Memory Recovery Research Articles

Cornus mas (Cornelian Cherry) Exerts Neuroprotective Effects on Cerebral Ischemia/Reperfusion Injury via Anti-Inflammatory and Antioxidant Properties

Background: Stroke is one of the most important causes of mortality and disability in the world. Over 80% of strokes are ischemic, resulting from blockages in cerebral arteries. Increasing evidence suggests that enriching the diet with nutritional antioxidants could decrease brain damage and enhance cognitive function. Cornelian cherry has anti-inflammatory and antioxidant properties and is introduced as a potential source of active ingredients, like anthocyanins, vitamin C, phenolic compounds, and minerals. Objective: Our research study aimed to evaluate the neuroprotective impact of Cornus mas L. (cornelian cherry) on a rat model of Cerebral Ischemia/Reperfusion Injury (CIRI). Methods: Middle cerebral artery blockage induced CIRI for 60 minutes. After inducing CIRI, intraperitoneal injections of Cornus mas Extract (CME) were administered for 14 days in a dosedependent manner (30, 60, and 120 mg/kg body weight). The effects of CME on learning and memory recovery were evaluated using a shuttle box behavioral test. Two weeks following CIRI, several factors of oxidative stress, such as nitrite (NO2-), Ferric ion Reducing Antioxidant Power (FRAP), and Malondialdehyde (MDA), were measured in the hippocampal tissues and serum. Anti-inflammatory genes, such as miR-125b, and the target genes (TNF-α and iNOS) were evaluated via real-time PCR assay. Additionally, neural damage in the CA1 and CA3 regions of the hippocampus was assessed using Hematoxylin and Eosin (H&E) staining. Results: The avoidance time in the shuttle-box behavior test supported our finding that CME exhibited improved fear memory. Furthermore, it increased the CA1 and CA3 hippocampal post-stroke pyramidal cell layers. Levels of NO2- and MDA were decreased, and FRAP was considerably increased in both the hippocampus and serum by CME. Additionally, CME increased miR-125b expression, while modulating TNF-α and iNOS production in the hippocampal regions. Conclusion: Based on our findings, we can conclude CME to possess antioxidant and antiinflammatory properties, which confer neuroprotective potential against CIRI, thereby protecting neurons from ischemic death.

Analysis of alleviating memory loss in Alzheimers disease

Abstract. There are two types of memory: prospective memory and retrospective memory. The capacity to recall future occurrences is known as prospective memory, whereas the recall of previous events is known as retrospective memory. Individuals with Alzheimers Disease (AD) typically exhibit a general memory decline. These patients are unable to recall past events and struggle to form new memories. A comprehensive review of a vast body of literature indicates that the recovery of retrospective memory poses a significant challenge and can only be treated through a few simple external stimuli, such as utilizing auditory or olfactory cues, which are familiar to AD patients, to stimulate the recall of relevant memories. In the current research landscape, there are limited options for the recovery of retrospective memory, whereas there are numerous treatments available for the improvement of prospective memory, including the administration of medications and techniques that can specifically target the condition, significantly enhancing the likelihood of recovery in patients.

River volunteers: emergent, popular and amusing water discoverers

The paper aims to verify whether volunteering and environmentalism are two phenomena that overlap both conceptually and empirically. The actions for the protection and enhancement of rivers in Italy are taken as a testing ground. Two packages of literature are used to understand the overlap between volunteering and environmentalism, one on neo-institutionalism and the other on new social movements. The starting framework is a general typology of voluntary organisations, which is then adapted to the environmental movement. The hypothesis of growing disintermediation and light commitment by the new generations of volunteers finds original answers in river volunteering. Alongside classic environmentalist militancy, forms of popular action in favour of rivers are emerging that show detachment from politics and attraction to intrinsic benefits, such as the pleasure of recreation and collective memory recovery. This raises new questions about the role of organised civil society in maintaining democracy and helping the ecological transition.

Cognitive improvement via cortical cannabinoid receptors and choline-containing lipids.

Recent research linking choline-containing lipids to degeneration of basal forebrain cholinergic neurons in neuropathological states illustrates the challenge of balancing lipid integrity with optimal acetylcholine levels, essential for memory preservation. The endocannabinoid system influences learning and memory processes regulated by cholinergic neurotransmission. Therefore, we hypothesised that activation of the endocannabinoid system may confer neuroprotection against cholinergic degeneration. We examined the neuroprotective potential of sub-chronic treatments with the cannabinoid agonist WIN55,212-2, using ex vivo organotypic tissue cultures including nucleus basalis magnocellularis and cortex and in vivo rat models of specific cholinergic damage induced by 192IgG-saporin. Levels of lipids, choline and acetylcholine were measured with histochemical and immunofluorescence assays, along with [35S]GTPγS autoradiography of cannabinoid and muscarinic GPCRs and MALDI-mass spectrometry imaging analysis. Learning and memory were assessed by the Barnes maze and the novel object recognition test in rats and in the 3xTg-AD mouse model. Degeneration, induced by 192IgG-saporin, of baso-cortical cholinergic pathways resulted in memory deficits and decreased cortical levels of lysophosphatidylcholines (LPC). WIN55,212-2 restored cortical cholinergic transmission and LPC levels via activation of cannabinoid receptors. This activation altered cortical lipid homeostasis mainly by reducing sphingomyelins in lesioned animals. These modifications were crucial for memory recovery. We hypothesise that WIN55,212-2 facilitates an alternative choline source by breaking down sphingomyelins, leading to elevated cortical acetylcholine levels and LPCs. These results imply that altering choline-containing lipids via activation of cannabinoid receptors presents a promising therapeutic approach for dementia linked to cholinergic dysfunction.

Ethylene vinyl acetate/copper sulphide with near-infrared light active shape memory behavior

This thesis presents the preparation of ethylene vinyl acetate (EVA)-based shape memory polymer composites (SMPC) (EVA/CuS) with near-infrared light photo-thermal response. The composites were prepared using EVA as the matrix material and copper sulphide (CuS) particles as the functional phase. The designability of SMPs was considered in the preparation of these composites. The results demonstrated that the incorporation of CuS, as a functional phase, enhanced the cross-linking degree and augmented the shape memory properties of EVA. Additionally, it served as a photo-thermal functional filler, imparting its photo-thermal properties. It can be observed that as the quantity of CuS particles incorporated into the EVA/CuS composite film increases, the photothermal conversion performance of the composite film improves, the shape fixation rate rises, and the rate of recovery of light-responsive shape memory accelerates. The temperature of the composites increased to 116.7°C in 20 s when the CuS addition was 2 wt% and the NIR light intensity was 0.5 W/cm2. At a NIR light intensity of 0.6 W/cm2, the “U” shape of the sample was restored to a straight state in 30 s, and the shape recovery rate reached 100%. In this experiment, optical near-infrared photostimulation-responsive EVA/CuS composites have been successfully prepared. These composites demonstrate the ability to achieve remote control and fast response of EVA shape memory behavior, offering a new avenue for the preparation of photo-responsive EVA-based shape memory materials.

Microemulsion of Trichilia catigua A. Juss. (Meliaceae) improves memory recovery and reduces oxidative stress after cerebral ischemia in rats

We reported that a lyophilized ethyl-acetate fraction (EAF-L) of Trichilia catigua (popular ‘Catuaba’) facilitated memory recovery and reduced oxidative stress after cerebral ischemia in rats. However, oral doses as high as 400 mg/kg seem necessary to achieve those effects. Here we used an EAF microemulsion (EAF-ME) to evaluate whether a dose lower than that used previously can be suitable for memory neuroprotection. Intact rats were trained in the aversive radial maze (LRA) and subjected to transient global cerebral ischemia (TGCI). EAF-ME or EAF-L (100 mg/kg each) was administered at 4 hours of reperfusion and repeated in the next 6 days. Retrograde memory performance was assessed 7-, 14-, and 21-days postischemia. In a second experiment, a single EAF-ME dose was given at 4 h of reperfusion. Oxidative stress of brain tissue was assessed at 24 h of reperfusion. Lastly, after the FAE-ME treatment, the brain was examined for GFAP and Iba-1 immunoreactivity as neuroinflammation markers. The rats' ability to recall the AvRM task learned before ischemia was significantly reduced after ischemia (amnesia). Treatment with EAF-ME (100 mg/kg) mitigated this outcome, whereas the same dose of the EAF-L formulation did not. Furthermore, a single administration of the EAF-ME prevented oxidative stress by restoring SOD and CAT activities and reducing protein carbonylation and lipoperoxidation. Ischemia-induced glial cell immunoreactivity, however, was not precluded by the EAF-ME formulation. The current findings demonstrate that the neuroprotective efficacy of T. catigua can be improved by developing appropriate formulations that may enhance the bioavailability of polyphenolic constituents in the brain.

Shape memory and shape recovery characterization of thermoplastic urethane

ABSTRACT Polyurethane shape memory polymer, as a smart material, has been becoming more and more popular due to its greater multifunctionality in various industrial and biomedical applications. Here, the authors reported the characterization, and comprehensive methodology and acquired the results of thermoplastic urethane (SMTPU) as a shape memory polymer, with 35°C as the glass transition temperature, by examining its creep. This smart polymer exhibits excellent shape memory behaviour due to its steady, chemically cross-linked network. Such behaviour of shape memory polymer determines its usability in various functional applications. Furthermore, the activation temperature range of SMPTPU is close to body temperature and room temperature as well, so it can be employed in more demanding industrial applications. Thus, it becomes essential to investigate the shape-changing/memory behaviour of commercial SMTPU. A quantitative analysis was done to determine the effects of programming temperature, maximum uniaxial strain, and compressive strain on shape memory characteristics viz. the shape recovery ratios and shape fixity ratios. Along with the excellent shape memory effect, this material also exhibits high creep and elasticity at room temperature, indicating that it may be used for various industrial and biomedical applications.

Shape memory resin with high temperature resistance for plugging fracture formations drilled with oil-based drilling fluid

Lost circulation usually occurs when drilling fracture formations using oil-based drilling fluids (OBDFs). This study synthesized the shape memory epoxy resins (EHN) with a glass transition temperature range of 94–122 °C. They exhibited good thermal stability and dynamical mechanism performance. The EHN did not swell in oil at different temperatures; however, its shape changed with temperature. Optimized by an orthogonal experiment, the thickness swelling rate prepared under the optimal conditions was more than 74%. The particle size reduction rate did not exceed 5% after aging at 150 °C in oil, which was less than 1/4 of that of the nutshell. The EHN1 with a glass transition temperature of 122 °C, prepared under the optimal conditions (OEHN1), was utilized to control lost circulation in OBDF at high temperatures. At a heating rate of 1–10 °C/min, the shape memory rate of OEHN1 required 14–107 min to reach 100% in the temperature range of 30–150 °C, respectively. The shape memory recovery rate of OEHN1 reached to 10, 28, 57, and 97% at 80, 100, 120, and 125 °C within 60 min, respectively. In addition, it required 4–10 min to recover to 100% at 135–150 °C, respectively. OEHN1 did not recover below 80 °C, partially recovered between 80 and 120 °C, and completely recovered above 125 °C (>glass transition temperature). When plugging the wedge fracture with inlet/outlet fracture widths of 3/1 mm at 80–150 °C, formula 2 (F2) containing OEHN1 exhibited lower fluid loss and stabler pressure-bearing capacity under 15 MPa. When plugging the wedge fracture with inlet/outlet fracture widths of 4/2 mm, F2 withstood a pressure of 5 MPa at 80 °C and 15 MPa at 120 °C and 150 °C. Further, OEHN1 exhibited excellent temperature responsiveness and plugging performance. They transformed from the glassy to rubber state following full activation at 125–150 °C. They became elastic particles, expanded from flakes to cubes, and could adapt to different crack sizes. In addition, they bridged, accumulated, filled, and formed compact cracks with other lost circulation materials. Consequently, they formed a force-chain network that improved the stability of the plugging layer.

In Vivo Evaluation of Nose-to-Brain Delivery of Liposomal Donepezil, Memantine, and BACE-1 siRNA for Alzheimer's Disease Therapy.

Our study took an innovative approach by evaluating, in vivo, the efficacy of intranasal (IN) administration of liposomal formulations of donepezil, memantine, and beta-site amyloid precursor protein-cleaving enzyme (BACE-1) siRNA, and their combination as a "triple-drug therapy" in treating Alzheimer's disease (AD). Female APP/PS1 homozygous, transgenic mice were used as an AD model. The spatial short-term memory of the APP/PS1 mice was evaluated by a Y-maze behavioral test. IN-administered formulations demonstrated better short-term memory recovery than oral administration. Triple-drug therapy induced short-term memory recovery and lowered beta-amyloid (Aβ) 40 and 42 peptide levels and BACE-1 mRNA expression. Additionally, inflammatory cytokine mRNA expression was downregulated. This innovative approach opens new possibilities for Alzheimer's disease treatment and nose-to-brain delivery.

Neutrophil membrane-based biomimetic metal-polyphenol self-assembled nanozyme for the targeting treatment of early brain injury following subarachnoid hemorrhage

Early brain injury (EBI) refers to the immediate injury and neuroinflammation in the brain after subarachnoid hemorrhage (SAH). The current drugs used to treat SAH are inadequate due to their disappointing ability to penetrate the blood–brain barrier (BBB) and their limited anti-inflammatory effects, leading to unsatisfactory therapeutic outcomes for EBI. Herein, we developed a biomimetic nanozyme (Fe-DMY) using a metal-polyphenol self-assembly method, involving the coordination of ferric ion (Fe3+) and dihydromyricetin (DMY), then encapsulated Fe-DMY in neutrophil membranes (NM) to form NM@Fe-DMY, which targets to neuroinflammatory regions. NM@Fe-DMY exhibits strong catalase- and superoxide dismutase-like catalytic activities, suggesting its potential to reduce oxidative stress in SAH. This leads to reduced lipid peroxidation, increased expression of glutathione peroxidase 4 and prevented ferroptosis. Furthermore, The NM@Fe-DMY has demonstrated effective penetration of the BBB in vivo, accumulating in SAH injury region and exhibiting significant therapeutic efficacy including neural function recovery and improvement of spatial memory. Importantly, NM@Fe-DMY also induces the polarization of microglia from M1-like to M2-like subtypes, interrupting the detrimental cycle of neuroinflammation in EBI. This study introduces a new NM-wrapped biomimetic nanozyme strategy for effectively targeting neuroinflammatory regions and enhancing the treatment of EBI following SAH.

Star poly(lactide-co-glycolide) and poly(ε-caprolactone) polyurethanes with shape memory properties for biomedical applications

Shape memory polyurethane (SMPU) have the capacity to alter and regain their form in reaction to a stimulus (eg. temperature, pH) and have been investigated in biomedical applications. In this work, the shape memory properties of poly(ester-urethane)s (PEU) are studied as a function of the functionality of the poly(lactide-co-glycolide) (PLGA) and poly(e-caprolactone) (PCL) pre-polymers. Two distinct series of PEU are synthesized by reaction between linear and star-shaped PLGA polyols initiated by pentaerythritol (4-arms PLGA) or dipentaerythritol (6-arms PLGA) with PCL di-isocyanate prepolymers. The different PEUs exhibit thermally actuated shape memory properties and tunable mechanical properties with Young’s moduli reaching up to 96 MPa and elongation at break reaching 930 %. The integration of low amounts of PLGA star within the PEU structure increases the material’s shape memory properties, enhancing both fixity (from 45 % to 96 %) and recovery ratios (from 88 % to 92 %). Further exploration into potential applications led to the formulation of porous foams via the solvent casting/particles leaching (SC/PL) process. These foams exhibited high porosity ranging from 74 % to 83 % with pore sizes spanning from 100 to 300 µm. Their mechanical properties are close to the human meniscus with Young’s modulus ranging from 0.13 MPa to 0.53 MPa. Moreover, integration of PLGA star within the PEU scaffold decreases the flexural strength that is an important parameter for potential mini-invasive surgery.

Early sleep apnea treatment in stroke (eSATIS) - a multicentre, randomised controlled, rater-blinded, clinical trial: The association of post-stroke cognition with sleep-disordered breathing and its treatment.

Sleep-disordered breathing (SDB) is linked to cognitive dysfunction. Although SDB is common in stroke patients, the impact of SDB and its early treatment on cognitive functioning after stroke remains poorly investigated. Therefore, we explored the association between SDB and post-stroke cognitive functioning, including the impact of early SDB treatment with adaptive servo-ventilation (ASV) on cognitive recovery from acute event to 3 months post-stroke. We used data from two studies, which included ischaemic stroke patients (n = 131) and no-stroke controls (n = 37) without SDB (apnea-hypopnea index, AHI <5/h) and with SDB (AHI≥20/h). Cognitive functioning was assessed within 7 days and 3 months post-stroke in stroke patients, or at study inclusion in no-stroke control group, respectively. Stroke patients with SDB were randomized to ASV treatment (ASV+) or usual care (ASV-). Linear regression adjusted for main confounders assessed the impact of SDB and its treatment on cognitive recovery. The intention-to-treat analysis did not show significant associations of SDB ASV+ (n = 30) versus SDB ASV- (n = 29) with cognitive recovery. In an exploratory subanalysis, compliant SDB ASV+ (n = 14) versus SDB ASV- showed improvements with ASV in visual memory and cognitive flexibility. Combining the stroke and non-stroke datasets, SDB (n = 85) versus no-SDB (n = 83) was associated with deficits in visual memory and response inhibition independently of stroke. SDB ASV- versus no-SDB (n = 51) was associated with less improvement in visual memory. There was no substantial evidence for benefits of intention-to-treat ASV on cognitive recovery. Exploratory analysis indicated that compliant ASV treatment could benefit visual memory and cognitive flexibility, whereas untreated SDB could contribute to a poor recovery of visual memory.

A comparative study of the microstructure and shape memory behaviour of NiTi, NiTiHf, and Pt-added NiTiHf alloys

The microstructure, substructure, transformation temperature, and recovery ratio of a novel Ni45Pt 5 Ti30Hf20 alloy are reported in the current work. The properties of binary TiNi and ternary TiNiHf alloys are also characterized to establish a comparative basis for shape memory behaviour. The microstructure of the cast structure of Ni45Pt5Ti30Hf20 alloy showed a dendritic matrix and interdendritic eutectic-like mixture, and that of the homogenized structure consisted of martensitic matrix and secondary phase of dark contrast having the composition (Ti+Hf)2(Ni+Pt). Pt substitution of Ni in the ternary alloy with 20 at.% Hf by 5 at.% leads to a decrease in the Af, As, Ms, and Mf . Ms and Mf represent the temperatures at which austenite to martensite transformation starts and completes, respectively, while As and Af represent the temperatures at which martensite to austenite transformation starts and completes, respectively. The XRD studies showed that the structure of martensite is B19′ and TEM studies showed that the substructure of martensite in Pt modified NiTiHf alloy is similar to that of ternary NiTiHf alloy. The shape memory recovery of the Pt-modified alloy is similar to the ternary alloy at higher strength levels. The recovery ratio determined using Vickers indentation is compared with that determined using compression tests to provide an efficacy of small volume tests for screening of these alloys.

Regulator of G protein signaling 6 mediates exercise-induced recovery of hippocampal neurogenesis, learning, and memory in a mouse model of Alzheimer's disease.

JOURNAL/nrgr/04.03/01300535-202510000-00027/figure1/v/2024-11-26T163120Z/r/image-tiff Hippocampal neuronal loss causes cognitive dysfunction in Alzheimer's disease. Adult hippocampal neurogenesis is reduced in patients with Alzheimer's disease. Exercise stimulates adult hippocampal neurogenesis in rodents and improves memory and slows cognitive decline in patients with Alzheimer's disease. However, the molecular pathways for exercise-induced adult hippocampal neurogenesis and improved cognition in Alzheimer's disease are poorly understood. Recently, regulator of G protein signaling 6 (RGS6) was identified as the mediator of voluntary running-induced adult hippocampal neurogenesis in mice. Here, we generated novel RGS6 fl/fl ; APP SWE mice and used retroviral approaches to examine the impact of RGS6 deletion from dentate gyrus neuronal progenitor cells on voluntary running-induced adult hippocampal neurogenesis and cognition in an amyloid-based Alzheimer's disease mouse model. We found that voluntary running in APP SWE mice restored their hippocampal cognitive impairments to that of control mice. This cognitive rescue was abolished by RGS6 deletion in dentate gyrus neuronal progenitor cells, which also abolished running-mediated increases in adult hippocampal neurogenesis. Adult hippocampal neurogenesis was reduced in sedentary APP SWE mice versus control mice, with basal adult hippocampal neurogenesis reduced by RGS6 deletion in dentate gyrus neural precursor cells. RGS6 was expressed in neurons within the dentate gyrus of patients with Alzheimer's disease with significant loss of these RGS6-expressing neurons. Thus, RGS6 mediated voluntary running-induced rescue of impaired cognition and adult hippocampal neurogenesis in APP SWE mice, identifying RGS6 in dentate gyrus neural precursor cells as a possible therapeutic target in Alzheimer's disease.

Neuronal Remodelling as a Predictor of Autism Spectrum Disorder Diagnosis

People with Autism Spectrum Disorder (ASD) are a neurodevelopmental symptom group characterized by significant deficits in information connectivity, mainly caused by specific genetic mutations affecting the fluency of the gamma-aminobutyric acid (GABAergic) system. This disruption, to a greater or lesser degree, hinders the interactive process of incoming stimuli with previously stored information, preventing working memory from fulfilling its role of facilitating access to information in permanent memory and later recovery. In addition to the genetic components, environmental processes occurring, above all, in early childhood, related to specific organic and severe psycho-emotional diseases can produce the same effects in the brain system as the genetic karyotypic component through the concept of neuronal remodelling. In this sense, this research aims to empirically show the influence of neuronal remodelling on the GABAergic pathway leading to the traits of autism spectrum behaviour. A total of 175 participants from the three levels of ASD intensity have participated in this study. Data have been analysed through Linear Logistic Regression, which shows that both components, the genetic process and the environmental process, significantly influence the neural connective pathway that relates information, unlike other operationalized covariates, such as gender or age of the participants. Likewise, as shown by the Chi-Square Test, the interactions between genetic and environmental variables showed no differences in their interaction regarding the connectivity level that would explain the different levels of disorder. However, when there is a combination of genetic mutations in the diagnostic karyotype, there are significant differences between the genetic group and the environmental process over the neural network.

Recovery of Verbal Working Memory Depends on Left Hemisphere White Matter Tracts.

Researchers propose that the recovery of language function following stroke depends on the recruitment of perilesional regions in the left hemisphere and/or homologous regions in the right hemisphere (Kiran, 2012). Many investigations of recovery focus on changes in gray matter regions (e.g., Turkeltaub et al., 2011), whereas relatively few examine white matter tracts (e.g., Schlaug et al., 2009) and none address the role of these tracts in the recovery of verbal working memory (WM). The present study addressed these gaps, examining the role of left vs. right hemisphere tracts in the longitudinal recovery of phonological and semantic WM. For 24 individuals with left hemisphere stroke, we assessed WM performance within one week of stroke (acute timepoint) and at more than six months after stroke (chronic timepoint). To address whether recovery depends on the recruitment of left or right hemisphere tracts, we assessed whether changes in WM were related to the integrity of five white matter tracts in the left hemisphere which had been implicated previously in verbal WM and their right hemisphere analogues. Behavioral results showed significant improvement in semantic but not phonological WM from the acute to chronic timepoints. Improvements in semantic WM significantly correlated with tract integrity as measured by functional anisotropy in the left direct segment of the arcuate fasciculus, inferior fronto-occipital fasciculus and inferior longitudinal fasciculus. The results confirm the role of white matter tracts in language recovery and support the involvement of the left rather than right hemisphere in the recovery of semantic WM.

Judges and lawyers’ beliefs in repression and dissociative amnesia may imperil justice: further guidance required

ABSTRACT This article examines continuing misunderstanding about memory function especially for trauma, across three UK samples (N = 717). Delayed allegations of child sexual and physical abuse are prevalent in Western legal systems and often rely upon uncorroborated memory testimony to prove guilt. U.K. legal professionals and jurors typically assess the reliability of such memory recall via common sense, yet decades of scientific research show common sense beliefs often conflict with science. Recent international surveys show controversial notions of repression and accurate memory recovery remain strongly endorsed. In historical cases, these notions may lead to wrongful convictions. The current study surveyed the U.K. public, lawyers, and mental health professionals’ beliefs about repression, dissociative amnesia and false memories. Study findings give unique data on judges’ and barristers’ beliefs. Overall, the study findings reinforce international scientists’ concerns of a science – knowledge-gap. Repression was strongly endorsed by lay, legal and clinical participants (> 78%) as was dissociative amnesia (> 87%). Moreover, suboptimal professional legal education and juror guidance may increase misunderstanding. Correcting beliefs about memory function, and extending the contribution of memory science in the courtroom remains an important quest for cognitive scientists.

Dissociable effects of mild COVID-19 on short- and long-term memories.

Recent studies have highlighted the presence of cognitive deficits following COVID-19 that persist beyond acute infection, regardless of the initial disease severity. Impairments in short- and long-term memory are among the core deficits reported by patients and observed in objective tests of memory performance. We aimed to extend previous studies by examining performance in a task that allows us to directly compare and contrast memories at different timescales. More specifically, we assessed both short- and long-term memories for contextual-spatial associations encoded during a common session and probed at different durations using an equivalent task in non-hospitalized individuals recovering from mild COVID-19 compared to healthy controls. The approach equated all aspects of memory materials and response demands, isolating performance changes resulting only from memory timescales and thus allowing us to quantify the impact of COVID-19 on cognition. In addition to providing measures of accuracy and response times, the task also provided a sensitive continuous readout of the precision of memory representations, specifically by examining the resolution with which spatial locations were retained in memory. The results demonstrated selective impairment of long-term memory performance in individuals recovering from mild COVID-19 infection. Short-term memory performance remained comparable to healthy controls. Specifically, poor precision of long-term memory representations was demonstrated, which improved with days since diagnosis. No such relationship was observed for short-term memory performance. Our findings reveal a specific impairment to the precision of spatial-contextual long-term memory representations in individuals recovering from mild COVID-19 and demonstrate evidence of recovery in long-term memory over time. Further, the experimental design provides a carefully controlled and sensitive framework to assess memory across different durations with the potential to provide more detailed phenotyping of memory deficits associated with COVID-19 in general.

Acute rimonabant treatment prevents anhedonia and memory loss in rats submitted to mild restraint stress

Stress-related disorders are becoming increasingly common and are often associated with cognitive impairments. Within this context, the endocannabinoid (ECB) system, particularly the type 1 cannabinoid (CB1) receptor, seems to play a decisive role in restoring body homeostasis. There is consistent evidence in the literature that disrupted CB1-mediated neurotransmission can ultimately contribute to stress-related diseases. Therefore, the present study aimed to evaluate the participation of CB1 receptors in the integrity of stress-induced peripheral and behavioral responses. For this purpose, male adult Wistar rats underwent physical restraint (1 h/day, for 7 days), followed by a single administration of rimonabant (CB1 receptor antagonist, 3 mg/Kg, intraperitonial) at the end of stress protocol. Animals were then subjected to evaluation of neuroendocrine responses, behavioral tests and quantification of Iba-1 (microglial) immunoreactivity in the parvocellular subdivisions of the paraventricular nucleus of the hypothalamus (PVN). No effects of restraint stress or rimonabant administration were detected on body mass variation. However, stress significantly increased adrenal relative mass and corticosterone secretion, and reduced thymus relative size. The stress effects on adrenal size and corticosterone plasma levels were absent in rimonabant-treated rats, but the thymus size was further reduced in the restraint-rimonabant group. Restraint stress also induced anhedonia, a depression-like behavior, and reduced object recognition index, indicating memory recovery impairment. Treatment with the CB1 antagonist significantly reversed stress-induced anhedonia and memory deficit. In the PVN, restraint stress reduced the number of Iba-1 positive cells in the medial parvocellular region of vehicle- but not rimonabant-treated animals. Taken together, these results indicate that the acute inhibition of the CB1-mediated endogenous pathway restores stress-induced depression-like behaviors and memory loss, suggesting a role for endocannabinoids in the neuro-immune-endocrine interplay at both peripheral and hypothalamic levels.

Fluorescent Polylactic acid composite incorporating lignin-based carbon quantum dots for sustainable 4D printing applications

Fluorescent 4D printing materials, as innovative materials that combine fluorescent characteristics with 4D printing technology, have attracted widespread interest and research. In this study, green lignin-derived carbon quantum dots (CQDs) were used as the fluorescent module, and renewable poly(propylene carbonate) polyurethane (PPCU) was used for toughening. A new low-cost fluorescent polylactic acid (PLA) composite filament for 4D printing was developed using a simple melt extrusion method. The strength of the prepared composite was maintained at 32 MPa, while the elongation at break increased 8-fold (34 % increase), demonstrating excellent shape fixed ratio (∼99 %), recovery ratio (∼92 %), and rapid shape memory recovery speed. The presence of PPCU prevented fluorescence quenching of the CQDs in the PLA matrix, allowing the composite to emit bright green fluorescence under 365 nm ultraviolet light. The composite exhibited shear thinning behavior and had an ideal melt viscosity for 3D printing. The results obtained demonstrated the versatility of these easy-to-manufacture and low-cost filaments, opening up a novel and convenient method for the preparation of strong, tough, and multifunctional PLA materials, increasing their potential application value.