Memory Trace Research Articles

The medial prefrontal cortex leaves the hippocampus when it prepares for the future.

Our memories help us plan for the future. In some cases, we use memories to repeat the choices that led to preferable outcomes in the past. The success of these memory-guided decisions depends on close interactions between the hippocampus and medial prefrontal cortex. In other cases, we need to use our memories to deduce hidden connections between the present and past situations to decide the best choice of action based on the expected outcome. Our recent study investigated neural underpinnings of such inferential decisions by monitoring neural activity in the medial prefrontal cortex and hippocampus in rats. We identified several neural activity patterns indicating awake memory trace reactivation and restructuring of functional connectivity among multiple neurons. We also found that these patterns occurred concurrently with the ongoing hippocampal activity when rats recalled past events but not when they planned new adaptive actions. Here, we discussed how these computational properties might contribute to success in inferential decision-making and propose a working model on how the medial prefrontal cortex changes its interaction with the hippocampus depending on whether it reflects on the past or looks into the future.

A comment on the order of report in two-pair dichotic digit testing in children assessed for auditory processing

Objective This clinical note aimed to 1) describe the order-of-report (OoR) strategies used by a large sample of children who completed 2pDD testing in the free-recall condition as part of an audiological assessment of auditory processing (AP), and 2) determine if use of OoR correlated with 2pDD test performance. Design A retrospective (case-review), single observation design. Study sample A convenient sample of 77 children (50 males and 27 females aged 7.0 to 17.4 years [median = 8.8 years]) referred to audiology for an AP assessment. Results The participating children used temporal more than ear or sequential OoR and showed decreased test scores with increased use of ear OoR. Conclusions These findings suggest children referred for an AP assessment could favour a temporal OoR when completing 2pDD testing for its opportunity to rehearse the first digit pair (possibly strengthening its memory trace) prior to processing the second digit pair, while their use of an ear OoR could come at the cost detrimental ear dominance effects that reduce their test performance. Future research could consider if similar results are observed in other child populations and if preferred dichotic processing strategy could inform auditory training for children with dichotic listening deficits.

Comparative analysis of classical and Caputo models for COVID-19 spread: vaccination and stability assessment

Several epidemiological models use the Caputo fractional-order differential operator without establishing its significance. This study verifies a Caputo operator-based fractional-order epidemiological model of the SAIVR type. COVID-19 kills. Infection weakens the immune system. The fractional Caputo operator describes COVID-19 immunization. Fundamental system characteristics are determined using fractional calculus. Our analysis included the fractional system’s Hyers–Ulam–Rassias stability and stable states. The uniqueness and existence of fractional Caputo system solutions are explored. The least-squares approach determines system parameters. The Caputo fractional-order α value is optimized to 6.757e−01\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$6.757\ ext{e}{-}01$\\end{document}, indicating that the system best fits real-life medical data for infection. Caputo and classical systems were compared for absolute mean errors. The Box-Whisker chart case summaries show the Caputo operator superiority. When α→1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$\\alpha \\rightarrow 1$\\end{document}, the memory traces and hereditary traits are also observed. Finally, the Caputo fractional framework simulates COVID-19 using strong numerical methods.

Encoding without perceiving: Can memories be implanted?

ABSTRACT The origin of memories is thought to be found in sensory perception. This conception is central to how the memory sciences characterize encoding. This paper considers how novel memory traces can be formed independently of external sensory inputs. I present a case study in which memory traces are created without sensory perception using a technique I call optogenetic memory implantation. Comparing this artificial process with normal memory encoding, I consider its implications for rethinking the causal chain that leads to remembering.

Regionally specific cortical lateralization of abstract and concrete verb processing: Magnetic mismatch negativity study

The neural underpinnings of processing concrete and abstract semantics remain poorly understood. Previous fMRI studies have shown that multimodal and amodal neural networks respond differentially to different semantic types; importantly, abstract semantics activates more left-lateralized networks, as opposed to more bilateral activity for concrete words. Due to the lack of temporal resolution, these fMRI results do not allow to easily separate language- and task-specific brain responses and to disentangle early processing stages from later post-comprehension phenomena. To tackle this, we used magnetoencephalography (MEG), a time-resolved neuroimaging technique, in combination with a task-free oddball mismatch negativity (MMN) paradigm, an established approach to tracking early automatic activation of word-specific memory traces in the brain. We recorded the magnetic MMN responses in 30 healthy adults to auditorily presented abstract and concrete action verbs to assess lateralization of word-specific lexico-semantic processing in a set of neocortical areas. We found that MMN responses to these stimuli showed different lateralization patterns of activity in the upper limb motor area (BA4) and parts of Broca's area (BA45/BA47) within ∼100–350 ms after the word disambiguation point. Importantly, the greater leftward response lateralization for abstract semantics was due to the lesser involvement of the right-hemispheric homologues, not increased left-hemispheric activity. These findings suggest differential region-specific involvement of bilateral sensorimotor systems already in the early automatic stages of processing abstract and concrete action semantics.

Cooperativity, Information Gain, and Energy Cost During Early LTP in Dendritic Spines.

We investigate a mutual relationship between information and energy during the early phase of LTP induction and maintenance in a large-scale system of mutually coupled dendritic spines, with discrete internal states and probabilistic dynamics, within the framework of nonequilibrium stochastic thermodynamics. In order to analyze this computationally intractable stochastic multidimensional system, we introduce a pair approximation, which allows us to reduce the spine dynamics into a lower-dimensional manageable system of closed equations. We found that the rates of information gain and energy attain their maximal values during an initial period of LTP (i.e., during stimulation), and after that, they recover to their baseline low values, as opposed to a memory trace that lasts much longer. This suggests that the learning phase is much more energy demanding than the memory phase. We show that positive correlations between neighboring spines increase both a duration of memory trace and energy cost during LTP, but the memory time per invested energy increases dramatically for very strong, positive synaptic cooperativity, suggesting a beneficial role of synaptic clustering on memory duration. In contrast, information gain after LTP is the largest for negative correlations, and energy efficiency of that information generally declines with increasing synaptic cooperativity. We also find that dendritic spines can use sparse representations for encoding long-term information, as both energetic and structural efficiencies of retained information and its lifetime exhibit maxima for low fractions of stimulated synapses during LTP. Moreover, we find that such efficiencies drop significantly with increasing the number of spines. In general, our stochastic thermodynamics approach provides a unifying framework for studying, from first principles, information encoding, and its energy cost during learning and memory in stochastic systems of interacting synapses.

Mismatch negativity and polygenic risk scores for schizophrenia and bipolar disorder

ObjectiveAuditory mismatch negativity (MMN) impairment is a candidate endophenotype in psychotic disorders, yet the genetic underpinnings remain to be clarified. Here, we examined the relationships between auditory MMN and polygenic risk scores (PRS) for individuals with psychotic disorders, including schizophrenia spectrum disorders (SSD) and bipolar disorder (BD) and in healthy controls (HC). MethodsGenotyped and clinically well-characterized individuals with psychotic disorders (n = 102), including SSD (n = 43) and BD (n = 59), and HC (n = 397) underwent a roving MMN paradigm. In addition MMN, we measured the memory traces of the repetition positivity (RP) and the deviant negativity (DN), which is believed to reflect prediction encoding and prediction error signals, respectively. SCZ and BD PRS were computed using summary statistics from the latest genome-wide association studies. The relationships between the MMN, RP, and DN and the PRSs were assessed with linear regressions. ResultsWe found no significant association between the SCZ or BD PRS and grand average MMN in the psychotic disorders group or in the HCs group (all p > 0.05). SCZ PRS and BD PRS were negatively associated with RP in the psychotic disorders group (β = −0.46, t = −2.86, p = 0.005 and β = −0.29, t = −0.21, p = 0.034, respectively). No significant associations were found between DN and PRS. ConclusionThese findings suggest that genetic variants associated with SCZ and BD may be associated with MMN subcomponents linked to predictive coding among patients with psychotic disorders. Larger studies are needed to confirm these findings and further elucidate the genetic underpinnings of MMN impairment in psychotic disorders.

Neurotrophin-3 into the insular cortex strengthens conditioned taste aversion memory

Memory consolidation is an essential process of long-term memory formation. Neurotrophins have been suggested as key regulators of activity dependent changes in the synaptic efficacy and morphology, which are considered the downstream mechanisms of memory consolidation. The neurotrophin 3 (NT-3), a member of the neurotrophin family, and its high affinity receptor TrkC, are widely expressed in the insular cortex (IC), a region with a critical role in the consolidation of the conditioned taste aversion (CTA) paradigm, in which an animal associates a novel taste with nausea. Nevertheless, the role of this neurotrophin in the cognitive processes that the IC mediates remains unexamined. To answer whether NT-3 is involved in memory consolidation at the IC, adult male Wistar rats were administered with NT-3 or NT-3 in combination with the Trk receptors inhibitor K252a into the IC, immediately after CTA acquisition under two different conditions: a strong-CTA (0.2 M lithium chloride i.p.) or a weak-CTA (0.1 M lithium chloride i.p.). Our results show that NT-3 strengthens the memory trace of CTA, transforming a weak conditioning into a strong one, in a Trk-dependent manner. The present evidence suggests that NT-3 has a key role in the consolidation process of an aversive memory in a neocortical region.

Age-Related Differences in Motor Skill Transfer with Brief Memory Reactivation.

Motor memories can be strengthened through online practice and offline consolidation. Offline consolidation involves the stabilization of memory traces in post-practice periods. Following initial consolidation of a motor memory, subsequent practice of the motor skill can lead to reactivation and reconsolidation of the memory trace. The length of motor memory reactivation may influence motor learning outcomes; for example, brief, as opposed to long, practice of a previously learned motor skill appears to optimize intermanual transfer in healthy young adults. However, the influence of aging on reactivation-based motor learning has been scarcely explored. Here, the effects of brief and long motor memory reactivation schedules on the retention and intermanual transfer of a visuomotor tracing task are explored in healthy older adults. Forty older adults practiced a virtual star-tracing task either three ("brief reactivation") or ten ("long reactivation") times per session over a two-week period. Comparison with a previously reported group of younger adults revealed significant age-related differences in the effect of the motor memory reactivation schedule on the intermanual transfer of the motor task. In older adults, unlike younger adults, no significant between-group differences were found by practice condition in the speed, accuracy, or skill of intermanual task transfer. That is, motor task transfer in healthy younger, but not older, adults appears to benefit from brief memory reactivation. These results support the use of age-specific motor training approaches and may inform motor practice scheduling, with possible implications for physical rehabilitation, sport, and music.

Analyse du processus créatif en photographie et son implication clinique en photo-thérapie

ContextThe author, a photographer and photo-therapist, tries to develop a new therapeutic approach based on the photographic act. AimsThis article aims to examine the psychic processes involved in the dynamics of taking photos and to explore what can be done with the photographic medium in clinical practice. MethodWe will listen to the photographic works of the famous Japanese photographer Hiroshi Sugimoto to see what they say about clinical work involving photo-therapy. ResultsDuring his artistic practice, Hiroshi Sugimoto summons up memory traces related to his own history and that of his ancestors and updates them in his photos. He experiences all kinds of bodily sensations and hallucinations. His photos are already within him in the form of inner visions, even before he has expressed them materially. The elaborative transposition of the inner image, which has become pre-conscious, takes place in a very specific material: his antique medium-format camera and his special lighting not only serve to create an atmosphere, but also to take him on a journey through the history of humanity and his own inner history. He comes to identify completely with his camera, which helps to plunge him into a state of fusion with the object being photographed. DiscussionDuring his creative process, the photographer goes through phases similar to those that the baby goes through during his development, in an attempt to achieve a (re)actualization of the self: alternating phases of integration and non-integration of the self with more or less chaotic regressive phenomena, a primary identification with a quasi-fusional state between the photographer and the camera and between the photographer and the photographed object, the mobilization of bodily sensations and a return to a state of fluidity in the gaze and gesture. ConclusionsIn photo-therapy, this re-actualization of the self is sought and the creative process in photography seems to contribute to this to a certain extent. The regressive states accompanied by bodily sensations, that is to say, this state of pathos that runs through the photographing patient, can, in the aftermath, restore movement in the psyche and bring back to life certain aspects that had not been (sufficiently) represented. The inner images of the psyche are expressed in the form of material external photos but this fixation allows the initial inner image to be reworked in a retroactive loop, and thus to reshape the psyche, through the body. The camera, which has the particularity of being both the tool and the surface of inscription, becomes part of the body of the photographer-patient. The transference is thus diffracted between the analyst and the photographic medium. From the subjectivity of the photographing subject and that of the photographed object, a third subjectivity is created, a kind of “analytic third:” the photo is charged with meaning that can be analyzed in therapy.

Assessing the integrity of auditory sensory memory processing in CLN3 disease (Juvenile Neuronal Ceroid Lipofuscinosis (Batten disease)): an auditory evoked potential study of the duration-evoked mismatch negativity (MMN)

BackgroundWe interrogated auditory sensory memory capabilities in individuals with CLN3 disease (juvenile neuronal ceroid lipofuscinosis), specifically for the feature of “duration” processing. Given decrements in auditory processing abilities associated with later-stage CLN3 disease, we hypothesized that the duration-evoked mismatch negativity (MMN) of the event related potential (ERP) would be a marker of progressively atypical cortical processing in this population, with potential applicability as a brain-based biomarker in clinical trials.MethodsWe employed three stimulation rates (fast: 450 ms, medium: 900 ms, slow: 1800 ms), allowing for assessment of the sustainability of the auditory sensory memory trace. The robustness of MMN directly relates to the rate at which the regularly occurring stimulus stream is presented. As presentation rate slows, robustness of the sensory memory trace diminishes. By manipulating presentation rate, the strength of the sensory memory trace is parametrically varied, providing greater sensitivity to detect auditory cortical dysfunction. A secondary hypothesis was that duration-evoked MMN abnormalities in CLN3 disease would be more severe at slower presentation rates, resulting from greater demand on the sensory memory system.ResultsData from individuals with CLN3 disease (N = 21; range 6–28 years of age) showed robust MMN responses (i.e., intact auditory sensory memory processes) at the medium stimulation rate. However, at the fastest rate, MMN was significantly reduced, and at the slowest rate, MMN was not detectable in CLN3 disease relative to neurotypical controls (N = 41; ages 6–26 years).ConclusionsResults reveal emerging insufficiencies in this critical auditory perceptual system in individuals with CLN3 disease.

Neuroligin-3-Mediated Synapse Formation Strengthens Interactions between Hippocampus and Barrel Cortex in Associative Memory.

Memory traces are believed to be broadly allocated in cerebral cortices and the hippocampus. Mutual synapse innervations among these brain areas are presumably formed in associative memory. In the present study, we have used neuronal tracing by pAAV-carried fluorescent proteins and neuroligin-3 mRNA knockdown by shRNAs to examine the role of neuroligin-3-mediated synapse formation in the interconnection between primary associative memory cells in the sensory cortices and secondary associative memory cells in the hippocampus during the acquisition and memory of associated signals. Our studies show that mutual synapse innervations between the barrel cortex and the hippocampal CA3 region emerge and are upregulated after the memories of associated whisker and odor signals come into view. These synapse interconnections are downregulated by a knockdown of neuroligin-3-mediated synapse linkages. New synapse interconnections and the strengthening of these interconnections appear to endorse the belief in an interaction between the hippocampus and sensory cortices for memory consolidation.

Memory traces, phenomenology and the simulationist vs causal theory dispute

Phlosophy of memory is a hot topic in the cognitive sciences and philosophy of mind. This work examines the dispute between simulations and causal theoris of memory by means of an examination of the feeling of familiarity and its relation to memory traces, more specifically in how they increase the fluency of reconstruction of past episodes. Understanding the relationship between familiarity and memory traces, and furthermore, the relation between a fully-fledged phenomenology of memory and a sense of subjective certainty of the episode has occurred in the past leads to a different interpretation of the rivalry between the CTM and the simulationist account

Non-competitive NMDA antagonist MK-801 prevents memory reconsolidation impairment caused by protein synthesis inhibitors in young chicks.

Introduction: Reactivation of already consolidated memory can initiate its destabilization, making the memory trace labile. Normally, this destabilization is followed by reconsolidation of the memory trace, enriched by newly acquired experience. Disrupting the reconsolidation process, for example, by inhibiting protein synthesis, impairs subsequent memory retrieval, leading to reminder-related amnesia. Previous studies in various species have shown that this impairment can be prevented by using NMDA receptor antagonists, which interfere with memory destabilization. Methods: In the present study we examined this phenomenon using a one-trial passive avoidance learning model in newborn chicks, the hypothesis being that inactivation of the NMDA-mediated transmission during memory reactivation would inhibit the memory trace labilization and thus prevent the reminder-related amnesia. Results: We found that reminder-associated administration of the NMDA receptor antagonist MK-801 or one of the protein synthesis inhibitors (anisomycin, cycloheximide, 2-deoxygalactose) each alone produced amnesia. However, when combined, injection of MK-801 before the reminder prevented amnesia induced by protein synthesis inhibitors. Discussion: We suggest that the observed paradoxical effect implicates the involvement of NMDA receptors in both protein synthesis-independent engram destabilization upon its retrieval and protein synthesismediated engram stabilization after its updating. This puzzling dual role of NMDA receptors in memory destabilization/restabilization requires further investigation.

Unveiling Transcriptional and Epigenetic Mechanisms Within Engram Cells: Insights into Memory Formation and Stability.

Memory traces for behavioral experiences, such as fear conditioning or taste aversion, are believed to be stored through biophysical and molecular changes in distributed neuronal ensembles across various brain regions. These ensembles are known as engrams, and the cells that constitute them are referred to as engram cells. Recent advancements in techniques for labeling and manipulating neural activity have facilitated the study of engram cells throughout different memory phases, including acquisition, allocation, long-term storage, retrieval, and erasure. In this chapter, we will explore the application of next-generation sequencing methods to engram research, shedding new light on the contribution of transcriptional and epigenetic mechanisms to engram formation and stability.

Engrams of Fear Memory Attenuation.

Fear attenuation is an etiologically relevant process for animal survival, since once acquired information needs to be continuously updated in the face of changing environmental contingencies. Thus, when situations are encountered that were originally perceived as fearful but are no longer so, fear must be attenuated, otherwise, it risks becoming maladaptive. But what happens to the original memory trace of fear during fear attenuation? In this chapter, we review the studies that have started to approach this question from an engram perspective. We find evidence pointing to both the original memory trace of fear being suppressed, as well as it being updated towards safety. These seemingly conflicting results reflect a well-established dichotomy in the field of fear memory attenuation, namely whether fear attenuation is mediated by an inhibitory mechanism that suppresses fear expression, called extinction, or by an updating mechanism that allows the fear memory to reconsolidate in a different form, called reconsolidation-updating. Which of these scenarios takes the upper hand is ultimately influenced by the behavioral paradigms used to induce fear attenuation, but is an important area for further study as the precise cell populations underlying fear attenuation and the molecular mechanisms therein can now be understood at unprecedented resolution.

Singing Does Not Necessarily Improve Memory More Than Reading Aloud.

The production effect refers to the finding that words read aloud are better remembered than words read silently. This finding is typically attributed to the presence of additional sensorimotor features appended to the memory trace by the act of reading aloud, which are not present for items read silently. Supporting this perspective, the production effect tends to be larger for singing (the singing superiority effect) than reading aloud, possibly due to the inclusion of further sensorimotor features (e.g., more pronounced tone). However, the singing superiority effect has not always replicated. Across four experiments, we demonstrate a production effect for items read aloud but observe a singing superiority effect only when items are tested in the same color in which they were studied (with foils randomized to color). A series of meta-analytic models revealed the singing superiority effect to be smaller than previously thought and to emerge only when test items are presented in the same color in which they were studied. This outcome is inconsistent with common distinctiveness-based theoretical accounts.

Interference of the inclusive language in the creation of the memory trace during the reading comprehension of texts

Interference of the inclusive language in the creation of the memory trace during the reading comprehension of texts

Long-term consequences of acute toxic prenatal hypoxia induced by sodium nitrite in rat experiments

Introduction. Gestational hypoxia plays an important role in fetal development, as it causes the development of oxidative stress and delayed psychomotor development. The aim of the study was to evaluate the prenatal effect of sodium nitrite on indices characterizing orienting and exploratory activity, mental activity and the degree of hypoxia in rat offspring. Materials and methods. Acute hypoxia was modeled by administration of sodium nitrite at a dose of 30 mg/kg intramuscularly to five pregnant rats during 16–19 days of gestation. Five females constituted a control group. In 50 born rats, orientation and exploration activity, cognitive functions, intensity of lipid peroxidation and glycolysis were studied. Results. The offspring of females that underwent acute hypoxia significantly lagged behind in the positive dynamics of body weight gain compared to control individuals. Thirty-day-old rats showed a pronounced disorder of the structure of behavioral pattern, learning process and long-term memory, increased content of diene conjugates, malonic dialdehyde and the level of lactate dehydrogenase activity in blood. Discussion. It was found that offspring whose mothers suffered acute hypoxia of toxic genesis developed pronounced behavioral disorders of psychomotor agitation and cognitive dysfunction characterized by decreased learning ability and impaired long-term memory. The content of primary and secondary products of lipid peroxidation and lactate dehydrogenase was increased in rats. The development of cellular oxidative stress under conditions of intrauterine hypoxia leads to oxygen deficiency in the fetus and a switch from tissue respiration to glycolysis, which underlies CNS damage. Conclusion. It was shown that sodium nitrite administration during the period from the 16th to the 19th day of gestation caused hyperactivity, depressed emotional status, and decreased orienting and exploratory activity and the ability to learn and retain a memory trace in rat offspring. Increased levels of diene conjugates and malonic dialdehyde, lactate dehydrogenase activity were observed in rats.

“Hagiological Patronage” – a Theological Reflection on the Traces of Memory of Blessed Dorothy of Mątowy (in Poland)

The article presents the issue of holiness shown in the patronage of a medieval mystic and recluse living in Prussia (today's northern Poland). The study is included in the current reflection on the teaching of Francis on the universal call to holiness. The aim of the undertaken research is to define the relevance of the model of holiness presented by Blessed Dorota of Mątowy (1347-1394). The arguments are based on two sets of information: a map of Dorota's Polish places of worship and a work describing her life by Jan of Kwidzyn. Most signs of the cult of the recluse can be found in the following towns: Mątowy Wielkie, Kwidzyn, Elbląg, Gdańsk, Dorotowo, Koszalin. There are churches dedicated to Bl. Dorothy, and her images. In the liturgical calendar, the mystic is mentioned in the Archdiocese of Warmia and Gdańsk as well as in the Diocese of Elbląg and Koszalin-Kołobrzeg. The fame of her holiness developed immediately after her death. The beatification process was initiated several times and the cult was approved in 1976. The charism of Dorota is characterized by the love of God, penance, pilgrimage and steadfastness in faith. Spirituality developed according to this model and is close to the needs of Catholics living in dioceses where she is remembered. It is legitimate for these local churches to promote the Dorothean model of piety as appropriate to correlate the spiritual needs of contemporary Christians with the universal call to holiness.