Frontal Damage Research Articles

Verbal self-regulation of impulsive behavior of persons with frontal lobe brain injury

A multiple-baseline across participants design was used to examine effects of a verbal self-regulatory procedure on direct measures of impulsivity associated with frontal lobe brain damage. Four young men participated in socially interactive group sessions with a therapist who (a) assisted the participants in selecting individualized instructions on how to behave, (b) provided participants with feedback on their correspondence between instructions and nonverbal behavior, and (c) gradually reduced assistance while participants maintained self-monitoring. Results show that the verbal self-regulation was efficacious in reducing impulsive behavior to clinically significant levels during the group sessions, although effects with 1 participant were variable.

Updating and inhibition processes in working memory: A comparison between Alzheimer’s type dementia and frontal lobe focal damage

A large debate has recently focused on the componential nature of the working-memory system ( Baddeley, 1986), as evidenced by functional-imaging studies and by using more sophisticated experimental paradigms. The present work aims at further disentangling the role and effects of central executive (CE) and of phonological loop (PL). It is suggested that maintaining active verbal information mostly relates to an intact PL, while the inhibition of interfering information preponderantly involves the CE. To distinguish these effects, two groups of brain damaged patients were administered with an updating task. Frontal lobe patients showed major difficulties in inhibiting interfering information, an ability requiring an involvement of the CE component. In contrast, Alzheimer’s dementia patients evidenced a relative impairment in maintaining relevant information, requiring the intervention of the PL.

Enhancing the Sensitivity of a Sustained Attention Task to Frontal Damage: Convergent Clinical and Functional Imaging Evidence

Despite frequent reports of poor concentration following traumatic brain injury, studies have generally failed to find disproportionate time-on-task decrements using vigilance measures in this patient group. Using a rather different definition, neuropsychological and functional imaging research has however linked sustained attention performance to right prefrontal function – a region likely to be compromised by such injuries. These studies have emphasized more transitory lapses of attention during dull and ostensibly unchallenging activities. Here, an existing attention measure was modified to reduce its apparent difficulty or ‘challenge’. Compared with the standard task, its capacity to discriminate traumatically head-injured participants from a control group was significantly enhanced. Unlike existing functional imaging studies, that have compared a sustained attention task with a no-task control, in study 2 we used positron emission tomography to contrast the two levels of the same task. Significantly increased blood flow in the dorsolateral region of the right prefrontal cortex was associated with the low challenge condition. While the results are discussed in terms of a frontal system involved in the voluntary maintenance of performance under conditions of low stimulation, alternative accounts in terms of strategy application are considered.

Ventromedial frontal cortex mediates affective shifting in humans: evidence from a reversal learning paradigm.

How do the frontal lobes support behavioural flexibility? One key element is the ability to adjust responses when the reinforcement value of stimuli change. In monkeys, this ability--a form of affective shifting known as reversal learning--depends on orbitofrontal cortex. The present study examines the anatomical bases of reversal learning in humans. Subjects with lesions of the ventromedial prefrontal cortex were compared with a group with dorsolateral frontal lobe damage, as well as with normal controls on a simple reversal learning task. Neither form of frontal damage affected initial stimulus-reinforcement learning; ventromedial frontal damage selectively impaired reversal learning.

Modeling ADHD-type arousal with unilateral frontal cortex damage in rats and beneficial effects of play therapy

It has been recently shown that human adolescents with Attention Deficit/Hyperactivity Disorder (ADHD) have frontal lobe deficits, especially on the right sides of their brains ( Castellanos et al., 1996). ADHD is commonly treated with psychostimulants which may have adverse consequences. Hence, less invasive therapies need to be developed. In the present work, we tested the ability of right frontal lesions to induce hyperactivity in rats. We also evaluated the effects of chronic play therapy during early adolescence to reduce both hyperactivity and the elevated playfulness later in development. Play therapy was able to reduce both hyperactivity and excessive playfulness. In additional work, we found that access to rough-and-tumble play in normal animals could enhance subsequent behavioral indices of behavioral inhibition (i.e., freezing in response to a startle stimulus) that appeared to be independent of increased fearfulness and fatigue. Overall, these results suggest that (1) neonatal frontal lobe lesions can be used as an animal model of the overactivity in ADHD and (2) rough-and-tumble play therapy may be a new useful treatment for ADHD.

Impact of a unilateral brain lesion on cortisol secretion and emotional state: anterior/posterior dissociation in humans

The main goal of this study was to evaluate whether a unilateral brain lesion in a human population is associated with a modification of the circadian cortisol secretion profile, and/or patient’s emotional state. The second goal of this study was to assess whether there would be differences in both the pattern of cortisol secretion and emotional state in brain-damaged patients as a function of side of lesion, and localization (anterior vs posterior) of lesion. Eight patients with a left cortical lesion, six patients with a right cortical lesion, four patients with basal ganglia lesions (2 left and 2 right) and ten healthy volunteers were evaluated daily on measures of salivary cortisol levels and subjective feelings of joy and sadness at 0700, 1200, 1600 and 1900 hours over a 15-day period. Patients with cortical brain lesions presented higher cortisol levels and higher scores of sadness at the time of the morning peak (7:00 am), when compared to healthy volunteers and patients with basal ganglia lesions. Laterality of the lesion was not related to cortisol secretion, but frontal damage (anterior lesion) was associated with higher cortisol levels at the time of the morning peak (7:00 am) when compared to more posterior damage. There was no significant correlation between basal circulating levels of cortisol and emotional states in patients and healthy subjects. The results of this study suggest that hypothalamic–pituitary–adrenal (HPA) axis dysregulation is associated with unilateral injury particularly in frontal areas. These results, obtained in a human population, go along with recent animal studies reporting an implication of frontal regions in HPA activity.

A meta-analytic review of the sensitivity of the Wisconsin Card Sorting Test to frontal and lateralized frontal brain damage.

The author conducted 2 meta-analyses on the Wisconsin Card Sorting Test (WCST). The 1st compared participants with frontal lobe damage to those with posterior brain damage, whereas the 2nd compared participants with left and right frontal damage. Effect sizes based on the difference between groups were calculated for WCST variables and a composite measure. Effect sizes for these variables, except nonperseverative errors, indicated significantly poorer performance for participants with frontal damage. There were no significant differences for the left versus right comparisons. Moderator analyses using the composite measure for the frontal versus nonfrontal analyses indicated that the largest effect size was for dorsolateral damage. Though this study indicates that the WCST is sensitive to frontal lobe damage, caveats are discussed.

Distractibility during selection-for-action: differential deficits in Huntington’s disease and following frontal lobe damage

Selective attention can be measured through analysis of errors and reaction time (RT) for trials in which targets are presented alone compared with trials in which targets and distractors are presented. This study investigated selective attention using a reaching task, in which subjects made rapid reaches to targets. Thirty-seven patients with lesions of the prefrontal cortex (PFC) were compared with 19 healthy age- and IQ-matched volunteers and 18 patients with early-stage Huntington’s disease (HD), a neurodegenerative disease primarily affecting the basal ganglia. It was hypothesised that, if fronto-striatal circuits as a whole support selection-for-action, then the pattern of behavioural performance of both patient groups would be similar. Alternatively, if the functional roles of PFC and basal ganglia in selection-for-action are dissociable, then two different patterns would emerge. It was found that that both HD and frontal groups were significantly more distractible than controls for RT, but they had a different pattern of errors. Frontal patients made significantly more touches of the distractor location itself than did controls, while this was not the case for HD. It is argued that a reactive- inhibition mechanism, required in the circumstance of strong distractor activation, is affected by frontal damage, while a lateral- inhibition mechanism, invoked during the recruitment of selective attention, is affected in HD. Additionally, there were significant correlations between the degree of distractibility for RT and the extent of lateral PFC damage, and between cue-generated preparation and lateral PFC damage, thus highlighting the critical importance of lateral, rather than orbital or medial, PFC for attention to action.

Frontal syndrome and disorders of executive functions.

The study of executive functions began with the early description of behavioural disorders induced by frontal damage. The development of experimental neuropsychology has led to the description of a large variety of cognitive disorders. Such approach has generated numerous tests that are used in clinical practice. More recently, theoretical approaches have proposed an organisation of executive processes and have documented the diversity of executive functions and related anatomy. These studies have deeply influenced the clinical approach, the assessment and the diagnosis of planning and executive disorders. For clinical practice, these data have favoured specific assessment of some key behavioural and cognitive deficits based on a battery of tests.

Estudio neuropsicológico de la enfermedad de Huntington en familias de Antioquia, Colombia

Various neuropsychological studies have been conducted to determine the cognitive functioning of patients with Huntington s disease and their results have shown that the pattern of cognitive decline is thought to be typical of a frontal subcortical dementia. To determine if significant differences exist between the cognitive performances of a group diagnosed with Huntington s disease and a group of healthy, at risk relatives on a series of neuropsychological tests, and to examine the extent to which the Huntington group s cognitive performance profile corresponds to frontal subcortical damage as reported in other studies. The sample was comprised of a group of 18 subjects with a clinical diagnosis of initial stage Huntington s disease and a group of 15 healthy relatives at risk for Huntington s disease. A battery of tests (the CERAD) and additional neuropsychological tests were administered to all subjects. Compared to the at risk group, the Huntington s disease group scored significantly lower on 85.41% of the tests. The neuropsychological tests utilized in this study were useful to discriminate between diagnosed and at risk groups. The Huntington s disease group s global neuropsychological profile was similar to that of a frontal subcortical dementia in which the predominant features include executive functioning deficits, memory problems, visuo constructive alterations, attention deficits, verbal fluency problems and naming deficits.

Frontal Cortex as the Central Executive of Working Memory: Time to Revise Our View

For historical reasons (Bianchi, 1895; Harlow, 1968; Luria, 1966; Shallice, 1982), a specific link between the central executive of working memory and the frontal cortex was originally suggested by Baddeley (1986). This review discusses the evidence against such a univocal link. Two executive processes investigated in neuropsychology are discussed: inhibition (WCST, Stroop, proactive interference, go-no go, Stop signal and the Hayling test) and dual-task management. The evidence reviewed demonstrates (i) that executive processes involve links between different brain areas, not exclusively with the frontal cortex, (ii) that patients with no evidence of frontal damage present with executive deficits, and (iii) that patients with frontal lesions do not always show executive deficits. In conclusion, this review suggests that it is time for a more dynamic and flexible view of the neural substrate of executive processes to be considered. It also confirms, as recently suggested by Baddeley (1996, 1998a, 1998b), that the study of frontal patients cannot be used as a primary source of evidence to understand CE functions.

The Executive Brain: Frontal Lobes and the Civilized Mind

The Executive Brain: Frontal Lobes and the Civilized Mind

Word Retrieval Learning Modulates Right Frontal Cortex in Patients with Left Frontal Damage

Previous studies have suggested that recovery or compensation of language function after a lesion in the left hemisphere may depend on mechanisms in the right hemisphere. However, a direct relationship between performance and right hemisphere activity has not been established. Here, we show that patients with left frontal lesions and partially recovered aphasia learn, at a normal rate, a novel word retrieval task that requires the damaged cortex. Verbal learning is accompanied by specific response decrements in right frontal and right occipital cortex, strongly supporting the compensatory role of the right hemisphere. Furthermore, responses in left occipital cortex are abnormal and not modulated by practice. These findings indicate that frontal cortex is a source of top-down signals during learning.

The neural correlates of grammatical gender: an fMRI investigation.

In an fMRI experiment, subjects saw a written noun and made three distinct decisions in separate sessions: Is its grammatical gender masculine or feminine (grammatical feature task)? Is it an animal or an artifact (semantic task)? Does it contain a /tch/ or a /k/ sound (phonological task)? Relative to the other experimental conditions, the grammatical feature task activated areas of the left middle and inferior frontal gyrus and of the left middle and inferior temporal gyrus. These activations fit in well with neuropsychological studies that document the correlation between left frontal lesions and damage to morphological processes in agrammatism, and the correlation between left temporal lesions and failure to access lexical representations in anomia. Taken together, these data suggest that grammatical gender is processed in a left frontotemporal network. In addition, the observation that the grammatical feature task and the phonology task activated neighboring but distinct regions of the left frontal lobe provides a plausible neuroanatomical basis for the systematic occurrence of phonological errors in aphasic subjects with morphological deficits.

Theory of mind in patients with frontal variant frontotemporal dementia and Alzheimer's disease: theoretical and practical implications.

A key aspect of social cognition is the ability to infer other people's mental states, thoughts and feelings; referred to as 'theory of mind' (ToM). We tested the hypothesis that the changes in personality and behaviour seen in frontal variant frontotemporal dementia (fvFTD) may reflect impairment in this cognitive domain. Tests of ToM, executive and general neuropsychological ability were given to 19 fvFTD patients, a comparison group of Alzheimer's disease patients (n = 12) and matched healthy controls (n = 16). Neuropsychiatric assessment was undertaken using the Neuropsychiatric Inventory (NPI). Patients with fvFTD were impaired on all tests of ToM (first-order false belief; second-order false belief; faux pas detection; and Reading the Mind in the Eyes), but had no difficulty with control questions designed to test general comprehension and memory. By contrast, the Alzheimer's disease group failed only one ToM task (second-order false belief), which places heavy demands on working memory. Performance on the faux pas test revealed a double dissociation, with the fvFTD group showing deficits on ToM-based questions and the Alzheimer's disease group failing memory-based questions only. Rank order of the fvFTD patients according to the magnitude of impairment on tests of ToM and their degree of frontal atrophy showed a striking concordance between ToM performances and ventromedial frontal damage. There was a significant correlation between the NPI score and more sophisticated tests of ToM in the fvFTD group. This study supports the hypothesis that patients with fvFTD, but not those with Alzheimer's disease, are impaired on tests of ToM, and may explain some of the abnormalities in interpersonal behaviour that characterize fvFTD.

Order and Disorder in Everyday Action: the Roles of Contention Scheduling and Supervisory Attention

This paper describes the contention scheduling/supervisory attentional system approach to action selection and uses this account to structure a survey of current theories of the control of action. The focus is on how such theories account for the types of error produced by some patients with frontal and/or left temporoparietal damage when attempting everyday tasks. Four issues, concerning both the theories and their accounts of everyday action breakdown, emerge: first, whether multiple control systems, each capable of controlling action in different situations, exist; second, whether different forms of damage at the neural level result in conceptually distinct disorders; third, whether semantic/conceptual knowledge of objects and actions can be dissociated from control mechanisms, and if so what computational principles govern sequential control; and fourth, whether disorders of everyday action should be attributed to a loss of semantic/conceptual knowledge, a malfunction of control, or some combination of the two.

Emotional and cognitive processing in empathy and moral behavior

Within the perception-action framework, the underlying mechanisms of empathy and its related processes of moral behavior need to be investigated. fMRI studies have shown different frontal cortex activation patterns during automatic processing and judgment tasks when stimuli have moral content. Clinical neuropsychological studies reveal different patterns of empathic alterations after dorsolateral versus orbital frontal cortex damage, related to deficient cognitive and emotional processing. These processing streams represent different neural levels and mechanisms underlying empathy.

Odor discrimination in patients with frontal lobe damage and Korsakoff’s syndrome

The involvement of the frontal cortex and thalamic nucleus in odor discrimination in humans was assessed. Six patients with frontal lobe brain damage, seven patients with alcoholic Korsakoff’s syndrome and 16 healthy comparison subjects completed odor detection and odor discrimination tasks. Multivariate general linear modeling with age as a covariant revealed significantly decreased odor discrimination ability in frontal lobe damaged patients and marginally decreased odor discrimination ability in Korsakoff’s syndrome patients as compared to the healthy comparison subjects. No deficits were found in odor detection ability. The findings suggest that in human odor discrimination, there is more involvement of cortico-cortical pathways than of thalamo-cortical pathways.

SRT lengthening: role of an alertness deficit in frontal damaged patients

Numerous studies have documented the lengthening of reaction time (RT) following brain damage. However, the origin of response retardation and its anatomical basis still remain unknown. This study assessed simple RT (SRT) and choice RT (CRT) in patients with frontal or posterior damage. It showed (i) that RTs were longer in frontal damaged patients; (ii) with a constant response retardation across SRT and CRT tests; (iii) that minimum and percentile 25th SRTs of the frontal group were within normal ranges, indicating that they were able to produce fast responses; (iv) that percentiles 50 and 75th SRTs of the frontal group were longer, indicating that they produced a lower proportion of fast responses; (v) an interpretation supported by the decrement of the peak of SRT distribution. Such a pattern is highly suggestive of a disorder of an attentional process required to trigger the same response as fast as possible throughout the test. According to Posner’s model of attention, this function is devoted to the alerting network and the present study supports the key role of the frontal lobes for alertness.

Quantitive imaging in late traumatic brain injury. Part I: late imaging parameters in closed and penetrating head injuries

Objective : To ascertain the value of relatively simple quantitative radiologic measurements after head injury. Despite major advances in neuroradiology, analysis and reporting of imaging studies is based primarily on individual subjective and local experience, rather than on reproducible, standardized parameters; reliance on newer technologies can improve care, but also raises diagnostic costs. Design : Blinded, retrospective, quantitative assessment of computerized tomography studies done some 14 years post-injury. Outcome measures : Frontal horn width (FHW); septum-caudate distance (SCD); temporal horn width (THW); interuncal distance (IUD); third ventricle width (3VW); ventricular score (VS); sulcal width (SW); gray-white matter discriminability (GWMD) and subjective assessment of atrophy (SAOA). Results : Diffuse and frontal damage was noted in both closed (CHI) and penetrating (PHI) head injury groups. Enlargement of frontal lobe parameters (septum caudate distance and frontal horn width suggest frontal injury in both closed and penetrating traumatic brain injury (TBI). Temporal horn width and inter-uncal distance were related to VS, 3VW and FHW in closed, but not in penetrating head injury. Conclusions : Simple linear CSF space measurements are correlated with volumetric and parenchymal measures, and can represent valuable and reliable low-cost quantitative measures of long term brain damage after TBI.