Hemispheric and executive influences on low-level language processing after traumatic brain injury

Examining the occurrence and outcomes of concussion and mTBI in mixed martial arts athletes: a systematic review

INTRODUCTION

Mixed martial arts (MMA) is a sport growing in popularity around the world. However, many individuals participate in the sport with little understanding of the potential short- and long-term consequences of injuries sustained while participating. Specifically, individuals are placed at a high risk of minor traumatic brain injury (mTBI) and concussive episodes as a result of head injuries incurred during training and competition.

AIMS

The current review aimed to examine the literature surrounding the occurrence and outcomes of mTBI in MMA athletes to gain a better understanding of these consequences.

METHODS

Twenty-five studies were identified within the current review, of which 14 examined occurrence of mTBI within the sport setting, and elevenidentified outcomes of injury.

RESULTS

Overall, studies found that MMA athletes experienced mTBI and concussion to a greater extent than athletes in other sports. Deficits in memory, reaction time and processing speed were identified following occurrence of mTBI; however, several gaps in outcome measurement were identified within the current literature, including a lack of focus on speech and language outcomes.

CONCLUSION

Future research should examine a wider variety of outcomes to provide a clearer understanding of the consequences of participating in the sport.

Passive Elaborative Cueing of Retrieval ProcessesFollowing Traumatic Brain Injury

Purpose: Semantic elaboration is a process in which target information is analyzed in relation to content associated in meaning. The goal of the present study was to examine the use of phrasal cues intended to engage elaborative processes theorized to bolster cognitive performance.Methods: Twenty-two individuals with a history of traumatic brain injury (TBI) and twenty-six neurotypical (NT) individuals were studied. Short phrases intended to elicit elaborative encoding were presented prior to the introduction of a prospective memory task and word-stem completions. Phrases embodied one of three conditions: repeated, semantic, or unrelated information. The stem-completion task was presented between each prospective memory task with fixations serving as cues signaling task completion or functioning as distractors. Event-related potentials (ERPs) were captured during the presentation of word-stems. Following the completion of all word-stems, participants were presented with an old/new recognition task.Results: Linear mixed-effects model analyses revealed a significant effect of condition with respect to word retrieval and recognition memory. Captured ERPs revealed neural signatures resembling a P200.Conclusion: Semantic content increased stimulus saliency, facilitated lexical retrieval, and enhanced retention with the latter process revealing use of semantic cues as a more adept rehearsal strategy than repetition.

Assessing emergence from a prolonged disorder of consciousness: Current opinion and practice in the UK

BACKGROUND

A patient in PDOC must demonstrate functional object use or functional communication to confirm they have emerged from this state. A range of tasks and stimuli are used and patients must achieve 100% accuracy. As consciousness occurs along a continuum, determining emergence is not straightforward.

OBJECTIVE

To establish the opinions of expert clinicians on how emergence is determined in practice.

METHODS

An online survey was completed by clinicians working in specialist rehabilitation settings across the UK. Questions were asked about diagnosis and confidence, informal assessment, formal assessment, and family involvement. Descriptive statistics were used to analyse responses to closed questions. Responses to open questions were analysed using thematic analysis.

RESULTS

Seventy-five surveys were analysed. Approximately a third (30.4 %) used tasks other than those recommended to determine emergence. A lack of confidence in tasks to detect the return of functional communication was reported by 46.4%. The majority (78.6%) reported they worked with patients who they felt had emerged, but could not demonstrate it based on the current criteria. A range of stimuli were employed, but 30.6% of respondents were not confident they could choose stimuli appropriately. Respondents reported a range of benefits and challenges when involving family in assessment.

Comprehension of Legal Language by Adults With and Without Traumatic Brain Injury

OBJECTIVE

To characterize comprehension of written legal language in adults with and without traumatic brain injury (TBI).

PARTICIPANTS

Nineteen adults with moderate-to-severe TBI (11 females) and 21 adults without TBI (13 females), aged 24 to 64 years.

METHODS

Participants completed a multiple-choice assessment of legal-language comprehension, with written stimuli either presented in their original legal form or manipulated to simplify syntax or use more frequently occurring words.

RESULTS

Across stimulus types, TBI group participants were significantly less accurate and slower than comparison peers, with no effect of linguistic manipulation. Working memory and reading fluency test scores correlated with task accuracy and speed in both groups.

CONCLUSIONS

Adults with TBI underperformed their uninjured peers in both accuracy and speed on a task of legal-language comprehension, and these differences were attributable in part to differences in working memory and reading fluency. Results highlight the potential costs of TBI-related communication problems in criminal proceedings and the need to formally evaluate language comprehension in individuals with TBI who are in the criminal justice system.

Implicit causality bias in adults with traumatic brain injury

INTRODUCTION

Individuals with moderate or severe traumatic brain injury often experience impairments in pragmatic language functions. Pragmatic language has been studied primarily in connected language genres such as narratives. It may be, however, that individuals with traumatic brain injury also miss microscopic cues, such as social cues embedded in single word meanings or sentence structure. The current study examined one type of sentence-level pragmatic language cue: implicit causality bias. Implicit causality bias is the attribution of an interpersonal transitive verb action to either the subject noun phrase or object noun phrase of a sentence, and is an inherent property of English-language verbs.

METHOD

In this study, 19 adults with traumatic brain injury and 18 typical adults were asked to provide sensible and spontaneous completions to 96 sentence fragments. Each fragment contained one interpersonal transitive verb and two noun phrases to which the cause of the verb could be attributed.

RESULTS

Adults with traumatic brain injury showed significantly less implicit causality bias than typical adults, and also made more errors in assigning the causality of a clause.

CONCLUSIONS

These results challenge assumptions regarding intact implicit processing in adults with traumatic brain injury, and reveal mechanisms by which communication could fail in everyday social interactions.

Assessment of cognitive dysfunction in traumatic brain injury patients: a review

Traumatic brain injury (TBI) is one of the major causes of human mortality and morbidity in the world. Brain injury could affect the core of a person's being - their thinking, memory, personality and behaviour. Electrophysiological markers from the human electroencephalogram and brain imaging provide a rich source of data which helps to elucidate specific processing impairments in TBI patients. To assess the cognitive and social function in traumatic brain injury patients, this review will focus on some of methods for assessing the disabling cognitive and social function deficits induced by TBI. There are many new technologies available to address TBI and recognition related questions. Integration of the various techniques will help to facilitate our comprehending of TBI, cognitive function and social function, and improve treatment and rehabilitation.

Non-spatial pre-training in the water maze as a clinically relevant model for evaluating learning and memory in experimental TBI

Explicit and implicit learning and memory networks exist where each network can facilitate or inhibit cognition. Clinical evidence suggests that implicit networks are relatively preserved after traumatic brain injury (TBI). Non-spatial pre-training (NSPT) in the Morris Water Maze (MWM) provides the necessary behavioral components to complete the task, while limiting the formation of spatial maps. Our study utilized NSPT in the MWM to assess implicit and explicit learning and memory system deficits in the controlled cortical impact (CCI) model of TBI. 76 adult male Sprague-Dawley rats were divided: CCI vs. sham surgery, NSPT vs. No-NSPT, and cued vs. non-cued groups. NSPT occurred for 4d prior to surgery (dynamic hidden platform location, extra-maze cues covered, static pool entry point). Acquisition (d14-18), Probe/Visible Platform (d19), and Reversal (d20-21) trials were conducted with or without extra-maze cues. Novel time allocation and search strategy selection metrics were utilized. Results indicated implicit and explicit learning/memory networks are distinguishable in the MWM. In the cued condition, NSPT reduced thigmotaxis, improved place learning, and largely eliminated the apparent injury-induced deficits typically observed between untrained CCI and sham rats. However, among NSPT groups, incorporation of cues into search strategy selection for CCI rats was relatively impaired compared to shams. Non-cued condition performance showed sham/NSPT and CCI/NSPT rats perform similarly, suggesting implicit memory networks are largely intact 2weeks after CCI. Place learning differences between CCI/NSPT and sham/NSPT rats more accurately reflect spatial deficits in our CCI model compared to untrained controls. These data suggest NSPT as a clinically relevant construct for evaluating potential neurorestorative and neuroprotective therapies. These findings also support development of non-spatial cognitive training paradigms for evaluating rehabilitation relevant combination therapies.