Spatial relational memory in individuals with traumatic brain injury

Impact of menopause-associated frailty on traumatic brain injury

Navigating menopause involves traversing a complex terrain of hormonal changes that extend far beyond reproductive consequences. Menopausal transition is characterized by a decrease in estradiol-17β (E2), and the impact of menopause resonates not only in the reproductive system but also through the central nervous system, musculoskeletal, and gastrointestinal domains. As women undergo menopausal transition, they become more susceptible to frailty, amplifying the risk and severity of injuries, including traumatic brain injury (TBI). Menopause triggers a cascade of changes leading to a decline in muscle mass, accompanied by diminished tone and excitability, thereby restricting the availability of irisin, a crucial hormone derived from muscles. Concurrently, bone mass undergoes reduction, culminating in the onset of osteoporosis and altering the dynamics of osteocalcin, a hormone originating from bones. The diminishing levels of E2 during menopause extend their influence on the gut microbiota, resulting in a reduction in the availability of tyrosine, tryptophan, and serotonin metabolites, affecting neurotransmitter synthesis and function. Understanding the interplay between menopause, frailty, E2 decline, and the intricate metabolisms of bone, gut, and muscle is imperative when unraveling the nuances of TBI after menopause. The current review underscores the significance of accounting for menopause-associated frailty in the incidence and consequences of TBI. The review also explores potential mechanisms to enhance gut, bone, and muscle health in menopausal women, aiming to mitigate frailty and improve TBI outcomes.

An updated Barnes maze protocol for assessing the outcome of controlled cortical impact mouse models of traumatic brain injury

BACKGROUND

The Barnes Maze (BM) is a common method of testing cognitive deficits in rodents. Adapting BM protocols for specific neurological disorders could potentially aid in more effective testing, reduce research time, and help decrease variability between studies.

NEW METHOD

We tested differences an updated, shortened BM consisting of 6 days, 3 trials per day, only covering the equivalent of the spatial acquisition week BM protocol and a probe trial day consisting of one trial (7 total days).

RESULTS

Kaplan-Meier plots of escape percentage as a function of total latency showed a significant difference between control and CCI mice in the updated protocol on days 3 through 6. Additionally, probe trial data showed significant differences in primary latency, primary errors, and returns to goal.

COMPARISON WITH EXISTING METHODS

We tested differences between a traditional 5 days per week, 2 trials per day, spatial acquisition and reversal weeks BM protocol (12 total days with probe trials) with an updated 6-day BM protocol (7 total days with probe trial). In the probe trial, the updated protocol control mice showed an over 5-fold decrease in primary latency and primary errors and a 4.6-fold increase in returns to goal compared to the traditional protocol. Additionally, mice in both protocols performed similarly on a trial-by-trial basis suggesting that the changes made for the updated protocol increased learning and memory and was not simply an easier task.

CONCLUSION

The updated BM protocol showed an improved ability to distinguish between control and CCI mice and promoted improved and more consistent learning for both the control and CCI groups.

Word Learning as a Window to Memory and Rehabilitation Outcomes in Traumatic Brain Injury

PURPOSE

The purpose of this viewpoint is to advocate for increased study of word learning abilities and word learning interventions in traumatic brain injury (TBI).

METHOD

We describe the word learning process and the unique opportunities afforded by studying each component and stage. Building on discussions at the 2022 International Cognitive-Communication Disorders Conference, we describe how word learning may underlie a variety of functional outcomes after TBI, making it a promising target for rehabilitation. Finally, we discuss principles that may guide study in this critical area to advance outcomes after TBI for children and adults.

RESULTS

Word learning is a dynamic and iterative process taking place over time and in multiple stages. Thus, studying word learning affords the opportunity to parse the relative contributions of multiple memory systems to different phases and components of the process. However, single-timepoint designs are insufficient to capture the full word learning process, which occurs over time and across contexts. Word learning also presents an opportunity to assess the contributions of behavioral and lifestyle factors (e.g., sleep and exercise) to different memory phases. Understanding these interactions could drive clinical interventions aimed at improving memory through manipulable external behaviors.

CONCLUSIONS

Word learning is key to success in functional spheres across the life span. The importance of words to daily life remains after TBI, even as the memory systems that support word learning are disrupted. The empirical study of word learning and rehabilitation of word learning deficits in TBI presents a promising new direction in understanding the breadth of neurogenic cognitive-communication disorders and an opportunity to explore a potential driver of functional outcome and impactful rehabilitation target.

The Value of Patient Registries to Advance Basic and Translational Research in the Area of Traumatic Brain Injury

The number of individuals affected by traumatic brain injury (TBI) is growing globally. TBIs may cause a range of physical, cognitive, and psychiatric deficits that can negatively impact employment, academic attainment, community independence, and interpersonal relationships. Although there has been a significant decrease in the number of injury related deaths over the past several decades, there has been no corresponding reduction in injury related disability over the same time period. We propose that patient registries with large, representative samples and rich multidimensional and longitudinal data have tremendous value in advancing basic and translational research and in capturing, characterizing, and predicting individual differences in deficit profile and outcomes. Patient registries, together with recent theoretical and methodological advances in analytic approaches and neuroscience, provide powerful tools for brain injury research and for leveraging the heterogeneity that has traditionally been cited as a barrier inhibiting progress in treatment research and clinical practice. We report on our experiences, and challenges, in developing and maintaining our own patient registry. We conclude by pointing to some future opportunities for discovery that are afforded by a registry model.

Temporal order memory impairments in individuals with moderate-severe traumatic brain injury

INTRODUCTION

Temporal order memory is a core cognitive function that underlies much of our behavior. The ability to bind together information within and across events, and to reconstruct that sequence of information, critically relies upon the hippocampal relational memory system. Recent work has suggested traumatic brain injury (TBI) may particularly impact hippocampally mediated relational memory. However, it is currently unclear whether such deficits extend to temporal order memory, and whether deficits only arise at large memory loads. The present study assessed temporal order memory in individuals with chronic, moderate-severe TBI across multiple set sizes.

METHOD

Individuals with TBI and Neurotypical Comparison participants studied sequences of three to nine objects, one a time. At test, all items were re-presented in pseudorandom order, and participants indicated the temporal position (i.e., first, second, etc.) in which each object had appeared. Critically, we assessed both the frequency and the magnitude of errors (i.e., how far from its studied position was an item remembered).

RESULTS

Individuals with TBI were not impaired for the smallest set size, but showed significant impairments at 5+ items. Group differences in the error frequency did not increase further with larger set sizes, but group differences in error magnitude did increase with larger memory loads. Individuals with TBI showed spared performance for the first object of each list (primacy) but were impaired on the last object (recency), though error frequency was better for last compared to middle items.

CONCLUSIONS

Our findings demonstrate that TBI results in impaired temporal order memory for lists as small as five items, and that impairments are exacerbated with increasing memory loads. Assessments that test only small set sizes may be insufficient to detect these deficits. Further, these data highlight the importance of additional, sensitive measures in the assessment of cognitive impairments in TBI.

Moving Toward Accurate Assessment of Working Memory in Adults With Neurogenically Based Communication Disorders

Purpose This article presents a viewpoint highlighting concerns regarding currently available assessments of working memory in adults with neurogenic communication disorders. Additionally, we provide recommendations for improving working memory assessment in this population. Method This viewpoint includes a critique of clinical and experimental working memory tests relevant to speech-language pathologists. We consider the terminology used to describe memory, as well as discuss language demands and test construction. Results Clinical and experimental testing of working memory in adults with neurogenic communication disorders is challenged due to theoretical, methodological, and practical limitations. The major limitations are characterized as linguistic and task demands, presentation and response modality effects, test administration, and scoring parameters. Taking these limitations into consideration, several modifications to working memory testing and their relevance to neurogenic populations are discussed. Conclusions The recommendations provided in this article can better guide clinicians and researchers to advocate for improved tests of working memory in adults with neurogenic communication disorders. Future research should continue to address these concerns and consider our recommendations.

Traumatic brain injury in the acute care setting: assessment and management practices of speech-language pathologists

PRIMARY OBJECTIVE

To characterize current knowledge, beliefs, confidence, and practice patterns of acute care speech-language pathologists (SLPs) in assessing and managing cognitive-communication disorders following traumatic brain injury (TBI).

RESEARCH DESIGN

We developed an online survey to learn more about current TBI knowledge and practice patterns of acute care SLPs, with the goal of establishing a baseline upon which changes in SLP training and practice standards may be measured.

METHODS AND PROCEDURES

We distributed the survey to 1800 SLPs in 18 states via postal mail, in addition to posting it to relevant online groups. One hundred and eighty-two practicing acute care SLPs responded to the survey.

MAIN OUTCOMES AND RESULTS

Respondents were highly variable in their training and knowledge about TBI, their beliefs about cognitive-communication rehabilitation, and their practice patterns in assessing, managing, and communicating about TBI during the acute stage of injury.

CONCLUSIONS

These results highlight the need for more consistent training about cognitive-communication deficits during and after graduate school, as well as the development of sensitive, specific, and standardized assessment tools, education protocols, and shared language for describing patients with TBI along the continuum of care.

The Role of Gesture in Communication and Cognition: Implications for Understanding and Treating Neurogenic Communication Disorders

When people talk, they gesture. Gesture is a fundamental component of language that contributes meaningful and unique information to a spoken message and reflects the speaker's underlying knowledge and experiences. Theoretical perspectives of speech and gesture propose that they share a common conceptual origin and have a tightly integrated relationship, overlapping in time, meaning, and function to enrich the communicative context. We review a robust literature from the field of psychology documenting the benefits of gesture for communication for both speakers and listeners, as well as its important cognitive functions for organizing spoken language, and facilitating problem-solving, learning, and memory. Despite this evidence, gesture has been relatively understudied in populations with neurogenic communication disorders. While few studies have examined the rehabilitative potential of gesture in these populations, others have ignored gesture entirely or even discouraged its use. We review the literature characterizing gesture production and its role in intervention for people with aphasia, as well as describe the much sparser literature on gesture in cognitive communication disorders including right hemisphere damage, traumatic brain injury, and Alzheimer's disease. The neuroanatomical and behavioral profiles of these patient populations provide a unique opportunity to test theories of the relationship of speech and gesture and advance our understanding of their neural correlates. This review highlights several gaps in the field of communication disorders which may serve as a bridge for applying the psychological literature of gesture to the study of language disorders. Such future work would benefit from considering theoretical perspectives of gesture and using more rigorous and quantitative empirical methods in its approaches. We discuss implications for leveraging gesture to explore its untapped potential in understanding and rehabilitating neurogenic communication disorders.

Social Communication Following Adult Traumatic Brain Injury: A Scoping Review of Theoretical Models

Purpose Social communication is the set of abilities that allows individuals to achieve relevant social goals across contexts. Speech-language pathology evaluation and treatment of traumatic brain injury (TBI)-related social communication problems should be informed by evidence-supported theories of social communication. The primary purpose of this article is to summarize the results of a scoping review of theoretical models that speech-language pathologists may apply to the evaluation and treatment of social communication problems of adults with TBI. Method A scoping review was conducted of PubMed, PsycINFO, and Embase for sources published in English between 1989 and 2020 that described human social communication and participation. Resulting sources were systematically examined for social communication models. Results Nine theoretical models were identified that speech-language pathologists may apply to their assessment and treatment of social communication abilities of adults with TBI. Identified models were categorized thematically into one of three classes: cognitive models, social competence models, and pragmatic models. Using a framework developed for the purposes of this article, each identified model was evaluated, and one exemplar model in each class is described in depth. Conclusions Social communication problems in adults post-TBI are common. The existence of multiple models empowers speech-language pathologists to select individual-focused assessment and treatment approaches to maximize intervention outcomes.

Relational Memory at Short and Long Delays in Individuals With Moderate-Severe Traumatic Brain Injury

Memory deficits are a common and frequently-cited consequence of moderate-severe traumatic brain injury (TBI). However, we know less about how TBI influences relational memory, which allows the binding of the arbitrary elements of experience and the flexible use and recombination of relational representations in novel situations. Relational memory is of special interest for individuals with TBI, given the vulnerability of the hippocampus to injury mechanisms, as well as a growing body of literature establishing the role of relational memory in flexible and goal-directed behavior. In this study, participants with and without a history of moderate-severe TBI completed a continuous relational memory task for face-scene pairings. Participants with TBI exhibited a disruption in relational memory not only when tested after a delay, but also when tested with no experimenter-imposed delay after stimulus presentation. Further, canonical assessments of working and episodic memory did not correspond with performance on the face-scene task, suggesting that this task may tap into relational memory differently and with greater sensitivity than standardized memory assessments. These results highlight the need for rigorous assessment of relational memory in TBI, which is likely to detect deficits that have specific consequences for community reintegration and long-term functional outcomes.

Glucagon-like peptide-1 receptor agonist Exendin-4 improves neurological outcomes by attenuating TBI- induced inflammatory responses and MAPK activation in rats

Traumatic brain injury (TBI) can be exacerbated and prolonged for months or even years by chronic inflammatory processes with long-term consequences on neurodegeneration and neurological impairment. However, there are no clear pharmacological therapies of benefit to manage neurological dysfunctions, which, relating to the molecular mechanisms underlying the behavioral deficits after TBI, have yet to be fully identified. Recently, a glucagon-like peptide 1 (GLP-1) agonist, Exendin-4, was approved not only for the treatment of type 2 diabetes mellitus, but it also played a neurotrophic role in various CNS neurological diseases. In this study, we evaluated the neuroprotective effects of Exendin-4 on neurological outcome, cerebral blood flow, neurodegeneration, and inflammatory responses by utilizing a cortical contusion impact injury (CCI) model in rats. We found that TBI rats displayed neurological impairments, neurodegeneration, reduction of cerebral blood flow, and inflammatory responses, while Exendin-4 promoted neurological, cognitive, and cerebral blood flow recovery and attenuated neural degeneration and inflammatory cytokines after TBI. Furthermore, Exendin-4 treatment significantly diminished the TBI-induced overexpression of TNFα and IL-1β, as well as phosphorylation of p38 and ERK1/2. These data suggest a strong beneficial action of the glucagon-like peptide-1 receptor agonist Exendin-4 in improving neurological outcomes by attenuating inflammatory responses induced by traumatic brain injury, which is of therapeutic potential for TBI.