Margaret C. Jackson

Increasing children's fruit and vegetable consumption: a peer-modelling and rewards-based intervention

Objective: To evaluate a peer-modelling and rewards-based intervention designed to increase childrens fruit and vegetable consumption.Design: Over a 5-month period, children in an experimental and a control school were presented with fruit and vegetables at lunchtime. Children aged 5–7 y also received fruit at snacktime (mid-morning). The intervention was implemented in the experimental school and levels of fruit and vegetable consumption were measured at baseline, intervention and at 4-month follow-up.Setting: Two inner-city London primary schools.Subjects: In total, 749 children aged 5–11 y.Intervention: Over 16 days children watched video adventures featuring heroic peers (the Food Dudes) who enjoy eating fruit and vegetables, and received small rewards for eating these foods themselves. After 16 days there were no videos and the rewards became more intermittent.Main outcome measures: Consumption was measured (i) at lunchtime using a five-point observation scale; (ii) at snacktime using a weighed measure; (iii) at home using parental recall.Results: Compared to the control school, lunchtime consumption in the experimental school was substantially higher at intervention and follow-up than baseline (P<0.001), while snacktime consumption was higher at intervention than baseline (P<0.001). The lunchtime data showed particularly large increases among those who initially ate very little. There were also significant increases in fruit and vegetable consumption at home (P<0.05).Conclusions: The intervention was effective in bringing about substantial increases in childrens consumption of fruit and vegetables.Sponsorship: Horticultural Development Council, Fresh Produce Consortium, ASDA, Co-operative Group, Safeway, Sainsbury, Somerfield, Tesco and Birds Eye Walls.

Enhanced visual short-term memory for angry faces.

Although some views of face perception posit independent processing of face identity and expression, recent studies suggest interactive processing of these 2 domains. The authors examined expression-identity interactions in visual short-term memory (VSTM) by assessing recognition performance in a VSTM task in which face identity was relevant and expression was irrelevant. Using study arrays of between 1 and 4 faces and a 1,000-ms retention interval, the authors measured recognition accuracy for just-seen faces. Results indicated that significantly more angry face identities can be stored in VSTM than happy or neutral face identities. Furthermore, the study provides evidence to exclude accounts for this angry face benefit based on physiological arousal, opportunity to encode, face discriminability, low-level feature recognition, expression intensity, or specific face sets. Perhaps processes activated by the presence of specifically angry expressions enhance VSTM because memory for the identities of angry people has particular behavioral relevance.

Familiarity enhances visual working memory for faces.

Although it is intuitive that familiarity with complex visual objects should aid their preservation in visual working memory (WM), empirical evidence for this is lacking. This study used a conventional change-detection procedure to assess visual WM for unfamiliar and famous faces in healthy adults. Across experiments, faces were upright or inverted and a low- or high-load concurrent verbal WM task was administered to suppress contribution from verbal WM. Even with a high verbal memory load, visual WM performance was significantly better and capacity estimated as significantly greater for famous versus unfamiliar faces. Face inversion abolished this effect. Thus, neither strategic, explicit support from verbal WM nor low-level feature processing easily accounts for the observed benefit of high familiarity for visual WM. These results demonstrate that storage of items in visual WM can be enhanced if robust visual representations of them already exist in long-term memory.

The Role of Attention and Familiarity in Face Identification

How is attention allocated during face identification? Previous work using famous and unfamiliar faces suggests that either no attention or a special attentional mechanism is required. We used a conventional attentional blink (AB) procedure to measure face identification with temporarily reduced attention. The participants viewed a rapid series of face images with one embedded nonface abstract pattern (T1). They judged the texture of T1 and then detected a prespecified face (T2) presented at varying lags after T1. T2 was either famous or unfamiliar, as were distractor faces. Regardless of distractor type, detection of an unfamiliar T2 face was significantly impaired at short versus long T1-T2 lags, indicating an attentional requirement for face identification. Detection of a famous T2 face was unaffected by lag, suggesting that familiarity protects against a temporal attentional bottleneck. These findings do not support propositions that face identification is ”special” in its need for attentional control.

Emotion-cognition interactions in schizophrenia: implicit and explicit effects of facial expression

Working memory (WM) and emotion classification are amongst the cognitive domains where specific deficits have been reported for patients with schizophrenia. In healthy individuals, the capacity of visual working memory is enhanced when the material to be retained is emotionally salient, particularly for angry faces. We investigated whether patients with schizophrenia also have an enhanced WM capacity for angry faces. We compared 34 inpatients with schizophrenia and 34 age-, handedness- and gender-matched control participants in three separate tasks. In the WM task, participants saw two faces with angry, happy or neutral emotional expressions for 2s and had to decide whether a probe face presented after a 1s delay was identical to one of them. In the emotion classification task, they had to assign these faces to the appropriate categorical emotion. They also rated faces for valence and arousal. Although patients performed generally worse on the working memory task, they showed the same benefit for angry faces as control participants. However, patients were specifically impaired for angry faces on the emotion classification task. These results indicate preserved implicit emotion processing in schizophrenia patients, which contrasts with their impairment in explicit emotion classification. With regard to clinical practice, our findings underline the importance of assessing responsiveness to emotions in patients with schizophrenia, with a view possibly to utilize preserved implicit emotion processing in cognitive remediation programs.

Neural Correlates of Enhanced Visual Short-Term Memory for Angry Faces: An fMRI Study

Background Fluid and effective social communication requires that both face identity and emotional expression information are encoded and maintained in visual short-term memory (VSTM) to enable a coherent, ongoing picture of the world and its players. This appears to be of particular evolutionary importance when confronted with potentially threatening displays of emotion - previous research has shown better VSTM for angry versus happy or neutral face identities. Methodology/Principal Findings Using functional magnetic resonance imaging, here we investigated the neural correlates of this angry face benefit in VSTM. Participants were shown between one and four to-be-remembered angry, happy, or neutral faces, and after a short retention delay they stated whether a single probe face had been present or not in the previous display. All faces in any one display expressed the same emotion, and the task required memory for face identity. We find enhanced VSTM for angry face identities and describe the right hemisphere brain network underpinning this effect, which involves the globus pallidus, superior temporal sulcus, and frontal lobe. Increased activity in the globus pallidus was significantly correlated with the angry benefit in VSTM. Areas modulated by emotion were distinct from those modulated by memory load. Conclusions/Significance Our results provide evidence for a key role of the basal ganglia as an interface between emotion and cognition, supported by a frontal, temporal, and occipital network.

Neural hyperactivation in carriers of the Alzheimer's risk variant on the clusterin gene

Recent GWAS identified a risk variant for Alzheimers disease (AD) at a locus (rs11136000) of the clusterin gene (CLU). Here we use functional magnetic resonance imaging (fMRI) during working memory to probe the effect of the risk variant on brain activation in healthy individuals. Participants with the CLU risk genotype had higher activity than participants with the protective allele in frontal and posterior cingulate cortex and the hippocampus, particularly during high memory demand. These results inform pathophysiological models of the preclinical progression of AD.

Dysbindin-1 genotype effects on emotional working memory

We combined functional imaging and genetics to investigate the behavioral and neural effects of a dysbindin-1 (DTNBP1) genotype associated with the expression level of this important synaptic protein, which has been implicated in schizophrenia. On a working memory (WM) task for emotional faces, participants with the genotype related to increased expression showed higher WM capacity for happy faces compared with the genotype related to lower expression. Activity in several task-related brain areas with known DTNBP1 expression was increased, including hippocampal, temporal and frontal cortex. Although these increases occurred across emotions, they were mostly observed in areas whose activity correlated with performance for happy faces. This suggests effects of variability in DTNBP1 on emotion-specific WM capacity and region-specific task-related brain activation in humans. Synaptic effects of DTNBP1 implicate that altered dopaminergic and/or glutamatergic neurotransmission may be related to the increased WM capacity. The combination of imaging and genetics thus allows us to bridge the gap between the cellular/molecular and systems/behavioral level and extend the cognitive neuroscience approach to a comprehensive biology of cognition.

Electrophysiological correlates of improved short-term memory for emotional faces

Long-term memory (LTM) is enhanced for emotional information, but the influence of stimulus emotionality on short-term memory (STM) is less clear. We examined the electrophysiological correlates of improved visual STM for emotional face identity, focusing on the P1, N170, P3b and N250r event-related potential (ERP) components. These correlates are taken to indicate which memory processing stages and cognitive processes contribute to the improved STM for emotional face identity. In the encoding phase, one or three angry, happy or neutral faces were presented for 2s, resulting in a memory load of one or three. The subsequent 1-s retention phase was followed by a 2-s retrieval phase, in which participants indicated whether a probe face had been present or not during encoding. Memory performance was superior for angry and happy faces over neutral faces at load three. None of the ERP components during encoding were affected by facial expression. During retrieval, the early P3b was decreased for emotional compared to neutral faces, which presumably reflects greater resource allocation to the maintenance of the emotional faces. Furthermore, the N250r during retrieval was increased for emotional compared to neutral faces, reflecting an enhanced repetition effect for emotional faces. These findings suggest that enhanced visual STM for emotional faces arises from improved maintenance and from improved detection of face repetition at retrieval.

Strategic resource allocation in the human brain supports cognitive coordination of object and spatial working memory

The ability to integrate different types of information (e.g., object identity and spatial orientation) and maintain or manipulate them concurrently in working memory (WM) facilitates the flow of ongoing tasks and is essential for normal human cognition. Research shows that object and spatial information is maintained and manipulated in WM via separate pathways in the brain (object/ventral versus spatial/dorsal). How does the human brain coordinate the activity of different specialized systems to conjoin different types of information? Here we used functional magnetic resonance imaging to investigate conjunction‐ versus single‐task manipulation of object (compute average color blend) and spatial (compute intermediate angle) information in WM. Object WM was associated with ventral (inferior frontal gyrus, occipital cortex), and spatial WM with dorsal (parietal cortex, superior frontal, and temporal sulci) regions. Conjoined object/spatial WM resulted in intermediate activity in these specialized areas, but greater activity in different prefrontal and parietal areas. Unique to our study, we found lower temporo‐occipital activity and greater deactivation in temporal and medial prefrontal cortices for conjunction‐ versus single‐tasks. Using structural equation modeling, we derived a conjunction‐task connectivity model that comprises a frontoparietal network with a bidirectional DLPFC‐VLPFC connection, and a direct parietal‐extrastriate pathway. We suggest that these activation/deactivation patterns reflect efficient resource allocation throughout the brain and propose a new extended version of the biased competition model of WM. Hum Brain Mapp, 2011.