Cerebral blood flow in 5‐ to 8‐month‐olds: Regional tissue maturity is associated with infant affect

Infancy is marked by rapid neural and emotional development. The relation between brain function and emotion in infancy, however, is not well understood. Methods for measuring brain function predominantly rely on the BOLD signal; however, interpretation of the BOLD signal in infancy is challenging because the neuronal‐hemodynamic relation is immature. Regional cerebral blood flow (rCBF) provides a context for the infant BOLD signal and can yield insight into the developmental maturity of brain regions that may support affective behaviors. This study aims to elucidate the relations among rCBF, age, and emotion in infancy. One hundred and seven mothers reported their infants' (infant age M ± SD = 6.14 ± 0.51 months) temperament. A subsample of infants completed MRI scans, 38 of whom produced usable perfusion MRI during natural sleep to quantify rCBF. Mother‐infant dyads completed the repeated Still‐Face Paradigm, from which infant affect reactivity and recovery to stress were quantified. We tested associations of infant age at scan, temperament factor scores, and observed affect reactivity and recovery with voxel‐wise rCBF. Infant age was positively associated with CBF in nearly all voxels, with peaks located in sensory cortices and the ventral prefrontal cortex, supporting the formulation that rCBF is an indicator of tissue maturity. Temperamental Negative Affect and recovery of positive affect following a stressor were positively associated with rCBF in several cortical and subcortical limbic regions, including the orbitofrontal cortex and inferior frontal gyrus. This finding yields insight into the nature of affective neurodevelopment during infancy. Specifically, infants with relatively increased prefrontal cortex maturity may evidence a disposition toward greater negative affect and negative reactivity in their daily lives yet show better recovery of positive affect following a social stressor.     

Binge eating proneness emerges during puberty in female rats: a longitudinal study

Puberty is a critical risk period for binge eating and eating disorders characterized by binge eating. Previous research focused almost entirely on psychosocial risk factors during puberty to the relative exclusion of biological influences. The current study addressed this gap by examining the emergence of binge eating during puberty in a rat model. We predicted that there would be minimal differences in binge eating proneness during pre-early puberty, but significant differences would emerge during puberty. Two independent samples of female Sprague-Dawley rats (n = 30 and n = 36) were followed longitudinally across pre-early puberty, mid-late puberty, and adulthood. Binge eating proneness was defined using the binge eating resistant (BER)/binge eating prone (BEP) model of binge eating that identifies BER and BEP rats in adulthood. Across two samples of rats, binge eating proneness emerged during puberty. Mixed linear models showed little difference in palatable food intake between BER and BEP rats during pre-early puberty, but significant group differences emerged during mid-late puberty and adulthood. Group differences could not be accounted for by changes in nonpalatable food intake or body weight. Similar to patterns in humans, individual differences in binge eating emerge during puberty in female rats. These findings provide strong confirming evidence for the importance of biological risk factors in developmental trajectories of binge eating risk across adolescence.     

Experience-guided attention: Uniform and implicit

Frequently finding a visual search target in one region of space induces a spatial attentional bias toward that region. Past studies on this effect typically tested fewer than 20 participants. The small sample prevents an investigation of two properties of learning: visual field uniformity and role of explicit awareness. Pooling data from multiple studies, here we examined location probability learning from ~120,000 visual search trials across 420 participants. Participants performed a serial search task. Unbeknownst to them, the target was disproportionately likely to appear in one visual quadrant. Location probability learning (LPL) was measured as the difference in reaction time to targets in the high-probability “rich” quadrant and the low-probability “sparse” quadrants. Results showed a lack of visual field effect. LPL was equivalent for “rich” quadrant in the upper left, upper right, lower left, and lower right. Learning did not induce a hotspot diagonal to the “rich” quadrant. To the contrary, RT was the longest in the diagonal quadrant. Recognition rate of the “rich” quadrant was above chance. However, recognition accuracy was unrelated to the size of LPL. Implicit learning induces visual-field-independent changes in spatial attention.     

A Note on the Comparative Value of the “True” Index of Studiousness for the Purpose of Prognosis

It was hypothesized that observers would be less inclined to expect a person to shift from one task to another when the initial task had been chosen than when it had been assigned, and when costs incurred while working on the initial task could not be recouped. Choice was also hypothesized to favor attribution of preference for the initial task and optimism concerning its completion, while unrecoupable costs were expected to encourage the attribution of preference but inhibit the attribution of optimism. It was also hypothesized that the effects of choice on attributed preference and optimism would be negated by the individual's failure to shift tasks at the earliest opportunity, but the effects of unrecoupable costs would not be. Ss were 188 male undergraduates who twice responded to paper-and-pencil instruments while watching video-taped experimental sessions. The manipulations created a 2 × 2 × 2 design. All hypotheses were supported. It was concluded that unrecoupable costs establish a strong and lasting presumption of commitment, whereas the effects of choice vs. assignment tend not to persist in the face of contradictory evidence.     

Contextual cueing in preview search

Frequently finding a target in the same location within a familiar context reduces search time, relative to search for objects appearing in novel contexts. This learned association between a context and a target location requires several blocks of training and has long-term effects. Short-term selection history also influences search, where previewing a subset of a search context shortly before the appearance of the target and remaining distractors speeds search. Here we explored the interactions between contextual cueing and preview benefit using a modified version of a paradigm from Hodsoll and Humphreys (Journal of Experimental Psychology: Human Perception and Performance, 31(6), 1346–1358, 2005). Participants searched for a T target among L distractors. Half of the distractors appeared 800 ms before the addition of the other distractors and the target. We independently manipulated the repetition of the previewed distractors and the newly added distractors. Though the previewed set never contained the target, repetition of either the previewed or the newly added context yielded contextual cueing, and the effect was greater when the previewed context repeated. Another experiment trained participants to associate the previewed context with a target location, then disrupted the association in a testing phase. This disruption eliminated contextual cueing, suggesting that learning of the previewed context was associative. These findings demonstrate an important interaction between distinct kinds of selection history effects.