Enhanced Memory Performance Research Articles

UV-sensing organic phototransistor memory devices with a doped organic polymer electret composed of triphenylamine-based aggregation-induced emission luminogens

The UV-sensing OFET memories with enhanced memory performance are developed by introducing the AIEgen-doped electret which could obtain better spectral overlap between the emission of doped electrets and the absorption of pentacene.

Let's replay.

Reactivating brain activity patterns during sleep enhances memory performance the next day.

A Protocol for Transcranial Photobiomodulation Therapy in Mice.

Transcranial photobiomodulation is a potential innovative noninvasive therapeutic approach for improving brain bioenergetics, brain function in a wide range of neurological and psychiatric disorders, and memory enhancement in age-related cognitive decline and neurodegenerative diseases. We describe a laboratory protocol for transcranial photobiomodulation therapy (PBMT) in mice. Aged BALB/c mice (18 months old) are treated with a 660 nm laser transcranially, once daily for 2 weeks. Laser transmittance data shows that approximately 1% of the incident red light on the scalp reaches a 1 mm depth from the cortical surface, penetrating the dorsal hippocampus. Treatment outcomes are assessed by two methods: a Barnes maze test, which is a hippocampus-dependent spatial learning and memory task evaluation, and measuring hippocampal ATP levels, which is used as a bioenergetics index. The results from the Barnes task show an enhancement of the spatial memory in laser-treated aged mice when compared with age-matched controls. Biochemical analysis after laser treatment indicates increased hippocampal ATP levels. We postulate that the enhancement of memory performance is potentially due to an improvement in hippocampal energy metabolism induced by the red laser treatment. The observations in mice could be extended to other animal models since this protocol could potentially be adapted to other species frequently used in translational neuroscience, such as rabbit, cat, dog, or monkey. Transcranial photobiomodulation is a safe and cost-effective modality which may be a promising therapeutic approach in age-related cognitive impairment.

Transcranial direct current stimulation induces hippocampal metaplasticity mediated by brain-derived neurotrophic factor

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique used to modulate neuronal excitability via externally applied electric fields. Despite the positive effects of tDCS in a wide range of neurological disorders in humans, its mechanism of action remains poorly understood. Here we investigated cellular and molecular mechanisms underlying the aftereffects of anodal tDCS on the induction of long-term potentiation (LTP), a cellular correlate of learning and memory, at Schaffer collateral-CA1 synapses. We found that hippocampal CA1 LTP was enhanced in slices from rats subjected to anodal tDCS with no significant changes in basal synaptic function. The enhancing effect of tDCS on LTP was still maintained 12 h after stimulation. Treatment of ex vivo hippocampal slices from tDCS-treated rats with tropomyosin receptor kinase B (TrkB) inhibitor ANA-12, but not D1 receptor antagonist SKF-83566 or β2-adrenergic receptor antagonist propranolol, efficiently prevented tDCS-induced enhancement of LTP. The tDCS-treated rats exhibited higher levels of brain derived neurotrophic factor (BDNF) in the hippocampal CA1 region compared to sham-treated rats. Anodal tDCS also enhances memory performance in hippocampal-dependent passive avoidance learning task, and this enhancement can be blocked by ANA-12 pretreatment. Altogether, our results underscore the importance of BDNF/TrkB-mediated metaplastic effect of anodal tDCS on the induction of hippocampal CA1 LTP.

Drawing as an Encoding Tool: Memorial Benefits in Younger and Older Adults

ABSTRACTBackground/Study Context. In a recent study, drawing pictures relative to writing words at encoding has been shown to benefit later memory performance in young adults. In the current study, we sought to test whether older adults’ memory might also benefit from drawing as an encoding strategy. Our prediction was that drawing would serve as a particularly effective form of environmental support at encoding as it encourages a more detailed perceptual representation.Methods. Participants were presented 30 nouns, one at a time, and asked to either draw a picture or repeatedly write out the word, which was followed by a free recall test for all words (Experiment 1). In Experiment 2, we added an elaborative processing task in which we asked participants to list physical characteristics of the objects. In Experiment 3, we probed recognition memory for the words.Results. Of the words recalled in Experiment 1, a larger proportion had been drawn than written at encoding, and this effect was larger in older relative to younger adults. In Experiment 2, we demonstrated that drawing improves memory in both younger and older adults more than does an elaborative encoding task consisting of listing descriptive characteristics of the target nouns. In Experiment 3, older and younger adults drew or wrote out words at encoding, and subsequently provided Remember-Know-New recognition memory decisions. We showed that drawing reduced age-related differences in Remember responses.Conclusions. We suggest that incorporating visuo-perceptual information into the memory trace, by drawing pictures at study, increases reliance of the memory trace on visual sensory regions, which are relatively intact in normal aging, relative to simply writing out or elaborately encoding words. Overall, results indicate that drawing is a highly valuable form of environmental support that can significantly enhance memory performance in older adults.

Probabilistic retro-cues do not determine state in visual working memory

The effective use of our capacity-limited visual working memory (VWM) requires mechanisms that govern how it represents information. Validly cueing an item in VWM after encoding, for instance, enhances memory performance for that item and biases its state in VWM, bringing its representation to an active state such that attentional selection is biased towards perceptually similar inputs. Critically, when the retro-cue is less than 100% valid (i.e., probabilistic rather than deterministic), the effect of the cue on memory performance varies. Here we investigated whether deterministic and probabilistic retro-cues also differ in their influence over item state in VWM. Participants encoded two colored squares, and a retro-cue indicated which item was most likely to be probed in a subsequent memory test. Across blocks, we manipulated cue validity to be deterministic (100% valid) or probabilistic (70% valid). On a subset of trials, no memory probe was presented and the trial ended with a visual search task in which a colored distractor -matching the cued memory item, the non-cued item, or neither - was presented. Predictably, in the deterministic condition, the presence of a singleton distractor matching the cued item reliably slowed reaction times during visual search. In the probabilistic condition, however, there were no differences in reaction times when the singleton matched the cued item or the non-cued item, despite a reliable benefit to memory performance on valid memory trials. We suggest that, while probabilistic retro-cues improve memory of the cued item, they are not sufficient to bias its state in VWM.

Stress impacts the fidelity but not strength of emotional memories

Psychological stress during memory encoding influences resulting memory representations. However, open questions remain regarding how stress interacts with emotional memory. This interaction has mainly been studied by characterizing the correct identification of previously observed material (memory “hits”), with few studies investigating how stress influences the endorsement of unobserved material as remembered (memory “false alarms”). While hits can provide information about the presence or strength of a memory representation, false alarms provide insight into memory fidelity, indicating to what extent stored memories are confused with similar information presented at retrieval. This study examined the effects of stress on long-term memory for negative and neutral images, considering the separate contributions of hits and false alarms. Participants viewed images after repeated exposure to either a stress or a control manipulation. Stress impaired memory performance for negative pictures and enhanced memory performance for neutral pictures. These effects were driven by false alarms rather than hits: stressed participants false alarmed more often for negative and less often for neutral images. These data suggest that stress undermines the benefits of emotion on memory by changing individuals’ susceptibility towards false alarms, and highlight the need to consider both memory strength and fidelity to characterize differences in memory performance.

Olfactory Context Dependent Memory: Direct Presentation of Odorants.

Information is retrieved more effectively when the retrieval occurs in the same context as that in which the information was first encoded. This is termed context dependent memory (CDM). One category of cues that have been shown to effectively produce CDM effects are odors. However, it is unclear what the boundary conditions of these CDM effects are. In particular, given that olfaction has been called an implicit sense, it is possible that odors are only effective mnemonic cues when they are presented in the background. This assertion seems even more likely given that previous research has shown odors to be poor cues during paired associate memory tests, where odors are in the focus of attention as mnemonic cues for other information. In order to determine whether odors are only effective contextual mnemonic cues when presented outside the central focus of an observer, an olfactory CDM experiment was performed in which odorants were presented directly, rather than ambiently. Direct presentation was accomplished with the aid of an olfactometer. The olfactometer not only allows for direct presentation of odorants, but provides other methodological benefits, including the allowance of trial by trial manipulations of odorant presentations and, relatedly, time-specific releases of odorants. The presence of the same odor during both encoding and retrieval enhanced memory performance, regardless of whether the odor was presented ambiently or directly. This finding can serve as a basis for future olfactory CDM research which can utilize the benefits of direct presentation.

Distinctiveness and the attentional boost effect.

The typical pattern of results in divided attention experiments is that subjects in a full attention (FA) condition perform markedly better on tests of memory than subjects in a divided attention (DA) condition which forces subjects to split their attention between studying to-be-remembered stimuli and completing some peripheral task. Nevertheless, recent research has revealed an exception wherein stimuli presented concurrently with targets in a detection task are better remembered than stimuli which co-occur with distractors. Research on this phenomenon-the Attentional Boost Effect (ABE)-has demonstrated that the ABE is reduced or eliminated for words made distinct by their word frequency or orthographic properties-forms of secondary distinctiveness. However, it is unclear how primary distinctiveness effects may interact with the ABE. The current study observed how perceptual and semantic manipulations of primary distinctiveness via the isolation paradigm interact with the ABE, and revealed these interactions to be fundamentally different than those of secondary distinctiveness. Specifically, whereas the effects of secondary distinctiveness in earlier studies were found to be redundant with the ABE, the current study demonstrated that items characterized by primary distinctiveness enhanced memory performance independently of the ABE. (PsycINFO Database Record

Estimation in self-initiated working memory for spatial locations

The short-term maintenance of precise location information is fundamental in many daily activities. Often, individuals memorize spatial information provided to them, but in many other occasions memory is self-initiated, meaning that individuals memorize locations they selected themselves. While prevalent in everyday behavior, research on self-initiated working memory (WM) is scarce. The current study employed a modified spatial precision memory task in which participants temporarily memorized single locations they themselves selected within a square area that appeared during encoding. We explored the distribution of locations participants selected, guided by the assumption that participants would select locations that they perceived would maximize accuracy. The results of two experiments demonstrated that, to enhance memory performance, participants most often selected prototypical locations within the square area, namely, at its center and at its corners, which were closest to the center and the corners of the entire screen. When asked to disrupt memory performance, participants mostly avoided these locations. Furthermore, memory accuracy for self-initiated locations was superior to memory for provided locations, even when the distribution of locations in the two conditions was matched. We interpret the results within the framework of models that emphasize the utility of spatial categories in maximizing memory accuracy in spatial-estimation tasks. The results provide the first illustration of self-initiated representations in spatial precision WM tasks, suggesting that participants have access to metacognitive knowledge about the usefulness of spatial categories in location memory. Moreover, the results demonstrate that spatial precision is enhanced when participants reproduce locations they selected themselves.

Examining the contributions of desirable difficulty and reminding to the spacing effect.

Although substantial evidence indicates that spacing repeated study events with intervening material generally enhances memory performance relative to massing study events, the mechanism underlying this benefit is less clear. Two experiments examined the role of reminding difficulty during the acquisition of material in modulating final memory performance for spaced repetitions utilizing recognition (Experiment 1) and recall tests (Experiment 2). Specifically, participants studied a list of words presented one or two times separated by one or five items. On each trial participants reported whether the item had been previously presented (i.e., repetition detection judgment), and the response latency served as a proxy for reminding difficulty such that longer response latencies reflected more difficult reminding. A third experiment extended this paradigm with the inclusion of a massed condition and novel lag conditions (three and ten items). Results revealed significant lag effects in final test performance across experiments despite comparable repetition detection difficulty between lag conditions during acquisition. Moreover, results from within-participant point-biserial analyses and mediation analyses converged on overall performance measures in suggesting that repetition detection difficulty failed to modulate final test performance in the current paradigm. Discussion considers the implications of the current results for mechanisms proposed to underlie the benefits of spaced study and spaced retrieval practice.

Encoding strategies in self-initiated visual working memory.

During a typical day, visual working memory (VWM) is recruited to temporarily maintain visual information. Although individuals often memorize external visual information provided to them, on many other occasions they memorize information they have constructed themselves. The latter aspect of memory, which we term self-initiated WM, is prevalent in everyday behavior but has largely been overlooked in the research literature. In the present study we employed a modified change detection task in which participants constructed the displays they memorized, by selecting three or four abstract shapes or real-world objects and placing them at three or four locations in a circular display of eight locations. Half of the trials included identical targets that participants could select. The results demonstrated consistent strategies across participants. To enhance memory performance, participants reported selecting abstract shapes they could verbalize, but they preferred real-world objects with distinct visual features. Furthermore, participants constructed structured memory displays, most frequently based on the Gestalt organization cue of symmetry, and to a lesser extent on cues of proximity and similarity. When identical items were selected, participants mostly placed them in close proximity, demonstrating the construction of configurations based on the interaction between several Gestalt cues. The present results are consistent with recent findings in VWM, showing that memory for visual displays based on Gestalt organization cues can benefit VWM, suggesting that individuals have access to metacognitive knowledge on the benefit of structure in VWM. More generally, this study demonstrates how individuals interact with the world by actively structuring their surroundings to enhance performance.

Effects of resveratrol on memory performance, hippocampus connectivity and microstructure in older adults – A randomized controlled trial

IntroductionThe polyphenol resveratrol has been suggested to exert beneficial effects on memory and the aging hippocampus due to calorie-restriction mimicking effects. However, the evidence based on human interventional studies is scarce. We therefore aimed to determine the effects of resveratrol on memory performance, and to identify potential underlying mechanisms using a broad array of blood-based biomarkers as well as hippocampus connectivity and microstructure assessed with ultra-high field magnetic resonance imaging (UHF-MRI). MethodsIn this double-blind, randomized controlled trial, 60 elderly participants (60–79 years) with a wide body-mass index (BMI) range of 21–37 kg/m2 were randomized to receive either resveratrol (200 mg/day) or placebo for 26 weeks (registered at ClinicalTrials.gov: NCT02621554). Baseline and follow-up assessments included the California Verbal Learning Task (CVLT, main outcome), the ModBent task, anthropometry, markers of glucose and lipid metabolism, inflammation and neurotrophins derived from fasting blood, multimodal neuroimaging at 3 and 7 T, and questionnaires to assess confounding factors. ResultsMultivariate repeated-measures ANOVA did not detect significant time by group effects for CVLT performance. There was a trend for preserved pattern recognition memory after resveratrol, while performance decreased in the placebo group (n.s., p = 0.07). Further exploratory analyses showed increases in both groups over time in body fat, cholesterol, fasting glucose, interleukin 6, high sensitive C-reactive protein, tumor necrosis factor alpha and in mean diffusivity of the subiculum and presubiculum, as well as decreases in physical activity, brain-derived neurotrophic factor and insulin-like growth factor 1 at follow-up, which were partly more pronounced after resveratrol. DiscussionThis interventional study failed to show significant improvements in verbal memory after 6 months of resveratrol in healthy elderly with a wide BMI range. A non-significant trend emerged for positive effects on pattern recognition memory, while possible confounding effects of unfavorable changes in lifestyle behavior, neurotrophins and inflammatory markers occurred. Our findings also indicate the feasibility to detect (un)healthy aging-related changes in measures of hippocampus microstructure after 6 months using 7T diffusion MRI. More studies incorporating a longer duration and larger sample size are needed to determine if resveratrol enhances memory performance in healthy older adults.

New waves: Rhythmic electrical field stimulation systematically alters spontaneous slow dynamics across mouse neocortex

The signature rhythm of slow-wave forebrain activity is the large amplitude, slow oscillation (SO: ∼1 Hz) made up of alternating synchronous periods of activity and silence at the single cell and network levels. On each wave, the SO originates at a unique location and propagates across the neocortex. Attempts to manipulate SO activity using electrical fields have been shown to entrain cortical networks and enhance memory performance. However, neural activity during this manipulation has remained elusive due to methodological issues in typical electrical recordings. Here we took advantage of voltage-sensitive dye (VSD) imaging in a bilateral cortical preparation of urethane-anesthetized mice to track SO cortical activity and its modulation by sinusoidal electrical field stimulation applied to frontal regions. We show that under spontaneous conditions, the SO propagates in two main opposing directional patterns along an anterior lateral – posterior medial axis, displaying a rich variety of possible trajectories on any given wave. Under rhythmic field stimulation, new propagation patterns emerge, which are not observed under spontaneous conditions, reflecting stimulus-entrained activity with distributed and varied anterior initiation zones and a consistent termination zone in the posterior somatosensory cortex. Furthermore, stimulus-induced activity patterns tend to repeat cycle after cycle, showing higher stereotypy than during spontaneous activity. Our results show that slow electrical field stimulation robustly entrains and alters ongoing slow cortical dynamics during sleep-like states, suggesting a mechanism for targeting specific cortical representations to manipulate memory processes.

A daily single dose of a novel modafinil analogue CE-123 improves memory acquisition and memory retrieval

Dopamine reuptake inhibitors have been shown to improve cognitive parameters in various tasks and animal models. We recently reported a series of modafinil analogues, of which the most promising, 5-((benzhydrylsulfinyl)methyl) thiazole (CE-123), was selected for further development. The present study aims to characterize pharmacological properties of CE-123 and to investigate the potential to enhance memory performance in a rat model. In vitro transporter assays were performed in cells expressing human transporters. CE-123 blocked uptake of [3H] dopamine (IC50 = 4.606 μM) while effects on serotonin (SERT) and the norepinephrine transporter (NET) were negligible. Blood-brain barrier and pharmacokinetic studies showed that the compound reached the brain and lower elimination than R-modafinil. The Pro-cognitive effect was evaluated in a spatial hole-board task in male Sprague-Dawley rats and CE-123 enhances memory acquisition and memory retrieval, represented by significantly increased reference memory indices and shortened latency. Since DAT blockers can be considered as indirect dopamine receptor agonists, western blotting was used to quantify protein levels of dopamine receptors D1R, D2R and D5R and DAT in the synaptosomal fraction of hippocampal subregions CA1, CA3 and dentate gyrus (DG). CE-123 administration in rats increased total DAT levels and D1R protein levels were significantly increased in CA1 and CA3 in treated/trained groups. The increase of D5R was observed in DG only. Dopamine receptors, particularly D1R, seem to play a role in mediating CE-123-induced memory enhancement. Dopamine reuptake inhibition by CE-123 may represent a novel and improved stimulant therapeutic for impairments of cognitive functions.

Morin hydrate mitigates rapid eye movement sleep deprivation-induced neurobehavioural impairments and loss of viable neurons in the hippocampus of mice

Rapid eye movement sleep deprivation distorts the body’s homeostasis and results in oxidative breakdown which may be responsible for a variety of neurological disorders. Some naturally occurring compounds of plant origin with antioxidant and neuroprotective properties are known to attenuate the detrimental effects of REM sleep deprivation. Morin hydrate, a flavonoid from Mulberry has demonstrated antioxidant and neuroprotective activities but its effect in sleep disturbed mice is unknown. The study was designed to explore the neuroprotective effect of Morin hydrate on 48 h. REM sleep deprivation-induced behavioural impairments and neuronal damage in mice.Mice were allotted into six treatment groups (n = 6): groups 1 and 2 received vehicle (10 ml/kg normal saline), groups 3–5 received Morin hydrate (5, 10, 20 mg/kg i.p) while group 6 received ginseng (25 mg/kg) which served as the reference drug. Treatment was performed daily for 5 days and animals were sleep-deprived on the last 48 h. Various behavioural tests (Elevated plus maze, Y-maze, locomotor activity) followed by oxidative parameters (malondialdehyde, nitric oxide, reduced glutathione) and histolopathological changes in the Cornu ammonis 1 (CA1) region of the hippocampus were assessed. Data were analysed using ANOVA at α0.05.Morin hydrate (5, 10, 20 mg/kg) significantly enhanced memory performance, improves anxiolytic-like behaviour, reverses hyperlocomotion, restored depleted reduced glutathione, attenuated raised malondialdehyde and nitric oxide levels as compared to control animals and protects against loss of hippocampal neurons.Results of this present study suggest that Morin hydrate possess neuroprotective effects against sleep deprivation-induced behavioural impairments, oxidative stress and neuronal damage.

Solution-Processed Wide-Bandgap Organic Semiconductor Nanostructures Arrays for Nonvolatile Organic Field-Effect Transistor Memory.

In this paper, the development of organic field-effect transistor (OFET) memory device based on isolated and ordered nanostructures (NSs) arrays of wide-bandgap (WBG) small-molecule organic semiconductor material [2-(9-(4-(octyloxy)phenyl)-9H-fluoren-2-yl)thiophene]3 (WG3 ) is reported. The WG3 NSs are prepared from phase separation by spin-coating blend solutions of WG3 /trimethylolpropane (TMP), and then introduced as charge storage elements for nonvolatile OFET memory devices. Compared to the OFET memory device with smooth WG3 film, the device based on WG3 NSs arrays exhibits significant improvements in memory performance including larger memory window (≈45 V), faster switching speed (≈1 s), stable retention capability (>104 s), and reliable switching properties. A quantitative study of the WG3 NSs morphology reveals that enhanced memory performance is attributed to the improved charge trapping/charge-exciton annihilation efficiency induced by increased contact area between the WG3 NSs and pentacene layer. This versatile solution-processing approach to preparing WG3 NSs arrays as charge trapping sites allows for fabrication of high-performance nonvolatile OFET memory devices, which could be applicable to a wide range of WBG organic semiconductor materials.

Chronic administration of parecoxib exerts anxiolytic-like and memory enhancing effects and modulates synaptophysin expression in mice

BackgroundPrevious studies have shown that cyclooxygenase-2, a key enzyme that converts arachidonic acid to prostaglandins, is involved in anxiety and cognitive processes, but few studies have investigated the effects of chronic administration of cyclooxygenase-2 inhibitors on anxiety, learning and memory under normal physiological conditions. The aim of the study was to investigate the effects of chronic administration of parecoxib, a cyclooxygenase-2 inhibitor, on anxiety behavior and memory performance under normal physiological conditions and to explore the possible neural mechanism underlying parecoxib-mediated effects.MethodsAdult male ICR mice were randomly divided into four groups: the control group and three parecoxib groups. Mice received normal saline or parecoxib (2.5, 5.0 or 10 mg/kg) intraperitoneal injection once a day for 21 days, respectively. Elevated plus-maze, novel object recognition and Y maze tests were conducted on day 23, 24 and 26, respectively. Four additional groups that received same drug treatment were used to measure synaptophysin protein levels by western blot and prostaglandin E2 (PGE2) levels by ELISA in the amygdala and hippocampus on day 26.ResultsChronic parecoxib exerted an anxiolytic-like effect in the plus-maze test test, and enhanced memory performance in the novel object recognition and Y maze tests. Western blot analysis showed that chronic parecoxib down-regulated synaptophysin levels in the amygdala and up-regulated synaptophysin levels in the hippocampus. ELISA assay showed that chronic parecoxib inhibited PGE2 in the hippocampus but not amygdala.ConclusionsChronic parecoxib exerts anxiolytic-like and memory enhancing effects, which might be mediated through differential modulation of synaptophysin and PGE2 in the amygdala and hippocampus.

Diminishing-cues retrieval practice: A memory-enhancing technique that works when regular testing doesn't.

Retrieval practice has been shown to be a highly effective tool for enhancing memory, a fact that has led to major changes to educational practice and technology. However, when initial learning is poor, initial retrieval practice is unlikely to be successful and long-term benefits of retrieval practice are compromised or nonexistent. Here, we investigate the benefit of a scaffolded retrieval technique called diminishing-cues retrieval practice (Finley, Benjamin, Hays, Bjork, & Kornell, Journal of Memory and Language, 64, 289-298, 2011). Under learning conditions that favored a strong testing effect, diminishing cues and standard retrieval practice both enhanced memory performance relative to restudy. Critically, under learning conditions where standard retrieval practice was not helpful, diminishing cues enhanced memory performance substantially. These experiments demonstrate that diminishing-cues retrieval practice can widen the range of conditions under which testing can benefit memory, and so can serve as a model for the broader application of testing-based techniques for enhancing learning.

Mind your music: The effects of music-induced mood and arousal across different memory tasks.

Music is prevalent in our daily lives. Many of us listen to music to help improve focus, to block out distractions, or to make a tedious task more enjoyable. However, it is unclear how this daily soundtrack affects our cognitive performance, particularly learning and memory. Although many studies support the idea that listening to music can aid learning and facilitate memory (de Groot, 2006; Foster & Valentine, 2001; Lord & Garner, 1993), other studies have shown that listening to music can interfere with important processes required for learning and memory (Iwanaga & Ito, 2002; Jancke & Sandmann, 2010; Salame & Baddeley, 1989). Some of the discrepancies in the literature may have arisen from the use of different memory paradigms across studies (e.g., recall vs. recognition). Therefore, the current study examined the effect of background music on different types of memory. Two potential mechanisms have been proposed to explain how background music influences memory, and these factors form the foundation of the current study. The first possibility is that background music modulates the listener's internal mood and arousal levels, which may then enhance memory performance (Greene, Bahri, & Soto, 2010; Husain, Thompson, & Schellenberg, 2002; Thompson, Schellenberg, & Husain, 2001). For example, negative moods can worsen memory, whereas positive moods can improve memory (Aube, Peretz, & Armony, 2013; Eschrich, Munte, & Altenmuller, 2008; Rowe, Hirsh, & Anderson, 2007). Furthermore, extremely high and low levels of arousal can impair memory performance, whereas moderate levels can enhance memory performance (Berlyne, 1971; Diamond, Campbell, Park, Halonen, & Zoladz, 2007; Dutton & Carroll, 2001). The second possibility is that background music operates through associative mechanisms, establishing a context that, when reinstated, cues memory recall (Balch & Lewis, 1996; Balch, Myers, & Papotto, 1999; Mead & Ball, 2007; Smith, 1985; Standing, Bobbitt, Boisvert, Dayholos, & Gagnon, 2008). Thus, hearing a piece of music might bring to mind the information that was previously encoded when the music was present. Both of these possibilities have experimental support; however, to our knowledge their influences on memory have not been compared in the same study. Therefore, the current study examined whether background music affects verbal memory and whether that effect can be attributed to mood, arousal, context, or some combination of all these factors.Background Music and MemoryThe benefit of music on memory often requires the integration of the music with the to-be-remembered items of the task (Rubin, 1977; Serafine, Crowder, & Repp, 1984; Wallace, 1994). For example, there is evidence that text is better recalled when it is heard as a song rather than as speech (Wallace, 1994). In the current study, however, the focus was to examine the effect of background music on memory, which is different from music that might be integrated with the to-be-remembered items. Here, the background music was arbitrarily paired rather than intentionally paired with the to-be-remembered items because the background music that we experience in our daily lives is not typically integrated with the task we are performing.Whether background music enhances learning and memory has yet to be fully elucidated because the effects are inconsistent. Some studies have found that background music has either no effect on memory (Hirokawa, 2004; Jancke & Sandmann, 2010; Miller & Schyb, 1989), worsens memory (Hallam, Price, & Katsarou, 2002; Iwanaga & Ito, 2002; Reaves, Graham, Grahn, Rabannifard, & Duarte, 2016), or improves memory (de Groot, 2006; Eschrich et al., 2008; Richards, Fassbender, Bilgin, & Thompson, 2008). Although the findings of the aforementioned studies are mixed, one meta-analysis has identified several studies where background music had a detrimental effect on memory compared with silence (Kampfe, Sedlmeier, & Renkewitz, 2011). …