Human Memory Function Research Articles

Tissue localization and virus specificity shape the maintenance and function of human virus-specific memory T cells recognizing HCMV and influenza A

Abstract Generation and maintenance of memory T cells within tissue sites of infection is critical for long-term antiviral protection. Current knowledge of human antiviral responses is largely derived from studies sampling peripheral blood. Yet, little is known about human tissue-localized antiviral immunity. Utilizing our human donor tissue resource established in collaboration with LiveOnNY, we investigated how tissue, virus, and age shape T cell maintenance across diverse tissues and their function when presented with antigens derived from human cytomegalovirus (HCMV) or influenza A virus (flu). Using flow cytometry, we show that virus-specific CD8 T cells are maintained in diverse tissues with subset differentiation and distribution shaped by virus specificity and age. Compared to T cells recognizing HCMV, flu-specific T cells display higher levels of residency markers—CD69 and CD103—particularly in adult compared to pediatric donors. In contrast, HCMV-specific T cells are maintained in greater abundance as terminally-differentiated effector T cells. Sequencing of the T cell receptor CDR3b chain reveals that, while both HCMV- and flu-specific T cells demonstrate clonal overlap across multiple tissues, HCMV-specific T cells display greater clonality and less diversity. When presented with viral antigens, HCMV- and flu-specific T cells are polyfunctional. Additionally, single-cell transcriptome profiling reveals tissue localization is the primary determinant of antigen-driven responses. Together, these studies demonstrate the dynamics of T cell differentiation and maintenance throughout the human body, which is primarily driven by virus specificity, and the role of tissue localization in shaping antiviral response.

Theta power and theta-gamma coupling support long-term spatial memory retrieval.

Hippocampal theta oscillations have been implicated in spatial memory function in both rodents and humans. What is less clear is how hippocampal theta interacts with higher frequency oscillations to support long‐term memory. Here we asked 10 presurgical epilepsy patients undergoing intracranial EEG recording to perform a long‐term spatial memory task in desktop virtual reality and found that increased theta power in two discrete bands (“low” 2‐5 Hz and “high” 6‐11 Hz) during cued retrieval was associated with improved task performance. Similarly, increased coupling between “low” theta phase and gamma amplitude during the same period was associated with improved task performance. Finally, low and high gamma amplitude appeared to peak at different phases of the theta cycle; providing a novel connection between human hippocampal function and rodent data. These results help to elucidate the role of theta oscillations and theta‐gamma phase‐amplitude coupling in human long‐term memory.

THE PHENOMENON OF HISTORICAL MEMORY IN THE CONTEXT OF THE GENESIS OF HISTORICAL METHODOLOGY

The article analyzes the phenomenon of historical memory and approaches to its study in contemporary scientific discourse. It is stated that its emergence is associated with methodo-logical transformations in the historical science of the last two centuries. Initially, in the course of theoretical research, historical memory was understood as a way of reconstructing the past, when an ethnos or a separate social group builds an image of the past to please the present. As a result of the crisis of traditional historiography, caused by the postmodern criticism of metanarratives, a re-actualization of historical memory occurs. In practice, this occurs in the form of mass commemorations, museumification of common and individual historical heritage, and the creation of an infrastructure for memorial tourism. Historical memory reveals its capabilities to form person’s identity and life guidelines, rooted in the fundamental and universal function of human memory. An important feature of the contemporary research situation is that the rise of historical memory occurs in a crisis of the idea of objectivity and faith in the future. The current stage in the development of historical consciousness gives a new characteristic associated with the general nature of changes concerning various layers and forms of memory, as well as with the collapse of world history and structural changes in historical representations.

Fc receptor-like 4 and 5 define human atypical memory B cells.

Atypical memory B cells accumulate in chronic infections and autoimmune conditions, and commonly express FCRL4 and FCRL5, respective IgA and IgG receptors. We characterized memory cells from tonsils on the basis of both FCRL4 and FCRL5 expression, defining three subsets with distinct surface proteins and gene expression. Atypical FCRL4+FCRL5+ memory cells had the most discrete surface protein expression and were enriched in cell adhesion pathways, consistent with functioning as tissue-resident cells. Atypical FCRL4-FCRL5+ memory cells expressed transcription factors and immunoglobulin genes that suggest poised differentiation into plasma cells. Accordingly, the FCRL4-FCRL5+ memory subset was enriched in pathways responding to endoplasmic reticulum stress and IFN-γ. We reconstructed ongoing B-cell responses as lineage trees, providing crucial in vivo developmental context. Each memory subset typically maintained its lineage, denoting mechanisms enforcing their phenotypes. Classical FCRL4-FCRL5- memory cells were infrequently detected in lineage trees, suggesting the majority were in a quiescent state. FCRL4-FCRL5+ cells were the most represented memory subset in lineage trees, indicating robust participation in ongoing responses. Together, these differences suggest FCRL4 and FCRL5 are unlikely to be passive markers but rather active drivers of human memory B-cell development and function.

Training set coherence and set size effects on concept generalization and recognition.

Building conceptual knowledge that generalizes to novel situations is a key function of human memory. Category-learning paradigms have long been used to understand the mechanisms of knowledge generalization. In the present study, we tested the conditions that promote formation of new concepts. Participants underwent 1 of 6 training conditions that differed in the number of examples per category (set size) and their relative similarity to the category average (set coherence). Performance metrics included rates of category learning, ability to generalize categories to new items of varying similarity to prototypes, and recognition memory for individual examples. In categorization, high set coherence led to faster learning and better generalization, while set size had little effect. Recognition did not differ reliably among conditions. We also tested the nature of memory representations used for categorization and recognition decisions using quantitative prototype and exemplar models fit to behavioral responses. Prototype models posit abstract category representations based on the category's central tendency, whereas exemplar models posit that categories are represented by individual category members. Prototype strategy use during categorization increased with increasing set coherence, suggesting that coherent training sets facilitate extraction of commonalities within a category. We conclude that learning from a coherent set of examples is an efficient means of forming abstract knowledge that generalizes broadly. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

A novel humanized mouse model to study the function of human cutaneous memory T cells in vivo in human skin

Human skin contains a population of memory T cells that supports tissue homeostasis and provides protective immunity. The study of human memory T cells is often restricted to in vitro studies and to human PBMC serving as primary cell source. Because the tissue environment impacts the phenotype and function of memory T cells, it is crucial to study these cells within their tissue. Here we utilized immunodeficient NOD-scid IL2rγnull (NSG) mice that carried in vivo-generated engineered human skin (ES). ES was generated from human keratinocytes and fibroblasts and was initially devoid of skin-resident immune cells. Upon adoptive transfer of human PBMC, this reductionist system allowed us to study human T cell recruitment from a circulating pool of T cells into non-inflamed human skin in vivo. Circulating human memory T cells preferentially infiltrated ES and showed diverse functional profiles of T cells found in fresh human skin. The chemokine and cytokine microenvironment of ES closely resembled that of non-inflamed human skin. Upon entering the ES T cells assumed a resident memory T cell-like phenotype in the absence of infection, and a proportion of these cutaneous T cells can be locally activated upon injection of monocyte derived dendritic cells (moDCs) that presented Candida albicans. Interestingly, we found that CD69+ memory T cells produced higher levels of effector cytokines in response to Candida albicans, compared to CD69- T cells. Overall, this model has broad utility in many areas of human skin immunology research, including the study of immune-mediated skin diseases.

Spermidine intake is associated with cortical thickness and hippocampal volume in older adults

BackgroundThe natural polyamine spermidine, known to be important for cellular function, decreases during aging. Previous research has demonstrated beneficial impact of spermidine intake on memory functions in both animal models and humans, suggesting that spermidine may be a preventive approach to delay age-related cognitive decline and possibly even Alzheimer’s disease (AD). However, the association of spermidine intake with brain health in humans is still unknown. In this study, we aimed to determine the association between dietary spermidine intake and structural brain measures in older individuals with subjective cognitive decline (SCD) and healthy controls (HC). MethodsDietary spermidine intake and adherence to Mediterranean Diet (MeDi) were assessed by a self-reported food frequency questionnaire in 90 older adults with SCD and 47 HC. Processing of structural MRI data yielded global brain volumes, hippocampal volume, mean and regional cortical thickness, and cortical thickness in a template encompassing AD-vulnerable regions. In exploratory analyses, the association between spermidine intake and structural brain measures was assessed using adjusted and unadjusted linear regression models. Additionally, we tested for differential associations as a function of group. Mediation analyses were performed to examine whether dietary spermidine intake mediates the associations between adherence to MeDi and structural brain measures. ResultsHigher spermidine intake was associated with larger hippocampal volume (standardized β ​= ​0.262, p ​= ​0.002), greater mean cortical thickness (standardized β ​= ​0.187, p ​= ​0.031), and greater cortical thickness in AD-vulnerable brain regions (standardized β ​= ​0.176, p ​= ​0.042), the parietal (standardized β ​= ​0.202, p ​= ​0.020), and temporal lobes (standardized β ​= ​0.217, p ​= ​0.012). No significant differential effect emerged between older adults with SCD and HC. Moreover, a substantial mediating effect of dietary spermidine intake on the associations between adherence to MeDi and structural brain measures was observed. ConclusionHigher dietary spermidine intake was positively associated with several structural brain measures, irrespective of the presence of SCD, and substantially mediated the relationship of adherence to MeDi and structural brain measures. Our data suggest that higher spermidine intake might be a promising dietary approach to preserve brain health in older adults, a hypothesis currently tested in an interventional trial.

Polymorphisms in CRYBB2 encoding \u03b2B2-crystallin are associated with antisaccade performance and memory function

βB2-crystallin (gene symbol: Crybb2/CRYBB2) was first described as a structural protein of the ocular lens before it was detected in various brain regions of the mouse, including the hippocampus and the cerebral cortex. Mutations in the mouse Crybb2 gene lead to alterations of sensorimotor gating measured as prepulse inhibition (PPI) and reduced hippocampal size, combined with an altered number of parvalbumin-positive GABAergic interneurons. Decreased PPI and alterations of parvalbumin-positive interneurons are also endophenotypes that typically occur in schizophrenia. To verify the results found in mice, we genotyped 27 single nucleotide polymorphisms (SNPs) within the CRYBB2 gene and its flanking regions and investigated different schizophrenia typical endophenotypes in a sample of 510 schizophrenia patients and 1322 healthy controls. In the case-control study, no association with schizophrenia was found. However, 3 of the 4 investigated haplotype blocks indicated a decreased CRYBB2 mRNA expression. Two of these blocks were associated with poorer antisaccade task performance and altered working memory-linked functional magnetic resonance imaging signals. For the two haplotypes associated with antisaccade performance, suggestive evidence was found with visual memory and in addition, haplotype block 4 showed a nominally significant association with reduced sensorimotor gating, measured as P50 ratio. These results were not schizophrenia-specific, but could be detected in a combined sample of patients and healthy controls. This is the first study to demonstrate the importance of βB2-crystallin for antisaccade performance and memory function in humans and therefore provides implications for βB2-crystallin function in the human brain.

Two Routes to Incidental Memory under Arousal: Dopamine and Norepinephrine.

Because we cannot remember everything we experience, our memory systems must be able to flexibly determine which information to store for future use. Characterizing the neural systems that underlie this selectivity is therefore critical to understanding human memory function. The release of

An historical perspective on Endel Tulving's episodic-semantic distinction

The distinction between episodic and semantic memory, proposed by Endel Tulving in 1972, remains a key concept in contemporary Cognitive Neuroscience. Here we review how this distinction evolved in Tulving's writings over the years. Crucially, from 1972 onward, he argued that the two forms of memory were inter-dependent and that their interaction was an essential feature of normal episodic memory function. Moreover, later elaborations of the theory clearly proposed that these interactions formed the basis of normal declarative memory functioning. A later but crucial aspect of Tulving's contribution was his stress on the importance of subjective experience, which, according to him, “should be the ultimate object of interest, the central aspect of remembering that is to be explained and understood”. We relate these and his numerous other ideas to current perspectives about the organization and function of human memory.

Citicoline Improves Human Vigilance and Visual Working Memory: The Role of Neuronal Activation and Oxidative Stress.

Introduction:Psychomotor performance task is used to assess the arousal and cognitive functions of the central nervous system. Alternatively, human visual working memory reflects the capability of the individual’s short-term memory. Psycho-mental stimuli are linked to the stimulation of Malondialdehyde (MDA) formations. Citicoline is a nootropic nucleotide agent with a favorable effect on the augmentation of human memory and cognitive function. Thus, the purpose of this study was to determine the effect of citicoline on human vigilance, visual working memory, and oxidative stress using healthy volunteers.Methods:40 healthy volunteers were enrolled and divided into two groups: group A: 20 volunteers received 500mg/day starch capsule for two weeks and group B: 20 volunteers received 500mg/day citicoline capsule for two weeks. Human vigilance, visual working memory, and oxidative stress markers of each volunteer were assessed before and after citicoline and placebo intake. The obtained data were analyzed by SPSS regarding P<0.05 as statistically significant.Results:Placebo had no significant effect on human vigilance and visual working memory after two weeks of therapy (P>0.05), whereas citicoline improved most variables of psychomotor performances and working memory (P<0.01). Placebo significantly increased serum MDA levels from 19.44±2.11 to 29.66±3.28 nmol/mL (P=0.0001), while citicoline significantly decreased MDA serum levels from 19.11±2.66 to 15.63±1.33 nmol/mL (P=0.0001).Conclusion:Citicoline improves human psychomotor vigilance, arousal, and visual working memory with significant amelioration of oxidative stress compared with placebo.

P2‐116: GRIN2A GENOTYPES AND APOE HAPLOTYPES AFFECT THE AGE AT ONSET OF ALZHEIMER'S DEMENTIA BUT NOT FUNCTIONAL OR COGNITIVE RESPONSE TO MEMANTINE

Earlier evidence showed that Memantine antagonizes the N-methyl-D-aspartate (NMDA) type of glutamate receptor leading to possible behavioral improvement and a synergistic effect with cholinesterase inhibitors over slower functional and cognitive decline in Alzheimer's dementia (AD). Variations in some receptor genes can contribute to AD pathogenesis and pharmacological response, particularly regarding cholinesterase inhibitors. GRIN2A is a common subunit of functional NMDA receptors, whereas the GRIN2A gene is mapped to 16p13, and rs1868291 is strongly associated with memory function and hippocampal activity in humans. We sought to evaluate associations of GRIN2A genotypes and APOE haplotypes with functional and cognitive response to Memantine and age at onset of AD. In this prospective pharmacogenetic study, participants with late-onset AD according to National Institute on Aging – Alzheimer's Association criteria were screened with the Clinical Dementia Rating Sum-of-Boxes, the Index of Independence in Activities of Daily Living, Lawton's Scale for Instrumental Activities of Daily Living, the Mini-Mental State Examination and a 15-item Clock Drawing Test, and followed for one year. Genotyping was undertaken with TaqMan® Real-Time Polymerase Chain Reactions for rs429358 and rs7412 (APOE haplotypes), and for rs1868291 (GRIN2A). APOE haplotypes and rs1868291 genotypes were correlated with age at dementia onset and, after stratification according to APOE haplotypes, the presence of each genotype of rs1868291 was correlated with use of Memantine or not for test score variations, with the threshold of significance set at p<0.05. Among 189 consecutive outpatients, 142 used Memantine (75.1%); mean age at dementia onset was 73.44±6.3 years-old, with 130 women (68.8%) and 59 men (31.2%), 103 APOE4+ carriers (54.5%) and 86 APOE4- carriers (45.5%). APOE-ε4/ε4 carriers had earlier AD onset by almost five years (p=0.0011), whereas each T allele of rs1868291 led to almost three years later onset of AD (p=0.0046). Genotypes of rs1868291 (p>0.22) or use of Memantine (p>0.09) did not affect functional or cognitive decline in one year, regardless of APOE haplotypes. Genotypes of rs1868291 and APOE haplotypes are associated with the age at onset of AD, but not with functional or cognitive decline, nor with response to Memantine. (Supported by FAPESP grant #2015/10109-5).

The Role of Hierarchical Dynamical Functions in Coding for Episodic Memory and Cognition

Behavioral research in human verbal memory function led to the initial definition of episodic memory and semantic memory. A complete model of the neural mechanisms of episodic memory must include the capacity to encode and mentally reconstruct everything that humans can recall from their experience. This article proposes new model features necessary to address the complexity of episodic memory encoding and recall in the context of broader cognition and the functional properties of neurons that could contribute to this broader scope of memory. Many episodic memory models represent individual snapshots of the world with a sequence of vectors, but a full model must represent complex functions encoding and retrieving the relations between multiple stimulus features across space and time on multiple hierarchical scales. Episodic memory involves not only the space and time of an agent experiencing events within an episode but also features shown in neurophysiological data such as coding of speed, direction, boundaries, and objects. Episodic memory includes not only a spatio-temporal trajectory of a single agent but also segments of spatio-temporal trajectories for other agents and objects encountered in the environment consistent with data on encoding the position and angle of sensory features of objects and boundaries. We will discuss potential interactions of episodic memory circuits in the hippocampus and entorhinal cortex with distributed neocortical circuits that must represent all features of human cognition.

Effects of Al Exposure on Mitochondrial Dynamics in Rat Hippocampus.

Aluminum (Al) exposure impairs learning and memory function in humans and in animal models. Several studies have shown that the neurotoxicity of Al is associated with damage to mitochondrial morphology and mitochondrial dysfunction, but the molecular mechanism is unclear. The present study was performed to elucidate the possible molecular mechanism related to the Al-induced abnormal mitochondrial dynamics that lead to learning and memory disorders. SD rats were exposed to Al-maltolate complex (Al(mal)3) (blank, 0, 0.41, 0.81, or 1.62mg/kg) for 30, 60, or 90days, and neurobehavior, mitochondrial morphology, mitochondrial function, the levels of fission proteins such as dynamin-related protein 1 (Drp1) and fission protein 1 (Fis1), and the levels of fusion proteins such as optic atrophy 1 (Opa1), mitofusin 1 (Mfn1), and mitofusin 2 (Mfn2) were explored. The results indicated that exposure to Al(mal)3 increased the concentration of Al in the brain in a time- and dose-dependent manner and impaired spatial learning and memory. Al(mal)3 damaged mitochondrial morphology and impaired mitochondrial function in the hippocampus. Dose-dependent elevations in the levels of mitochondrial fission (Drp1 and Fis1) and fusion (Opa1, Mfn1, and Mfn2) proteins were observed. In addition, the upregulation of calcineurin (CaN) and the reduced phosphorylation of Drp1 (s637) may have disturbed the balance of mitochondrial fission and fusion in the hippocampus. These results showed that Al-induced learning and memory impairment may be related to mitochondrial fission and fusion disorders.

Okadaic Acid and Hypoxia Induced Dementia Model of Alzheimer's Type in Rats.

Alzheimer's disease (AD) is the most common cause of progressive decline of memory function in aged humans. To study about a disease mechanism and progression, animal models for the specific disease are needed. For AD, although highly valid animal models exist, none of the existing models recapitulates all aspects of human AD. The pathogenic mechanisms involved in AD are diverse and thus it is difficult to recapitulate human AD in model organisms. Intracerebroventricular (ICV) injection of okadaic acid (OKA), a protein phosphatase 2A (PP2A) inhibitor, in rats causes neurotoxicity associated with neurofibrillary degeneration. However, this model lacks amyloid pathology as observed in AD. We aimed at combining two different treatments and hence producing a better animal model of AD which may mimic most of the neuropathological, neurobehavioral, and neurochemical changes observed in AD. For this, OKA (200ng) was microinjected bilaterally into the hippocampus of male Wistar rats followed by exposure of same rats to hypoxic conditions (10%) for 3days. The result of which, the combination model exhibited tau hyperphosphorylation along with Aβ upregulation as evident by western blotting and immunohistochemistry. The observed changes were accompanied with dysfunction of neurotransmitter system, i.e., decreased acetylcholine activity and expression. This combinatorial model also exhibited cognitive deficiency which was assessed by Morris water maze and avoidance tests along with enhanced oxidative stress which is thought to be a major player in AD pathogenesis. Taken together, we established an easily reproducible and reliable rat model for sporadic dementia of Alzheimer's type in rats which allows effective testing of new therapeutic strategies.

Czas utracony - czas odzyskany - czas osobny. Szkic o pisarstwie Róży Ostrowskiej

&lt;p&gt;Celem niniejszego artykułu jest interpretacja dwu powieści Róży Ostrowskiej (1926–1975). Wyspa (1960) i nieukończony, wydany pośmiertnie Mój czas osobny (1977) zajmują ważne miejsce w polskiej literaturze lat 50. i 60. XX wieku. Akcja tych powieści rozgrywa się w dwóch czasoprzestrzeniach – współcześnie na Kaszubach i w przeszłości na Wileńszczyźnie. Dla pisarki są to znaczące „miejsca autobiograficzne”. W budowie fabuły i kreacji bohaterów Ostrowska wykorzystała własne doświadczenia życiowe, które stają się pretekstem do podjęcia ważnych zagadnień dotyczących ludzkiej egzystencji (życia, przemijania, miłości, śmierci) i tożsamości. Pisarstwo to bazuje zatem na autobiografzmie i autofkcji. W omawiane powieści wpisana jest filozofia człowieczeństwa. Za podstawowy klucz do odczytania obydwu utworów należy uznać czas – osobniczy, interioryzowany, „osobny”, związany z ludzką egzystencją i funkcjonowaniem pamięci. Sposób działania czasu w tych utworach pozwolił pisarce na wprowadzenie w struktury powieści mitów – miejsca i osobniczego. Analiza prowadzi do ciekawych wniosków. Przede wszystkim: proza Ostrowskiej okazuje się oryginalną kombinacją autobiografii (a raczej autofikcji) z mitologią, której efektem jest nie tyle uwznioślenie przeszłości czy teraźniejszości, ile kreacja „nekronarracji” podejmowanej jakby z perspektywy pośmiertnej. A zatem Wyspa i Mój czas osobny to nie powieści polityczne, obyczajowe czy psychologiczne, tylko mityczne.&lt;/p&gt;

Intensity-specific effects of acute exercise on human memory function: considerations for the timing of exercise and the type of memory.

Background: The purpose of this review was to evaluate whether acute exercise intensities have unique effects on memory function, and whether this is influenced by memory type as well as the temporality of the acute exercise bout.Methods: A systematic review was employed, using several databases (PubMed, PsychInfo,Sports Discus, Google Scholar, Embase).Results: In total, 9 articles met the study criteria. All 9 studies evaluated either working memory capacity or episodic-related memory function. The main findings across these studies were 1) when acute exercise occurs before the memory task, high-intensity exercise may be less favorable for working memory but may favor episodic memory; 2) when acute exercise occurs during the memory task, high-intensity exercise may be less favorable for working memory capacity; and 3) high-intensity exercise may not associate with long-term memory function when it occurs shortly after memory encoding.Conclusion: The relationship between acute exercise and memory is complex and may vary based on the intensity of exercise, the temporality of exercise, and the memory type evaluated.

Dopamine effects on stress-induced working memory deficits

The prefrontal cortex (PFC) plays a critical role in mediating executive functions and orchestrating the way in which we think, decide, and behave. Many studies have shown that PFC neurons not only play a major role in mediating behavioral responses to stress but are also sensitive to stress and undergo remodeling following stress exposure. Activation of the hypothalamic-pituitary-adrenal axis as a result of stress initiates a flood of alterations in prefrontal neurotransmitter release. Dopamine (DA) neurotransmission in the PFC is involved in the modulation of stress responsiveness. Compelling results show that stressful events are associated with increased DA concentrations in the medial PFC. Excessive DA-ergic activity in the medial prefrontal cortex following stress has a negative impact on working memory and executive functions in rodents, monkeys, and humans, making them unable to processing information selectively and impairing cognitive function. Therefore, an exact understanding of these mechanisms may provide important insights into the pathophysiology of executive dysfunction and novel treatment avenues. The present review provides a summary of the neuronal circuitry involved in alterations of PFC dopaminergic neurons under conditions of stress, and then addresses the interaction of PFC DA with glucocorticoids leading to impairment of working memory under conditions of stress.

Centella asiatica ethanol extract increases hippocampal brain derived neurotrophic factor in male Wistar rats

BackgroundSynaptic plasticity, which primarily takes place in the hippocampus, is the molecular basis of long- term memory formation. Brain derived neurotrophic factor (BDNF), a member of the neurotrophin family, plays a significant role in synaptic plasticity and memory formation. When BDNF is released, it binds to its receptor and activates various intracellular signal transduction pathways leading to synaptic plasticity. Several methods to improve memory function in humans have been studied, one of which is the use of herbal compounds, such as Centella asiatica (CeA), an herbaceous plant that has been used for improving memory. This study aims to examine the effects of CeA ethanol extract on BDNF protein expression in the CA1 hippocampal region in adult male rats.MethodsA randomized experimental design was performed involving 18 adult male Wistar rats. The rats were randomized into three groups: one control/distilled water group and two groups treated with doses of CeA ethanol extract of 300 mg/kgBW (CeA300) and 600 mg/kgBW (CeA600), respectively. CeA ethanol extract was administered orally for 28 consecutive days with weekly weight-adjusted dose. After 28 days, the rats were decapitated, and the hippocampus was isolated from the brain. BDNF protein expression was assessed using immunohistochemistry. Data was analyzed using Kruskal-Wallis test and continued with post-hoc analysis. ResultsThere was a significant increase in BDNF protein expression in the CeA600 group compared to the control group (p&lt;0.001). ConclusionAdministration of CeA ethanol extract increased BDNF protein expression in the CA1 hippocampal region of adult male rats.

Enhanced brain activity associated with memory access in highly superior autobiographical memory

Brain systems underlying human memory function have been classically investigated studying patients with selective memory impairments. The discovery of rare individuals who have highly superior autobiographical memory (HSAM) provides, instead, an opportunity to investigate the brain systems underlying enhanced memory. Here, we carried out an fMRI investigation of a group of subjects identified as having HSAM. During fMRI scanning, eight subjects with HSAM and 21 control subjects were asked to retrieve autobiographical memories (AMs) as well as non-AMs (e.g., examples of animals). Subjects were instructed to signal the "access" to an AM by a key press and to continue "reliving" it immediately after. Compared with controls, individuals with HSAM provided a richer AM recollection and were faster in accessing AMs. The access to AMs was associated with enhanced prefrontal/hippocampal functional connectivity. AM access also induced increased activity in the left temporoparietal junction and enhanced functional coupling with sensory cortices in subjects with HSAM compared with controls. In contrast, subjects with HSAM did not differ from controls in functional activity during the reliving phase. These findings, based on fMRI assessment, provide evidence of interaction of brain systems engaged in memory retrieval and suggest that enhanced activity of these systems is selectively involved in enabling more efficient access to past experiences in HSAM.