Lori G. Cook

Impaired discourse gist and working memory in children after brain injury

Emerging evidence suggests that a traumatic brain injury (TBI) in childhood may disrupt the ability to abstract the central meaning or gist-based memory from connected language (discourse). The current study adopts a novel approach to elucidate the role of immediate and working memory processes in producing a cohesive and coherent gist-based text in the form of a summary in children with mild and severe TBI as compared to typically developing children, ages 8-14 years at test. Both TBI groups showed decreased performance on a summary production task as well as retrieval of specific content from a long narrative. Working memory on n-back tasks was also impaired in children with severe TBI, whereas immediate memory performance for recall of a simple word list in both TBI groups was comparable to controls. Interestingly, working memory, but not simple immediate memory for a word list, was significantly correlated with summarization ability and ability to recall discourse content.

Higher-order reasoning training years after traumatic brain injury in adults.

Objective:To conduct a feasibility study to compare the effects of top-down Strategic Memory and Reasoning Training (SMART) versus information-based Brain Health Workshop (BHW, control) on gist-reasoning (ie, abstracting novel meaning from complex information), memory, executive functions, and daily function in adults with traumatic brain injury. Participants:Twenty-eight participants (of the 35 recruited), 16 men & 12 women, aged 20 to 65 years (M = 43, SD = 11.34) at chronic stages posttraumatic brain injury (2 years or longer) completed the training. Fourteen participants that received SMART and 14 participants that completed BHW were assessed both pre- and posttraining. Thirteen of the SMART trained and 11 from BHW participated in a 6-month testing. Design:The study was a single blinded randomized control trial. Participants in both groups received a minimum of 15 hours of training over 8 weeks. Results:The SMART group significantly improved gist-reasoning as compared to the BHW group. Benefits of the SMART extended to untrained measures of working memory and participation in functional activities. Exploratory analyses suggested potential transfer effects of SMART on memory and executive functions. The benefits of the SMART program as compared to BHW were evident at immediately posttraining and 6 months posttraining. Conclusion:This study provides preliminary evidence that short-term intensive training in top-down modulation of information benefits gist-reasoning and generalizes to measures of executive function and real life function at chronic stages of post-TBI.

Effects of traumatic brain injury on a virtual reality social problem solving task and relations to cortical thickness in adolescence.

Social problem solving was assessed in 28 youth ages 12-19 years (15 with moderate to severe traumatic brain injury (TBI), 13 uninjured) using a naturalistic, computerized virtual reality (VR) version of the Interpersonal Negotiations Strategy interview (Yeates, Schultz, & Selman, 1991). In each scenario, processing load condition was varied in terms of number of characters and amount of information. Adolescents viewed animated scenarios depicting social conflict in a virtual microworld environment from an avatars viewpoint, and were questioned on four problem solving steps: defining the problem, generating solutions, selecting solutions, and evaluating the likely outcome. Scoring was based on a developmental scale in which responses were judged as impulsive, unilateral, reciprocal, or collaborative, in order of increasing score. Adolescents with TBI were significantly impaired on the summary VR-Social Problem Solving (VR-SPS) score in Condition A (2 speakers, no irrelevant information), p=0.005; in Condition B (2 speakers+irrelevant information), p=0.035; and Condition C (4 speakers+irrelevant information), p=0.008. Effect sizes (Cohens D) were large (A=1.40, B=0.96, C=1.23). Significant group differences were strongest and most consistent for defining the problems and evaluating outcomes. The relation of task performance to cortical thickness of specific brain regions was also explored, with significant relations found with orbitofrontal regions, the frontal pole, the cuneus, and the temporal pole. Results are discussed in the context of specific cognitive and neural mechanisms underlying social problem solving deficits after childhood TBI.

Mental State Attributions and Diffusion Tensor Imaging After Traumatic Brain Injury in Children

We studied social cognition in 49 children 3 months after moderate to severe traumatic brain injury (TBI) and in 39 children with orthopedic injury (OI). Children underwent diffusion tensor imaging (DTI) and a mental attribution task showing two triangles. Mental state attributions increased when one triangle reacted to intentions of the other, but less so in the TBI than the OI group. DTI identified injury to white matter microstructure in the TBI group, but the relation of DTI to mental attributions did not differ between groups. Moderate to severe TBI produces white matter disconnections that may affect social cognitive networks.

Strategic Learning in Youth with Traumatic Brain Injury: Evidence for Stall in Higher-Order Cognition.

Little is known about strategic learning ability in preteens and adolescents with traumatic brain injury (TBI). Strategic learning is the ability to combine and synthesize details to form abstracted gist-based meanings, a higher-order cognitive skill associated with frontal lobe functions and higher classroom performance. Summarization tasks were used to measure strategic learning ability through the production of abstracted gist-based concepts, and specific probes measured memory for explicit details. Twenty middle school-aged preteens and teenagers who sustained a moderate to severe TBI 1 year postinjury and a control group of 20 typically developing 10-to 15-year-old subjects participated in this study. The results revealed that the youth with moderate to severe TBI were able to recall specific details at a comparable level to the control group. However, the youth with TBI demonstrated significantly lower strategic learning competence, as manifested by a reduced ability to combine details into gist-based ideas. The present findings advance the notion that skills that have not yet developed at the time of brain injury or are in a stage of development may be particularly vulnerable to the long-term and lasting sequelae of TBI in youth, although a longitudinal study is needed to verify this claim.

Deficits in analogical reasoning in adolescents with traumatic brain injury.

Individuals with traumatic brain injury (TBI) exhibit deficits in executive control, which may impact their reasoning abilities. Analogical reasoning requires working memory and inhibitory abilities. In this study, we tested adolescents with moderate to severe TBI and typically developing (TD) controls on a set of picture analogy problems. Three factors were varied: complexity (number of relations in the problems), distraction (distractor item present or absent), and animacy (living or non-living items in the problems). We found that TD adolescents performed significantly better overall than TBI adolescents. There was also an age effect present in the TBI group where older participants performed better than younger ones. This age effect was not observed in the TD group. Performance was affected by complexity and distraction. Further, TBI participants exhibited lower performance with distractors present than TD participants. The reasoning deficits exhibited by the TBI participants were correlated with measures of executive function that required working memory updating, attention, and attentional screening. Using MRI-derived measures of cortical thickness, correlations were carried out between task accuracy and cortical thickness. The TD adolescents showed negative correlations between thickness and task accuracy in frontal and temporal regions consistent with cortical maturation in these regions. This study demonstrates that adolescent TBI results in impairments in analogical reasoning ability. Further, TBI youth have difficulty effectively screening out distraction, which may lead to failures in comprehension of the relations among items in visual scenes. Lastly, TBI youth fail to show robust cortical–behavior correlations as observed in TD individuals.

Monetary incentive effects on event-based prospective memory three months after traumatic brain injury in children

Information regarding the remediation of event-based prospective memory (EB-PM) impairments following pediatric traumatic brain injury (TBI) is scarce. Addressing this, two levels of monetary incentives were used to improve EB-PM in children ages 7 to 16 years with orthopedic injuries (OI, n = 51), or moderate (n = 25) and severe (n = 39) TBI at approximately 3 months postinjury. The EB-PM task consisted of the child giving a specific verbal response to a verbal cue from the examiner while performing a battery of neuropsychological measures (ongoing task). Significant effects were found for age-at-test, motivation condition, period, and group. Within-group analyses indicated that OI and moderate TBI groups performed significantly better under the high- than under the low-incentive condition, but the severe TBI group demonstrated no significant improvement. These results indicate that EB-PM can be significantly improved at 3 months postinjury in children with moderate, but not severe, TBI.

Cognitive gains from gist reasoning training in adolescents with chronic-stage traumatic brain injury.

Adolescents with traumatic brain injury (TBI) typically demonstrate good recovery of previously acquired skills. However, higher-order and later emergent cognitive functions are often impaired and linked to poor outcomes in academic and social/behavioral domains. Few control trials exist that test cognitive treatment effectiveness at chronic recovery stages. The current pilot study compared the effects of two forms of cognitive training, gist reasoning (top-down) versus rote memory learning (bottom-up), on ability to abstract meanings, recall facts, and utilize core executive functions (i.e., working memory, inhibition) in 20 adolescents (ages 12–20) who were 6 months or longer post-TBI. Participants completed eight 45-min sessions over 1 month. After training, the gist reasoning group (n = 10) exhibited significant improvement in ability to abstract meanings and increased fact recall. This group also showed significant generalizations to untrained executive functions of working memory and inhibition. The memory training group (n = 10) failed to show significant gains in ability to abstract meaning or on other untrained specialized executive functions, although improved fact recall approached significance. These preliminary results suggest that relatively short-term training (6 h) utilizing a top-down reasoning approach is more effective than a bottom-up rote learning approach in achieving gains in higher-order cognitive abilities in adolescents at chronic stages of TBI. These findings need to be replicated in a larger study; nonetheless, the preliminary data suggest that traditional cognitive intervention schedules need to extend to later-stage training opportunities. Chronic-stage, higher-order cognitive trainings may serve to elevate levels of cognitive performance in adolescents with TBI.

Event-based prospective memory performance during subacute recovery following moderate to severe traumatic brain injury in children: Effects of monetary incentives

There are very few studies investigating remediation of event-based prospective memory (EB-PM) impairments following traumatic brain injury (TBI). To address this, we used 2 levels of motivational enhancement (dollars vs. pennies) to improve EB-PM in children with moderate to severe TBI in the subacute recovery phase. Children with orthopedic injuries (OI; n = 61), moderate (n = 28), or severe (n = 30) TBI were compared. Significant effects included Group x Motivation Condition (F(2, 115) = 3.73, p < .03). The OI (p < .002) and moderate TBI (p < .03) groups performed significantly better under the high- versus low-incentive condition; however, the severe TBI group failed to demonstrate improvement (p = .38). EB-PM performance was better in adolescents compared to younger children (p < .02). These results suggest that EB-PM can be significantly improved in the subacute phase with this level of monetary incentives in children with moderate, but not severe, TBI. Other strategies to improve EB-PM in these children at a similar point in recovery remain to be identified and evaluated.

How functional connectivity between emotion regulation structures can be disrupted: Preliminary evidence from adolescents with moderate to severe traumatic brain injury

Outcome of moderate to severe traumatic brain injury (TBI) includes impaired emotion regulation. Emotion regulation has been associated with amygdala and rostral anterior cingulate (rACC). However, functional connectivity between the two structures after injury has not been reported. A preliminary examination of functional connectivity of rACC and right amygdala was conducted in adolescents 2 to 3 years after moderate to severe TBI and in typically developing (TD)control adolescents, with the hypothesis that the TBI adolescents would demonstrate altered functional connectivity in the two regions. Functional connectivity was determined by correlating fluctuations in the blood oxygen level dependent(BOLD) signal of the rACC and right amygdala with that of other brain regions. In the TBI adolescents, the rACC was found to be significantly less functionally connected to medial prefrontal cortices and to right temporal regions near the amygdala (height threshold T = 2.5, cluster level p < .05, FDR corrected), while the right amygdala showed a trend in reduced functional connectivity with the rACC (height threshold T = 2.5, cluster level p = .06, FDR corrected). Data suggest disrupted functional connectivity in emotion regulation regions. Limitations include small sample sizes. Studies with larger sample sizes are necessary to characterize the persistent neural damage resulting from moderate to severe TBI during development.