ASSOCIATION OF TRANSCRANIAL DIRECT CURRENT STIMULATION AND NEUROFEEDBACK, IN THE DECLARATIONAL MEMORY AND CEREBRAL ARTERIAL FLOW IN UNIVERSITY YOUNG PEOPLE - A RANDOMIZED, DOUBLE-BLIND AND CONTROLLED STUDY PROTOCOL (Preprint)

BACKGROUND The performance of a task depends on ongoing brain activity which can be influenced by attention, excitement or motivation. Scientific studies confirm that mindfulness leads to better performance, health and well-being. However, these cognitive efficiency modulating factors are nonspecific, can be difficult to control, and are not suitable to specifically facilitate neural processing. OBJECTIVE The aim of the present study is to evaluate the effects of tDCS associated with Neurofeedback on declarative memory and cerebral blood flow in university students. METHODS In this work, we will use Transcranial Direct Current Stimulation (tDCS), a low-cost physical resource, easy to apply and few adverse effects, associated with a Neurofeedback resource. This, in turn, has been shown to be a training program capable of improving working memory function. RESULTS The trial began in December 2021 and we are currently performing the statistical analysis for the secondary outcomes. CONCLUSIONS We believe that the resources used in this study can help improve some aspects of declarative memory, since learning and memory processes modify the brain. Strategies to enhance the acquisition, storage and use of information must be able to sensitize (motivate) and involve volunteers in the learning process, thus clarifying their role CLINICALTRIAL https://ensaiosclinicos.gov.br/rg/RBR-4m5j4s

Mapping of Language-and-Memory Networks in Patients With Temporal Lobe Epilepsy by Using the GE2REC Protocol

Preoperative mapping of language and declarative memory functions in temporal lobe epilepsy (TLE) patients is essential since they frequently encounter deterioration of these functions and show variable degrees of cerebral reorganization. Due to growing evidence on language and declarative memory interdependence at a neural and neuropsychological level, we propose the GE2REC protocol for interactive language-and-memory network (LMN) mapping. GE2REC consists of three inter-related tasks, sentence generation with implicit encoding (GE) and two recollection (2REC) memory tasks: recognition and recall. This protocol has previously been validated in healthy participants, and in this study, we showed that it also maps the LMN in the left TLE (N = 18). Compared to healthy controls (N = 19), left TLE (LTLE) showed widespread inter- and intra-hemispheric reorganization of the LMN through reduced activity of regions engaged in the integration and the coordination of this meta-network. We also illustrated how this protocol could be implemented in clinical practice individually by presenting two case studies of LTLE patients who underwent efficient surgery and became seizure-free but showed different cognitive outcomes. This protocol can be advantageous for clinical practice because it (a) is short and easy to perform; (b) allows brain mapping of essential cognitive functions, even at an individual level; (c) engages language-and-memory interaction allowing to evaluate the integrative processes within the LMN; (d) provides a more comprehensive assessment by including both verbal and visual modalities, as well as various language and memory processes. Based on the available postsurgical data, we presented preliminary results obtained with this protocol in LTLE patients that could potentially inform the clinical practice. This implies the necessity to further validate the potential of GE2REC for neurosurgical planning, along with two directions, guiding resection and describing LMN neuroplasticity at an individual level.

The Vulnerability of the Developing Brain: Analysis of Highly Expressed Genes in Infant C57BL/6 Mouse Hippocampus in Relation to Phenotypic Annotation Derived From Mutational Studies

The hippocampus has been shown to have a major role in learning and memory, but also to participate in the regulation of emotions. However, its specific role(s) in memory is still unclear. Hippocampal damage or dysfunction mainly results in memory issues, especially in the declarative memory but, in animal studies, has also shown to lead to hyperactivity and difficulty in inhibiting responses previously taught. The brain structure is affected in neuropathological disorders, such as Alzheimer’s, epilepsy, and schizophrenia, and also by depression and stress. The hippocampus structure is far from mature at birth and undergoes substantial development throughout infant and juvenile life. The aim of this study was to survey genes highly expressed throughout the postnatal period in mouse hippocampus and which have also been linked to an abnormal phenotype through mutational studies to achieve a greater understanding about hippocampal functions during postnatal development. Publicly available gene expression data from C57BL/6 mouse hippocampus was analyzed; from a total of 5 time points (at postnatal day 1, 10, 15, 21, and 30), 547 genes highly expressed in all of these time points were selected for analysis. Highly expressed genes are considered to be of potential biological importance and appear to be multifunctional, and hence any dysfunction in such a gene will most likely have a large impact on the development of abilities during the postnatal and juvenile period. Phenotypic annotation data downloaded from Mouse Genomic Informatics database were analyzed for these genes, and the results showed that many of them are important for proper embryo development and infant survival, proper growth, and increase in body size, as well as for voluntary movement functions, motor coordination, and balance. The results also indicated an association with seizures that have primarily been characterized by uncontrolled motor activity and the development of proper grooming abilities. The complete list of genes and their phenotypic annotation data have been compiled in a file for easy access.

Revisiting the Role of the Medial Temporal Lobe in Motor Learning

Classic taxonomies of memory distinguish explicit and implicit memory systems, placing motor skills squarely in the latter branch. This assertion is in part a consequence of foundational discoveries showing significant motor learning in amnesics. Those findings suggest that declarative memory processes in the medial temporal lobe (MTL) do not contribute to motor learning. Here, we revisit this issue, testing an individual (L. S. J.) with severe MTL damage on four motor learning tasks and comparing her performance to age-matched controls. Consistent with previous findings in amnesics, we observed that L. S. J. could improve motor performance despite having significantly impaired declarative memory. However, she tended to perform poorly relative to age-matched controls, with deficits apparently related to flexible action selection. Further supporting an action selection deficit, L. S. J. fully failed to learn a task that required the acquisition of arbitrary action–outcome associations. We thus propose a modest revision to the classic taxonomic model: Although MTL-dependent memory processes are not necessary for some motor learning to occur, they play a significant role in the acquisition, implementation, and retrieval of action selection strategies. These findings have implications for our understanding of the neural correlates of motor learning, the psychological mechanisms of skill, and the theory of multiple memory systems.

Pitfalls in Sleep and Memory Research and How to Avoid Them: A Consensus Paper

Understanding the complex relationship between sleep and memory is a major challenge in neuroscience. Thousands of studies on memory consolidation in humans suggest that sleep triggers offline memory processes, resulting in less forgetting of declarative memory and performance stabilization in non-declarative memory. However, an increasing number of contradictory findings reveal potential issues with how research is conducted in this field and call into question the reliability and interpretation of the results. In this consensus paper, we describe four sets of prevalent methodological pitfalls in human sleep and memory research: (i) non-optimal experimental designs, (ii) task complexity, (iii) fatigue effects in repetitive tasks, and (iv) inappropriate data analysis practices. We then offer solutions to each of these pitfalls. We believe that implementing these solutions in future research of sleep and memory will lead to more reliable results and significantly advance our understanding in this field.

Dual-task gait speed and mobility are positively associated with declarative memory

In the US, it is not recommended to perform routine screening assessments for cognitive function or impairment among older adults, due to the lack of effective pharmacological treatments. These common practices result in delayed identification and treatments for slowing cognitive decline progression. Thus, the purpose of the present investigation was to determine the ability to predict cognition from common measures of physical function. Seventy-five community-dwelling older adults (80.7±5.4 years) completed physical function and cognitive assessments. Physical function was assessed using the Short Physical Performance Battery (SPPB), peak velocity during a power sit-to-stand task, and dual-task walking test. Cognition (declarative memory) was assessed using a validated Visual Paired Comparison test. 38% of the variance in cognition was accounted for by the predictor variables (age, sex, education, SPPB, dual-task, peak velocity). Significant predictors included dual-task walking (p = .03), SPPB (p = .02), and education (p = .02). For each 1 second faster during the dual-task performance, cognition increased by 4 percentile units. Likewise, each 1 unit increase in SPPB resulted in an increase of 4 percentile points in cognition. The results indicate more than a third of the variance in declarative memory can be predicted by commonly assessed measures of physical function. This information is useful when identifying older adults that may have cognitive impairment before overt signs are realized. With the lack of recommended cognitive testing, using physical function declines to identify possible cognitive decline is promising. These results are preliminary in nature and longitudinal determination is warranted.

Effects of exploring a novel environment on memory across the lifespan

Exploration is a crucial aspect of mammalian behavior, and new environments provide unique opportunities to learn. Exploration of a novel environment has been shown to promote memory formation in healthy adults, even for unrelated events. Studies in animals have suggested that such novelty-induced memory boosts are mediated by hippocampal dopamine. The dopaminergic system is known to develop and deteriorate over the lifespan, but so far, the effects of novelty on memory across the lifespan have not yet been investigated. In the current study, we used novel and previously familiarized virtual environments to pinpoint the effects of spatial novelty on declarative memory in humans across the lifespan. After exploring a novel or familiar environment, participants were presented a list of words, and either performed a semantic task (deep encoding) or judged whether the first letter of the shown word was open or closed (shallow encoding). Incidental memory was quantified in a surprise test. Our sample (n = 439) included children, adolescents, younger adults, and older adults. Results showed that participants in the deep encoding condition remembered more words than those in the shallow condition, but novelty did not influence this effect. Interestingly, however, children, adolescents and younger adults benefitted from exploring a novel compared to a familiar environment as evidenced by better word recall, while these effects were absent in older adults. Our findings suggest that the beneficial effects of novelty on memory follow the deterioration of pathways in the brain involved in novelty-related processing across the lifespan.

Making weak memory models fair

Liveness properties, such as termination, of even the simplest shared-memory concurrent programs under sequential consistency typically require some fairness assumptions about the scheduler. Under weak memory models, we observe that the standard notions of thread fairness are insufficient, and an additional fairness property, which we call memory fairness, is needed. In this paper, we propose a uniform definition for memory fairness that can be integrated into any declarative memory model enforcing acyclicity of the union of the program order and the reads-from relation. For the well-known models, SC, x86-TSO, RA, and StrongCOH, that have equivalent operational and declarative presentations, we show that our declarative memory fairness condition is equivalent to an intuitive model-specific operational notion of memory fairness, which requires the memory system to fairly execute its internal propagation steps. Our fairness condition preserves the correctness of local transformations and the compilation scheme from RC11 to x86-TSO, and also enables the first formal proofs of termination of mutual exclusion lock implementations under declarative weak memory models.