Prefrontal inhibition of threat processing reduces working memory interference

Bottom-up processes can interrupt ongoing cognitive processing in order to adaptively respond to emotional stimuli of high potential significance, such as those that threaten wellbeing. However it is vital that this interference can be modulated in certain contexts to focus on current tasks. Deficits in the ability to maintain the appropriate balance between cognitive and emotional demands can severely impact on day-to-day activities. This fMRI study examined this interaction between threat processing and cognition; 18 adult participants performed a visuospatial working memory (WM) task with two load conditions, in the presence and absence of anxiety induction by threat of electric shock. Threat of shock interfered with performance in the low cognitive load condition; however interference was eradicated under high load, consistent with engagement of emotion regulation mechanisms. Under low load the amygdala showed significant activation to threat of shock that was modulated by high cognitive load. A directed top-down control contrast identified two regions associated with top-down control; ventrolateral PFC and dorsal ACC. Dynamic causal modeling provided further evidence that under high cognitive load, top-down inhibition is exerted on the amygdala and its outputs to prefrontal regions. Additionally, we hypothesized that individual differences in a separate, non-emotional top-down control task would predict the recruitment of dorsal ACC and ventrolateral PFC during top-down control of threat. Consistent with this, performance on a separate dichotic listening task predicted dorsal ACC and ventrolateral PFC activation during high WM load under threat of shock, though activation in these regions did not directly correlate with WM performance. Together, the findings suggest that under high cognitive load and threat, top-down control is exerted by dACC and vlPFC to inhibit threat processing, thus enabling WM performance without threat-related interference.

Variation, asymmetry and working memory in the process of second language acquisition

Calls for understanding the interface between L2 linguistic knowledge and development (Gregg 1996; Carroll 2001; Towell 2003) provide a context for analysing the role of memory (Paradis 2004), specifically working memory (Baddeley 1986, 2003) in L2 development. Miyake and Friedman (1998) have claimed that Working Memory (WM) may be the key to L2 acquisition, especially in explaining individual variation in L2 acquisition. Recent findings found a robust connection between greater working memory (WM) capacity and rapid, successful acquisition of L2 vocabulary, reading and oral fluency (Service 1992; Harrington and Sawyer 1992; Fortkamp 1999). This study adds to the growing body of research by investigating correlations between WM and variation in grammatical development, focusing on asymmetries in processing L2 English wh-constructions in an immersion setting.

Memory versus naive T-cell migration

Our established understanding of lymphocyte migration suggests that naive and memory T cells travel throughout the body via divergent pathways; naive T cells circulate between blood and lymph whereas memory T cells additionally migrate through non-lymphoid organs. Evidence is now gradually emerging which suggests such disparate pathways between naive and memory T cells may not strictly be true, and that naive T cells gain access to the non-lymphoid environment in numbers approaching that of memory T cells. We discuss here the evidence for naive T-cell traffic into the non-lymphoid environment, compare and contrast this movement with what is known of memory T cells, and finally discuss the functional importance of why naive T cells might access the parenchymal tissues.

Dietary levels of pure flavonoids improve spatial memory performance and increase hippocampal brain-derived neurotrophic factor.

Evidence suggests that flavonoid-rich foods are capable of inducing improvements in memory and cognition in animals and humans. However, there is a lack of clarity concerning whether flavonoids are the causal agents in inducing such behavioral responses. Here we show that supplementation with pure anthocyanins or pure flavanols for 6 weeks, at levels similar to that found in blueberry (2% w/w), results in an enhancement of spatial memory in 18 month old rats. Pure flavanols and pure anthocyanins were observed to induce significant improvements in spatial working memory (p = 0.002 and p = 0.006 respectively), to a similar extent to that following blueberry supplementation (p = 0.002). These behavioral changes were paralleled by increases in hippocampal brain-derived neurotrophic factor (R = 0.46, p<0.01), suggesting a common mechanism for the enhancement of memory. However, unlike protein levels of BDNF, the regional enhancement of BDNF mRNA expression in the hippocampus appeared to be predominantly enhanced by anthocyanins. Our data support the claim that flavonoids are likely causal agents in mediating the cognitive effects of flavonoid-rich foods.

Phenolic acid intake, delivered via moderate champagne wine consumption, improves spatial working memory via the modulation of hippocampal and cortical protein expression/activation.

Aims: While much data exist for the effects of flavonoid-rich foods on spatial memory in rodents, there are no such data for foods/beverages predominantly containing hydroxycinnamates and phenolic acids. To address this, we investigated the effects of moderate Champagne wine intake, which is rich in these components, on spatial memory and related mechanisms relative to the alcohol- and energy-matched controls. Results: In contrast to the isocaloric and alcohol-matched controls, supplementation with Champagne wine (1.78 ml/kg BW, alcohol 12.5% vol.) for 6 weeks led to an improvement in spatial working memory in aged rodents. Targeted protein arrays indicated that these behavioral effects were paralleled by the differential expression of a number of hippocampal and cortical proteins (relative to the isocaloric control group), including those involved in signal transduction, neuroplasticity, apoptosis, and cell cycle regulation. Western immunoblotting confirmed the differential modulation of brain-derived neurotrophic factor, cAMP response-element-binding protein (CREB), p38, dystrophin, 2',3'-cyclic-nucleotide 3'-phosphodiesterase, mammalian target of rapamycin (mTOR), and Bcl-xL in response to Champagne supplementation compared to the control drink, and the modulation of mTOR, Bcl-xL, and CREB in response to alcohol supplementation. Innovation: Our data suggest that smaller phenolics such as gallic acid, protocatechuic acid, tyrosol, caftaric acid, and caffeic acid, in addition to flavonoids, are capable of exerting improvements in spatial memory via the modulation in hippocampal signaling and protein expression. Conclusion: Changes in spatial working memory induced by the Champagne supplementation are linked to the effects of absorbed phenolics on cytoskeletal proteins, neurotrophin expression, and the effects of alcohol on the regulation of apoptotic events in the hippocampus and cortex. Antioxid. Redox Signal. 00, 000-000.

An investigation of working memory effects on oral grammatical accuracy and fluency in producing questions in English

This article addresses the question of how far working memory may affect second language (L2) learners' improvement in spoken language during a period of immersion. Research is presented testing the hypothesis that individual differences in working memory (WM) capacity are associated with individual variation in improvements in oral production of questions in English. Thirty-two Chinese adult speakers of English were tested, before and after a year's postgraduate study in the United Kingdom, to measure grammatical accuracy and fluency using a question elicitation task, and to measure WM using a battery of first language (L1) and L2 WM tests. Story recall in L1 (Mandarin) was significantly associated with individuals' improvement in oral grammatical measures (p < .05). However, there was no significant mean improvement across the cohort in grammatical accuracy, although there was for fluency. The findings suggest that WM may aid certain aspects of individuals' L2 oral proficiency during academic immersion through postgraduate study. They also indicate that academic immersion in itself can lead to improvements in oral proficiency, independent of WM capacity, but there is no general guarantee of significant grammatical change. Further research to clarify the opportunities for input and interaction available in academic immersion settings is called for.

Amygdala functional connectivity with medial prefrontal cortex at rest predicts the positivity effect in older adults’ memory

As people get older, they tend to remember more positive than negative information. This age-by-valence interaction has been called “positivity effect.” The current study addressed the hypotheses that baseline functional connectivity at rest is predictive of older adults' brain activity when learning emotional information and their positivity effect in memory. Using fMRI, we examined the relationship among resting-state functional connectivity, subsequent brain activity when learning emotional faces, and individual differences in the positivity effect (the relative tendency to remember faces expressing positive vs. negative emotions). Consistent with our hypothesis, older adults with a stronger positivity effect had increased functional coupling between amygdala and medial PFC (MPFC) during rest. In contrast, younger adults did not show the association between resting connectivity and memory positivity. A similar age-by-memory positivity interaction was also found when learning emotional faces. That is, memory positivity in older adults was associated with (a) enhanced MPFC activity when learning emotional faces and (b) increased negative functional coupling between amygdala and MPFC when learning negative faces. In contrast, memory positivity in younger adults was related to neither enhanced MPFC activity to emotional faces, nor MPFC–amygdala connectivity to negative faces. Furthermore, stronger MPFC–amygdala connectivity during rest was predictive of subsequent greater MPFC activity when learning emotional faces. Thus, emotion–memory interaction in older adults depends not only on the task-related brain activity but also on the baseline functional connectivity.

Emotion strengthens high priority memory traces but weakens low priority memory traces

When people encounter emotional events, their memory for those events is typically enhanced. But it has been unclear how emotionally arousing events influence memory for preceding information. Does emotional arousal induce retrograde amnesia or retrograde enhancement? The current study revealed that this depends on the top-down goal relevance of the preceding information. Across three studies, we found that emotional arousal induced by one image facilitated memory for the preceding neutral item when people prioritized that neutral item. In contrast, an emotionally arousing image impaired memory for the preceding neutral item when people did not prioritize that neutral item. Emotional arousal elicited by both negative and positive pictures showed this pattern of enhancing or impairing memory for the preceding stimulus depending on its priority. These results indicate that emotional arousal amplifies the effects of top-down priority in memory formation.

Money enhances memory consolidation – but only for boring material

Money’s ability to enhance memory has received increased attention in recent research. However, previous studies have not directly addressed the time-dependent nature of monetary effects on memory, which are suggested to exist by research in cognitive neuroscience, and the possible detrimental effects of monetary rewards on learning interesting material, as indicated by studies in motivational psychology. By utilizing a trivia question paradigm, the current study incorporated these perspectives and examined the effect of monetary rewards on immediate and delayed memory performance for answers to uninteresting and interesting questions. Results showed that monetary rewards promote memory performance only after a delay. In addition, the memory enhancement effect of monetary rewards was only observed for uninteresting questions. These results are consistent with both the hippocampus-dependent memory consolidation model of reward learning and previous findings documenting the ineffectiveness of monetary rewards on tasks that have intrinsic value.

The role of working memory in the processing of reflexives

We report results from two eye-movement experiments that examined how differences in working memory (WM) capacity affect readers' application of structural constraints on reflexive anaphor resolution during sentence comprehension. We examined whether binding Principle A, a syntactic constraint on the interpretation of reflexives, is reducible to a memory friendly “recency” strategy, and whether WM capacity influences the degree to which readers create anaphoric dependencies ruled out by binding theory. Our results indicate that low and high WM span readers applied Principle A early during processing. However, contrary to previous findings, low span readers also showed immediate intrusion effects of a linearly closer but structurally inaccessible competitor antecedent. We interpret these findings as indicating that although the relative prominence of potential antecedents in WM can affect online anaphor resolution, Principle A is not reducible to a processing or linear distance based “least effort” constraint.

Achievement motivation and memory: achievement goals differentially influence immediate and delayed remember–know recognition memory

Little research has been conducted on achievement motivation and memory and, more specifically, on achievement goals and memory. In the present research, the authors conducted two experiments designed to examine the influence of mastery-approach and performance-approach goals on immediate and delayed remember–know recognition memory. The experiments revealed differential effects for achievement goals over time: Performance-approach goals showed higher correct remember responding on an immediate recognition test, whereas mastery-approach goals showed higher correct remember responding on a delayed recognition test. Achievement goals had no influence on overall recognition memory and no consistent influence on know responding across experiments. These findings indicate that it is important to consider quality, not just quantity, in both motivation and memory, when studying relations between these constructs. (PsycINFO Database Record (c) 2012 APA, all rights reserved)(journal abstract)

Consolidation power of extrinsic rewards: reward cues enhance long-term memory for irrelevant past events

Recent research suggests that extrinsic rewards promote memory consolidation through dopaminergic modulation processes. However, no conclusive behavioral evidence exists given that the influence of extrinsic reward on attention and motivation during encoding and consolidation processes are inherently confounded. The present study provides behavioral evidence that extrinsic rewards (i.e., monetary incentives) enhance human memory consolidation independently of attention and motivation. Participants saw neutral pictures, followed by a reward or control cue in an unrelated context. Our results (and a direct replication study) demonstrated that the reward cue predicted a retrograde enhancement of memory for the preceding neutral pictures. This retrograde effect was observed only after a delay, not immediately upon testing. An additional experiment showed that emotional arousal or unconscious resource mobilization cannot explain the retrograde enhancement effect. These results provide support for the notion that the dopaminergic memory consolidation effect can result from extrinsic reward. (PsycINFO Database Record (c) 2013 APA, all rights reserved)(journal abstract)