Alissa Westerlund

The NimStim set of facial expressions: Judgments from untrained research participants

A set of face stimuli called the NimStim Set of Facial Expressions is described. The goal in creating this set was to provide facial expressions that untrained individuals, characteristic of research participants, would recognize. This set is large in number, multiracial, and available to the scientific community online. The results of psychometric evaluations of these stimuli are presented. The results lend empirical support for the validity and reliability of this set of facial expressions as determined by accurate identification of expressions and high intra-participant agreement across two testing sessions, respectively.

Personal familiarity influences the processing of upright and inverted faces in infants

Infant face processing becomes more selective during the first year of life as a function of varying experience with distinct face categories defined by species, race, and age. Given that any individual face belongs to many such categories (e.g. A young Caucasian mans face) we asked how the neural selectivity for one aspect of facial appearance was affected by category membership along another dimension of variability. 6-month-old infants were shown upright and inverted pictures of either their own mother or a stranger while event-related potentials (ERPs) were recorded. We found that the amplitude of the P400 (a face-sensitive ERP component) was only sensitive to the orientation of the mothers face, suggesting that “tuning” of the neural response to faces is realized jointly across multiple dimensions of face appearance.

Neural Markers of Categorization in 6-Month-Old Infants

Little is known of the neural processes that underlie concept-formation abilities in human infants. We investigated category-learning processes in infants both by using a common behavioral measure and by recording the brains electrical activity (event-related potentials, or ERPs). ERPs were recorded while 6-month-olds viewed cat images during training, followed by novel cat images interspersed with novel dog images during test. The data indicate that distinct neural signals correspond with learning of a category presented during familiarization, preferential responding to a novel category, and representation of category exemplars at multiple levels of in-clusiveness. The results suggest that fundamental components of the neural architecture supporting object categorization are functional within the first half-year of postnatal life, before infants acquire language and young children engage in formal learning of semantic categories. The findings are discussed in terms of their implications for models of category learning and development.

An Event-Related Potential Study of Attention and Recognition Memory in Infants With Iron-Deficiency Anemia

OBJECTIVES. The purpose of this work was to determine whether iron-deficiency anemia in infancy represents a risk factor for deficits in attention and memory development using event-related potentials. METHODS. Artifact-free event-related potential data were obtained at 9 and/or 12 months from 15 infants with iron-deficiency anemia and 19 who were iron sufficient during a test of the infants ability to discriminate a highly familiar stimulus, the mothers face, from a strangers face. RESULTS. A midlatency negative component associated with attention and a late-occurring positive slow wave associated with memory updating were identified at both ages in the iron-deficiency anemia and iron-sufficient groups. Consistent with the age-appropriate pattern of development at 9 months, the iron-sufficient group showed a greater attentional response (negative component) to the mother and a greater updating of memory for the stranger (positive slow wave). This pattern of responses was not evident in the iron-deficiency anemia group until 12 months, suggesting a delay in cognitive development. CONCLUSIONS. These data suggest that iron-deficiency anemia adversely affects the allocation of neurophysiologic resources to attention and recognition memory during the processing of information about familiar and unfamiliar stimuli. This delay in cognitive development may reflect alterations in efficiency of central nervous system functions that seem related to early iron deficiency.

Iron deficiency in infancy is associated with altered neural correlates of recognition memory at 10 years.

OBJECTIVE To determine the long-term effects of iron deficiency on the neural correlates of recognition memory. STUDY DESIGN Non-anemic control participants (n=93) and 116 otherwise healthy formerly iron-deficient anemic Chilean children were selected from a larger longitudinal study. Participants were identified at 6, 12, or 18 months as iron-deficient anemic or non-anemic and subsequently received oral iron treatment. This follow-up was conducted when participants were 10 years old. Behavioral measures and event-related potentials from 28 scalp electrodes were measured during an new/old word recognition memory task. RESULTS The new/old effect of the FN400 amplitude, in which new words are associated with greater amplitude than old words, was present within the control group only. The control group also showed faster FN400 latency than the formerly iron-deficient anemic group and larger mean amplitude for the P300 component. CONCLUSIONS Although overall behavioral accuracy is comparable in groups, the results show that group differences in cognitive function have not been resolved 10 years after iron treatment. Long-lasting changes in myelination and energy metabolism, perhaps especially in the hippocampus, may account for these long-term effects on an important aspect of human cognitive development.

Early adversity and neural correlates of executive function: Implications for academic adjustment

Early adversity can negatively impact the development of cognitive functions, although little is known about whether such effects can be remediated later in life. The current study examined one facet of executive functioning - inhibitory control - among children who experienced institutional care and explored the impact of a foster care intervention within the context of the Bucharest Early Intervention Project (BEIP). Specifically, a go/nogo task was administered when children were eight years old and behavioral and event-related potential (ERP) measures were collected. Results revealed that children assigned to care as usual (i.e. institutional care) were less accurate and exhibited slower neural responses compared to children assigned to the foster care intervention and children who had never been institutionalized. However, children in both the care as usual and foster care groups exhibited diminished attention processing of nogo cues as assessed via P300 amplitude. Foster care children also showed differential reactivity between correct and error responses via the error-related negativity (ERN) as compared to children in the care as usual group. Combined, the results highlight perturbations in neural sources of behavioral and attention problems among children experiencing early adversity. Potential implications for academic adjustment in at risk children are discussed.

The effect of early deprivation on executive attention in middle childhood.

BACKGROUND Children reared in deprived environments, such as institutions for the care of orphaned or abandoned children, are at increased risk for attention and behavior regulation difficulties. This study examined the neurobehavioral correlates of executive attention in post institutionalized (PI) children. METHODS The performance and event-related potentials (ERPs) of 10- and 11-year-old internationally adopted PI children on two executive attention tasks, go/no-go and Flanker, were compared with two groups: children internationally adopted early from foster care (PF) and nonadopted children (NA). RESULTS Behavioral measures suggested problems with sustained attention, with PIs performing more poorly on go trials and not on no-go trials of the go/no-go and made more errors on both congruent and incongruent trials on the Flanker. ERPs suggested differences in inhibitory control and error monitoring, as PIs had smaller N2 amplitude on go/no-go and smaller error-related negativity on Flanker. CONCLUSIONS This pattern of results raises questions regarding the nature of attention difficulties for PI children. The behavioral errors are not specific to executive attention and instead likely reflect difficulties in overall sustained attention. The ERP results are consistent with neural activity related to deficits in inhibitory control (N2) and error monitoring (error-related negativity). Questions emerge regarding the similarity of attention regulatory difficulties in PIs to those experienced by non-PI children with ADHD.

The Effects of Early Experience on Face Recognition: An Event‐Related Potential Study of Institutionalized Children in Romania

Data are reported from 3 groups of children residing in Bucharest, Romania. Face recognition in currently institutionalized, previously institutionalized, and never-institutionalized children was assessed at 3 time points: preintervention (n = 121), 30 months of age (n = 99), and 42 months of age (n = 77). Children watched photographs of caregiver and stranger faces while event-related potentials were recorded. Results demonstrate that institutionalized children show pervasive cortical hypoarousal in response to faces and that foster care is somewhat effective in remediating this deficit by 42 months of age. All 3 groups of children distinguished between the familiar and unfamiliar faces. These results have the potential to inform an understanding of the role of early experience in the development of the neural systems that subserve face recognition.

Iron-deficiency anemia in infancy and poorer cognitive inhibitory control at age 10 years.

The aim of this study was to assess the effects of iron‐deficiency anemia (IDA) in infancy on executive functioning at age 10 years, specifically inhibitory control on the Go/No‐Go task. We predicted that children who had IDA in infancy would show poorer inhibitory control.

An event-related potential study of response inhibition in ADHD with and without prenatal alcohol exposure.

BACKGROUND The attention and cognitive problems seen in individuals with a history of prenatal alcohol exposure often resemble those associated with attention deficit hyperactivity disorder (ADHD), but few studies have directly assessed the unique influence of each on neurobehavioral outcomes. METHODS We recorded event-related potentials (ERPs) during a Go/No-go response inhibition task in young adults with prospectively obtained histories of prenatal alcohol exposure and childhood ADHD. RESULTS Regardless of prenatal alcohol exposure, participants with childhood ADHD were less accurate at inhibiting responses. However, only the ADHD group without prenatal alcohol exposure showed a markedly diminished P3 difference between No-go and Go, which may reflect a more effortful strategy related to inhibitory control at the neural processing level. CONCLUSION This finding supports a growing body of evidence suggesting that the manifestation of idiopathic ADHD symptoms may stem from a neurophysiologic process that is different from the ADHD symptomatology associated with prenatal alcohol exposure. Individuals who have been prenatally exposed to alcohol and present with ADHD symptomatology may represent a unique endophenotype of the disorder, which may require different treatment approaches from those found to be effective with idiopathic ADHD.