Adaptive decision making, ecological validity, and the frontal lobes

Early cognitive impairment in a subset of patients with presumed low-grade glioma

We investigated the presence of cognitive impairment, in adults with presumed low-grade glioma at early stage of disease prior to major treatments, in relation to neurological symptoms and radiological characteristics of the tumour. Sixteen patients were evaluated. A subset of patients was identified with clearly impaired cognition. Patients with cognitive impairment often had large tumours in the left frontal lobe, were relatively young, and most of them were males. We conclude that cognitive dysfunction may be present already at early stage of disease, and that early identification of patients at risk is warranted.

Neuropsychological assessment in traumatic brain injury

Traumatic brain injury (TBI) is a neurological injury that can affect the cognitive, emotional, psychological, and physical functioning of an individual. The clinical neuropsychologist working with TBI patients must take a holistic approach when assessing and treating the patient and consider the patient in total, including premorbid and post-incident factors, to formulate a comprehensive and accurate picture of the patient. This approach will guide the clinician regarding multiple types of treatment the patient may require.

Subjective rating of working memory is associated with frontal lobe volume in schizophrenia

BACKGROUND

Patients with schizophrenia commonly show deficits in working memory on objective neuropsychological measures, and brain imaging studies have documented neural abnormalities during performance of working memory tasks. It remains unclear to what extent such patients are able to accurately gauge the integrity of their working memory in their daily lives.

AIMS

We evaluated the relationship between subjective rating of working memory integrity in daily life and volumes of the frontal, temporal, and parietal lobes in patients with schizophrenia.

METHODS

Participants included 29 patients with schizophrenia and 26 healthy comparison subjects. Participants completed a structural magnetic resonance imaging (MRI) scan, the Self Report form of the Behavioral Rating Inventory of Executive Function - Adult version (BRIEF-A), and Digit Span Backwards as an objective measure of working memory. Lobar volumes were obtained using an automated processing package and adjusted for total intracranial volume.

RESULTS

The patient group reported worse working memory in daily life, and performed worse on Digit Span Backwards, than the comparison group. Within the patient group, poorer working memory in daily life was associated with smaller left and right frontal lobe volumes. Shorter backwards digit span was associated with smaller left frontal and left and right temporal lobe volumes.

CONCLUSIONS

The significant relationship between frontal lobe volumes and subjective working memory in daily life provides some support for the validity of self report measures of cognitive functioning in patients with schizophrenia, and provides further evidence for a contribution of frontal lobe abnormality to executive dysfunction in the illness.

Contextual cues remediate problem solving: deficits in Parkinson's disease

This study examined the contribution of executive functions to arrangement problem-solving performance in Parkinson's disease (PD), with a particular focus on self-directed cognitive flexibility. PD patients and healthy age-matched adults completed a battery of neuropsychological measures of executive function and a series of anagram puzzles, some of which were modified to include graphemic cues designed to prime potential solutions. PD patients were less successful than healthy controls (HC) at resolving the anagram puzzles, but when a cue accompanied the anagram stimulus, PD patients performed normally. Anagram performance was associated with measures of verbal fluency and inhibition; no association emerged with working memory or set shifting ability. These data suggest that subjects with PD may have difficulty sufficiently inhibiting their automatic response to the experimental stimulus in order to generate the novel arrangements required to produce a successful response. Such deficits might be remediated through the use of environmental cues designed to support strategy generation.

Implicit cognition and substance use: a meta-analysis

A meta-analysis of 89 effect sizes based on the responses of 19,930 participants was conducted to estimate the magnitude of the relationship between substance-related implicit cognitions and the use of legal and illegal substances. The analysis produced a weighted average effect size of r=.31. Moderation analyses revealed significant heterogeneity in effect sizes related to facet of implicit cognition, measurement strategy, sample composition, and substance type. The largest effect sizes were found in studies that assessed implicit semantic associations, employed word association measures, and focused on marijuana use. The findings suggest that implicit cognition is a reliable predictor of substance use, although effect sizes vary as a function of several methodological factors.

The relationship between motor programming and executive abilities: Constructs measured by the Push–Turn–Taptap task from the Behavioral Dyscontrol Scale–Electronic Version

The relationship between executive functioning and three components of motor programming (motor control, motor planning, and motor learning) was examined. Participants were 54 adults aged 18 to 68 years. Instruments included the Push-Turn-Taptap task from the Behavioral Dyscontrol Scale-Electronic Version and a battery of traditional neuropsychological measures. The results showed that, after controlling for age, processing speed, and motor speed, all three components of motor programming accounted for additional 12 to 19% of variance in executive functioning. Additionally, task complexity, but not task novelty, accounted for the relationship between executive functioning and motor learning and motor control, but not motor planning.

Profile of executive deficits in cocaine and heroin polysubstance users: common and differential effects on separate executive components

OBJECTIVES

Structure of executive function was examined and we contrasted performance of substance dependent individuals (polysubstance users) and control participants on neuropsychological measures assessing the different executive components obtained. Additionally, we contrasted performance of polysubstance users with preference for cocaine vs heroin and controls to explore possible differential effects of the main substance abused on executive impairment.

METHODS

Two groups of participants were recruited: abstinent polysubstance users and controls. Polysubstance users were further subdivided based on their drug of choice (cocaine vs heroin). We administered to all participants a comprehensive protocol of executive measures, including tests of fluency, working memory, reasoning, inhibitory control, flexibility, and decision making.

RESULTS

Consistent with previous models, the principal component analysis showed that executive functions are organized into four separate components, three of them previously described: updating, inhibition, and shifting; and a fourth component of decision making. Abstinent polysubstance users had clinically significant impairments on measures assessing these four executive components (with effect sizes ranging from 0.5 to 2.2). Cocaine polysubstance users had more severe impairments than heroin users and controls on measures of inhibition (Stroop) and shifting (go/no go and category test). Greater severity of drug use predicted poorer performance on updating measures.

CONCLUSION

Executive functions can be fractionated into four relatively independent components. Chronic drug use is associated with widespread impairment of these four executive components, with cocaine use inducing more severe deficits on inhibition and shifting. These findings show both common and differential effects of two widely used drugs on different executive components.

The cerebral response during subjective choice with and without self-reference

The anterior medial prefrontal (AMPFC) and retrosplenial (RSC) cortices are active during self-referential decision-making tasks such as when participants appraise traits and abilities, or current affect. Other appraisal tasks requiring an evaluative decision or mental representation, such as theory of mind and perspective-taking tasks, also involve these regions. In many instances, these types of decisions involve a subjective opinion or preference, but also a degree of ambiguity in the decision, rather than a strictly veridical response. However, this ambiguity is generally not controlled for in studies that examine self-referential decision-making. In this functional magnetic resonance imaging experiment with 17 healthy adults, we examined neural processes associated with subjective decision-making with and without an overt self-referential component. The task required subjective decisions about colors-regarding self-preference (internal subjective decision) or color similarity (external subjective decision) under conditions where there was no objectively correct response. Results indicated greater activation in the AMPFC, RSC, and caudate nucleus during internal subjective decision-making. The findings suggest that self-referential processing, rather than subjective judgments among ambiguous response alternatives, accounted for the AMPFC and RSC response.

The neural implementation of multi-attribute decision making: a parametric fMRI study with human subjects

Decision making is not a unitary entity but involves rather a series of interdependent processes. Decisions entail a choice between two or more alternatives. Within the complex series of decisional processes, at least two levels can be differentiated: a first level of information integration (process level) and a second level of information interpretation (control level), leading to a subsequent motor response or cognitive process. The aim of this study was to investigate the neural network of these decisional processes. In a single trial fMRI study, we implemented a simple decision-making task, where subjects had to decide between two alternatives represented on five attributes. The similarity between the two alternatives was varied systematically in order to achieve a parametric variation of decisional effort. For easy trials, the two alternatives differed significantly in several attributes, whereas for difficult trials, the two alternatives differed only in small details. The results show a distributed neural network related to decisional effort. By means of time course analysis different subprocesses within this network could be differentiated: regions subserving the integration of the presented information (premotor areas and superior parietal lobe) and regions subserving the interpretation of this information (frontolateral and frontomedial cortex, anterior insula, and caudate) as well as a region in the inferior frontal junction updating task rules.

Altered adaptive but not veridical decision-making in substance dependent individuals

Drug addiction is associated with impaired judgment in unstructured situations in which success depends on self-regulation of behavior according to internal goals (adaptive decision-making). However most executive measures are aimed at assessing decision-making in structured scenarios, in which success is determined by external criteria inherent to the situation (veridical decision-making). The aim of this study was to examine the performance of Substance Abusers (SA, n = 97) and Healthy Comparison participants (HC, n = 81) in two behavioral tasks that mimic the uncertainty inherent in real-life decision-making: the Cognitive Bias Task (CB) and the Iowa Gambling Task (IGT) (administered only to SA). A related goal was to study the interdependence between performances on both tasks. We conducted univariate analyses of variance (ANOVAs) to contrast the decision-making performance of both groups; and used correlation analyses to study the relationship between both tasks. SA showed a marked context-independent decision-making strategy on the CB's adaptive condition, but no differences were found on the veridical conditions in a subsample of SA (n = 34) and HC (n = 22). A high percentage of SA (75%) also showed impaired performance on the IGT. Both tasks were only correlated when no impaired participants were selected. Results indicate that SA show abnormal decision-making performance in unstructured situations, but not in veridical situations.

Test–re-test reliability of the virtual planning test

PRIMARY OBJECTIVE

To determine test-re-test reliability of the virtual planning test (VIP), an executive functioning test of planning and organization, in a group of healthy young adults as a pre-cursor to determining the appropriateness of using the VIP with individuals with traumatic brain injury (TBI).

RESEARCH DESIGN

Single-group repeated measures design.

METHODS AND PROCEDURES

Seventy-five healthy university students were administered the VIP and the Hopkins Verbal Learning Test-Revised (HVLT-R) twice, with 6-8 weeks between each subject's two test sessions.

MAIN OUTCOMES AND RESULTS

VIP test-re-test reliability ranged from 0.194-0.489.

CONCLUSIONS

Knowing how well a healthy young adult performs the first time taking the VIP predicts little about how well that adult will perform the second time. However, given limitations of other tests of planning and organization and potential clinical benefits of the VIP, research of the test with individuals with TBI is warranted.

Functional neuroimaging and cognitive rehabilitation for people with traumatic brain injury

Cognitive deficits are a common consequence of traumatic brain injury. Although such deficits are amenable to rehabilitation, methods for individualizing cognitive interventions are still unrefined. Functional neuroimaging methods such as positron emission tomography and functional magnetic resonance imaging are emerging as possible technologies for measuring and monitoring the cerebral consequences of plasticity associated with brain injury and for evaluating the effectiveness of rehabilitation interventions. Functional neuroimaging may even enable more customized and efficient selection, design, or adaptation of individual cognitive rehabilitation programs. We review the current literature on functional neuroimaging after traumatic brain injury, relating these findings to cognitive rehabilitation. Overall, functional neuroimaging after traumatic brain injury has shown reliable differences in brain activity within several regions of frontal cortex, partly but not uniformly consistent with neuropsychological and structural findings in traumatic brain injury. We also outline a number of promising research opportunities for applying functional neuroimaging in traumatic brain injury settings, along with associated challenges.

Assessment of executive function in preschool-aged children

Assessment of the overarching self-regulatory mechanisms, or executive functions, in any age group is challenging, in part due to the complexity of this domain, in part due to their dynamic essence, and in part due to the inextricable links between these central processes and the associated domain-specific processes, such as language, motor function, and attention, over which they preside. While much progress has been made in clinical assessment approaches for measuring executive functions in adults and to some extent in adolescents and school-aged children, the toolkit for the preschool evaluator remains sparse. The past decade, however, has seen a substantial increase in attention to executive functions in very young children from a developmental neuropsychological perspective. With this has come a necessity for better, more specific, and more internally valid performance measures, many of which are now described in the experimental literature. Few such tasks, however, have adequately demonstrated psychometric properties for clinical application. We present two performance tasks designed to tap selective aspects of executive function in preschoolers that are emerging from the experimental laboratory and hold promise of appropriate reliability and validity for the clinical laboratory. Performance tests alone, however, are insufficient to develop a comprehensive picture of a child's executive functioning. Thus, we present a rating scale of preschoolers' executive function in the everyday context, and advocate a model of executive function assessment that incorporates both controlled performance tasks that target specific aspects of executive function and parent/teacher ratings that target more global aspects of self-regulation in the everyday context.

Patients with Right Frontal Lesions are Unable to Assess and Use Advice to Make Predictive Judgments

Frontal lobe damage impairs decision-making. Most studies have employed gambling and probabilistic tasks, which have an emotional (reward-punishment) component and found that patients with ventromedial sector lesions have exceptional difficulty performing normally on these tasks. We have recently presented an economic decision-making task to patients and normal volunteers that required them to not only forecast an economic outcome but also to weigh advice from four advisors about the possible outcome across 40 trials. We studied 20 patients with right frontal lobe lesions and 9 patients with parietal lobe lesions and compared their performance to 20 matched controls. Frontal lobe lesion patients were inconsistent at using advice and their forecasts were poor. Patients with dorsolateral but not orbito-frontal lesions showed some ability to assess advice. Patients with parietal lobe lesions were good at assessing advice but were slow at doing so; they were consistent but poor at using advice and their use of advice was unrelated to their forecasting. All three patient groups were overconfident in their own performance. In contrast, controls could both use and assess advice, their ability to use advice was mediated by their ability to assess it, and they were not overconfident. Group differences on an overall measure of accuracy on this task were associated with an ability to accurately plan. Differences in ability to assess and forecast were associated with planning and working memory performance. These findings indicate that patients with both right dorsolateral and orbito-frontal lesions may be impaired when required to make complex decisions related to forecasting and judgment. Our findings enlarge the scope of decision-making deficits seen in patients with frontal lobe lesions and indicate additional circumstances in which patients with frontal lobe lesions will have difficulty in deciding.

Visual and anticipatory bias in three cortical eye fields of the monkey during an adaptive decision-making task

To examine the role of three cortical eye fields during internally guided decision-making processes, we recorded neuronal activities in the frontal eye field (FEF), supplementary eye field (SEF), and lateral intraparietal cortex (LIP) using a free-choice delayed saccade task with two synchronized targets. Although the monkeys must perform the task in a time-locked manner, they were free to choose either the receptive field (RF) target or the nonreceptive field (nRF) target to receive reward. In all three areas we found neurons with stronger activation during trials when the monkey was going to make a saccade to the RF target (RF trials) than to the nRF target (nRF trials). Modulation occurred not only during target presentation (visual bias) but also before target presentation (anticipatory bias). The visual bias was evident as an attenuated visual response to the RF stimulus in nRF trials. The anticipatory bias, however, was seen as an enhancement of pretarget activity in the RF trials. We analyzed the activity during the 500 msec before target presentation and found that 22.5% of FEF and 31.3% of LIP neurons and 49.1% of SEF neurons showed higher activity during the RF trials. To more accurately determine when each neuron started to show preferential activity, we used a new inverse interspike interval analysis procedure. Our results suggest that although all three cortical eye fields reflect attentional and intentional aspects of sensorimotor processing, SEF plays an earlier and perhaps more cognitive role in internally guided decision-making processes for saccades.

Behavioral Aspects of Frontal Lobe Epilepsy

There is growing interest in disorders of behavior, personality, and mood associated with focal epilepsies, though the neuropsychological and behavioral or psychiatric aspects of epilepsy have usually been treated separately. The causes of behavioral disorders in patients with focal epilepsies are multifactorial, though the positive effects of seizure control on behavior suggest that state dependency is a major contributing factor. Patients with temporal lobe epilepsy manifest depression, anxiety, neuroticism, and social limitations, as well as impaired memory. By contrast, studies of cognitive function in patients with frontal lobe epilepsy show executive dysfunctions in response selection/initiation and inhibition, as well as cognitive impairment, hyperactivity, conscientiousness, obsession, and addictive behaviors.