Prefrontal Recruitment Research Articles

Neural mechanisms of the relationship between aerobic fitness and working memory in older adults: An fNIRS study

Abstract A growing number of studies have revealed that higher aerobic fitness is associated with better working memory (WM) performance in older adults. However, the underlying functional neural mechanisms of this association remain under debate. It has been reported that aging increases recruitment of the prefrontal cortex (PFC) during cognitive tasks, and that this is associated with task performance in a compensatory manner. Therefore, this study aimed to clarify the prefrontal activation pattern that is associated with the relationship between aerobic fitness and WM performance in older adults, focusing on age-related extended prefrontal recruitment. Forty-seven older adults (65–74 years, 29 females) and 49 younger adults (18–24 years, 23 female) performed verbal and spatial n-back tasks, which included 0-, 1-, and 2-back conditions. Reaction time (RT) and accuracy (ACC) were assessed as indices of task performance. Prefrontal activation during the experimental tasks was monitored using functional near-infrared spectroscopy (fNIRS) and analyzed using an adaptive GLM method. We compared task performance and prefrontal activation between age groups to find age-related prefrontal activation patterns. Only older adults underwent a graded exercise test (GXT) to determine their ventilation thresholds (VT) as a measure of aerobic fitness, and, subsequently, the relationships among aerobic fitness, n-back task performance, and prefrontal activation in older adults were examined using correlation analysis and mediation analysis controlling for possible covariates. A comparison of task performance between groups revealed that older adults had slower RT and lower ACC than did younger adults, especially in the higher WM load 2-back condition. Group comparisons of prefrontal activation showed that older adults exhibited additional or greater activation than younger adults mainly in the ventrolateral PFC (VLPFC) and front polar area (FPA) in both the verbal and spatial 2-back conditions. Correlation analysis showed a relationship between higher VT, shorter RT for the verbal 2-back condition, and greater prefrontal activation of the bilateral FPA and right VLPFC during verbal 2-back conditions in older adults. In addition, mediation analyses indicated the possibility of a mediation effect of the prefrontal activation on the relationship between VT and RT for the verbal 2-back condition. These results suggest that older adults with higher aerobic fitness levels recruited more extended PFC regions, possibly for compensatory activation, to enhance their performance of the verbal n-back task. This study sheds light on the neural mechanisms underpinning the relationship between aerobic fitness and cognitive function in older adults.

Transcranial Direct Current Stimulation May Reduce Prefrontal Recruitment During Dual Task Walking in Functionally Limited Older Adults - A Pilot Study.

IntroductionTranscranial direct current stimulation (tDCS) targeting the left dorsolateral prefrontal cortex (dlPFC) improves dual task walking in older adults, when tested just after stimulation. The acute effects of tDCS on the cortical physiology of walking, however, remains unknown.MethodsIn a previous study, older adults with slow gait and executive dysfunction completed a dual task walking assessment before and after 20 min of tDCS targeting the left dlPFC or sham stimulation. In a subset of seven participants per group, functional near-infrared spectroscopy (fNIRS) was used to quantify left and right prefrontal recruitment defined as the oxygenated hemoglobin response to usual and dual task walking (ΔHbO2), as well as the absolute change in this metric from usual to dual task conditions (i.e., ΔHbO2cost). Paired t-tests examined pre- to post-stimulation differences in each fNIRS metric within each group.ResultsThe tDCS group exhibited pre- to post-stimulation reduction in left prefrontal ΔHbO2cost (p = 0.03). This mitigation of dual task “cost” to prefrontal recruitment was induced primarily by a reduction in left prefrontal ΔHbO2 specifically within the dual task condition (p = 0.001), an effect that was observed in all seven participants within this group. Sham stimulation did not influence ΔHbO2cost or ΔHbO2 in either walking condition (p > 0.35), and neither tDCS nor sham substantially influenced right prefrontal recruitment (p > 0.16).DiscussionThis preliminary fNIRS data suggests that tDCS over the left dlPFC may modulate prefrontal recruitment, as reflected by a relative reduction in the oxygen consumption of this brain region in response to dual task walking.

P.0887 Extended prefrontal cortex recruitment in euthymic bipolar patients during a self-referential task

P.0887 Extended prefrontal cortex recruitment in euthymic bipolar patients during a self-referential task

Obstacle negotiation in older adults: prefrontal activation interpreted through conceptual models of brain aging

Age-related decline in executive function is associated with walking deficits in older adults. The main objective of this study was to better understand the cognitive control of obstacle negotiation in older adults by identifying predictors of prefrontal recruitment during the task. The study also examined the association between prefrontal recruitment and walking performance as well as interpretation of prefrontal activity relative to cognitive models of brain aging. Prefrontal oxygenated hemoglobin concentration (O2Hb) was measured by functional near-infrared spectroscopy during typical walking (Typical) and obstacle negotiation (Obstacles) tasks in older adults. The primary outcome was change in prefrontal recruitment (∆PFR), measured as Obstacles ∆O2Hb minus Typical ∆O2Hb. Stepwise regression was used to identify potential predictors of ∆PFR. Additional analyses were conducted to further examine the relationship between ΔPFR and the identified predictors. Greater ∆PFR was predicted by lower age, worse executive function, and their interaction (R2=0.19 , p=0.02). Particularly, the effect of executive function on ∆PFR was more pronounced for “early aging” than for “late aging” older adults (p<0.001). Greater ∆PFR was significantly associated with a smaller reduction in walking speed during Obstacles compared to Typical. In conclusion, age, executive function, and their interaction predict prefrontal recruitment during obstacle negotiation in older adults. These findings are generally consistent with existing cognitive models of brain aging including neural inefficiency, compensatory overactivation, and capacity-limitation with a recruitment ceiling effect.

Obstacle Negotiation in Older Adults: Prefrontal Activation Interpreted Through Conceptual Models of Brain Aging.

The influence of interindividual differences on brain activation during obstacle negotiation and the implications for walking performance are poorly understood in older adults. This study investigated the extent to which prefrontal recruitment during obstacle negotiation is explained by differences in age, executive function, and sex. These data were interpreted according to the Compensation-Related Utilization of Neural Circuits Hypothesis (CRUNCH) framework of brain aging. We also tested the association between prefrontal recruitment and walking performance. Prefrontal oxygenated hemoglobin concentration (O2Hb) was measured during typical walking (Typical) and obstacle negotiation (Obstacles) tasks in 50 adults aged 65 years and older using functional near-infrared spectroscopy. The primary outcome was the change in prefrontal recruitment (∆PFR), measured as Obstacles ∆O2Hb minus Typical ∆O2Hb. Multiple regression was used to test the relationship between ∆PFR and age, executive function measured by the Trail Making Test, and sex. Pearson's correlation coefficient was used to investigate the association between ∆PFR and the cost of Obstacles walking speed relative to Typical walking. Age, executive function, and their interaction significantly predicted greater ∆PFR (R 2 = 0.34, p = .01). Participants were subgrouped according to age and executive function to examine the interaction effects. Adults of lower age and with lower executive function exhibited greater ∆PFR during Obstacles compared to their peers with higher executive function (p = .03). Adults of advanced age exhibited a ceiling of prefrontal recruitment during obstacle negotiation, regardless of executive function level (p = .87). Greater ∆PFR was significantly associated with a smaller cost of Obstacles (r = 0.3, p = .03). These findings are consistent with the CRUNCH framework: neural inefficiency where a greater amount of brain activation is needed for task performance at a similar level, compensatory overactivation to prevent a steeper decline in task performance, and capacity limitation with a recruitment ceiling effect.

Older adults recruit dorsomedial prefrontal cortex to decrease negativity during retrieval of emotionally complex real-world events

Recent research from our lab has highlighted a prefrontally-mediated control mechanism that decreases the subjective richness of negative episodic events during older adults' episodic memory retrieval. The current study examined whether such a mechanism was also engaged during retrieval of real-world negative events. In a scanned autobiographical memory task, 56 participants (ages 18–83) were presented with images associated with the 2013 Boston Marathon Bombings. Images fell into three categories: primarily positive, primarily negative, and mixed-valence. Participants retrieved a personal memory associated with each image, elaborated on that memory in as much detail as possible, and rated memory positivity and memory negativity. Unlike in recent episodic memory studies, young and older adults did not differ in how prefrontal regions contributed to retrieval of autobiographical memories associated with primarily negative images. However, there was an age-related reversal in the role of dorsomedial prefrontal recruitment during retrieval of autobiographical memories associated with mixed-valence images: Activity was associated with increased negativity ratings in young adults and decreased negativity in older adults. These findings are the first evidence that older adults engage a prefrontally-mediated mechanism at the time of retrieval to reduce the negativity of memories for real-world emotional events, and further suggest that they may only do so in the case of emotional ambiguity. Such a mechanism could have important implications for understanding how older adults may respond to and evaluate negative events in their daily lives.

Interpreting Prefrontal Recruitment During Walking After Stroke: Influence of Individual Differences in Mobility and Cognitive Function.

Background: Functional near-infrared spectroscopy (fNIRS) is a valuable neuroimaging approach for studying cortical contributions to walking function. Recruitment of prefrontal cortex during walking has been a particular area of focus in the literature. The present study investigated whether task-related change in prefrontal recruitment measured by fNIRS is affected by individual differences in people post-stroke. The primary hypotheses were that poor mobility function would contribute to prefrontal over-recruitment during typical walking, and that poor cognitive function would contribute to a ceiling in prefrontal recruitment during dual-task walking (i.e., walking with a cognitive task).Methods: Thirty-three adults with chronic post-stroke hemiparesis performed three tasks: typical walking at preferred speed (Walk), serial-7 subtraction (Serial7), and walking combined with serial-7 subtraction (Dual-Task). Prefrontal recruitment was measured with fNIRS and quantified as the change in oxygenated hemoglobin concentration (ΔO2Hb) between resting and active periods for each task. Spatiotemporal gait parameters were measured on an electronic walkway. Stepwise regression was used to assess how prefrontal recruitment was affected by individual differences including age, sex, stroke region, injured hemisphere, stroke chronicity, 10-meter walking speed, balance confidence measured by Activities-specific Balance Confidence (ABC) Scale, sensorimotor impairment measured by Fugl-Meyer Assessment, and cognitive function measured by Mini-Mental State Examination (MMSE).Results: For Walk, poor balance confidence (ABC Scale score) significantly predicted greater prefrontal recruitment (ΔO2Hb; R2 = 0.25, p = 0.003). For Dual-Task, poor cognitive function (MMSE score) significantly predicted lower prefrontal recruitment (ΔO2Hb; R2 = 0.25, p = 0.002).Conclusions: Poor mobility function predicted higher prefrontal recruitment during typical walking, consistent with compensatory over-recruitment. Poor cognitive function predicted lower prefrontal recruitment during dual-task walking, consistent with a recruitment ceiling effect. These findings indicate that interpretation of prefrontal recruitment should carefully consider the characteristics of the person and demands of the task.

Cognitive reappraisal capacity mediates the relationship between prefrontal recruitment during reappraisal of anger-eliciting events and paranoia-proneness

Difficulties in emotion regulation, particularly in using adaptive regulation strategies such as cognitive reappraisal, are a commonly observed correlate of paranoia. While it has been suggested that poor implementation of cognitive reappraisal in dealing with aversive events precedes the onset of subclinical paranoid thinking, there is little empirical research on neural activation patterns during cognitive reappraisal efforts that might indicate vulnerability towards paranoid thinking. Prefrontal EEG alpha asymmetry changes were recorded while n = 57 participants were generating alternative appraisals of anger-eliciting events, and were linked to a behavioral measure of basic cognitive reappraisal capacity and self-reported paranoia proneness (assessed by personality facets of hostility and suspiciousness; Personality Inventory for DSM-5). Mediation analysis revealed that less left-lateralized activation at ventrolateral prefrontal sites during reappraisal efforts predicted a higher degree of paranoia proneness. This relationship was mediated through poorer cognitive reappraisal capacity. Matching previous evidence, findings suggest that inappropriate brain activation during reappraisal efforts impairs individuals’ capacity to come up with effective alternative interpretations for anger-evoking situations, which may accentuate personality features related to increased paranoid thinking. The findings add to our understanding of neurally underpinned impairments in the capacity to generate cognitive reappraisals and their link to maladaptive personality and behavior.

Older adults use a prefrontal regulatory mechanism to reduce negative memory vividness of a highly emotional real-world event.

Previous research has revealed an age-related shift in how individuals recall events from their personal past, with older adults reporting events that are more positive than young adults. We recently showed that age-by-valence interactions may be partially driven by a prefrontally mediated control mechanism recruited by older adults during retrieval of negative laboratory events to reduce phenomenological richness. Specifically, age was associated with greater increases in prefrontal recruitment during retrieval of negative relative to positive events, with this recruitment linked to decreases in hippocampal activity and subjective vividness ratings. In the current study, we examined whether older adults may rely on a similar mechanism during retrieval of a complex, highly emotional real-world event. Participants (n=58, age: 18-87 years) were presented with images related to the 2013 Boston Marathon Bombings and were asked to retrieve a memory associated with each image. Images cued participants with either negative (associated with fear, destruction, and sadness) or positive (images of hope, resilience, support) features. This study replicated previous episodic memory tasks: age was associated with more negative hippocampal connectivity with dorsomedial prefrontal regions during retrieval of memories triggered by negative relative to positive cues. Such findings suggest that older adults may be recruiting a similar regulatory mechanism during retrieval of both negative laboratory stimuli and highly negative events from their past. These findings are discussed in relation to previous work showing that young and older adults interact differently with the negative details related to a highly negative event.

When less is more: mindfulness predicts adaptive affective responding to rejection via reduced prefrontal recruitment.

Social rejection is a distressing and painful event that many people must cope with on a frequent basis. Mindfulness—defined here as a mental state of receptive attentiveness to internal and external stimuli as they arise, moment-to-moment—may buffer such social distress. However, little research indicates whether mindful individuals adaptively regulate the distress of rejection—or the neural mechanisms underlying this potential capacity. To fill these gaps in the literature, participants reported their trait mindfulness and then completed a social rejection paradigm (Cyberball) while undergoing functional magnetic resonance imaging. Approximately 1 hour after the rejection incident, participants reported their level of distress during rejection (i.e. social distress). Mindfulness was associated with less distress during rejection. This relation was mediated by lower activation in the left ventrolateral prefrontal cortex during the rejection incident, a brain region reliably associated with the inhibition of negative affect. Mindfulness was also correlated with less functional connectivity between the left ventrolateral prefrontal cortex and the bilateral amygdala and the dorsal anterior cingulate cortex, which play a critical role in the generation of social distress. Mindfulness may relate to effective coping with rejection by not over-activating top-down regulatory mechanisms, potentially resulting in more effective long-term emotion-regulation.

Prefrontal Recruitment Mitigates Risk-Taking Behavior in Human Immunodeficiency Virus-Infected Young Adults.

Human immunodeficiency virus (HIV)-infected (HIV+) young adults often engage in risk-taking behavior. However, the disruptive effects of HIV on the neurobiological underpinnings of risky decision making are not well understood. Risky decision making, measured via the Iowa Gambling Task (IGT), was compared voxel-wise to resting cerebral blood flow (rCBF) acquired via arterial spin labeling. Separate topographical maps were obtained for HIV-uninfected (HIV-; n = 62) and HIV+ (n = 41) young adults (18-24 years old) and were compared to the full cohort of participants. For the HIV+ group, rCBF was compared to recent and nadir CD4. IGT performance was supported by rCBF in 3 distinct brain regions: regions I, II, and III. The relationship between IGT performance and rCBF in HIV+ individuals was most robust in region I, the ventromedial prefrontal and insular cortices. Region II contained strong relationships for both HIV- and HIV+. Region III, dorsolateral prefrontal and posterior cingulate cortices, contained relationships that were strongest for HIV- controls. IGT performance was intact among HIV+ participants with higher rCBF in either region I or region III. By contrast, performance was worse among HIV+ individuals with lower rCBF in both regions I and III when compared to HIV- controls (P = .01). rCBF in region III was reduced in HIV+ compared with HIV- individuals (P = .04), and positively associated with nadir CD4 cell count (P = .02). Recruitment of executive systems (region III) mitigates risk-taking behavior in HIV+ and HIV- individuals. Recruitment of reward systems (region I) mitigates risk-taking behavior when region III is disrupted due to immunological compromise. Identifying individual recruitment patterns may aid anatomically directed therapeutics or psychosocial interventions.

Prefrontally-mediated alterations in the retrieval of negative events: Links to memory vividness across the adult lifespan.

Prior research has identified age-by-valence interactions in both behavior and neural recruitment; age has been associated with increased retrieval of positive relative to negative information as well as an increased tendency to recruit prefrontal regions during negative event retrieval and for this recruitment to correspond to decreased hippocampal connectivity. To date, the explicit relation between prefrontal recruitment and memory phenomenology has not been examined. The current study examined the link between these two measures by examining age-by-valence interactions in the relation between prefrontal recruitment and subjective ratings of memory vividness. Participants (ages 18-85) encoded visual images paired with verbal titles. During a scanned retrieval session, they were presented with titles and asked whether each had been seen with an image during encoding. Participants provided vividness ratings following retrieval of each image. Age was associated with greater prefrontally-mediated alterations in negative event phenomenology, with age-related increases in the relation between ventral prefrontal regions and negative event vividness and age-related decreases in the relation between dorsal prefrontal regions and negative event vividness. This analysis confirmed a critical role of PFC regions in age-by-valence interactions, where age reversed the relation between PFC recruitment and the subjective richness of retrieved memory representation. These findings are consistent with studies that reveal age-related enhancements in emotion regulation, and suggest that older adults may be engaging in these processes during retrieval of negative events.

Age-Related Reversals in Neural Recruitment across Memory Retrieval Phases.

Over the last several decades, neuroimaging research has identified age-related neural changes that occur during cognitive tasks. These changes are used to help researchers identify functional changes that contribute to age-related impairments in cognitive performance. One commonly reported example of such a change is an age-related decrease in the recruitment of posterior sensory regions coupled with an increased recruitment of prefrontal regions across multiple cognitive tasks. This shift is often described as a compensatory recruitment of prefrontal regions due to age-related sensory-processing deficits in posterior regions. However, age is not only associated with spatial shifts in recruitment, but also with temporal shifts, in which younger and older adults recruit the same neural region at different points in a task trial. The current study examines the possible contribution of temporal modifications in the often-reported posterior-anterior shift. Participants, ages 19-85, took part in a memory retrieval task with a protracted retrieval trial consisting of an initial memory search phase and a subsequent detail elaboration phase. Age-related neural patterns during search replicated prior reports of age-related decreases in posterior recruitment and increases in prefrontal recruitment. However, during the later elaboration phase, the same posterior regions were associated with age-related increases in activation. Further, ROI and functional connectivity results suggest that these posterior regions function similarly during search and elaboration. These results suggest that the often-reported posterior-anterior shift may not reflect the inability of older adults to engage in sensory processing, but rather a change in when they recruit this processing.SIGNIFICANCE STATEMENT The current study provides evidence that the often-reported posterior-anterior shift in aging may not reflect a global sensory-processing deficit, as has often been reported, but rather a temporal modification in this processing in which older adults engage the same neural regions during a detail elaboration phase that younger adults engage during memory search. In other words, older adults may ultimately be able to engage the same processes as younger adults during some cognitive tasks when given the time to do so. Future research should examine the generalizability of this effect and the importance of encouraging older adults to engage in these processes through task instruction or questions.

Time-source of neural plasticity in complex bimanual coordinative tasks: Juggling

Brain plasticity is especially stimulated by complex bimanual tasks, because, as for juggling, they require simultaneous control of multiple movements, high level of bimanual coordination, balance and sustained swapping attention to multiple objects interacting with both hands. Neuroimaging studies on jugglers showed changes in white and grey matter after juggling training, while the very few electroencephalographic (EEG) studies showed changes in the frequency domain. However, no study has focused on the fine temporal brain activations during a bimanual coordinative task in ecological settings. We aimed at understanding the neural correlates of juggling tasks comparing expert jugglers to non-jugglers. Both groups performed two juggling tasks with increasing difficulty (1-ball fountain and 2-ball shower in non-jugglers, 2- and 3-ball shower in expert jugglers), while the EEG was recorded. This design allowed to compare brain activities related to increasing task difficulty within the same group, and the two groups on the same task. The movement-related cortical potentials (MRCPs) for each task were segmented into epochs lasting 4.5s (−1.5/+3.0s). Results showed enhanced prefrontal recruitment with increasing task difficulty in both groups, even before movement onset. Comparing the groups on the same task, non-jugglers showed enhanced activation of prefrontal regions before and during the task execution, whereas jugglers showed enhanced activity in motor-related regions. The results provide a clear indication of practice-induced brain efficiency during the performance of complex bimanual coordinative skills.

The transition from childhood to adolescence is marked by a general decrease in amygdala reactivity and an affect-specific ventral-to-dorsal shift in medial prefrontal recruitment

Understanding how and why affective responses change with age is central to characterizing typical and atypical emotional development. Prior work has emphasized the role of the amygdala and prefrontal cortex (PFC), which show age-related changes in function and connectivity. However, developmental neuroimaging research has only recently begun to unpack whether age effects in the amygdala and PFC are specific to affective stimuli or may be found for neutral stimuli as well, a possibility that would support a general, rather than affect-specific, account of amygdala-PFC development. To examine this, 112 individuals ranging from 6 to 23 years of age viewed aversive and neutral images while undergoing fMRI scanning. Across age, participants reported more negative affect and showed greater amygdala responses for aversive than neutral stimuli. However, children were generally more sensitive to both neutral and aversive stimuli, as indexed by affective reports and amygdala responses. At the same time, the transition from childhood to adolescence was marked by a ventral-to-dorsal shift in medial prefrontal responses to aversive, but not neutral, stimuli. Given the role that dmPFC plays in executive control and higher-level representations of emotion, these results suggest that adolescence is characterized by a shift towards representing emotional events in increasingly cognitive terms.

VlPFC-vmPFC-Amygdala Interactions Underlie Age-Related Differences in Cognitive Regulation of Emotion.

Emotion regulation is a critical life skill that develops throughout childhood and adolescence. Despite this development in emotional processes, little is known about how the underlying brain systems develop with age. This study examined emotion regulation in 112 individuals (aged 6-23 years) as they viewed aversive and neutral images using a reappraisal task. On "reappraisal" trials, participants were instructed to view the images as distant, a strategy that has been previously shown to reduce negative affect. On "reactivity" trials, participants were instructed to view the images without regulating emotions to assess baseline emotional responding. During reappraisal, age predicted less negative affect, reduced amygdala responses and inverse coupling between the ventromedial prefrontal cortex (vmPFC) and amygdala. Moreover, left ventrolateral prefrontal (vlPFC) recruitment mediated the relationship between increasing age and diminishing amygdala responses. This negative vlPFC-amygdala association was stronger for individuals with inverse coupling between the amygdala and vmPFC. These data provide evidence that vmPFC-amygdala connectivity facilitates vlPFC-related amygdala modulation across development.

How do negative emotions impair self-control? A neural model of negative urgency

Self-control often fails when people experience negative emotions. Negative urgency represents the dispositional tendency to experience such self-control failure in response to negative affect. Neither the neural underpinnings of negative urgency nor the more general phenomenon of self-control failure in response to negative emotions are fully understood. Previous theorizing suggests that an insufficient, inhibitory response from the prefrontal cortex may be the culprit behind such self-control failure. However, we entertained an alternative hypothesis: negative emotions lead to self-control failure because they excessively tax inhibitory regions of the prefrontal cortex. Using fMRI, we compared the neural activity of people high in negative urgency with controls on an emotional, inhibitory Go/No-Go task. While experiencing negative (but not positive or neutral) emotions, participants high in negative urgency showed greater recruitment of inhibitory brain regions than controls. Suggesting a compensatory function, inhibitory accuracy among participants high in negative urgency was associated with greater prefrontal recruitment. Greater activity in the anterior insula on negatively-valenced, inhibitory trials predicted greater substance abuse one month and one year after the MRI scan among individuals high in negative urgency. These results suggest that, among people whose negative emotions often lead to self-control failure, excessive reactivity of the brain's regulatory resources may be the culprit.

Distinct frontal and amygdala correlates of change detection for facial identity and expression.

Recruitment of ‘top-down’ frontal attentional mechanisms is held to support detection of changes in task-relevant stimuli. Fluctuations in intrinsic frontal activity have been shown to impact task performance more generally. Meanwhile, the amygdala has been implicated in ‘bottom-up’ attentional capture by threat. Here, 22 adult human participants took part in a functional magnetic resonance change detection study aimed at investigating the correlates of successful (vs failed) detection of changes in facial identity vs expression. For identity changes, we expected prefrontal recruitment to differentiate ‘hit’ from ‘miss’ trials, in line with previous reports. Meanwhile, we postulated that a different mechanism would support detection of emotionally salient changes. Specifically, elevated amygdala activation was predicted to be associated with successful detection of threat-related changes in expression, over-riding the influence of fluctuations in top-down attention. Our findings revealed that fusiform activity tracked change detection across conditions. Ventrolateral prefrontal cortical activity was uniquely linked to detection of changes in identity not expression, and amygdala activity to detection of changes from neutral to fearful expressions. These results are consistent with distinct mechanisms supporting detection of changes in face identity vs expression, the former potentially reflecting top-down attention, the latter bottom-up attentional capture by stimulus emotional salience.

On Weight and Waiting: Delay Discounting in Anorexia Nervosa Pretreatment and Posttreatment

BackgroundIndividuals with anorexia nervosa (AN) override the drive to eat, forgoing immediate rewards in favor of longer-term goals. We examined delay discounting and its neural correlates in AN before and after treatment to test a potential mechanism of illness persistence. MethodsInpatients with AN (n = 59) and healthy control subjects (HC, n = 39) performed a delay discounting task at two time points. A subset (n = 30 AN, n = 22 HC) participated in functional magnetic resonance imaging scanning during the task. The task consisted of a range of monetary choices with variable delay times, yielding individual discount rates—the rate by which money loses value over time. ResultsBefore treatment, the AN group showed a preference for delayed over earlier rewards (i.e., less steep discount rates) compared with HC; after weight restoration, AN did not differ from HC. Underweight AN showed slower response times for earlier versus delayed choices; this reversed with treatment. Underweight AN showed abnormal neural activity in striatum and dorsal anterior cingulate; normalization of behavior was associated with increased activation in reward regions (striatum and dorsal anterior cingulate) and decision-making regions (dorsolateral prefrontal cortex and parietal cortex). ConclusionsThe undernourished state of AN may amplify the tendency to forgo immediate rewards in favor of longer-term goals. The results suggest that behavior that looks phenotypically like excessive self-control does not correspond with enhanced prefrontal recruitment. Rather, the results point to alterations in cingulostriatal circuitry that offer new insights on the potential role of abnormalities in decision-making neural systems in the perpetuation of AN.

Prefrontal recruitment during social rejection predicts greater subsequent self-regulatory imbalance and impairment: neural and longitudinal evidence

Social rejection impairs self-regulation, yet the neural mechanisms underlying this relationship remain unknown. The right ventrolateral prefrontal cortex (rVLPFC) facilitates self-regulation and plays a robust role in regulating the distress of social rejection. However, recruiting this region’s inhibitory function during social rejection may come at a self-regulatory cost. As supported by prominent theories of self-regulation, we hypothesized that greater rVLPFC recruitment during rejection would predict a subsequent self-regulatory imbalance that favored reflexive impulses (i.e., cravings), which would then impair self-regulation. Supporting our hypotheses, rVLPFC activation during social rejection was associated with greater subsequent nucleus accumbens (NAcc) activation and lesser functional connectivity between the NAcc and rVLPFC to appetitive cues. Over seven days, the effect of daily felt rejection on daily self-regulatory impairment was exacerbated among participants who showed a stronger rVLPFC response to social rejection. This interactive effect was mirrored in the effect of daily felt rejection on heightened daily alcohol cravings. Our findings suggest that social rejection likely impairs self-regulation by recruiting the rVLPFC, which then tips the regulatory balance towards reward-based impulses.