A selective and critical review of neuropsychological deficits and the frontal lobes

Presumptions about the functions of the frontal lobes, and the sensitivity and specificity of certain tests to measure frontal lobe functions, are having a substantial influence on both clinical and research conclusions. In this paper the authors examine the details of the studies that have contributed to these presumptions, and find that the evidence to support these conclusions is weak. A detailed evaluation of the evidence relating to the Wisconsin Card Sorting Test and the Thurstone Word Fluency Test is also presented. Finally, the development of the belief that frontal lobe functions can be specifically measured is reviewed. The authors of this paper conclude that the bewildering array of deficits attributed to frontal lesions still seems to prevail.     

Regulate to facilitate: A scoping review of prefrontal asymmetry in sport and exercise

BackgroundPrefrontal asymmetry (PFA) describes the relative activity of the right PFC compared to the left PFC. It has been shown that PFA is associated with affective and motivational variables in several contexts, including sport and exercise. Considering the significant roles of affect and motivation in different performance settings, PFA might also be an important indicator of athletic performance. However, the relevance of PFA in the sport and exercise setting has not yet been addressed in its entirety. Instead, previous systematic reviews have solely focused on affective variables. Mapping out the complex interactions between PFA and affective, motivational as well as performance variables could help to understand what determines successful athletic performance as well as the positive psychological effects associated with exercise.ApproachScientific databases were searched for quantitative studies in English language published in international peer-reviewed journals. All 27 selected studies assessed physical activity and measured PFA in the brain locations F4-F3 and/or F8-F7 using electroencephalography.FindingsThe majority of the studies used a non-athlete sample (78%) and exercise types were diverse. While all studies focused on affective or motivational processes, 19% also reported associations with performance. Even though findings are inconsistent, they support the assumption that PFA plays a role in self-regulation.ConclusionThere is evidence for an involvement of PFA in affective, motivational and performance processes in the sport and exercise setting that can be interpreted as regulatory mechanisms. Future research on the underlying mechanisms is warranted, in particular, associations with motivational processes and performance need to be investigated more explicitly.     

EDITORIAL

The aim of the present study was to evaluate the usefulness of Barkley’s (1997a) model of inhibition and executive functioning in describing the deficits associated with Attention Deficit Hyperactivity Disorder (ADHD). Besides group differences, the present study addressed the question of independent effects of inhibition and the other executive functions in discriminating between children with ADHD and controls and how well, in terms of sensitivity and specificity, these measures can classify the children into the correct group. The results showed that children with ADHD differed significantly from controls with regard to measures of inhibition as well as all other executive function measures, except repetition of hand movements. In logistic regression models, three different measures tapping inhibition, working memory and emotion regulation were shown to be significant independent predictors of group membership. The sensitivity for these three variables as a set was 76.2, the specificity was 90.5, with a total of 86% of the sample correctly classified. When excluding the parental rating of emotion regulation, the overall classification rate decreased some, but was still relatively high in comparison with previous studies within this area of research.     

The egocentric reference for visual exploration and orientation

Clinical signs of damage to the egocentric reference system range from the inability to detect stimuli in the real environment to a defect in recovering items from an internal representation. Despite clinical dissociations, current interpretations consider all symptoms as due to a single perturbation, differentially expressed according to the medium explored (perceptual or representational). We propose an alternative account based on the functional distinction between two separate egocentric mechanisms: one allowing construction of the immediate point of view, the other extracting a required perspective within a mental representation. Support to this claim comes from recent results in the domain of navigation, showing that separate cognitive mechanisms maintain the egocentric reference when actively exploring the visual space as opposed to moving according to an internal map. These mechanisms likely follow separate developmental pathways, seemingly depend on distinct neural pathways and are used independently by healthy adults, reflecting task demands and individual cognitive style. Implications for spatial cognition and social skills are discussed.     

Frontal-Lobe Involvement in Spatial Memory: Evidence from PET,fMRI, and Lesion Studies

Many studies have identified the prefrontal cortex as the brain area that is critical for spatial memory, both in humans and in other primates. Other studies, however, have failed to establish this relation. Therefore, the aim of this paper was to review the literature regarding the role of the human prefrontal lobe in spatial memory. This was done by examining the evidence obtained from neuropsychological patients and from studies using brain-imaging techniques (PET and fMRI). Evidence supporting the notion that the prefrontal cortex is extensively involved in spatial working memory was found. The majority of these studies, however, suggests that frontal-lobe involvement is not related to the type of material that is being processed (e.g., spatial vs. nonspatial), but to process-specific functions, such as encoding and retrieval. Theoretically, these functions could be linked to the central executive within Baddeley's working-memory model, or to recent theories that emphasize the various processes that play a role in working memory. Also, methodological issues were discussed. Further research is needed to enhance our understanding of the precise interaction of domain-specific and general processes.     

Memory for action events: findings in neurological patients

Encoding action phrases by enacting leads normally to better memory performance than verbal encoding. In order to gain additional insight into the representational basis of the enactment effect, neurological patients are contrasted with healthy participants. Persons suffering from Parkinson's disease, which primarily impairs the motor system, and patients suffering from Frontal Lobe Syndrome, which primarily affects action-related planning processes, were involved. We investigated whether the enactment effect would be differentially affected by these disorders. In addition, the characteristics of information processing after encoding by enacting was analyzed by varying memory material (unrelated versus clusterable actions) and by adding an encoding condition that included obligatory action planning (director condition). The findings indicate that the impact of motor information for the enactment effect is not dominant compared to the role of action-related cognitive and motivational processes, in particular planning processes. The findings of the two experiments are explained within traditional conceptual memory theories.     

Learning new names for new objects: cortical effects as measured by magnetoencephalography

We tracked the evolvement of naming-related cortical dynamics with magnetoencephalography when five normal adults successfully learned names and/or meanings of unfamiliar objects. In all subjects, the learning of new names was associated with pronounced cortical effects. The learning effect was of long latency and emerged as a change of activation in the same cortical network that was active during naming of familiar items. In four out of five subjects, the cortical learning effect occurred in the inferior parietal lobe. In three of these subjects, the cortical effect was left-sided. These results suggest that the inferior parietal lobe plays an important role in the acquisition of novel words, presumably as a part of working memory systems.     

The nature and treatment of stuttering as revealed by fMRI A within- and between-group comparison

This article reviews some of our recent functional magnetic resonance imaging (fMRI) studies of stuttering. Using event-related fMRI experiments, we investigated brain activation during speech production. Results of three studies comparing persons who stutter (PWS) and persons who do not stutter (PWNS) are outlined. Their findings point to a region in the right frontal operculum (RFO) that was consistently implicated in stuttering. During overt reading and before fluency shaping therapy, PWS showed higher and more distributed neuronal activation than PWNS. Immediately after therapy differential activations were even more distributed and left sided. They extended to frontal, temporal, and parietal regions, anterior cingulate, insula, and putamen. These over-activations were slightly reduced and again more right sided two years after therapy. Left frontal deactivations remained stable over two years of observation, and therefore possibly indicate a dysfunction. After therapy, we noted higher activations in persons who stutter moderately than in those who stutter severely. These activations might reflect patterns of compensation. We discuss why these findings suggest that fluency-inducing techniques might synchronize a disturbed signal transmission between auditory, speech motor planning, and motor areas.

Educational objectives: The reader will learn about and be able to: (1) identify regions of brain activations and deactivations specific for PWS; (2) describe brain activation changes induced by fluency shaping therapy; and (3) discuss the correlation between stuttering severity and brain activation.     

Pragmatic communication skills in patients with Parkinson's disease

BACKGROUND: Pragmatic communication abilities may depend on intact frontal lobe systems. Independent evidence suggests that some persons with Parkinson's disease (PD) are impaired on measures of frontal lobe function. HYPOTHESIS: We therefore hypothesized in Study 1 that pragmatic communication skills would be impaired in some persons with PD and would be linked to frontal dysfunction in these patients. In Study 2 we hypothesized that PD patients would be unaware of their pragmatic communication deficits. METHODS: In Study 1 we administered tests of pragmatic abilities and frontal lobe functioning to twenty-two persons with Parkinson's disease (PD) and 10 healthy controls. In Study 2 we obtained self-ratings of pragmatic abilities from 11 PD patients and then checked these self-ratings against ratings of these same abilities by the patient's spouses. RESULTS: We found in Study 1 that patients with PD were: (a) significantly impaired on measures of pragmatic communication abilities, especially in the areas of conversational appropriateness, turn-taking, prosodics and proxemics, and that this impairment was significantly related to measures of frontal lobe function. In study 2 we found that PD patients overestimated their own abilities relative to spousal ratings of those abilities and thus were unaware of the extent of their problems with pragmatic social communication skills. CONCLUSION: We conclude that pragmatic social communication skills are impaired in PD and that this impairment may be related to frontal lobe dysfunction.