Individual differences in executive attention predict self-regulation and adolescent psychosocial behaviors

This study examined temperament, executive attention, parental monitoring and relationships, and involvement in pro- and antisocial behaviors in an ethnically diverse sample of adolescents. We sought to relate parent- and self-reported effortful control to performance on measures of executive attention and to better understand the relative contributions of individual-difference variables and environmental variables in predicting behaviors in adolescence. The results indicated a relationship between poor executive attention and mother-reported effortful control. Inclusion of individual-difference variables significantly increased prediction of problem-behavior scores, suggesting the importance of including such variables in studies of adolescent deviance.

Does each hemisphere monitor the ongoing process in the contralateral one?

The present study was conducted to examine hemispheric division of labor in the initial processing and error monitoring in tasks for which hemispheric specialization exists. We used lexical decision as a left hemisphere task and bargraph judgment as a right hemisphere task, and manipulated cognitive load. Participants had to respond to one of two stimuli presented to both visual fields and were instructed to correct their errors. To achieve enough correctable errors, participants were encouraged to respond quickly by using a bonus system. The results showed the classical asymmetry for initial responses in both tasks and reversed asymmetry for corrections in the bargraph task at both load conditions, and in the lexical decision task at the high load condition. The results suggest that each hemisphere monitors the ongoing process in the contralateral one and that the dissociation of initial process and its monitoring grows with load of task.

Relational integration and executive function in Alzheimer's disease

Executive functions depend on the ability to represent relations between objects and events, and the prefrontal cortex provides the neural substrate for this capacity. Patients with probable Alzheimer's disease (AD) and control participants were administered measures of working memory and reasoning that varied systematically in their relational complexity. AD patients showed impairment on reasoning measures that required the online integration of relations but performed as well as control participants on nonrelational items and items requiring the processing of only single relations. When AD patients were divided into subgroups based on their performance on relational reasoning measures, the subgroup that showed significant impairment on relational integration measures exhibited a neuropsychological profile consistent with prefrontal cortical dysfunction.

Executive dysfunctions in schizophrenia. Relationships to clinical manifestation

Studies suggest that executive functions in patients with schizophrenia are markedly impaired as compared with normal controls. Most previous studies employed tests of executive functions adopted from frontal lobe neuropsychological paradigms based on lesion studies. This study employed several more recently developed theory-driven tests of executive functions addressing the construct of the supervisory attentional system. We explore the pattern of executive function impairment using factor analysis and subsequently investigate the relationships between these executive function factors and the clinical features in a sample of chronic schizophrenic patients. A total of 51 patients with chronic schizophrenia were recruited. The Sustained Attention Response to Task (SART), Six Elements Test (SET) and Hayling Sentence Completion Test (HSC) were used to assess executive functions. Three factors were identified within the executive function tests: 1) The "semantic inhibition factor" comprised items in the HSC, 2) the "action/attention inhibition" factor comprised the SART commission error and the SET rule-breaking score and 3) the "output generation factor" comprised the SET raw score and the correct SART response. Significant relationships were found between these derived factors and clinical features after partialling out the confounding effect of age, education and illness duration. The three theory-based tests of executive function were shown to have good construct validity among the group of chronic schizophrenic patients.

Executive Functions Following Traumatic Brain Injury in Young Children: A Preliminary Analysis

To examine executive processes in young children with traumatic brain injury (TBI), we evaluated performance of 44 children who sustained moderate-to-severe TBI prior to age 6 and to 39 comparison children on delayed response (DR), stationary boxes, and spatial reversal (SR) tasks. The tasks have different requirements for holding mental representations in working memory (WM) over a delay, inhibiting prepotent responses, and shifting response set. Age at the time of testing was divided into 10- to 35- and 36- to 85-month ranges. In relation to the community comparison group, children with moderate-to-severe TBI scored significantly lower on indexes of WM/inhibitory control (IC) on DR and stationary boxes tasks. On the latter task, the Age x Group interaction indicated that performance efficiency was significantly reduced in the older children with TBI relative to the older comparison group; performance was similar in younger children irrespective of injury status. The TBI and comparison groups did not differ on the SR task, suggesting that shifting response set was not significantly altered by TBI. In both the TBI and comparison groups, performance improved with age on the DR and stationary boxes tasks. Age at testing was not significantly related to scores on the SR task. The rate of acquisition of working memory (WM) and IC increases steeply during preschool years, but the abilities involved in shifting response set show less increase across age groups (Espy, Kaufmann, & Glisky, 2001; Luciana & Nelson, 1998). The findings of our study are consistent with the rapid development hypothesis, which predicts that skills in a rapid stage of development will be vulnerable to disruption by brain injury.

Participation of the thalamofugal visual pathway in a coarse pattern discrimination task in an open arena

The purpose of this study was to examine the role of the thalamofugal pathway in far-field visual processing. Experiment 1 examined the role of the visual wulst and the ectostriatum in a far-field pattern discrimination task in a large open arena. Control pigeons, pigeons with ectostriatum lesions, and pigeons with wulst lesions were trained to discriminate between four patterns within the arena. Ectostriatum-lesioned pigeons were unimpaired and behaved similar to controls. By contrast, wulst-lesioned pigeons were severely impaired in the pattern discrimination task in the open arena and performed poorer than control pigeons and pigeons with ectostriatum lesions. Statistical analyses of regional contributions to the observed impairment identified the left visual wulst and bilateral hyperstriatum ventrale, which lies outside the wulst, as interesting areas. To ensure that the impairment was not due to a general learning deficit, experiment 2 involved training the pigeons in a pattern discrimination task carried out in an operant chamber, which presumably required use of near-field visual information. Wulst-lesioned pigeons were able to learn the task and performed at a level no different from control pigeons. The results of these experiments support the proposal that the wulst may be important for processing far-field information.

Hand movement distribution in the motor cortex: the influence of a concurrent task and motor imagery

The aim of this work was to study the relevance of the primary motor cortex (M1) for motor functions different to the simple execution of motor orders. The M1 activity during the performance with individual fingers of a simple motor task (tonic flexion), a motor task that includes a complex motor computation but not motor execution (motor imagery), and a motor task that involves both the computation and execution of movements (phasic movement) was evaluated by functional magnetic resonance imaging (fMRI). The possible influence of other cortical tasks on the M1 activation induced by finger movements was assessed by evaluating the effect of a distracting concurrent task (numeric calculation). Data show that both the dimension of the area activated and the intensity of response were higher during motor planning than during motor execution. There is a mosaic-like distribution for motor-planning M1 functions, with the movement of individual fingers being controlled from several M1 loci. The concurrent mental-task induces a rapid functional reconfiguration of M1, adding M1 subsets to motor programming but excluding others. Present data support the involvement of the M1 in more than just simple motor execution, showing broader and more intense modifications during motor tasks not accompanied by movements (motor imagery) than during the execution of simple motor acts (tonic flexion).

Differences in spatial learning comparing transgenic p75 knockout, New Zealand Black, C57BL/6, and Swiss Webster mice

Four strains of mice were compared regarding their relative abilities to solve the Morris water maze test of spatial memory. Members of the New Zealand Black (NZB) strain revealed steady improvement over the 6 days of training comparable to C57BL/6 mice. The neurotrophin low affinity receptor p75 knockout mouse, in which the binding region is rendered refractory to ligand, displayed profound deficits in the acquisition of this task. Members of the Swiss Webster strain performed intermediate between the poor performance of the p75 mice and the progressively improving learning curves of the NZB and C57 mice. The present results support the notion that interference with functioning of nerve growth factor (NGF) receptors on forebrain cholingergic neurons negatively impacts the animal's ability to utilize the spatial cues necessary for successful spatial navigation. This effect on NGF receptors was more behaviorally disrupting than the influence of neocortical and hippocampal ectopias as present in the NZB mice. These results support the use of the p75 knockout mouse as a model of forebrain cholinergic neuron dysfunction. On the other hand, these results do not support the use of the NZB mouse as an animal model of human learning disability and dementia.

Problem-solving ability in chronic schizophrenia. A comparison study of patients with traumatic brain injury

We tested the hypothesis that patients with schizophrenia are more prone to impairment in planning and problem-solving as compared with normal controls and patients with traumatic brain injury (TBI) by administering the Tower of Hanoi (TOH) task. A total of one hundred and fifty-three participants (51 in each group) were recruited. The performance of the patient groups was markedly worse than normal controls in terms of profile score, number of rule-breaking behaviour, and mean execution time. Two-way 3 (group) x 6 (complexity) ANOVAs indicated that significant main effects of group and complexity were observed in the number of moves, planning time to initiate the first move and subsequent execution time. The general performance of TOH in the schizophrenia group was very similar to that of the TBI group. Subsequent comparison of sub-groups of frontal and posterior lobe damage indicated the pattern of performance in schizophrenia patients lie between them. Taken together, these findings suggest that neither focal frontal nor temporal lobe damage is a sufficient explanation for the problem-solving deficits in patients with schizophrenia.

Dissociation in undergraduate students: disruptions in executive functioning

The concept of dissociation refers to disruptions in attentional control. Attentional control is an executive function. Few studies have addressed the link between dissociation and executive functioning. Our study investigated this relationship in a sample of undergraduate students (N = 185) who completed the Dissociative Experiences Scale and the Random Number Generation Task. We found that minor disruptions in executive functioning were related to a subclass of dissociative experiences, notably dissociative amnesia and the Dissociative Experiences Scale Taxon. However, the two other subscales of the Dissociative Experiences Scale, measuring depersonalization and absorption, were unrelated to executive functioning. Our findings suggest that a failure to inhibit previous responses might contribute to the pathological memory manifestations of dissociation.

The impact of problem structure on planning: insights from the Tower of London task

Despite the large number of behavioral and functional neuroimaging studies employing the Tower of London (ToL), the task's structural parameters and particularly their impact on planning have not been addressed so far. In this paper, we highlight the structural properties of ToL problems and provide evidence for their systematic and substantial effects on the cognitive processes involved in planning. In a problem set with three-move problems, the following structural parameters were experimentally manipulated: the ambiguity of goal hierarchy, the demand for subgoal generation, and the existence of suboptimal alternatives. Analysis of preplanning time as an indicator for the planning process revealed highly significant effects for all three parameters which seems to reflect differences in cognitive processing due to structural task properties. Therefore, we suggest that the common consideration of ToL problem difficulty solely in terms of the minimum number of moves is not sufficient. Moreover, the applied problem sets should be more carefully selected and their structural parameters explicitly noted.

Dissociable concurrent activity of lateral and medial frontal lobe during negative feedback processing

External feedback on results of one's behavior guides flexible adaptation to changing environments. It has been suggested that the lateral and medial parts of the frontal lobe are responsible for cognitive and emotional functions, respectively. In the present fMRI study, multiple mental components evoked by the presentation of negative feedback were dissociated along the cognitive-emotional axis in set-shifting paradigms. The double dissociation of the concurrent feedback-related activity was observed in the right frontal lobe: the lateral frontal lobe was associated with the inferential component, whereas the medial frontal lobe was associated with the emotional component. However, among the multiple right lateral frontal regions, a region of interest (ROI) analysis indicated that the inferential component was not dominant in the region near the inferior frontal junction. The medial frontal activations were observed ventral and anterior to the presupplementary motor area, and dorsal and posterior to the anterior cingulate cortex. The double dissociation in the right frontal lobe suggests that the lateral and medial frontal lobe cooperatively but differentially contributes to the negative feedback processing, demonstrating the lateral-medial dichotomy of the frontal lobe functions suggested by previous neuropsychological studies. At the same time, the functional heterogeneity in the lateral and medial frontal lobe demands modifications of the traditional view of the functional organization of the frontal lobe.

Impaired Neuropsychological Functioning in Lead-Exposed Children

Neuropsychological functions were assessed in 174 children participating in a longitudinal study of low-level lead exposure. At age 5 1/2 years, children were administered the Working Memory and Planning Battery of the Cambridge Neuropsychological Testing Automated Battery. Measures of sociodemographic characteristics of the family, prenatal and perinatal risk, quality of caregiving and crowding in the home, and maternal and child intelligence were used as covariates to test the hypothesis that children with higher lifetime average blood lead concentrations would perform more poorly on tests of working memory, attentional flexibility, and planning and problem solving. The lifetime average blood lead level in this sample was 7.2 micrograms per deciliter (mug/dL; range: 0-20 mug/dL). Children with greater exposure performed more poorly on tests of executive processes. In both bivariate and multivariate analyses, children with higher lifetime average blood lead concentrations showed impaired performance on the tests of spatial working memory, spatial memory span, intradimensional and extradimensional shifts, and an analog of the Tower of London task. Many of the significant associations remained after controlling for children's intelligence test scores, in addition to the other covariates. These findings indicate that the effects of pediatric lead exposure are not restricted to global indexes of general intellectual functioning, and executive processes may be at particular risk of lead-induced neurotoxicity.

Effects of changing reward on performance of the delayed spatial win-shift radial maze task in pedunculopontine tegmental nucleus lesioned rats

Because it was designed to assess working memory, the delayed spatial win-shift (DSWS) radial maze task has been used to investigate the involvement of corticostriatal structures in executive processing. Excitotoxic lesions of the pedunculopontine tegmental nucleus (PPTg) produce profound deficits in performance of this task that are not accounted for by motor impairment. Thus, PPTg DSWS deficits are hypothesized to support a role for PPTg in complex cognitive processing. However, other studies indicate that the behaviour of PPTg lesioned rats varies depending on level of motivational excitement, assessed by the presence or absence of deprivation, or by manipulations of reward value. Since DSWS performance may also be affected by motivational dysfunction, the present experiment was conducted to examine the effects of post-surgical presentation of a more positive food reward (chocolate drops) on the DSWS retention performance of PPTg lesioned rats. Results confirmed a PPTg lesion deficit: lesioned rats made significantly more errors in both training and test phases, and made errors significantly earlier in their choice sequence in the test phase. Main effects of phase on number of errors indicated that the PPTg test phase deficit was not simply the result of a carry-over impairment from the training phase. PPTg rats receiving chocolate made significantly fewer errors than PPTg rats receiving food pellets. Results suggest that PPTg DSWS deficits are not the result of altered motivation or hedonic appreciation of reward value (or reward change) and therefore support the hypothesis of executive cognitive deficits in PPTg lesioned rats.

What is measured by verbal fluency tests in schizophrenia?

INTRODUCTION

Schizophrenia patients perform below the norm on verbal fluency tests. The causes for this are unknown, but defective memory, executive functioning and psychomotor speed may play a role.

METHOD

We examined 50 patients with schizophrenia and related disorders, and 25 healthy controls with a cognitive test battery containing tests for verbal memory, executive functioning and psychomotor speed, and a categorical fluency test.

RESULTS

Patients obtained significantly lower test results than the controls on most cognitive measures including the verbal fluency test. During the fluency test, they formed as many clusters, and switched as often between clusters as the controls did, but they generated fewer words per cluster. Interestingly, in the control group, fluency performance was predicted by memory and executive functioning, but not by psychomotor speed. In patients, verbal fluency was predicted by psychomotor speed, but not by memory or executive functioning.

DISCUSSION

We conclude that psychomotor speed could be a crucial factor in cognition, and its influence on cognitive test performance should be considered in schizophrenia research. Furthermore, these data illustrate the importance of qualitative analysis of cognitive impairments in schizophrenia patients, as traditional cognitive tests often only provide quantitative information.

Assessment of executive dysfunction during activities of daily living in schizophrenia

Many neuropsychological studies have described deficits of memory and executive functions in patients with schizophrenia, and the severity of these deficits seems to be determinant in predicting the community outcome of these patients [Schizophr. Bull. 26 (2000) 119]. However, neuropsychological evaluation does not provide valuable information about how the cognitive deficits directly affect daily living, that is, which cognitive deficit affects which behavior. The present study aimed at determining whether executive dysfunction in schizophrenia could be directly measured by analyzing three activities of daily living (ADL), in addition to assessing the ecological validity of commonly used neuropsychological tests. Within specific ADL (choosing a menu, shopping the ingredients, cooking a meal), the sequences of behaviors that have been performed by 27 control subjects and 27 patients with schizophrenia were both analyzed by using a preset optimal sequence of behavior. When compared with control subjects, patients with schizophrenia showed more omissions when choosing the menu, more sequencing and repetitions errors during the shopping task, and more planning, sequencing, repetition and omission errors during the cooking task. These behavioral errors correlated significantly with negative, but not with positive symptoms of the patients. Furthermore, they also correlated with the poor performances on executive neuropsychological tests, especially those sensitive to shifting and sequencing abilities, but not with memory tests. These results suggest that executive deficits in schizophrenia may specifically affect ADL and that such deficits can be quantitatively assessed with a behavioral scale of action sequences.

Development of orbitofrontal function: current themes and future directions

In recent years, an exciting thrust in the developmental research literature has been the focus on "executive" functions (EF). However, the emphasis has been on the more purely cognitive aspects of EF operative in abstract reasoning and problem solving-aspects associated mainly with dorsolateral frontal regions. Although the literature on adult neuropsychology has seen an emerging and growing interest in the study of processes more related to orbitofrontal cortex (OFC), including emotion and personality, research on the development of EF has lagged behind. This special issue of Brain and Cognition is intended to redress this imbalance by bringing together researchers who are studying the nature and development of orbitofrontal function from a wide variety of perspectives.

Task-specific recruitment of dorsal and ventral visual areas during tactile perception

Many studies have found that visual cortical areas are active during tactile perception. Here we used positron emission tomographic (PET) scanning in normally sighted humans to show that extrastriate cortical regions are recruited in a task-specific manner during perceptual processing of tactile stimuli varying in two dimensions. Mental rotation of tactile Forms activated a focus around the anterior part of the left intraparietal sulcus. Since prior studies have reported activity nearby during mental rotation of visual stimuli, this focus appears to be associated with the dorsal visual (visuospatial) pathway. Discrimination between tactile Forms activated the right lateral occipital complex, an object-selective region in the ventral visual (visual Form) pathway. Thus, tactile tasks appear to recruit cortical regions that are active during corresponding visual tasks. Activation of these areas in both visual and tactile tasks could reflect visual imagery during tactile perception, activity in multisensory representations, or both.

Comparing arithmetic and semantic fact retrieval: effects of problem size and sentence constraint on event-related brain potentials

Event-related potentials were recorded with 61 electrodes from 16 students who verified either the correctness of single-digit multiplication problems or the semantic congruency of sentences. Multiplication problems varied in size and sentence fragments in constraint. Both semantic and arithmetic incongruencies evoked a typical N400 with a clear parieto-central maximum. In addition, numerically larger problems (8x7), in comparison to smaller problems (3x2), evoked a negativity starting at about 360 ms whose maximum was located over the right temporal-parietal scalp. These results indicate that the arithmetic incongruency and the problem-size effect are functionally distinct. It is suggested that the arithmetic and the semantic incongruency effects are both functionally related to a context-dependent spread of activation in specialized associative networks, whereas the arithmetic problem-size effect is due to rechecking routines that go beyond basic fact retrieval.

Striatal dopamine and learning strategy-an (123)I-FP-CIT SPECT study

Patients with Parkinson's disease (PD) have difficulty in processing learning tasks that lack external guidelines and, consequently, necessitate the subjects to generate their own problem-solving strategy. While the contribution of striatal dopaminergic deficiency to PD-specific motor symptoms is well established, its role in the PD-characteristic deviant learning style remains unclear. The aim of this study was to assess the relation between striatal dopamine activity as revealed by single photon emission computed tomography (SPECT) with (123)I-FP-CIT, a ligand for the dopamine transporter (DaT), and type of learning strategy, as identified by the California Verbal Learning Task (CVLT) in 19 patients with probable PD. The results showed a robust inverse correlation between striatal dopamine DaT binding and the externally guided, serial learning strategy: the lower the DaT in caudate nucleus as well as in putamen, the more the patient group appeared to rely on externally structured learning. Additionally, a significant positive correlation was found between caudatal DaT activity and the internally generated, semantic learning strategy. Unlike these strategic learning characteristics, IQ equivalent and recall total score appeared to vary independently from striatal DaT availability.

CONCLUSION

our findings provide direct evidence that striatal dopaminergic activity is specifically involved in the regulation of strategic learning processes.

Brain lateralization of motor imagery: motor planning asymmetry as a cause of movement lateralization

Movement asymmetry in humans and animals is often considered as being induced by the brain lateralization of the motor system. In the present work, the hemispheric asymmetry for motor planning as a cause of behavioral lateralization was examined. This study was carried out on normal volunteers and patients suffering unilateral brain damage caused by a stroke. Motor planning was evaluated by using the motor imagery of hand movement, a mental representation of a motor pattern that includes its internal simulation but not its real execution. The present study shows marked similarities between virtual movement executed during motor imagery and real movements. Thus, performance time showed a high correlation between real and virtual movements in the following conditions: (1) during dominant and non-dominant hand movements; (2) in simple and complex motor tasks; (3) in young control subjects; (4) in stroke patients; and (5) control subjects aged-matched to stroke patients. Brain strokes increased the performance time in both real and virtual movements. Left-brain strokes decreased the velocity of the real movements in both hands, whereas right-brain strokes mainly disturbed movements in the left hand. A similar effect was observed for virtual movements, suggesting a left-brain dominance for motor planning in humans. However, two-handed movement tasks suggest a complex interaction during motor planning, an interaction that facilitates motor performance during mirror movements and delays motor execution during non-mirror movements.

BIS-BAS sensitivity and cardiac autonomic stress profiles

This study examined the relationship of sensitivities of Gray's behavioral inhibition system (BIS) and behavioral approach system (BAS) to cardiac autonomic stress responses during laboratory tasks among 65 healthy men (n=34) and women (n=31) aged 22-37 years. Carver and White's BIS-BAS scales were used to measure BIS and BAS sensitivities. We measured heart rate (HR), respiratory sinus arrhythmia, and preejection period during mental arithmetic, a reaction time task, and a speech task. Results revealed that BAS sensitivity was related to HR reactivity and parasympathetic withdrawal during the tasks, but was unrelated to baseline levels. BIS sensitivity was unrelated to both reactivity and baseline levels of all measures. Overall, our results suggest that the relationship of the BAS with cardiac reactivity seems to be mediated by the parasympathetic nervous system.

Serial position effects in HIV-infected injecting drug users

This study examined memory and serial position effects in HIV-positive injecting drug users (IDUs), HIV-negative IDUs, and nondrug using control participants. Exploratory analyses investigating a possible mediating role of executive functions with HIV infection, drug use, and memory were also performed. Control participants showed stronger primacy effects than did both HIV-positive and HIV-negative IDUs and also outperformed the drug using groups on all memory measures. Interestingly, analysis of the role of executive functions with HIV infection, drug use, and memory suggested that executive functioning may mediate the verbal memory deficits associated with HIV infection, but not those associated with IDU.

Self-representation: searching for a neural signature of self-consciousness

Human self-consciousness operates at different levels of complexity and at least comprises five different levels of representational processes. These five levels are nonconceptual representation, conceptual representation, sentential representation, meta-representation, and iterative meta-representation. These different levels of representation can be operationalized by taking a first-person-perspective that is involved in representational processes on different levels of complexity. We refer to experiments that operationalize a first-person-perspective on the level of conceptual and meta-representational self-consciousness. Interestingly, these experiments show converging evidence for a recruitment of medial cortical and parietal regions during taking a first-person-perspective, even when operating on different degrees of complexity. These data lend support for the speculative hypothesis, that there exist a neural signature for human self-consciousness that is recruited independent from the degree of representational complexity to be performed.

Relationship of affect recognition with psychopathology and cognitive performance in schizophrenia

The purpose of the present study was to explore the relationship between emotion perception and both psychopathology and cognitive functioning in a group of Greek patients with schizophrenia. Thirty-five patients with schizophrenia were assessed with computerized tests of emotion perception, using visual faces (Kinney's Affect Matching Test, KAMT), prosody (Affective Prosody Test, APT), and visual everyday scenarios (Fantie's Cartoon Test, FCT), as well as a facial recognition test (Kinney's Identity Matching Test, KIMT). The patients were also evaluated with the symptoms dimensions derived from the PANSS (positive, negative, cognitive, depression, and excitement) and a battery of neuropsychological tests measuring executive functions, attention, working memory, verbal and visual memory, visuospatial ability, and visual scanning/psychomotor speed. The three emotion perception and face recognition tests correlated significantly with each other. The KAMT was significantly related to the cognitive symptoms dimension of the PANSS and executive functions. The FCT was significantly related to level of education and attention. Finally, the APT was significantly related to the cognitive symptoms dimension, executive functions, and attention. Our findings regarding the significant relationships of affect perception, both facial and vocal, as well as in everyday scenarios, with several cognitive abilities support the notion that deficits in decoding affective information in schizophrenia could be attributed to impairment in more basic neurocognitive domains.