Age-related differences in brain electrical activity during extended continuous face recognition in younger children, older children and adults

Preschoolers' Sensitivity to Negative and Positive Emotional Facial Expressions: An ERP Study

The study examined processing differences for facial expressions (happy, angry, or neutral) and their repetition with early (P1, N170) and late (P3) event-related potentials (ERPs) in young children (N = 33). EEG was recorded while children observed sequentially presented pairs of facial expressions, which were either the same (repeated trials) or differed in their emotion (novel trials). We also correlated ERP amplitude differences with parental and child measures of socio-emotional competence (emotion recognition, empathy). P1 amplitudes were increased for angry and happy as compared to neutral expressions. We also detected larger P3 amplitudes for angry expressions as compared to happy or neutral expressions. Repetition effects were evident at early and late processing stages marked by reduced P1 amplitudes for repeated vs. novel happy expressions, but enhanced P3 amplitudes for repeated vs. novel facial expressions. N170 amplitudes were neither modulated by facial expressions nor their repetition. None of the repetition effects were associated with measures of socio-emotional competence. Taken together, negative facial expressions led to increased neural activations in early and later processing stages, indicative of enhanced saliency to potential threating stimuli in young children. Processing of repeated facial expression seem to be differential for early and late neural stages: Reduced activation was detected at early neural processing stages particularly for happy faces, indicative of effective processing for an emotion, which is most familiar within this age range. Contrary to our hypothesis, enhanced activity for repeated vs. novel expression independent of a particular emotion were detected at later processing stages, which may be linked to the creation of new memory traces. Early and late repetition effects are discussed in light of developmental and perceptual differences as well as task-specific load.

The effect of fearful expressions on recognition memory for faces: Behavioral and electrophysiological data

Facial expressions affect memory for face identity. We tested how fearful expressions modulate recognition memory for faces. In two studies, participants completed a continuous recognition task with fearful and neutral faces while their electroencephalogram was recorded. Each face stimulus was presented twice and participants were instructed to indicate whether it was presented for the first ('new') or second time ('old'). The false alarm rate was higher for fearful than neutral faces, which is opposite to the emotion enhancement effect on memory but in line with the liberal response bias for emotional information. There was no evidence of emotional modulation of the N400 old/new effect, which suggests that the sense of familiarity was not affected by fearful facial expressions. The LPC old/new effect, however, was modulated by facial expression, as it was absent for fearful faces because of a greater positivity in response to new fearful than new neutral faces. This LPC old/new effect finding may reflect that the emotional salience of fearful new faces is mistaken for a sense of recollection, resulting in an increased false alarm rate. In short, people seem more likely to (mistakenly) think that they have encountered a person before when the person looks scared compared to non-emotional, which has relevance for daily life and forensic situations such as police lineups.

Prefrontal Cortex Response to Threat: Race by Age Variation in 9-10 Year Old Children

BACKGROUND

Considerable research has suggested that race and age are two major determinants of brain development, including but not limited to development of the prefrontal cortex (PFC). Minorities' Diminished Returns (MDRs), however, suggests that race (as a proxy of racism) may interact with various determinants of human and brain development. Minimal knowledge, however, exists on whether age and race also interact on shaping PFC response to threat among American children.

PURPOSE

Using data from a task-based functional brain imaging study and considering race as a sociological rather than a biological construct, we investigated combined effects of race and age on prefrontal cortical (PFC) response to threat. We explored racial heterogeneities in the association between age and PFC response to threat by comparing Black and White children.

METHODS

This study used the task-based functional Magnetic Resonance Imaging (fMRI) data from the Adolescents Brain Cognitive Development (ABCD) study, a national, landmark, multi-center brain imaging investigation of 9-10 years old children in the US. The primary outcomes were mean beta weights of n-back runs measuring PFC response to threating versus neutral face contrast in the following regions of interest (ROIs): left hemisphere-lateral orbito-frontal, left hemisphere -superior-frontal, right hemisphere -caudal middle frontal, and right hemisphere -superior frontal cortex. The independent variable was age. Covariates were sex, ethnicity, family socioeconomic status, and neighborhood socioeconomic status. Race was the focal moderator. To analyze the data, we used linear regression models without and with interactions and SES as covariates.

RESULTS

We included 5,066 9-10 years old children. Age and race did not show direct effects on PFC response to threatening relative to neutral faces. While ethnicity, sex, and socioeconomic status were controlled, age and race showed a systematic interaction on PFC response to threatening relative to neutral faces.

CONCLUSIONS

For American children, race and age do not have direct effects but multiplicative effects on PFC response to threat. The results may be reflective of social inequalities in how Black and White children are socialized and developed. The results are important given the role of the PFC in regulating the limbic system response to threat. Coordinated work of the limbic system and PFC is a core element of children's behavioral and emotional development. Future research is needed on how social stratification and racism shape emotion processing and regulation of American children in response to threat.

Breath-focused mindfulness alters early and late components during emotion regulation

Breath-focused mindfulness (BFM), which induces changes in brain structure and function, is applied in the clinical treatment of mental disorders as a method to regulate one's emotions. However, whether BFM works through a top-down emotional regulation strategy to alter brain dynamics and its relationship with individual differences in trait mindfulness are unclear. Event-related potentials (ERPs) of 20 healthy BFM-naïve undergraduates were recorded when they conducted BFM/viewing tasks while viewing affective pictures. Participants completed the Attentional Control Scale (ACS) and the Mindful Attention Awareness Scale (MAAS). The results indicated that under the viewing condition, positive and negative pictures elicited greater P1, N2, and late positive potential (LPP) amplitudes than did neutral pictures. However, BFM attenuated P1, N2, and LPP amplitudes for positive and negative pictures but not for neutral pictures. P1 amplitudes for emotional minus neutral pictures correlated with individual differences in focus attention measured by the ACS, while N2 amplitudes for emotional minus neutral pictures correlated with individual differences in trait mindfulness measured by the MAAS. These observations suggest that, consistent with the dual-process model, BFM is an effective emotion regulation strategy and might activate the dorsal top-down prefrontal system to alter early and late neural dynamics of affective processing.

Does the late positive component reflect successful reading acquisition? A longitudinal ERP study

Developmental dyslexia is a reading disorder that is associated with deficits in phonological processing, where the exact neural basis for those processing deficits remains unclear. In particular, disagreement exists whether degraded phonological representations or an impaired access to the phonological representations causes these deficits. To investigate this question and to trace changes in neurophysiology during the process of reading acquisition, we designed a longitudinal study with event related potentials (ERPs) in children between kindergarten and second grade. We used an explicit word processing task to elicit the late positive component (LPC), which has been shown to reflect phonological processing. A brain-wide analysis of the LPC with an electrode-wise application of mixed effects models showed significantly attenuated amplitudes in the left temporo-parietal region in dyslexic children. Since these differences were only present in the word and not in the picture (i.e. control) condition, the attenuated amplitudes might reflect impaired access to the phonological representations of words. This was further confirmed by the longitudinal development, which showed a rapid increase in amplitude at the beginning of reading instruction and a decrease with continuing automatization, possibly pointing to a progression from grapheme-phoneme parsing to whole word reading. Our longitudinal study provides the first evidence that it is possible to detect neurophysiological differences in the LPC between children with dyslexia and control children in both preliterate and very early stages of reading acquisition, providing new insights about the neurophysiological development and a potential marker of later reading problems.

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First longitudinal study of the late positive component (LPC)

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Left temporo-parietal LPC differs between control and dyslexic children.

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LPC increase at reading acquisition and decrease with automatization in typical readers.

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Dyslexic children do not show this neurophysiological course of development.

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Findings might indicate an impaired access to phonological representations.

An ERP study of recognition memory for concrete and abstract pictures in school-aged children

Recognition memory for concrete, nameable pictures is typically faster and more accurate than for abstract pictures. A dual-coding account for these findings suggests that concrete pictures are processed into verbal and image codes, whereas abstract pictures are encoded in image codes only. Recognition memory relies on two successive and distinct processes, namely familiarity and recollection. Whether these two processes are similarly or differently affected by stimulus concreteness remains unknown. This study examined the effect of picture concreteness on visual recognition memory processes using event-related potentials (ERPs). In a sample of children involved in a longitudinal study, participants (N=96; mean age=11.3years) were assessed on a continuous visual recognition memory task in which half the pictures were easily nameable, everyday concrete objects, and the other half were three-dimensional abstract, sculpture-like objects. Behavioral performance and ERP correlates of familiarity and recollection (respectively, the FN400 and P600 repetition effects) were measured. Behavioral results indicated faster and more accurate identification of concrete pictures as "new" or "old" (i.e., previously displayed) compared to abstract pictures. ERPs were characterized by a larger repetition effect, on the P600 amplitude, for concrete than for abstract images, suggesting a graded recollection process dependent on the type of material to be recollected. Topographic differences were observed within the FN400 latency interval, especially over anterior-inferior electrodes, with the repetition effect more pronounced and localized over the left hemisphere for concrete stimuli, potentially reflecting different neural processes underlying early processing of verbal/semantic and visual material in memory.

Posterior P1 and early frontal negativity reflect developmental changes in attentional distraction during adolescence

Previous studies in adults have revealed that attentional distraction modulates the late positive potential (LPP) during emotion regulation. To determine whether early visual components reflect developmental changes in attentional distraction during adolescence, we collected event-related potentials from 20 young adolescents, 18 older adolescents, and 18 young adults as they performed a distraction task (counting) while viewing affective images. Consistent with previous findings obtained in distraction studies, the distraction task (counting) reduced emotional modulation of the LPP. At an early stage of processing, counting reduced emotional modulation of P1 and increased the negativity bias of early frontal negativity (eFN) for negatively valenced pictures compared to simple viewing with no distraction. sLORETA analyses further revealed eFN indexing of rostral prefrontal cortical activation, a cortical area that has been shown in recent fMRI studies to be activated by distraction. Moreover, P1 amplitudes in young and older adolescents did not differ but were both larger than the P1s in young adults. In addition, eFN amplitudes significantly decreased with age. The dissociable distraction patterns between the posterior P1 and eFN provide evidence not only for the timing hypothesis of emotion regulation but also for different developmental trajectories of visual processing areas and the prefrontal cortex during affective processing in adolescence.

Common polymorphism in the oxytocin receptor gene (OXTR) is associated with human social recognition skills

The neuropeptides oxytocin and vasopressin are evolutionarily conserved regulators of social perception and behavior. Evidence is building that they are critically involved in the development of social recognition skills within rodent species, primates, and humans. We investigated whether common polymorphisms in the genes encoding the oxytocin and vasopressin 1a receptors influence social memory for faces. Our sample comprised 198 families, from the United Kingdom and Finland, in whom a single child had been diagnosed with high-functioning autism. Previous research has shown that impaired social perception, characteristic of autism, extends to the first-degree relatives of autistic individuals, implying heritable risk. Assessments of face recognition memory, discrimination of facial emotions, and direction of gaze detection were standardized for age (7-60 y) and sex. A common SNP in the oxytocin receptor (rs237887) was strongly associated with recognition memory in combined probands, parents, and siblings after correction for multiple comparisons. Homozygotes for the ancestral A allele had impairments in the range -0.6 to -1.15 SD scores, irrespective of their diagnostic status. Our findings imply that a critical role for the oxytocin system in social recognition has been conserved across perceptual boundaries through evolution, from olfaction in rodents to visual memory in humans.

Emotional distraction in boys with ADHD: neural and behavioral correlates

Although, in everyday life, patients with attention deficit hyperactivity disorder (ADHD) are frequently distracted by goal-irrelevant affective stimuli, little is known about the neural and behavioral substrates underlying this emotional distractibility. Because some of the most important brain responses associated with the sudden onset of an emotional distracter are characterized by their early latency onset and short duration, we addressed this issue by using a temporally agile neural signal capable of detecting and distinguishing them. Specifically, scalp event-related potentials (ERPs) were recorded while 20 boys with ADHD combined type and 20 healthy comparison subjects performed a digit categorization task during the presentation of three types of irrelevant, distracting stimuli: arousing negative (A-), neutral (N) and arousing positive (A+). Behavioral data showed that emotional distracters (both A- and A+) were associated with longer reaction times than neutral ones in the ADHD group, whereas no differences were found in the control group. ERP data revealed that, compared with control subjects, boys with ADHD showed larger anterior N2 amplitudes for emotional than for neutral distracters. Furthermore, regression analyses between ERP data and subjects' emotional ratings of distracting stimuli showed that only in the ADHD group, emotional arousal (ranging from calming to arousing) was associated with anterior N2: its amplitude increased as the arousal content of the visual distracter increased. These results suggest that boys with ADHD are more vulnerable to the distracting effects of irrelevant emotional stimuli than control subjects. The present study provides first data on the neural substrates underlying emotional distractibility in ADHD.

Electrophysiological evidence of altered memory processing in children experiencing early deprivation

Associations between early deprivation and memory functioning were examined in 9- to 11-year-old children. Children who had experienced prolonged institutional care prior to adoption were compared to children who were adopted early from foster care and children reared in birth families. Measures included the Paired Associates Learning task from the Cambridge Neuropsychological Test and Automated Battery (CANTAB) and a continuous recognition memory task during which ERPs were also recorded. Children who experienced prolonged institutionalization showed deficits in both behavioral memory measures as well as an attenuated P300 parietal memory effect. Results implicate memory function as one of the domains that may be negatively influenced by early deprivation in the form of institutional care.