Facilitation of memory performance through induced semantic processing in survivors of severe closed-head injury

Additive effects of mild head trauma, blast exposure, and aging within white matter tracts: A novel Diffusion Tensor Imaging analysis approach

Existing diffusion tensor imaging (DTI) studies of neurological injury following high-level blast exposure (hlBE) in military personnel have produced widely variable results. This is potentially due to prior studies often not considering the quantity and/or recency of hlBE, as well as co-morbidity with non-blast head trauma (nbHT). Herein, we compare commonly used DTI metrics: fractional anisotropy and mean, axial, and radial diffusivity, in Veterans with and without history of hlBE and/or nbHT. We use both the traditional method of dividing participants into 2 equally weighted groups and an alternative method wherein each participant is weighted by quantity and recency of hlBE and/or nbHT. While no differences were detected using the traditional method, the alternative method revealed diffuse and extensive changes in all DTI metrics. These effects were quantified within 43 anatomically defined white matter tracts, which identified the forceps minor, middle corpus callosum, acoustic and optic radiations, fornix, uncinate, inferior fronto-occipital and inferior longitudinal fasciculi, and cingulum, as the pathways most affected by hlBE and nbHT. Moreover, additive effects of aging were present in many of the same tracts suggesting that these neuroanatomical effects may compound with age.

The Effect of Traumatic Brain Injury on Memory

Having a good memory is essential for carrying out daily tasks. People cannot study, plan, remember or navigate life effectively if they are memoryless. People may be at risk when mistakes made in the past will be repeated and lessons regarding danger cannot be learned. In the community, traumatic brain injury (TBI) is common and individuals with TBI frequently have memory problems. It is crucial to study how TBI affects memory to better understand the underlying mechanism and to tailor rehabilitation for patients with a range of pathologies and severity levels. Thus, this paper aimed to review studies related to TBI's effect on memory. This review examined recent studies to learn more regarding and comprehend the connection between TBI and memory, including short-term memory (STM), working memory (WM) and long-term memory (LTM). This will undoubtedly have a big impact on how memory problems that may arise after TBI will be addressed. Virtual reality and other technological advancements have given the medical community a new way to investigate rehabilitative therapy.

Combined Memory Training: An Approach for Episodic Memory Deficits in Traumatic Brain Injury

Purpose The study aimed to test a combination of semantic memory and traditional episodic memory therapies on episodic memory deficits in adults with traumatic brain injury. Method Twenty-five participants who had been diagnosed with traumatic brain injury and had episodic memory deficits were randomly assigned either to a combined memory treatment group (n = 16) or to a wait-list control group (n = 9). Before and after treatment, they completed standardized neuropsychological testing for episodic memory and related cognitive domains, including the California Verbal Learning Test-Second Edition, the Controlled Oral Word Association Test, the University of Southern California Repeatable Episodic Memory Test, the Wechsler Abbreviated Scale of Intelligence-Second Edition Matrices, the Test of Everyday Attention, the Memory Assessment Clinics Self-Rating Scale, the Expressive Vocabulary Test-Second Edition, and the Story Recall subtest from the Rivermead Behavioural Memory Test. In addition to a traditional episodic memory therapy, the treatment group received a novel semantic memory-focused therapy, which involved participants finding meaningful connections between diverse concepts represented by sets of two or three words. Results The treatment group demonstrated statistically significant improvement in memory for list learning tasks, and there was a significant difference from pretest to posttest between the treatment group and the wait-list control group. Clinical significance was demonstrated for the treatment group using minimally important difference calculations. Conclusion Combined memory therapy resulted in significant improvements in episodic memory, semantic memory, and attention, in comparison to no treatment. Supplemental Material https://doi.org/10.23641/asha.14049968.

Effects of distinctiveness and memory on lateralized and unlateralized brain-electrical activity during visual word encoding

The present study investigated a recently introduced left-lateralized component in the event-related potential (ERP), the posterior semantic asymmetry (PSA), in the context of an isolation paradigm. The PSA is a relative negativity that is most pronounced at temporoparietal electrodes, peaks around 300 ms, and is assumed to reflect early semantic processing of visual words. A free-recall, word-list-learning paradigm was conducted. The learning list comprised two stimuli which were physically isolated from the other stimuli (by different font size or different typeface). The typical behavioral isolation effect with higher recall for isolated stimuli was observed. Furthermore, ERP effects of stimulus type and subsequent memory were analyzed. A left-lateralized negativity that matched the topography of the PSA but occurred somewhat later showed an effect of stimulus distinctiveness, with increased amplitudes for isolates, thus suggesting their deeper semantic processing. However, PSA amplitude did not predict subsequent recall. Unlateralized ERPs replicated previous findings of a greater late frontal positivity during elaborated encoding of both isolated stimuli and subsequently recalled stimuli. This recall effect was greater for isolated than standard stimuli. We argue that physical distinctiveness during encoding facilitates recall to the extent that it promotes the frontally-mediated processes that predict better recall in general.

Cognitive interventions post acquired brain injury

OBJECTIVE

Cognitive rehabilitation represents a substantial portion of rehabilitative efforts put forth in increasing independence following an acquired brain injury.

MAIN OUTCOMES AND RESULTS

This review examined four major areas of cognitive therapy including: attention/concentration, learning and memory, executive functioning, and general cognitive rehabilitation approaches. In total, 64 studies were evaluated throughout the four major areas, which provided the evidence-base for 18 conclusions. The majority of the conclusions were based on moderate and limited evidence, however three strong and one conflicting conclusions were made.

CONCLUSIONS

Future research should explore functional outcome measures and long-term effects of treatment interventions through follow-up.

Memory assessment on an interdisciplinary rehabilitation team: a theoretically based framework

PURPOSE

To describe a cognitive neuroscience model of memory that can be used to guide assessment and promote consistent terminology among members of the rehabilitation team, and to relate the model to frequently used assessment measures.

METHOD

Description of a model of memory, description of how frequently used memory measures relate to the model, and presentation of case studies to exemplify the application of the model to the clinical assessment of memory.

CONCLUSIONS

Use of a theoretical framework is important for choosing assessment instruments, interpreting the results of test performance, and communicating with patients, their family members, and other members of the interdisciplinary team. Understanding where in the memory process a breakdown occurs can guide treatment recommendations and feedback to patients and family members.

The Effect of Moderate to Severe Traumatic Brain Injury (TBI) on Different Aspects of Memory:A Selective Review

Deficient learning and memory are frequently reported as a consequence of traumatic brain injury (TBI). Because of the diffuse nature of the injury, patients with TBI are not the ideal group for studying brain-behavior relations. Nevertheless, characterization of the memory breakdown following TBI could contribute to the assessment and rehabilitation of this patient population. It is well documented that memory is not a unitary system. Accordingly, in this article I review studies that have investigated the long-term effect of moderate to severe TBI on different memory aspects, including explicit and implicit tests of memory. This review demonstrates that TBI affects a large range of memory aspects. One of the conclusions is that the memory impairment observed in TBI patients could be viewed, at least to some degree, as a consequence of a more general cognitive deficit. Thus, unlike patients suffering from global amnesia, memory in patients with TBI is not selectively impaired. Nevertheless, it is possible to detect a subgroup of patients that do meet the criteria of amnesia. However, the most common vulnerable memory processes following TBI very much resemble the memory deficits reported in patients following frontal lobe damage, e.g., difficulties in applying active or effortful strategy in the learning or retrieval process. The suggested similarity between patients with TBI and those suffering from frontal lobe injury should be viewed cautiously; considering the nature of TBI, patients suffering from such injuries are not a homogeneous group. In view of this limitation, the future challenge in this field will be to identify subgroups of patients, either a priori according to a range of factors such as severity of injury, or a posteriori based on their specific memory deficit characteristics. Such a research approach has the potential of explaining much of the variability in findings reported in the literature on the effect of TBI on memory.

Compensating for executive function impairments after TBI: a single case study of functional intervention

The purpose of this study was to demonstrate the effectiveness of compensatory strategies for impairments in executive function. The strategies were designed to enable a client with traumatic brain injury (TBI) to obtain professional employment. In a series of individual speech-language therapy sessions, compensatory strategies were developed, refined, and trained in mock-interview situations. Significant improvements were noted in report-writing accuracy and self-reported stress during report-writing. The client was able to obtain and maintain competitive employment in his chosen profession. The results support the use of strategies aimed at supporting executive function to improve performance on verbal tasks, and were informative regarding the effects of self-perceived efficacy and stress on performance after TBI. They illustrate that intervention based on real-life supports may be effective even many years post-TBI.

LEARNING OUTCOMES

At the conclusion of this article, readers will: (1) identify aspects of executive function that relate to communication in the workplace, (2) describe the steps in considering intervention within a single subject research design framework, and (3) consider the effects of stress and perceived self-efficacy on performance of communication tasks.

Older age, traumatic brain injury, and cognitive slowing: some convergent and divergent findings

Reaction time (RT) meta-analyses of cognitive slowing indicate that all stages of processing slow equivalently and task independently among both older adults (J. Cerella & S. Hale, 1994) and adults who have suffered a traumatic brain injury (TBI; F. R. Ferraro, 1996). However, meta-analyses using both RT and P300 latency have revealed stage-specific and task-dependent changes among older individuals (T. R. Bashore, K. R. Ridderinkhof, & M. W. van der Molen, 1998). Presented in this article are a meta-analysis of the effect of TBI on processing speed, assessed using P300 latency and RT, and a qualitative review of the literature. They suggest that TBI induces differential slowing. Similarities in the effects of older age and TBI on processing speed are discussed and suggestions for future research on TBI-induced cognitive slowing are offered.

Therapeutic effects of environmental enrichment on cognitive function and tissue integrity following severe traumatic brain injury in rats

Postinjury environmental enrichment (EE) has been shown to alter functional and anatomical outcomes in a number of injury paradigms, including traumatic brain injury (TBI). The question of whether EE alters functional outcome following TBI in a model which produces overt histopathological consequences has not been addressed. We investigated this question using the severe, parasagittal fluid percussion injury (FPI) model. Rats (n = 7 per group, enriched and standard for behavior; n = 15 per group for histology) underwent severe (2.2-2.6 atm) FPI, with sham-operated rats (n = 7 per group, enriched and standard for behavior; n = 6 enriched, n = 3 standard for histology) serving as controls. Animals were allowed to recover for 11 days either in standard single housing or together (injured and sham) in an enriched environment consisting of a 92 x 61 x 77-cm ferret cage filled with various stimulatory objects. Consistent with earlier reports, injured animals recovering in the enriched environment showed significantly (P < 0.05) shorter latencies to find the platform in a Morris Water Maze task versus injured/standard animals on day 12 post-TBI. However, both injured groups showed significant deficits versus sham groups (P < 0.05). There were no differences between the sham/enriched and sham/standard groups. No significant group differences in swim speed were observed. At 14 days post-TBI, enriched animals had approximately twofold smaller lesion areas in regions of the cerebral cortex posterior to the injury epicenter (-4.5, -5.8, -6.8 mm relative to bregma; P < 0.05) compared to injured/standard animals. In addition, overall lesion volume for the entire injured cortical hemisphere was significantly smaller in animals recovering in the enriched environment. These results indicate that noninvasive environmental stimulation is beneficial in attenuating cognitive deficits and preserving tissue integrity in a TBI model which causes cerebral contusion and cell death.

Deficient intentional access to semantic knowledge in patients with severe closed-head injury

Patients after severe closed-head injury (CHI) demonstrate reduced ability to spontaneously utilize semantic memory during word-list memory tests and when requested to answer questions regarding general knowledge. However, they show normal lexical facilitation in both automatic and intentional semantic priming paradigms. The present study was aimed at investigating two alternative hypotheses a) that the deficit in semantic processing after CHI is the result of impaired access to an otherwise normal semantic system or b) that it reflects a loss of knowledge from a deteriorated semantic store. For this purpose, the performance of 15 CHI patients on an automatic Semantic Priming paradigm and on tests of Picture Naming and Semantic Judgment were compared to those of 14 normal controls (NC). Although CHI patients' reaction times were significantly slower than those of NCs, the semantic priming effect was comparable in the two groups. Instead, CHI patients performed significantly worse than NCs in the naming and semantic judgment tasks. These results provide evidence that CHI patients access semantic memory automatically at a normal rate. However, when the task is more demanding in terms of processing requests, then CHI patients' performance becomes defective.

Divided attention impairments after traumatic brain injury

This research investigated whether people with severe traumatic brain injury (TBI) are impaired on divided attention tasks requiring working memory. In experiment 1, a severe TBI and control group performed two tasks requiring working memory separately and concurrently. Results showed that the TBI group had impaired divided attention when performing the two tasks concurrently, although the two groups did not differ in performance when these tasks were performed separately. Experiment 2 showed that performance on the paced auditory serial addition task improved with increases in the intertrial interval for both TBI and control groups. A meta-analysis showed that TBIs are impaired on divided attention when the tasks require controlled processing, but not when the tasks can be carried out relatively automatically.

Effects of divided attention on perceptual and conceptual memory tests: an analysis using a process-dissociation approach

In two experiments, the nature of the relation between attention available at learning and subsequent automatic and controlled influences of memory was explored. Participants studied word lists in full and divided encoding conditions. Memory for the word lists was then tested with a perceptually driven task (stem completion) in Experiment 1 and with a conceptually driven task (category association) in Experiment 2. For recall cued with word stems, automatic influences of memory derived using the process-dissociation procedure remained invariant across a manipulation of attention that substantially reduced conscious recollection for the learning episode. In contrast, for recall cued with category names, dividing attention at learning significantly reduced the parameter estimates representing both controlled and automatic memory processes. These findings were similar to those obtained using indirect test instructions. The results suggest that, in contrast to perceptual priming, conceptual priming may be enhanced by semantic processing, and this effect is not an artifact of contamination from conscious retrieval processes.

Language Testing in Adolescents With Brain Injury

The validity of the Clinical Evaluation of Language Fundamentals-Third Edition (CELF-3, Semel, Wiig, & Secord, 1995) for the identification and description of language disorders following traumatic brain injury (TBI) was considered in 11 adolescents with TBI. In general, the CELF-3 identified only the individuals who had previously been diagnosed as language impaired, not the individuals with verbal information processing impairments but no diagnosis of language impairment. The test did not permit the identification of strengths and weaknesses.

Intercorrelations among subtest standard scores were as high in the TBI group as in the standardization sample, which is consistent with the CELF-3 being a one-factor test. Test performance may have been influenced by the interaction of the subjects’ memory abilities and the subtests’ memory demands, although this relationship was not statistically significant in the present data.

Slow information processing after very severe closed head injury: impaired access to declarative knowledge and intact application and acquisition of procedural knowledge

As an explanation of the pattern of slow information processing after closed head injury (CHI), hypotheses of impaired access to declarative memory and intact application and acquisition of procedural memory after CHI are presented. These two hypotheses were tested by means of four cognitive reaction-time tasks, a semantic memory task, a memory comparison task, a mental rotation task and a mirror reading task. These tasks were administered on two different days to 12 survivors of a CHI tested more than 5 years after injury and a healthy control group of comparable age and education. In three tasks the difficulty of access to declarative knowledge was varied and it was expected that this would slow the CHI group more than the controls. In two tasks opportunities for procedural learning were provided by repeatedly presenting the same cognitive tasks and in one task, the difficulty of access to procedural memory was varied. It was expected that the CHI group would profit as much from this as would the control group. Both hypotheses were supported.

Towards a conceptualization of language and cognitive impairment in closed-head injury: use of clinical measures

Language deficits following closed-head injury (CHI) are widely considered as impairments secondary to the cognitive disruptions common to closed-head injury. In addition, the use of standardized measures to assess the functioning of the language system in closed-head injury has mostly been limited to aphasia test batteries which examine primary language functions only. This has resulted in generalizations as to the integrity of the language system following closed-head injury, and as a consequence, consideration of the contribution of the language system to the achievement of communicative competence in this population has been minimized. This paper presents a framework in which the functional language system is identified as a hierarchical system containing primary and higher-order language processes involved in reciprocal relationships with cognitive functions at each level. A group of 25 closed-head injury subjects and 23 demographically matched control subjects were examined for linguistic proficiency using a battery of standardized tests which investigated the language system across a hierarchy of complexity, structure and predictability. In addition, 23 of the closed-head subjects were administered a comprehensive neuropsychological test battery in order to determine the nature and extent of concomitant impairments in cognitive processes and their relationship with impairments in the language system. The language battery was found to consistently discriminate between the control and clinical groups indicating that the linguistic system is significantly impaired following CHI, with the lexical-semantic system being the most vulnerable to disruption. A strong influential relationship between language and cognitive processes was statistically confirmed and the nature of the relationship between aspects of language and cognition further delineated.

Assessment of syntax after adolescent brain injury: effects of memory on test performance

In this study, we investigated the influence of working memory load on performance of a task designed to measure receptive syntax ability. Subjects were 6 brain-injured adolescents and 6 hospitalized control subjects matched for age, sex, and general ability. Each subject was administered the Listening/Grammar subtest of the Test of Adolescent Language (TOAL-3) and a modified version of this subtest with identical syntax and fewer response choices (i.e., a reduced working memory processing and storage load). The syntactic structures tested on these tasks also were measured in spontaneous narratives. The brain-injured subjects' performance was significantly worse than that of controls on both versions of the syntax comprehension subtest. There was a significant group-by-task interaction, as brain-injured subjects' performance was significantly worse on the Listening/Grammar subtest than the modified subtest, whereas Control subjects'performance did not differ across the two tasks. In their spontaneous narratives, subjects in both groups produced the syntactic structures tested on the receptive syntax tasks, with no between-groups difference in syntax production. The results are discussed in terms of test validity and the impact of measurement methods on test performance in disordered groups.

Verbal rehearsal and memory in children with closed head injury: a quantitative and qualitative analysis

Nine closed head injured (CRI) children (mean age = 11.4 years) with post-onset intervals of seven months to eight years were studied. The CRI children ranged from mild-moderate to severely impaired. Nine normally developing children (mean age = 10.9 years) served as controls. An overt rehearsal free recall task was used. Subjects were instructed to "think aloud" following presentation of each item to-be-recalled. Quantitative analyses suggested impaired verbal recall and inefficient, passive rehearsal strategy use in severely injured subjects. Mild-moderate subjects performed similarly to controls and exhibited active rehearsal strategy use. Qualitative analysis revealed differences between CRI subjects and controls' range of rehearsal strategies, monitoring and metamemory. Implications for clinical assessment and intervention with respect to use of rehearsal strategies are discussed.

Content memory and temporal memory for actions in survivors of traumatic brain injury

Memory for performed actions, a rehearsal-independent form of memory, was compared to verbal memory in 30 survivors of traumatic brain injury (TBI) and 30 demographically matched controls. Subjects were tested on recognition and recall memory for the content of recently performed actions in the laboratory, as well as the ability to reconstruct the temporal order in which the actions were performed. Each subject performed actions under incidental and intentional memory instructions. Half of the subjects performed 12 actions, the other half 24 actions, with an equal number of usual and unusual actions in each list. Verbal memory was assessed with paired-associate and temporal order tests. Although recall was more proficient overall for the control compared to the brain-injured subjects on both content and temporal memory for actions, memory for actions was better than verbal memory in both groups. Both groups performed better overall on the short compared to the long list of actions and recalled unusual actions better than usual actions. The rehearsal-independent nature of action memory was supported, with no advantage for the intentional instruction. It is proposed that a retrieval deficit may be in part responsible for deficits in memory for actions following TBI. However, preserved ability to benefit from the abundant contextual cues available through motor actions may account for the better recall of actions compared to words.

Neurobehavioural consequences of closed head injury in older adults

This study examined the neurobehavioural effects of closed head injury (CHI) in adults aged 50 years and older. Twenty two mild to moderate CHI patients who were within seven months of the injury were administered measures of language, memory, attention, and executive functioning. Compared with demographically similar normal controls, the patients exhibited significantly poorer functioning on the cognitive domains. Naming and word fluency under timed conditions, verbal and visual memory, and the ability to infer similarities were especially vulnerable. These initial findings indicate that CHI in older adults produces considerable cognitive deficits in the early stages of recovery. Future research should characterise long term outcome and the potential links between head injury and the development of progressive dementia.

Speed of processing within semantic memory following severe closed head injury

This study investigated the effects of severe closed head injury (CHI) on the speed of information processing within semantic categories. The question of whether subjects were able to benefit from priming was also investigated. Survivors of severe CHI who were less than 1 year postinjury and survivors who were greater than 1 year postinjury were compared with neurologically normal matched controls utilizing a category judgement task. The results demonstrated slower processing within semantic memory for both groups of CHI patients compared to normal controls. Furthermore, individuals with CHI were able to benefit from priming to the same relative degree as control subjects. Overall, the results suggested semantic organization remains intact after severe CHI, but accessing semantic information is slowed.

The psychological treatment of memory impairment: a review of empirical studies

Memory impairment is a frequent effect of many different forms of brain dysfunction. Memory impairment is also a frequent focus of treatment interventions, and there have been many different treatment methods suggested. The suggested methods include direct retraining, the use of spared skills in compensating for the impairment (alternate functional systems), and the use of behavioral strategies to circumvent the manifest memory dysfunction (behavioral prosthetics). Unfortunately, there are very few studies comparing the various suggested treatment methods. The present paper evaluates the empirical evidence related to the treatment of memory dysfunction and suggests directions for future investigations. Although the evidence is not conclusive, it appears that some forms of treatment may be helpful in remediating certain types of memory impairment. An approach likely to be productive would include some consideration of the impaired neurological and psychological mechanisms responsible for the manifest memory deficit as well as a consideration of the etiology of the injury thought to be causally related to the memory deficit. As yet, there have been no rigorous empirical evaluations of these considerations.