is sufficient for infants to discriminate heading. These data suggest that spatial abilities associated with the dorsal visual stream undergo prolonged postnatal development and may depend on locomotor experience.

Egocentric Action in Early Infancy: Spatial Frames of Reference for Saccades

The extent to which infants combine visual (i e, retinal position) and nonvisual (eye or head position) spatial information in planning saccades relates to the issue of what spatial frame or frames of reference influence early visually guided action We explored this question by testing infants from 4 to 6 months of age on the double-step saccade paradigm, which has shown that adults combine visual and eye position information into an egocentric (head- or trunk-centered) representation of saccade target locations In contrast, our results imply that infants depend on a simple retinocentric representation at age 4 months, but by 6 months use egocentric representations more often to control saccade planning Shifts in the representation of visual space for this simple sensorimotor behavior may index maturation in cortical circuitry devoted to visual spatial processing in general

Examining individual differences in infants’ habituation patterns using objective quantitative techniques

The assessment of individual differences in infant habituation patterns is important for answering basic questions about continuity in cognitive development. Nevertheless, there are flaws with existing methods for determining relevant parameters of the cognitive processes associated with habituation. In this paper, a more rigorous, model-based alternative approach is illustrated. The approach demonstrates how the habituation data of individual infants may be fit by specific functions, how habituation may be distinguished from random responding, and how the parameter estimates of individual infants’ habituation functions might be analyzed for meaningful subgroups or clusters. The model-based approach provides novel insights about individual subgroups when applied to a real habituation data set and thereby demonstrates the feasibility and utility of the techniques advocated.

Habituation assessment in infancy

Infant-control habituation methodology, although serving the research community well, has never been carefully analyzed. A main use is to equate infants in their level of habituation prior to experimental manipulations in a posthabituation phase. When studied analytically and with simulation, it is found to have serious difficulties. It inadvertently recruits infants with large variations in performance while discriminating against those with less variable performance. For nonhabituating infants, its Type I error rates can approach 1. A model-based nonlinear regression framework is proposed, which, because of large individual differences in infants, takes as the unit of analysis the individual infant. It is shown to be more powerful and efficient than existing procedures and can offer practical and theoretical benefits.

Defective motion processing in children with cerebral visual impairment due to periventricular white matter damage

Aim  We sought to characterize visual motion processing in children with cerebral visual impairment (CVI) due to periventricular white matter damage caused by either hydrocephalus (eight individuals) or periventricular leukomalacia (PVL) associated with prematurity (11 individuals).

Changes in alcohol-related brain networks across the first year of college: A prospective pilot study using fMRI effective connectivity mapping

The upsurge in alcohol use that often occurs during the first year of college has been convincingly linked to a number of negative psychosocial consequences and may negatively affect brain development. In this longitudinal functional magnetic resonance imaging (fMRI) pilot study, we examined changes in neural responses to alcohol cues across the first year of college in a normative sample of late adolescents. Participants (N=11) were scanned three times across their first year of college (summer, first semester, second semester), while completing a go/no-go task in which images of alcoholic and non-alcoholic beverages were the response cues. A state-of-the-art effective connectivity mapping technique was used to capture spatiotemporal relations among brain regions of interest (ROIs) at the level of the group and the individual. Effective connections among ROIs implicated in cognitive control were greatest at the second assessment (when negative consequences of alcohol use increased), and effective connections among ROIs implicated in emotion processing were lower (and response times were slower) when participants were instructed to respond to alcohol cues compared to non-alcohol cues. These preliminary findings demonstrate the value of a prospective effective connectivity approach for understanding adolescent changes in alcohol-related neural processes.

Understanding the development of motion processing by characterizing optic flow experienced by infants and their mothers

Understanding the development of mature motion processing may require knowledge about the statistics of the visual input that infants are exposed to, how these change across development, and how they influence the maturation of motion-sensitive brain networks. Here we develop a set of techniques to study the optic flow experienced by infants and mothers during locomotion as a first step toward a broader analysis of the statistics of the natural visual environment during development.

Toward open behavioral science

Toward Open Behavioral Science Karen E. Adolph a , Rick O. Gilmore b , Clinton Freeman c , Penelope Sanderson c & David Millman d a Department of Psychology, New York University, New York, New York b Department of Psychology, The Pennsylvania State University, University Park, Pennsylvania c Department of Psychology, The University of Queensland, St Lucia, Queensland, Australia d Division of Libraries, New York University, New York, New York

Object-centered attention in 8-month-old infants

We examined the extent to which visual orienting in 8-month-old infants shows evidence of being guided by object-based representations. Infants’ preferences to look at conspicuous targets presented on one of two stationary objects were measured following an event (cue) which directed their covert attention to one of the objects. The results indicate that by 8 months of age a cue presented on one part of an object directs attention to the whole object (object-centered attention). This then affects responses to targets that appear elsewhere on the cued object.