Memory Test Research Articles

Processing speed in first episode of psychosis and first-degree relatives: A candidate endophenotype of spectrum schizophrenia disorders.

The processing speed (PS) is highly impacted in individuals experiencing their first episode of psychosis (FEP). Conducting family studies can help to determine whether PS can serve as an endophenotype of schizophrenia spectrum disorders (SSDs), offering valuable insights into the prevention and diagnosis of SSDs. A comprehensive cognitive battery, encompassing tests for PS, verbal memory, visual memory, working memory, executive functions, motor dexterity, and attention, was administered to a sample consisting of 133 FEP patients, 146 parents, 98 siblings, and 202 healthy controls (HCs). Univariate analyses (analysis of covariance [ANCOVA]) were conducted to compare the different cognitive domains between groups, utilizing sex, age, and years of education as covariates and Bonferroni corrections. Effect sizes (ESs) were calculated for estimating the magnitude of differences between groups. Group comparisons revealed significant differences in all cognitive domains. PS was the most impaired function in patients. Parents and siblings had intermediate PS performance between FEP patients and HC. Large ES were observed in PS between FEP versus siblings, FEP versus controls, parents versus controls, and parents versus siblings. Despite not meeting all the necessary criteria, the PS observed in FEP patients and their first-degree relatives suggests its potential as a promising endophenotype of SSDs. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Association between arterial health and cognition in adolescents: The PANIC study.

We investigated the associations of the measures of arterial health with cognition in adolescents and whether physical activity (PA) or sedentary time (ST) confounds these associations. One hundred sixteen adolescents (71 boys) aged 15.9 ± 0.4 participated in the study. PA and ST were assessed using a combined accelerometer/heart rate monitor. Overall cognition was computed from the results of psychomotor function, attention, working memory, and paired-associate learning tests. Pulse wave velocity was measured by impedance cardiography, carotid intima-media thickness, and carotid artery distensibility by carotid ultrasonography. Systolic and diastolic blood pressure (SBP and DBP) were measured using an aneroid sphygmomanometer. SBP was inversely associated with overall cognition (standardized regression coefficient [β] = -0.216, 95% confidence interval (CI) -0.406 to -0.027, p = 0.025). Pulse wave velocity (β = -0.199, 95% CI -0.382 to -0.017, p = 0.033) was inversely associated with working memory task accuracy. SBP was directly associated with reaction time in the attention (β = 0.256, 95% CI 0.069 to 0.443, p = 0.008) and errors in the paired-associate learning tasks (β = 0.308, 95% CI 0.126 to 0.489, p = 0.001). Blood pressure was inversely associated with overall cognition. PA or ST did not confound the associations. Results suggest that preventing high blood pressure is important for promoting cognition in adolescents.

Testing expectations and retrieval practice modulate repetition learning of visuospatial arrays.

One of the best-known demonstrations of long-term learning through repetition is the Hebb effect: Immediate recall of a memory list repeated amidst nonrepeated lists improves steadily with repetitions. However, previous studies often failed to observe this effect for visuospatial arrays. Souza and Oberauer (2022) showed that the strongest determinant for producing learning was the difficulty of the test: Learning was consistently observed when participants recalled all items of a visuospatial array (difficult test) but not if only one item was recalled, or recognition procedures were used (less difficult tests). This suggests that long-term learning was promoted by increased testing demands over the short term. Alternatively, it is possible that lower testing demands still lead to learning but prevented the application of what was learned. In four preregistered experiments (N = 981), we ruled out this alternative explanation: Changing the type of memory test midway through the experiment from less demanding (i.e., single item recall or recognition) to a more demanding test (i.e., full item recall) did not reveal hidden learning, and changing it from the more demanding to a less demanding test did not conceal learning. Mixing high and low demanding tests for nonrepeated arrays, however, eventually produced Hebb learning even for the less demanding testing conditions. We propose that testing affects long-term learning in two ways: Expectations of the test difficulty influence how information is encoded into memory, and retrieval consolidates this information in memory. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Curiosity Satisfaction Increases Event-related Potentials Sensitive to Reward.

Successful learning depends on various factors such as depth of processing, motivation, or curiosity about information. A strong drive to learn something or the expectation of receiving a reward can be crucial to enhance learning. However, the influence of curiosity on the processing of new information and its similarity with reward processing is not well understood. This study examined whether states of curiosity influence specific ERPs associated with reward processing and whether these ERPs are related with later memory benefits. In an initial screening phase, participants indicated their curiosity and confidence in prior knowledge about answers to various trivia questions. In a subsequent study phase, we targeted different time windows related to reward processing during the presentation of trivia answers containing the reward positivity (RewP; 250-350 msec), the P3 (250-500 msec), and the late-positive-potential (LPP; 600-1000 msec). In a following surprise memory test, we found that participants recalled more high- than low-curiosity answers. The RewP, P3, and LPP showed greater positive mean amplitudes for high compared with low curiosity, reflecting increased reward processing. In addition, we found that the RewP and the P3 showed more positive mean amplitudes for later recalled compared with later forgotten answers, but curiosity did not modulate this encoding-related results. These findings support the view that the satisfaction of curiosity resembles reward processing, indicated by ERPs.

Stressing out! Effects of acute stress on prepulse inhibition and working memory.

Prepulse inhibition (PPI) of the startle reflex serves as a pre-cognitive marker of sensorimotor gating, and its deficit may predict cognitive impairments. Startle reflex is modulated by many factors. Among them, stress has been a topic of interest, but its effects on both pre-cognitive and cognitive variables continue to yield divergent results. This study aims to analyze the effect of acute stress on PPI of the startle reflex and cognitive function (working memory, attention, inhibition, and verbal fluency). Participants were exposed to the MAST stress induction protocol or a stress-neutral task: stress group (n = 54) or control group (n = 54). Following stress induction, participants' startle responses were recorded, and cognition was assessed. The results revealed that participants in the stress group exhibited greater startle magnitude, lower PPI, and lower scores in working memory tests compared with the control group. Additionally, a correlation was found between working memory and PPI across all the participants, independent of stress group. These findings support the notion that after stress, both greater startle magnitude and diminished PPI could play an adaptive role by allowing for increased processing of stimuli potentially dangerous and stress-related. Similarly, our results lend support to the hypothesis that lower PPI may be predictive of cognitive impairment. Considering the impact of stress on both pre-cognitive (PPI) and cognitive (working memory) variables, we discuss the possibility that the effect of stress on PPI occurs through motivational priming and emphasize the relevance of considering stress in both basic and translational science.

Body Water Compartment and Sympathovagal Balance: Association with Visuomotor Retention in Young Adults

Cognitive functions are important for visuomotor learning and are associated with physiological factors such as body fluid compartment and cardiovascular reactivity. Previous studies found that body fluid compartment is associated with brain blood flow, which is regulated via sympathovagal balance. However, more evidence is needed to determine whether body fluid compartment and cardiovascular reactivity are associated with visuomotor learning. The purpose of this study was to explore the relationship of body fluid compartment and cardiovascular reactivity to visuomotor learning. We hypothesized that these physiological factors are associated with overall learning retention using upper extremity (including feedforward, volitional, and feedback conditions). Methods: Thirty young adults (12 males, 24.6 ± 3.9 years, right hand dominant) participated in this study. Participants tracked a sinusoidal wave with left arm at pre-test, learning, and post-test sessions on the first visit and at retention test session on the second visit seven days later. Participants performed one set of nine trials during each test and five sets of three trials during learning. Resistance and wave velocity were different in each trial. Learning error was calculated by the averaged absolute distance between the tracking line and the target line. Heart rate (HR), systolic blood pressure (SBP), and low to high frequency power ratio of heart rate variability (LF/HF) were continuously recorded during baseline before pre-test and during tests and learning. We analyzed participants’ extracellular to intracellular body water ratio (ECW/ICW) using an InBody body composition analyzer and tested their cognitive function with Picture Sequence Memory (PSMT), Pattern Comparison Processing Speed, Dimensional Change Card Sort, Flanker Inhibitory Control and Attention, and List Sorting Working Memory Tests from NIH Cognitive Toolbox. Data were statistically analyzed using linear regression analysis and quartile analysis. Results: ECW/ICW was associated with young adults’ ability to retain visuomotor learning after one week (R2 = 0.138, p = 0.043), whereas HR, SBP, and LF/HF at each session were not significantly associated with visuomotor retention. No differences were found in pre-test error among quartiles of five cognitive tests. Significant differences in retention error among quartiles were only found in PSMT, with participants scoring in the highest quartile of PSMT having lower SBP during the first visit and lower retention error compared to the lowest quartile. This finding suggests that young adults with better episodic memory were less stressed during learning and had better visuomotor retention. Conclusion: These findings support that ECW/ICW is associated with not only cognitive function but also visuomotor retention. In addition, cardiovascular reactivity during visuomotor learning may provide information for retention behavior. Relationship of body water compartment and sympathovagal balance to feedforward and feedback conditions in learning will be further discussed. Research Support: This study was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development: R01HD084645, R01HD082109. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Central auditory functions in post-COVID-19 adults; a case control study

BackgroundThis study aimed to evaluate the central auditory abilities in post-coronavirus disease 2019 (COVID-19) adults by using Central Auditory Tests (CATs). This study included a complaining group (GI), a non-complaining group (GII), and a control healthy group (GIII). All subjects were evaluated using CATsResultsResults demonstrated statistically significant differences across groups as regards Speech Perception in Noise Test (SPIN), Duration Pattern Sequence Test (DPT), Gap in Noise Test (GIN), and Memory Test (ANOVA, p-value ≤ 0.05). The post-hoc test revealed that, except for recognition memory, both study groups showed statistically significant differences from the control group. Also, significant differences were detected between both GI and GII groups regarding SPIN−10 signal-to-noise ratio (S/N), DPT, GIN threshold, memory for content, and memory for sequenceConclusionsCOVID-19 led to central auditory processing disorders (c)APD.

Cognitive Effects of Toxoplasma and CMV Infections: A Cross-Sectional Study of 557 Young Adults Considering Modulation by Sex and Rh Factor.

One-third of humanity harbors a lifelong infection with Toxoplasma gondii, and probably about 80% are infected with human cytomegalovirus (CMV). This study aims to delineate the associations between toxoplasmosis and cognitive abilities and compare these to the associations with CMV. We evaluated the cognitive performance of 557 students, who had been examined for Toxoplasma and CMV infections, using intelligence, memory, and psychomotor tests. The results indicated cognitive impairments in seropositive individuals for both pathogens, with variations in cognitive impact related to sex and the Rh factor. Specifically, Toxoplasma infection was associated with lower IQ in men, whereas CMV was predominantly associated with worse performance by women when testing memory and reaction speeds. Analysis of the antibody concentrations indicated that certain Toxoplasma-associated cognitive detrimental effects may wane (impaired intelligence) or worsen (impaired reaction times) over time following infection. The findings imply that the cognitive impairments caused by both neurotropic pathogens are likely due to pathological changes in the brain rather than from direct manipulative action by the parasites.

The contribution of written corrective feedback and its association with working memory on the development of EFL learners’ English plurals

Although numerous studies have attested to the effectiveness of written corrective feedback (WCF) in promoting second language (L2) accuracy, the extent to which WCF contributes to acquisition is still debatable. This study thus aimed to investigate the effects of WCF on the development of Thai EFL (English as a foreign language) learners’ implicit and explicit knowledge of English plurals, and the extent to which learner differences in working memory capacity (WMC) moderated the efficacy of WCF. This experimental study adopted a pre–post–delayed-posttest design and was carried out over the course of a 9-month period. Seventy-five low intermediate learners were randomly assigned to the direct focused, direct unfocused and the control group. All groups completed a metalinguistic knowledge, untimed grammatical judgement, timed writing, timed oral elicited imitation, and two working memory tests. Questionnaires and interviews were also administered to explore potential variables that may moderate the effect of WCF. During treatment, participants wrote a timed essay and received feedback. After the 6-week treatment period, the immediate posttest was completed and the delayed posttest was administered three months after the posttest. The results revealed that WCF was effective in assisting learners’ plural acquisition, suggesting that WCF is beneficial especially to the development of linguistic features influenced by learners’ first language (L1). However, WMC was not found to moderate the efficacy of WCF. The explicitness of WCF, instructional context and proficiency level may have contributed to the absence of working memory effect.

Peripherally-derived LGI1-reactive monoclonal antibodies cause epileptic seizures in vivo.

One striking clinical hallmark in patients with autoantibodies to leucine-rich glioma inactivated 1 (LGI1) is the very frequent focal seizure semiologies, including faciobrachial dystonic seizures (FBDS), in addition to the amnesia. Polyclonal serum IgGs have successfully modelled the cognitive changes in vivo but not seizures. Hence, it remains unclear whether LGI1-autoantibodies are sufficient to cause seizures. We tested this with the molecularly precise monoclonal antibodies directed against LGI1 (LGI1-mAbs), derived from patient circulating B cells. These were directed towards both major domains of LGI1, LRR and EPTP and infused intracerebroventricularly over 7 days into juvenile male Wistar rats using osmotic pumps. Continuous wireless EEG was recorded from a depth electrode placed in hippocampal CA3 plus behavioural tests for memory and hyperexcitability were performed. Following infusion completion (Day 9), post-mortem brain slices were studied for antibody binding and effects on Kv1.1. The LGI1-mAbs bound most strongly in the hippocampal CA3 region and induced a significant reduction in Kv1.1 cluster number in this subfield. By comparison to control-Ab injected rats video-EEG analysis over 9 days revealed convulsive and non-convulsive seizure activity in rats infused with LGI1-mAbs, with a significant number of ictal events. Memory was not impaired in the novel object recognition test. Peripherally-derived human LGI1-mAbs infused into rodent CSF provide strong evidence of direct in vivo epileptogenesis with molecular correlations. These findings fulfill criteria for LGI1-antibodies in seizure causation.

Grouping in working memory guides chunk formation in long-term memory: Evidence from the Hebb effect

The Hebb effect refers to the improvement in immediate memory performance on a repeated list compared to unrepeated lists. That is, participants create a long-term memory representation over repetitions, on which they can draw in working memory tests. These long-term memory representations are likely formed by chunk acquisition: The whole list becomes integrated into a single unified representation. Previous research suggests that the formation of such chunks is rather inflexible and only occurs when at least the beginning of the list repeats across trials. However, recent work has shown that repetition learning strongly depends on participants recognizing the repeated information. Hence, successful chunk formation may depend on the recognizability of the repeated part of a list, and not on its position in the list. Across six experiments, we compared these two alternatives. We tested immediate serial recall of eight-letter lists, some of which partially repeated across trials. We used different partial-repetition structures, such as repeating only the first half of a list, or only every second item. We manipulated the salience of the repeating structure by spatially grouping and coloring the lists according to the repetition structure. We found that chunk formation is more flexible than previously assumed: Participants learned contiguous repeated sequences regardless of their position within the list, as long as they were able to recognize the repeated structure. Even when the repeated sequence occurred at varying positions over repetitions, learning was preserved when the repeated sequence was made salient by the spatial grouping. These findings suggest that chunk formation requires recognition of which items constitute a repeating group, and demonstrate a close link between grouping of information in working memory, and chunk formation in long-term memory.

The self-reference effect in attention deficit hyperactivity disorder.

The self-memory system depends on the prioritization and capture of self-relevant information, so may be disrupted by difficulties in attending to, encoding and retrieving self-relevant information. The current study compares memory for self-referenced and other-referenced items in children with ADHD and typically developing comparison groups matched for verbal and chronological age. Children aged 5-14 (N = 90) were presented with everyday objects alongside an own-face image (self-reference trials) or an unknown child's image (other-referenced trials). They were asked whether the child shown would like the object, before completing a surprise source memory test. In a second task, children performed, and watched another person perform, a series of actions before their memory for the actions was tested. A significant self-reference effect (SRE) was found in the typically developing children (i.e. both verbal and chronological age-matched comparison groups) for the first task, with significantly better memory for self-referenced than other-referenced objects. However, children with ADHD showed no SRE, suggesting a compromised ability to bind information with the cognitive self-concept. In the second task, all groups showed superior memory for actions carried out by the self, suggesting a preserved enactment effect in ADHD. Implications and applications for the self-memory system in ADHD are discussed.

Everyday amnesia: Residual memory for high confidence misses and implications for decision models of recognition.

Despite studying a list of items only minutes earlier, when reencountered in a recognition memory test, undergraduate participants often say with total confidence that they have not studied some of the items before. Such high confidence miss (HCM) responses have been taken as evidence of rapid and complete forgetting and of everyday amnesia (Roediger & Tekin, 2020). We investigated (a) if memory for HCMs is completely lost or whether a residual memory effect exists and (b) whether dominant decision models predict the effect. Participants studied faces (Experiments 1a, 2, and 3) or words (Experiment 1b), then completed a single-item recognition memory task, followed by either (a) a two-alternative forced-choice recognition task, in which the studied and nonstudied alternatives on each trial were matched for their previous old/new decision and confidence rating (Experiments 1 and 2) or (b) a second single-item recognition task in which the targets and foils were HCMs and high confidence correct rejections, respectively (Experiment 3). In each experiment, participants reliably distinguished HCMs from high-confidence correct rejections. The unequal variance signal detection and dual-process signal detection models were fit to the single-item recognition data, and the parameter estimates were used to predict the memory effect for HCMs. The dual-process signal detection model predicted the residual memory effect (as did another popular model, the mixture signal detection theory model). However, the unequal variance signal detection model incorrectly predicted a negative, or no, effect, invalidating this model. The residual memory effect for HCMs demonstrates that everyday amnesia is not associated with complete memory loss and distinguishes between decision models. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Relationship between cognitive function and functional outcomes in remitted major depression

BackgroundFew studies have focused on functional impairment in depressed patients during symptomatic remission. The exact relationship between cognitive performance and functional outcomes of patients with Major depressive disorder (MDD) remains unclear.MethodsParticipants diagnosed with MDD were included and interviewed at both baseline and follow-up. Cognitive function was assessed during acute episodes using the Cambridge Neuropsychological Test Automated Battery (CANTAB), which targeted attention (Rapid Visual Processing - RVP), visual memory (Pattern Recognition Memory - PRM), and executive function (Intra-Extra Dimensional Set Shift - IED). The 17-item Hamilton Depression Scale (HAMD) was used for symptom assessment. Participants were divided into two groups based on their SDSS (Social Disability Screening Schedule) scores, and the differences between their demographic information, HAMD scores, and baseline CANTAB test results were compared. Logistic regression analysis was used to identify cognitive predictors of social function during symptomatic remission.ResultsAccording to the SDSS score at follow-up, 103 patients were divided into the normal social function group (n = 81,78.6%) and the poor social function group (n = 22, 21.4%) during clinical remission. Participants with poorer social function performed worse in the visual memory (PRM) and executive function tests (IED) at the baseline. Logistic regression analysis suggested that performance on the PRM (95%CI = 0.31–0.93, p = 0.030) and IED (95%CI = 1.01–1.13, p = 0.014) tests, instead of less severe symptoms, significantly contributed to functional outcomes.ConclusionBetter performance in visual memory and executive function during acute episodes may predict better social functional outcomes in individuals with MDD. A potential early intervention to improve social function in individuals with MDD could include the treatments for executive function and visual memory.

Research on the force-magnetic relationship of bridge steel under tensile stress based on magnetic memory effect

It’s of great significance to conduct the nondestructive evaluation of steel bridges to extend their service life. The metal magnetic memory testing (MMMT) method can effectively evaluate the stress states of ferromagnetic components. To improve the accuracy and reliability of the stress evaluation on bridge steel structures based on MMMT technology, an improved force-magnetic coupling model considering loading history is proposed, which can reflect the impact of material mechanical properties on magnetization behavior. The MMMT is carried out on the Q345qD bridge steel plates under load-unload tensile stress considering the relative location between the specimen and the geomagnetic field, according to the rotation angle θr. It comprehensively analyzes the variation laws of representative tangential and normal components of the magnetic signal, i.e. Hm(y) and Hm(z), corresponding to different inspection parameters during the loading process. The mean value Ay of the Hm(y) curves and the linear fitting slope Kz of Hm(z) curves are applied to characterize the variation laws of magnetic signal with respect to the applied load Fa. According to the fitting curves of Ay and Kz with Fa, it quantitatively demonstrates the applied loads. It further puts forward the normalized magnetic characteristic parameters Ayn and Kzn to characterize the force-magnetic relationship of the specimen, which are less affected by the position of the specimen in geomagnetic field. Finally, the proposed force-magnetic coupling model is applied to calculate the variation of normalized magnetization ΔMn. The theoretical results are compared with the synthetic magnetic characteristic parameter AKn obtained by experiment. It shows an average error of 8.53% between ΔMn and AKn, which proves the feasibility and effectiveness of the force-magnetic coupling model proposed in this paper.

Effects of CACNA1C and ANK3 on cognitive function in patients with bipolar disorder

Bipolar disorder (BD) is a complex, severe mental illness with cognitive impairment. Impairments in attention and memory are particularly evident. A large number of previous studies have identified CACNA1C and ANK3 gene variants as risk factors for BD and both affect cognitive function in people with BD. However, it is unclear whether there is an interaction effects between the two genes on cognitive impairment in patients. We used 153 Chinese Han Chinese patients with BD to explore the association of CACNA1C and ANK3 variants with attention and immediate memory using Plink software and and performed a epistatic interaction effects analysis. We found that CACNA1C and ANK3 gene variants respectively affected patients' scores on attention and memory tests. The significant SNP in the CACNA1C and ANK3 genes are rs73042126(P = 3.16 × 10−5,FDR = 0.0253) and rs2393640(P = 1.50 × 10−4,FDR = 0.0353) respectively. And they also interacted to affect cognitive functioning in BD patients (attention: P = 0.0289; immediate memory: P = 0.0398). Follow-up studies should increase the sample size, improve the assessment methods and experimental design, and further explore the pathogenic mechanisms of BD.

Speech Sounds Production, Narrative Skills, and Verbal Memory of Children with 22q11.2 Microdeletion.

22q11.2 deletion syndrome (22q11.2DS), the most frequent microdeletion syndrome in humans, is related to a high risk of developing neurodevelopmental disorders. About 95% of patients with 22q11.2DS have speech and language impairments. Global articulation, story generation, and verbal memory tests were applied to compare articulatory characteristics of speech sounds, spontaneous language abilities, and immediate verbal memory between four groups of Serbian-speaking children: patients with 22q11.2DS, children with clinical presentation of 22q11.2DS that do not have the microdeletion, children with non-syndromic congenital heart defects, and their peers with typical speech-sound development. The obtained results showed that children with this microdeletion have impaired articulation skills and expressive language abilities. However, we did not observe weaker receptive language skills and immediate verbal memory compared to healthy controls. Children with 22q11.2DS should be considered a risk category for the development of speech-sound pathology and expressive language abilities. Since speech intelligibility is an instrument of cognition and adequate peer socialization, and language impairment in school-aged children with 22q11DS might be an indicator of increased risk for later psychotic symptoms, patients with 22q11.2 microdeletion should be included in a program of early stimulation of speech-language development immediately after diagnosis is established.

Comparisons of Self-Report With Objective Measurements Suggest Faster Responding but Little Change in Response Quality Over Time in Ecological Momentary Assessment Studies.

Response times (RTs) to ecological momentary assessment (EMA) items often decrease after repeated EMA administration, but whether this is accompanied by lower response quality requires investigation. We examined the relationship between EMA item RTs and EMA response quality. In one data set, declining response quality was operationalized as decreasing correspondence over time between subjective and objective measures of blood glucose taken at the same time. In a second EMA study data set, declining response quality was operationalized as decreasing correspondence between subjective ratings of memory test performance and objective memory test scores. We assumed that measurement error in the objective measures did not increase across time, meaning that decreasing correspondence across days within a person could be attributed to lower response quality. RTs to EMA items decreased across study days, while no decrements in the mean response quality were observed. Decreasing EMA item RTs across study days did not appear problematic overall.

Class 1 histone deacetylases differentially modulate memory and synaptic genes in a spatial and temporal manner in aged and APP/PS1 mice

Epigenetics plays a vital role in aging and Alzheimer’s disease (AD); however, whether epigenetic alterations during aging can initiate AD and exacerbate AD progression remains unclear. In this study, using 3-, 12- and 18- month-old APP/PS1 mice and age matched WT littermates, we conducted a series of memory tests, measured synapse-related gene expression, class 1 histone deacetylases (HDACs) abundance, and H3K9ac levels at target gene promoters in the hippocampus and prefrontal cortex (PFC). Our results showed impaired recognition and long-term spatial memory in 18-month-old WT mice and impaired recognition, short-term working, and long-term spatial reference memory in 12-and 18- month-old APP/PS1 mice. These memory impairments are associated with changes of synapse-related gene (nr2a, glur1, glur2, psd95) expression, HDAC abundance, and H3K9ac levels; more specifically, increased HDAC2 was associated with synapse-related gene expression changes through modulation of H3K9ac at the gene promoters during aging and AD progression in the hippocampus. Conversely, increased HDAC3 was associated with synapse-related gene expression changes through modulation of H3K9ac at the gene promoters during AD progression in the PFC. These findings suggest memory impairments in aging and AD may associated with a differential HDAC modulation of synapse-related gene expression in the brain.

4D printing and annealing of PETG composites reinforced with short carbon fibers

In this study, for the first time, post-heat treatment was applied to improve the stress recovery of short carbon fiber reinforced PETG (SCFRPETG). PETG and SCFRPETG composite were printed under optimal conditions, and constrained and free shape memory cycles were applied under compression and three-point bending loadings to assess shape and stress recovery. The results of the free shape memory test for both vertical and horizontal patterns showed that PETG composite also has a higher shape memory effect (SME) compared to PETG. The SME was significantly improved by performing heat treatment. The stress recovery values for pure PETG, reinforced PETG before and after annealing are 2.48 MPa, 3.04 MPa and 3.18 MPa, respectively. It showed that the addition of 1.5% carbon fiber increases the stress recovery by 22%. The increasing trend reaches 28% by performing post-heat treatment. Additionally, altering the printing pattern affects the programming and stress recovery values. For the SCFRPETG composite samples before and after annealing, changing the printing pattern from horizontal to vertical, resulted in a 16% and 7% increase in recovery stress, respectively. SEM results confirm that the annealing process removes the layered structure, micro-holes caused by shrinkage and 4D printing mechanism. Using the controlled heat treatment method can be a practical solution to solve the problem of adhesion and reduce the anisotropy of FDM 3D printed layers.