Radial Arm Research Articles

Ecology dictates the value of memory for foraging bees

"Ecological intelligence" hypotheses posit that animal learning and memory evolve to meet the demands posed by foraging and, together with social intelligence and cognitive buffer hypotheses, provide a key framework for understanding cognitive evolution.1-5 However, identifying the critical environments where cognitive investment reaps significant benefits has proved challenging.6-8 Here, we capitalize upon seasonal variation in forage availability for a social insect model (Bombus terrestris audax) to establish how the benefits of short-term memory, assayed using a radial arm maze (RAM), vary with resource availability. Following a staggered design over 2 years, whereby bees from standardized colonies at identical life-history stages underwent cognitive testing before foraging in the wild, we found that RAM performance predicts foraging efficiency-a key determinant of colony fitness-in plentiful spring foraging conditions but that this relationship is reversed during the summer floral dearth. Our results suggest that the selection for enhanced cognitive abilities is unlikely to be limited to harsh environments where food is hard to find or extract,5,9-11 highlighting instead that the challenges of rich and plentiful environments, which present multiple options in short succession, could be a broad driver in the evolution of certain cognitive traits. VIDEO ABSTRACT.

Floral Categorization by Bumblebees: The Perceptual and the Functional

This study examines generalization and perceptual similarity judgments in bumblebees (Bombus impatiens) and addresses whether category formation of floral stimuli is based upon perceptual floral features alone or foraging experiences from reward associations. Previous experiments have found that bees transfer learning based on category membership, but little is known as to how membership is formed. Two experiments using twelve bumblebee colonies examined a) if bees were able to generalize between flowers with little or no perceptual similarity, and b) if bees were able to change which features of the flowers they generalize under different circumstances. All bees were given discrimination training in a radial arm maze using objects and corresponding photographs. Bees in Experiment 1 were trained to categorize stimuli based upon their reward associations while ignoring their perceptual features. Bees in Experiment 2 were trained to categorize either by floral type or dimensionality (2D vs 3D) of the stimuli. Results of tests using unrewarding stimuli revealed that bees were unable to group items without perceptual similarity cues. When perceptually similar flowers did not share the same reward, bees still generalized between them, regardless of experience. However, the reward values of the flowers were not spontaneously disregarded by the bees. Generalizations differed based on the bee’s experiences, although preferences for perceptual similarity remained. Bees grouped flowers based on the relevant features learned through experience rather than just relying on perceptual similarity, but also do not immediately discount similar flowers during foraging, giving a preliminary insight into the role of function in perceptual similarity judgments.

Amelioration of intracerebroventricular streptozotocin-induced cognitive dysfunction by Ocimum sanctum L. through the modulation of inflammation and GLP-1 levels.

DPP-4 inhibitors have been shown to reverse amyloid deposition in Alzheimer's disease (AD) patients with cognitive impairment. Ocimum sanctum L. leaves reported the presence of important phytoconstituents which are reported to have DPP-4 inhibitory activity. To investigate the effects of petroleum ether extract of Ocimum sanctum L. (PEOS) in Intracerebroventricular streptozotocin (ICV-STZ) induced AD rats. ICV-STZ (3mg/kg) was injected bilaterally into male Wistar rats, while sham animals received the artificial CSF. The ICV-STZ-induced rats were administered with three doses of PEOS (100, 200, and 400mg/kg, p.o.) for thirty days. All experimental rats were subjected to behaviour parameters (radial arm maze task and novel object recognition test), neurochemical parameters such as GLP-1, Aβ42, and TNF-α levels, and histopathological examination (Congo red staining) of the left brain hemisphere. PEOS significantly reversed the spatial learning and memory deficit exhibited by ICV-STZ-induced rats. Furthermore, PEOS also shows promising results in retreating Aβ deposition, TNF α, and increasing GLP-1 levels. The histopathological study also showed a significant dose-dependent reduction in amyloid plaque formation and dense granule in PEOS -treated rats as compared to the ICV-STZ induced rats (Negative control). The results show that extract of Ocimum sanctum L. attenuated ICV-STZ-induced learning and memory deficits in rats and has the potential to be employed in the therapy of AD.

The protocol for assessing olfactory working memory capacity in mice.

BackgroundWorking memory capacity (WMC) is the ability to maintain information over a few seconds. Although it has been extensively studied in healthy subjects and neuropsychiatric patients, few tasks have been developed to measure such changes in rodents. Many procedures have been used to measure WM in rodents, including the radial arm maze, the WM version of the Morris swimming task, and various delayed matching and nonmatching‐to‐sample tasks. It should be noted, however, that the memory components assessed in these procedures do not include memory capacity.MethodsWe developed an olfactory working memory capacity (OWMC) paradigm to assess the WMC of 3‐month‐old 5×FAD mice, a mouse model of Alzheimer's disease. The task is divided into five phases: context adaptation, digging training, rule learning for nonmatching to a single sample odor (NMSS), rule learning for nonmatching to multiple sample odors (NMMS), and capacity testing.ResultsIn the NMSS rule‐learning phase, there was no difference between wild‐type (WT) mice and 5×FAD mice in the performance correct rate, correct option rate, and correct rejection rate. The WT mice and 5×FAD mice showed similar memory capacity in the NMMS rule‐learning phase. After capacity test, we found that the WMC was significantly diminished in 5×FAD mice. As the memory load increased, 5×FAD mice also made significantly more errors than WT mice.ConclusionThe OWMC task, based on a nonmatch‐to‐sample rule, is a sensitive and robust behavioral assay that we validated as a reliable method for measuring WMC and exploring different components of memory in mice.

Age-related neuroendocrine, cognitive, and behavioral co-morbidities are promoted by HIV-1 Tat expression in male mice.

In the U.S. about half of the HIV-infected individuals are aged 50 and older. In men living with HIV, secondary hypogonadism is common and occurs earlier than in seronegative men, and its prevalence increases with age. While the mechanisms(s) are unknown, the HIV-1 trans-activator of transcription (Tat) protein disrupts neuroendocrine function in mice partly by dysregulating mitochondria and neurosteroidogenesis. We hypothesized that conditional Tat expression in middle-aged male transgenic mice [Tat(+)] would promote age-related comorbidities compared to age-matched controls [Tat(−)]. We expected Tat to alter steroid hormone milieu consistent with behavioral deficits. Middle-aged Tat(+) mice had lower circulating testosterone and progesterone than age-matched controls and greater circulating corticosterone and central allopregnanolone than other groups. Young Tat(+) mice had greater circulating progesterone and estradiol-to-testosterone ratios. Older age or Tat exposure increased anxiety-like behavior (open field; elevated plus-maze), increased cognitive errors (radial arm water maze), and reduced grip strength. Young Tat(+), or middle-aged Tat(−), males had higher mechanical nociceptive thresholds than age-matched counterparts. Steroid levels correlated with behaviors. Thus, Tat may contribute to HIV-accelerated aging.

The Repellent Potential of Herbal Oils Alone and in Combination in Mouse Behavioral Models (Mus musculus)

Abstract Natural repellent products are of interest worldwide due to their low toxicity, rapid degradation, and being friendly to the environment. The current study evaluated the efficiency of herbal oils from fragrant plants as mouse repellents. Orange oil (Citrus sinensis (L.) Osbeck), peppermint oil (Mentha × piperita L.), lemongrass oil (Cymbopogon citratus (DC.) Stapf), ginger oil (Zingiber officinale Roscoe), plai oil (Zingiber cassumunar Roxb.), menthol and their combination were tested in a radial arm maze and light/dark transition test. For the short-term effect (week 0), each of the herbal oils and their combination were effective as mouse repellents, as shown by increased latency times and decreased time spent in arms containing repellents in the radial arm maze. Similarly, mice exposed to each of the herbal oils and their combination in the dark chamber spent more time in the light chamber in the light/dark transition test. Only peppermint oil and menthol failed to maintain their repellent activity in the long-term effect (week 1). Thus, we recommend spraying orange oil, lemongrass oil, ginger oil, plai oil and the combination of all oils every week for effective mouse repellant activity. Keywords: Medicinal plant, Mice, Natural product, Essential oils, Anxiety

Exogenous Short Chain Fatty Acid Effects in APP/PS1 Mice.

Elucidating the impact of the gut microbiome on Alzheimer’s Disease (AD) is an area of intense interest. Short chain fatty acids (SCFAs) are major microbiota metabolites that have been implicated as a mediator of gut microbiome effects in the brain. Here, we tested the effects of SCFA-treated water vs. saline-treated water on APPswe/PSEN1dE9 mice maintained under standard laboratory conditions. Mice were treated with SCFAs from five months of age until ten months of age, when they were evaluated for microbiome profile, impaired spatial memory as evaluated with the radial arm water maze, astrocyte activation as measured by Gfap expression and amyloid burden as assessed by histochemistry and MSD ELISA. We report that SCFA treatment increased alpha-diversity and impacted the gut microbiome profile by increasing, in part, the relative abundance of several bacteria that typically produce SCFAs. However, SCFA treatment did not significantly affect behavior. Similarly, SCFAs did not affect cortical or hippocampal astrocyte activation observed in the APP/PS1 mice. Lastly, although robust levels of soluble and insoluble amyloid were present in the APP/PS1 mice, SCFA treatment had no effect on these indices. Overall, our findings are that SCFA treatment modifies the microbiome in a fashion that may increase further SCFA production. However, SCFA treatment did not alter behavior, astrocyte activation, nor amyloid neuropathology in APP/PS1 mice maintained with a conventional microbiome.

Opposing reduced VPAC1 and enhanced VPAC2 VIP receptors in the hippocampus of the Li2+-pilocarpine rat model of temporal lobe epilepsy

VIP binding sites are upregulated in mesial temporal lobe epilepsy (MTLE) patients, also suffering from severe cognitive deficits. Although altered VIP and VIP receptor levels were described in rodent models of epilepsy, the VIP receptor subtype(s) were never identified. We now investigated how VPAC1 and VPAC2 receptor levels change in the Li2+-pilocarpine rat model of MTLE. Cognitive decline and altered synaptic plasticity as estimated from phosphorylation of AMPA GluA1 subunit on Ser831 and Ser845 and AMPA GluA1/GluA2 ratio was also probed. Animals showing spontaneous recurrent seizures (SRSs) for at least 4 weeks showed impaired learning in the radial arm maze (RAM) and presented decreased VPAC1 and increased VPAC2 receptor levels. In addition, SRSs rats showed increased AMPA GluA1 phosphorylation in Ser831 and Ser845, marked decrease in GluA1 levels and a milder decrease in GluA2 levels. Consequently, the GluA1/GluA2 ratio was also decreased in SRSs rats.Altered VIP receptor levels may differentially prevent or contribute to MTLE pathology, since VPAC1 receptors promote the endogenous control of LTP, mediate endogenous VIP neuroprotection against altered synaptic plasticity following epileptiform activity, and mediate anti-inflammatory actions in microglia, while VPAC2 receptors mediate VIP endogenous neuroprotection against neonatal excitotoxicity and prevent reactive astrogliosis. This discovery imposes a different mindset for considering VIP receptors as therapeutic targets in MTLE, allowing a differential targeting of the cellular events contributing to epileptogenesis.

Anti-Alzheimer's and Antioxidant Activity of Ethanolic Seed Extract of Sapindus emarginatus Vahl on Scopolamine-Induced Cognitive Impairment in Mice

Background: Alzheimer's disease (AD) is a common nerve problem that leads to memory loss, particularly in the elderly. A shortage of acetylcholine in the brain, as well as oxidative stress, induces Alzheimer's disease. Currently, limited drugs are available to treat Alzheimer's disease because continuous use of these medications causes several side effects. Hence, we need high efficacious drugs to treat Alzheimer's disease with fewer side effects. Sapindus emarginatus Vahl or soap nut is a member of the Sapindaceae family. It's been used traditionally as an antiepileptic, antipruritic, antifertility, antiemetic, and anti-inflammatory agent. It is cheap, widely available, and reported to counteract chronic diseases linked to oxidative stress, such as ulcers and dyslipidemia. Objective: The purpose of this study was to determine the anti-Alzheimer and antioxidant properties of ethanolic seed extract of Sapindus emarginatus (ESSE) against scopolamine-induced amnesia. Methods: The total flavonoid level of the ESSE was estimated by a UV-visible spectrophotometer. The scopolamine (1 mg/kg/PO) was administered as a single intraperitoneal injection on the seventh day for induction of dementia in mice. The ESSE (250 and 500 mg/kg/PO) and donepezil (2.5 mg/kg/PO) was administered orally for 7 days. The neurobehavioral tests such as an elevated plus maze, radial arm maze, and Y-maze tests were undertaken for estimation of behavioral trials. The brain homogenate was used for the estimation of acetylcholine, acetylcholinesterase, and oxidative cell injury markers such as MDA, LH, SOD, CAT, and GSH. Results: The total flavonoid content of the extract was 0.47 mg of QE/g. Scopolamine degraded memory, as well as caused alterations in acetylcholine, acetylcholinesterase, and elevated oxidative stress in the brain. Pretreatment with ESSE reduced scopolamine-induced behavioral, neurochemical, and oxidative stress markers. Conclusion: The ESSE has an anti-amnesic impact, making it an attractive option for targeting multiple events as a possible technique to slow cognitive impairment.

Texas field crickets (Gryllus texensis) use visual cues to place learn but perform poorly when intra- and extra-maze cues conflict.

Central place foraging field crickets are an ideal system for studying the adaptive value of learning and memory, but more research is needed on ecologically relevant cognition in these invertebrates. Here, we test the visuospatial place learning of Texas field crickets (Gryllus texensis) in a radial arm maze. Our study expands previous work on G. texensis cognition for accuracy measures and extends our previous findings on females to both sexes. Additionally, our study examines whether crickets use intra- or extra-maze cues to locate a food reward using a maze rotation that puts the cues in conflict. We found that male and female crickets improved performance over trials when measured by accuracy variables but not latency variables. Thigmotaxis negatively impacted performance in both sexes. In a reward-absent trial, both male and female crickets demonstrated place memory. When intra- and extra-maze cues conflicted during a rotation trial, crickets' performance was not better than chance. Our rotation results suggest that crickets may experience reciprocal overshadowing of conflicting cues - a result most often seen in other taxa with conflicting multi-modal cues. We conclude that crickets do not rely solely on: (1) a single-cue association, (2) route-following, or (3) their own scent cues to navigate the maze. Instead, male and female Texas field crickets seem to learn the location of the reward using a combination of proximal and distal cues. The possibility to test large numbers of wild-caught or laboratory-reared individuals opens the door to future investigations on the evolutionary ecology of visuospatial learning in these invertebrates.

One-pot hydrothermal green synthesis of Polygala tenuifolia mediated graphene quantum dots for acetylcholine esterase inhibitory activity

The present paper reports the synthesis of Donepezil hydrochloride functionalized Graphene quantum dots (DO-ptGQD) for the cure of Alzheimer disease. Graphene quantum dots were synthesized through root extract of Polygala tenuifolia by using one-pot hydrothermal synthesis method. Using UV/Visible spectroscopy, FTIR, SEM, TEM and XPS methods, the synthesized ptGQD was evaluated. Further the formulated DO-ptGQD was evaluated by SEM, TEM, FTIR, XPS techniques and was further evaluated for the encapsulation study, in-vitro study and various in-vivo models. Through behavioural model (Radial arm maze and Water morris maze assay) the learning and memory ability of the formulations was evaluated and the outcomes indicate that the DO-ptGQD markedly decreases the transmission latency to get in the baited arm in 12.19 ± 0.39 s or to the hidden stage in 15.37 ± 0.45 in 7 days. DO-ptGQD show more percentage inhibition of AchE enzyme that is 86.23 ± 1.28 as likened with the drug and ptGQD. DO-ptGQD considerably increases the protein and glutathione level and decreases the nitric oxide and lipid peroxide level. The Histopathological image indicates that DO-ptGQD treats the disorganization of the cell and show more preservation of small pyramidal cells as compared with the other formulations. In conclusion, DO-ptGQD was safe and effective drug delivery system for the treatment of Alzheimer disease and also the root extract of Polygala tenuifolia provide synergistic effect for the treatment of disease.

Phytochemical and Pharmacological Screening of Salvia Hispanica Seed Extracts against Alzeimer’s Disease in Rodents

The objective of this study was to identify the potential of salvia hispanica as protective and therapeutic agent against Alzheimer’s disease. The learning and memory enhancing activity of saliva hispanica seed extract were investigated in rats by using the ethanol induced cognitive impairment and diazepam induced amnesia and its effects on learning and memory were examined by using Morris water maze (MWM) test and 8-radial arm maze (8-RAM) test. For Morris water maze test all groups showed significantly (P value is < 0.01 &< 0.05) decreases transfer latency time at all periods as compared to ethanol and diazepam inducing group & for radial arm maze test all groups showed significantly (P value is< 0.0001) decreased in the time taken to reach the paired arm and number of entries in baited arm and non-baited arm as compared to ethanol inducing group. Therefore seed extracts of salvia hispanica exhibited significantly learning and memory activity in Alzheimer’s disease.

A Mediterranean Diet Enhances Cognitive Function and Modulates the Gut Microbiota

ObjectivesThe gut-microbiome-brain axis is an underexplored mechanism that may mitigate the development of mild cognitive impairment. The objective of this study was to elucidate the effects of a human-modeled Mediterranean diet (MeDi) and Western diet (WD) on cognitive function and gut microbial composition. We hypothesized that consumption of a MeDi would improve cognitive function and modulate beneficial changes to the gut microbiota compared to the WD.MethodsMale Sprague Dawley rats (10 weeks of age) were assigned to a MeDi (n = 10) or WD (n = 9) for 3 months. The radial arm water maze (RAWM) was used to assess aspects of short- and long-term memory using discrete error types (working and reference). Data were analyzed using a Two-Way Repeated Measures ANOVA including diet and period. Microbial composition was determined by 16S rRNA sequencing and analyzed using Linear discriminant analysis effect size (LEfSe). Simple linear regression was used to test if the significantly different genera predicted average total error scores.ResultsAnimals consuming the MeDi committed fewer reference memory (p = 0.02), working memory incorrect (p = 0.04), and total errors (p = 0.01), and had a trend toward fewer working memory correct errors (p = 0.08) compared to the WD. MeDi gut microbiota composition was distinct (p < 0.001) and had a trend to be move diverse (Shannon, p = 0.05; Simpson, p = 0.05; Chao1, p = 0.06) compared to the WD. LEfSe analysis revealed 9 differentially abundant genera between the MeDi and WD. The MeDi had an increased abundance of 6 genera including Lachnoclostridium (p < 0.001), Candidatus Saccharimonas (p < 0.001), and Romboutsia (p = 0.01). Decreased abundances in the MeDi group included Bifidobacterium (p < 0.001) and Erysipelatoclostridium (p = 0.003). It was found that Candidatus Saccharimonas (p = 0.02, r2 = 0.31, β = 0.007), Romboutsia (p = 0.03, r2 = 0.25, β = 0.033), and Bifidobacterium (p = 0.01, r2 = 0.35, β = −0.118) significantly predicted total errors.ConclusionsRelative to animals consuming the WD, the MeDi enhanced short- and long-term memory and differentially abundant genus level bacteria were predictive of memory outcomes. The MeDi may maintain cognitive function through modulation of the gut microbiota.Funding SourcesNone.

Alcohol-Drinking Under Limited-Access Procedures During Mature Adulthood Accelerates the Onset of Cognitive Impairment in Mice.

A history of heavy drinking increases vulnerability to, and the severity of, Alzheimer’s disease (AD) and related dementias, with alcohol use disorder identified as the strongest modifiable risk factor for early-onset dementia. Heavy drinking has increased markedly in women over the past 10 years, particularly in mature adult women during the coronavirus (COVID-19) pandemic. This is concerning as women are more sensitive to many alcohol-related disease states, including AD and related dementias. Herein, we conducted two studies to determine if a 1-month period of binge drinking during mature adulthood (i.e., 5–9 months of age) impairs spatial and working memory to a greater extent in female vs. male C57BL/6J (B6J) mice. The anxiogenic and cognitive-impairing effects of binge drinking were also compared between mature adult and old B6J mice (18 months of age) in a third study. Throughout, females consumed more alcohol than males, indicating that a sex difference in binge drinking persists into old age. Despite the sex difference in intake, we detected no consistent sex difference in our measures of alcohol withdrawal-induced anxiety during a behavioral test battery. Although mature adult females exhibited more cognitive deficits than males, the precise outcome exhibiting a female-selective effect varied across studies. Old mice drank lower amounts of alcohol than mature adult mice, yet their blood ethanol concentrations (BECs) were within error of the 80 mg/dl criterion for binge drinking, indicative of an age-related slowing of alcohol metabolism. As expected, 18-month-old controls exhibited more signs of cognitive impairment than their 6-month-old counterparts, and binge drinking history impaired the Morris water maze performance of mice of both ages. In contrast, binge drinking history impaired the radial arm maze performance of 6-month-old mice only, and the extent of the impairment was comparable to the behavior exhibited by the older mice. We conclude from our studies that: (1) both biological sex and the age of drinking onset are subject factors that impact voluntary alcohol consumption by mice into old age; (2) binge drinking during later life elicits a negative affective state that is relatively sex-independent; (3) binge drinking during both mature adulthood and old age impairs spatial learning and memory; (4) binge drinking during mature adulthood accelerates deficits in working memory; and (5) mature adult females tend to exhibit more alcohol-induced cognitive impairments than males. If relevant to humans, these findings suggest that binge-like drinking by older adult men and women induces a negative affective state and cognitive decline, but that mature adult women, in particular, may be more sensitive to both the immediate and persistent cognitive-impairing effects of heavy drinking.

Phytochemical Screening and Learning and Memory Activity of Cucurbita pepo against Ethanol Induced Cognitive Impairment in Rodents by Using 8-ARM Radial Maze [8-ARM

The present study was undertaken to investigate the learning and memory enhancing activity of Cucurbita pepo seed extract in rats by using the ethanol induced cognitive impairment and its effects were examined by using 8-radial arm maze (8-RAM) test. For radial arm maze test all groups showed significantly (P value is&lt; 0.0001&amp; &lt; 0.001) decreased in the time taken to reach the paired arm and number of entries in baited arm and non-baited arm as compared to ethanol inducing group. Therefore seed extracts of Cucurbita pepo exhibited significantly learning and memory activity in Alzheimer’s disease.

In utero exposure to dietary emulsifier alters the behavioral activity in offspring

ObjectivePediatric mental health disorder is a combination of neuroinflammatory conditions with unknown etiology and currently, there are less awareness on the impacts of food additives on pediatric neuroinflammatory conditions and adolescent mental health disorders. Food additives such as dietary emulsifier (DE) (polysorbate 80, carrageenan and maltodextrin) are added to a variety of processed foods, and their consumption has increased dramatically worldwide which could be a risk factor for pediatric mental health disorders. Therefore, there is a critical need to understand the impact of maternal exposure to food additives associated pediatric mental health and the underlying mechanism.Materials and MethodsBehavioral testing such as tail flick assay, radial arm, rotarod and hot plate assay was done on the offspring from both control and DE exposed mice for the impaired motor activity, pain sensitivity and cognitive behavior. Colonic microbial composition was determined through 16sRNA pyrosequencing of fecal DNA samples from control and in utero DE‐exposed offspring. Level of pro inflammatory cytokines in the colon tissue as well as the serum sample was measured using Multianalyte cytokine assay kit from Qiagen.Summary of ResultsOur results show that in utero exposure to DE leads to decreased brain sizes and impaired motor learning in the offspring. Additionally, in utero exposure to DE leads to decreased pain sensitivity as a sign of stress in offspring. In utero exposure to DE shows on onset of cognitive impairment in offspring. In utero exposure to DE leads to an elevated M1 macrophage cytokine profile and CLGI symptoms in the gastrointestinal tract of offspring. In utero exposure to DE leads to gut dysbiosis in offspring. Among the DE‐exposed adolescents, the male offspring had significantly higher impact on these parameters compared to the DE‐exposed female offspring. In utero exposure to DE leads to imbalance in serum levels of dihydrotestosterone (DHT) and estradiol (E2) in the Offspring.ConclusionOur data suggest that maternal exposure to food additive is associated with the male biased cognitive impairment and neurobehavioral changes in the offspring. In future, we will determine the specific mechanism responsible for the sex specific alternation in offspring born to DE exposed mother to develop a preventative and therapeutic strategies.

Assessing the Influence of Salvia triloba on Memory Deficit Caused by Sleep Deprivation in the Context of Oxidative Stress.

Learning and memory deficit has been reported to be correlated to oxidative mutilation in the hippocampus. Moreover, sleep deprivation (SD) mitigates memory via distressing oxidative stress balance. In the current report, the prospective neuroprotective role of oral sage (Salvia triloba) extract on cognitive impairment induced by chronic SD was investigated. The SD was induced in adult male Wistar rats employing a modified multiple platform (8 h/day; for six weeks). Simultaneously, S. triloba extract (375 mg/kg, orally) was administered for six weeks. Thereafter, the Radial Arm Water Maze test was utilized to evaluate spatial learning and memory. Moreover, activities of different hippocampal antioxidant parameters: glutathione peroxidase (GPx), oxidized glutathione (GSSG), reduced glutathione (GSH), catalase, superoxide dismutase (SOD), and the thiobarbituric acid reactive substance (TBARS) were measured in rats' hippocampus. Moreover, the level of brain derived neurotrophic factor (BDNF) was assessed. Current results illustrate that chronic SD significantly compromised both memories, shortand long-term, while sage extract inhibited these consequences. Moreover, sage extract remarkably stabilized the antioxidant enzyme levels, which were decreased by SD, such as: SOD, catalase, and GPx (P < 0.05), and remarkably augmented the GSH/GSSG ratio in SD rats (P < 0.05). However, no substantial alterations of GSH, TBARS or BDNF levels (P > 0.05) were seen with sage extract administration. Chronic treatment with sage extract (S. Triloba) precluded SD-induced memory impairment by regularizing antioxidant parameters levels in rats' hippocampus.

A subterminal growth zone at arm tip likely underlies life-long indeterminate growth in brittle stars

BackgroundEchinoderms are a phylum of marine invertebrates with close phylogenetic relationships to chordates. Many members of the phylum Echinodermata are capable of extensive post-traumatic regeneration and life-long indeterminate growth. Different from regeneration, the life-long elongation of the main body axis in adult echinoderms has received little attention. The anatomical location and the nature of the dividing progenitor cells contributing to adults’ growth is unknown.ResultsWe show that the proliferating cells that drive the life-long growth of adult brittle star arms are mostly localized to the subterminal (second from the tip) arm segment. Each of the major anatomical structures contains dividing progenitors. These structures include: the radial nerve, water-vascular canal, and arm coelomic wall. Some of those proliferating progenitor cells are capable of multiple rounds of cell division. Within the nervous system, the progenitor cells were identified as a subset of radial glial cells that do not express Brn1/2/4, a transcription factor with a conserved role in the neuronal fate specification. In addition to characterizing the growth zone and the nature of the precursor cells, we provide a description of the microanatomy of the four distal-most arm segments contrasting the distal with the proximal segments, which are more mature.ConclusionsThe growth of the adult brittle star arms occurs via proliferation of progenitor cells in the distal segments, which are most abundant in the second segment from the tip. At least some of the progenitors are capable of multiple rounds of cell division. Within the nervous system the dividing cells were identified as Brn1/2/4-negative radial glial cells.

L-Carnitine prevents memory impairment induced by post-traumatic stress disorder.

Post-traumatic stress disorder (PTSD) is a genuine obstructing mental disorder. As indicated by the name, it is related to the patients' stress augmented by life-threatening conditions or accidents. The PTSD has linked to oxidative stress that can result in neurodegeneration. L-carnitine (L-CAR) is known for its antioxidant properties, which can protect against neuronal damage. In the current study, we investigated the beneficial effects of L-CAR on the memory impairment induced by PTSD using a rat model. A model of single-prolonged stress (a cycle of restraining, forced swimming, rest, and finally diethyl ether exposure for 2 h, 20 min, 15 min, and 1-2 min, respectively) was used to induce PTSD-like behavior. Intraperitoneal L-CAR treatment (300 mg/kg/day) was introduced for four weeks. Both memory and special learning were evaluated utilizing the radial arm water maze (RAWM). Moreover, the levels of glutathione peroxidase (GPx), glutathione reduced (GSH), and glutathione oxidized (GSSG) were assessed as biomarkers oxidative stress in the hippocampus. The results demonstrated that both the short and long-term memories were impaired by PTSD/SPS model (P < 0.05), while L-CAR treatment prevented this memory impairment in PTSD rats. Besides, L-CAR prevented the reduction in GPx activity and increase in GSSG, which were altered in the hippocampus of the PTSD/SPS rats (P < 0.05). Levels of GSH were not changed in PTSD and/or L-CAR rats. L-CAR administration prevented short- and long-term memories' impairments induced in the PTSD/SPS rat model. This is probably related to its antioxidant effects in the hippocampus.

Application of Real and Virtual Radial Arm Maze Task in Human.

Virtual Reality (VR) emerges as a promising technology capable of creating different scenarios in which the body, environment, and brain are closely related, proving enhancements in the diagnosis and treatment of several spatial memory deficits. In recent years, human spatial navigation has increasingly been studied in interactive virtual environments. However, navigational tasks are still not completely adapted in immersive 3D VR systems. We stipulate that an immersive Radial Arm Maze (RAM) is an excellent instrument, allowing the participants to be physically active within the maze exactly as in the walking RAM version in reality modality. RAM is a behavioral ecological task that allows the analyses of different facets of spatial memory, distinguishing declarative components from procedural ones. In addition to describing the characteristics of RAM, we will also analyze studies in which RAM has been used in virtual modality to provide suggestions into RAM building in immersive modality.