Automatic process development following severe closed head injury

Is there more room to improve? The lifespan trajectory of procedural learning and its relationship to the between- and within-group differences in average response times

Characterizing the developmental trajectories of cognitive functions such as learning, memory and decision making across the lifespan faces fundamental challenges. Cognitive functions typically encompass several processes that can be differentially affected by age. Methodological issues also arise when comparisons are made across age groups that differ in basic performance measures, such as in average response times (RTs). Here we focus on procedural learning–a fundamental cognitive function that underlies the acquisition of cognitive, social, and motor skills–and demonstrate how disentangling subprocesses of learning and controlling for differences in average RTs can reveal different developmental trajectories across the human lifespan. Two hundred-seventy participants aged between 7 and 85 years performed a probabilistic sequence learning task that enabled us to separately measure two processes of procedural learning, namely general skill learning and statistical learning. Using raw RT measures, in between-group comparisons, we found a U-shaped trajectory with children and older adults exhibiting greater general skill learning compared to adolescents and younger adults. However, when we controlled for differences in average RTs (either by using ratio scores or focusing on a subsample of participants with similar average speed), only children (but not older adults) demonstrated superior general skill learning consistently across analyses. Testing the relationship between average RTs and general skill learning within age groups shed light on further age-related differences, suggesting that general skill learning measures are more affected by average speed in some age groups. Consistent with previous studies of learning probabilistic regularities, statistical learning showed a gradual decline across the lifespan, and learning performance seemed to be independent of average speed, regardless of the age group. Overall, our results suggest that children are superior learners in various aspects of procedural learning, including both general skill and statistical learning. Our study also highlights the importance to test, and control for, the effect of average speed on other RT measures of cognitive functions, which can fundamentally affect the interpretation of group differences in developmental, aging and clinical psychology and neuroscience studies.

Atypical Within-Session Motor Procedural Learning after Traumatic Brain Injury but Well-Preserved Between-Session Procedural Memory Consolidation

Using the finger-to-thumb opposition sequence (FOS) learning task, we characterized motor skill learning in sub-acute patients hospitalized for rehabilitation following traumatic brain injury (TBI). Ten patients (Trained TBI) and 11 healthy participants (Trained Healthy) were trained using a multi-session protocol: a single session was afforded in the first week of the study, and four daily sessions were afforded during the second week. Intensity of practice was adapted to patients. Performance speed and accuracy were tested before and after each session. Retention was tested 1 month later. Ten patients (Control TBI) had no FOS training and were tested only at the beginning and the end of the 6 week period. Although baseline performance on the FOS was very slow, all three phases of skill learning found in healthy adults (acquisition, between-session consolidation gains, and long-term retention) could be identified in patients with TBI. However, their time-course of learning was atypical. The Trained TBI group improved in speed about double the spontaneous improvements observed in the Control TBI group, with no speed-accuracy tradeoff. Normalized to their initial performance on the FOS, the gains accrued by the Trained TBI group after a first training were comparable to those accrued by healthy adults. Only during the second week with daily training, the rate of improvement of the Trained TBI group lagged behind that of the Trained Healthy group, due to increasing within-sessions losses in performance speed; no such losses were found in healthy participants. The Functional Independence Measure scores at the start of the study correlated with the total gains attained at the end of the study; no correlations were found with severity of injury or explicit memory impairments. Despite within-sessions losses in performance, which we propose reflect cognitive fatigue, training resulted in robust overall learning and long-term retention in patients with moderate-severe TBI. Given that the gains in performance evolved mainly between sessions, as delayed, offline, gains, our results suggest that memory consolidation processes can be effectively engaged in patients with TBI. However, practice protocols and schedules may need to be optimized to better engage the potential for long-term plasticity in these patients.

Training to Optimize Learning after Traumatic Brain Injury

One of the major foci of rehabilitation after traumatic brain injury is the design and implementation of interventions to train individuals to learn new knowledge and skills or new ways to access and execute previously acquired knowledge and skills. To optimize these interventions, rehabilitation professionals require a clear understanding of how traumatic brain injury impacts learning, and how specific approaches may enhance learning after traumatic brain injury. This brief conceptual review provides an overview of learning, the impact of traumatic brain injury on explicit and implicit learning, and the current state of the science examining selected training approaches designed to advance learning after traumatic brain injury. Potential directions for future scientific inquiry are discussed throughout the review.

Revisiting the neurofunctional approach: conceptualizing the core components for the rehabilitation of everyday living skills

BACKGROUND

Introduced in the 1980s, the neurofunctional approach (NFA) is one of the few interventions designed primarily for clients with severe deficits following traumatic brain injury (TBI). Specifically the NFA was intended for those individuals who were limited in their ability to solve novel problems or generalize skills from one setting to another and whose lack of insight limited their engagement in the rehabilitative process. DESCRIPTION OF THE APPROACH: The NFA is a client-centred, goal-driven approach that incorporates the principles of skill learning and promotes the development of routines and competencies in practical activities required for everyday living. Programmes based on the NFA are developed specifically to meet each client's unique needs, using a range of evidence-based interventions. RECENT EVIDENCE: Recently the NFA has been found to be more effective than cognitive-retraining for some individuals with moderate-to-severe TBI who have deficits in activities of daily living. This paper aims to define the core features of the NFA, outline the theoretical basis on which it is founded and consider implications of the findings for rehabilitation after TBI in general. The NFA is highly relevant for clients living in the community who require a case manager to direct an integrated, rehabilitation programme or provide structured input for the long-term maintenance of skills.

Prospective memory after moderate-to-severe traumatic brain injury: a multinomial modeling approach

OBJECTIVE

Prospective memory (PM), which can be understood as the processes involved in realizing a delayed intention, is consistently found to be impaired after a traumatic brain injury (TBI). Although PM can be empirically dissociated from retrospective memory, it inherently involves both a prospective component (i.e., remembering that an action needs to be carried out) and retrospective components (i.e., remembering what action needs to be executed and when). This study utilized a multinomial processing tree model to disentangle the prospective (that) and retrospective recognition (when) components underlying PM after moderate-to-severe TBI.

METHOD

Seventeen participants with moderate to severe TBI and 17 age- and education-matched control participants completed an event-based PM task that was embedded within an ongoing computer-based color-matching task.

RESULTS

The multinomial processing tree modeling approach revealed a significant group difference in the prospective component, indicating that the control participants allocated greater preparatory attentional resources to the PM task compared to the TBI participants. Participants in the TBI group were also found to be significantly more impaired than controls in the when aspect of the retrospective component.

CONCLUSIONS

These findings indicated that the TBI participants had greater difficulty allocating the necessary preparatory attentional resources to the PM task and greater difficulty discriminating between PM targets and nontargets during task execution, despite demonstrating intact posttest recall and/or recognition of the PM tasks and targets.

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.

Long-term retention of skilled visual search following severe traumatic brain injury

We examined the long-term retention of a learned automatic cognitive process in 17 severe TBI participants and 10 controls. Participants had initially received extensive consistent-mapping (CM) training (i.e., 3600 trials) in a semantic category visual search task (Schmitter-Edgecombe & Beglinger, 2001). Following CM training, TBI and control groups demonstrated dramatic performance improvements and the development of an automatic attention response (AAR), indicating task-specific and stimulus-specific skill learning. After a 5- or 10-month retention interval, participants in this study performed a New CM task and the originally trained CM task to assess for retention of task-specific and stimulus-specific visual search skills, respectively. No significant group differences were found in the level of retention for either skill type, indicating that individuals with severe TBI were able to retain the learned skills over a long-term retention interval at a level comparable to controls. Exploratory analyses revealed that TBI participants who returned at the 5-month retention interval showed nearly complete skill retention, and greater skill retention than TBI participants who returned at the 10-month interval, suggesting that "booster" or retraining sessions may be needed when a skill is not continuously in use.

Implications of basic science research for brain injury rehabilitation: a focus on intact learning mechanisms

Within a theoretical framework for rehabilitation that distinguishes between automatic and controlled processes, this article reviews basic science research and addresses the following issues: What cognitive abilities remain relatively intact after severe traumatic brain injury, and how can we incorporate intact skills into rehabilitative techniques? The reviewed research indicates that individuals with severe traumatic brain injury (a) generally perform similar to controls on cognitive tasks (or task components) that require automatic and implicit processes as opposed to consciously controlled processes; (b) can learn through implicit learning mechanisms; and (c) can acquire and use automatic processes in complex, cognitive task performance.

Event-based prospective memory following severe closed-head injury

Twenty-four severe closed-head injury (CHI) participants and 24 controls completed event-based prospective memory tasks concurrently with an ongoing working memory task. The event cue was either integrated with the ongoing working memory task (focal cue) or peripheral to it. Prospective remembering was poorer for the CHI group in both the focal- and peripheral-cue conditions. The groups did not differ on the ongoing task. The peripheral cue and the integrated focal cue also did not differ in ability to trigger prospective remembering. The results suggest that, even with highly salient event cues, severe CHI participants (> 1 year postinjury) are more likely than controls to exhibit prospective memory failures. The data revealed a link between CHI participants' prospective memory failures and momentary lapses of intention.

Retrieval inhibition in directed forgetting following severe closed-head injury

A variant of the list method directed forgetting procedure was used to examine the role of inhibition in memory performance following severe closed-head injury (CHI). Twenty-four participants with severe CHI and 24 controls studied picture and word stimuli in both forget and remember conditions. Memory testing for the to-be-forgotten and to-be-remembered items consisted of a free-recall test followed by a source-monitoring task. Despite poorer recall performance, the participants with CHI exhibited a directed forgetting effect similar to that in controls. Item recognition scores indicated that the inhibited items were not forgotten but rather were items whose accessibility had been lowered. These findings suggest that residual memory deficits in patients with severe CHI are unlikely to reflect inefficient retrieval inhibition.

Reflective and reflexive action control in patients with frontal brain lesions

Two types of action control derived from the model of action phases (H. Heckhausen & P. M. Gollwitzer, 1987) were analyzed in patients with frontal lesions, patients with nonfrontal lesions, and university students. In Study 1, reflective action control in terms of goal selection was assessed, and impaired deliberation was found in patients with frontal lesions. Study 2 assessed reflexive action control in terms of automatic action initiation as a result of forming implementation intentions (P. M. Gollwitzer, 1999). All participants sped up their responses to critical stimuli by forming implementation intentions. Moreover, lesion patients with weak performances on the Tower of Hanoi (TOH) task did worse than patients with strong TOH performances in Study 1 but better than control participants in Study 2. Findings are interpreted as a functional dissociation between conscious reflective action control and automatic reflexive action control.

Speed of information processing in traumatic brain injury: modality-specific factors

OBJECTIVE

To assess speed of information processing by two serial addition tests (one visual, one auditory) in individuals with moderate-to-severe traumatic brain injuries (TBIs) and in a healthy, normal control group (NC). The tasks were designed to equate and control for accuracy of performance across the TBI and NC groups, thus allowing for quantification of information processing speed.

DESIGN

Performance across groups and tasks were compared using 2 x 2 repeated measure analyses of variance (ANOVAs). In addition, each individual's processing speed was used to adjust rate of stimulus presentation on a subsequent "rehabilitation" trial to determine further whether this adjustment equated accuracy of performance.

SETTING

Rehabilitation hospital.

PATIENTS

22 outpatients with moderate-to-severe TBI (6 women, 16 men; mean age = 34.6 years; duration of loss of consciousness = 22.6 days) and 20 age- and education-matched healthy controls.

RESULTS

Processing speed was slower in TBI subjects, relative to controls and was significantly related to measures of executive functioning for those with TBI. Relative to controls, speed of processing in the TBI group was disproportionately slower when information was presented in the auditory, relative to the visual, modality.

CONCLUSIONS

Speed of information processing is a major impairment in those with TBI when unconfounded by performance accuracy. The modality-specific impairment observed in the TBI group may, in part, be due to a greater within-modality interference effect created by the auditory version of the task. By manipulating information at a pace customized for an individual through compensatory strategies and environmental modifications, information-processing performance of TBI participants can be enhanced significantly.

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.