Temporal and spatial context memory in patients with focal frontal, temporal lobe, and diencephalic lesions

Patients with focal frontal, temporal lobe, or diencephalic lesions were investigated on measures of temporal (recency) and spatial (position) context memory, after manipulating exposure times to match recognition memory for targets (pictorial stimuli) as closely as possible. Patients with diencephalic lesions from an alcoholic Korsakoff syndrome showed significant impairment on the temporal context (recency) task, as did patients with frontal lesions penetrating the dorsolateral frontal cortex, according to MRI (and PET) evidence. Patients with temporal lobe lesions showed only a moderate (non-significant) impairment on this task, and patients with medial frontal lesions, or large frontal lesions not penetrating the dorsolateral cortical margins, performed as well as healthy controls at this task. On the spatial context memory task, patients with lesions in the temporal lobes showed significant impairment, and patients with right temporal lesions performed significantly worse than patients with left temporal lesions. Patients with diencephalic lesions showed only a modest (non-significant) impairment on this task, and the frontal lobe group performed normally. When a group of patients with temporal lobe lesions resulting from herpes encephalitis were examined separately, an identical pattern of results was obtained, the herpes group being significantly impaired on spatial memory and showing a trend towards impairment for temporal context memory. There were strong correlations between anterograde memory quotients and context memory performance (despite the use of an exposure time titration procedure) and a weak association in the frontal group with one frontal/executive task [corrected] (card-sorting perservations). It is predicted that correlations between temporal context memory and frontal/executive tasks will be greater in samples of patients all of whom have frontal lesions invading the dorsolateral cortical margin.     

Cognitive planning in humans: neuropsychological, neuroanatomical and neuropharmacological perspectives

In recent years, considerable progress has been made in understanding the cognitive and neuroanatomical basis of high-level planning behaviour through a combination of neuropsychological, neuropharmacological and functional neuroimaging approaches. In this article, early evidence suggesting a relationship between planning impairments and damage to the frontal lobe is reviewed and several contemporary studies of planning behaviour in patients with circumscribed frontal lobe excisions are described in detail. These neuropsychological investigations, together with recent functional neuroimaging studies of normal control subjects, have identified a specific area within the mid-dorsolateral frontal cortex of humans which appears to be critically involved in the cognitive processes that mediate efficient planning. The functions of this region, both in cognitive planning and in related functions such as working memory, are then discussed in the context of a general theoretical framework for understanding the functional organization of "executive" processes within the human lateral frontal cortex. In the final sections, the relationship between the planning deficits observed after intrinsic frontal lobe damage and those exhibited by patients with neuropathology of primarily sub-cortical origin, such as Parkinson's disease, is discussed. A central model for much of this work has been the concept of cortico-striatal circuitry which emphasizes the relationship between the neocortex and the striatum. The combined evidence from comparative studies in patients and from functional neuroimaging studies on Parkinson's disease suggests that altered cortico-striatal interactions may disrupt normal planning function at a number of levels, possibly consequent upon intrinsic striatal pathology on the one hand and the partial loss of (frontal) cortical input to the basal ganglia on the other.     

Assessment of the dysexecutive syndrome in schizophrenia

BACKGROUND: Cognitive neuropsychological theories hypothesize a role for frontal lobe executive deficits in the aetiology of schizophrenic symptoms. The study examined the performance of a schizophrenic group on the Behavioural Assessment of the Dysexecutive Syndrome (BADS; Wilson et al. 1996), a test battery which assesses the 'everyday' difficulties associated with the dysexecutive syndrome. Performance of the schizophrenics was contrasted with that of brain injured and healthy volunteer groups. METHODS: Matched groups of 31 schizophrenic patients, 35 patients with brain injuries and 26 healthy volunteers were administered the BADS. Patients were also given tests of general intelligence and memory. Patients and their relatives/carers also completed a questionnaire rating day-to-day failures of executive functioning. RESULTS: Schizophrenic and brain-injured patients showed impairment on the BADS, compared to healthy controls. There were no significant differences between the two patient groups. Significant impairment was found in a subgroup of 16 schizophrenics who showed otherwise intact general intellectual functioning, suggesting the existence of a specific executive deficit. Among the schizophrenic patient group there was evidence of a dissociation between executive and memory impairments. A significant correlation existed between performance on the BADS and relatives ratings of executive problems for the brain injured group, but not for the schizophrenic group. CONCLUSIONS: The BADS is a useful tool for identifying executive deficits in people with a diagnosis of schizophrenia, especially those who are otherwise generally intellectually intact. This is particularly important in the context of rehabilitation and community transition programmes.     

Overestimation and unreliability in "feeling-of-doing" judgements about temporal ordering performance: impaired self-awareness following frontal lobe damage

"Feeling-of-doing" accuracy in a temporal ordering task in 33 patients with frontal lobe lesions and a matched control group was investigated. The temporal ordering task used word lists that had high, medium, or no semantic interrelatedness. Patients with frontal lobe lesions showed an impairment in temporal ordering across all three word lists. Both groups performed better on the lists with higher semantic interrelatedness. Patients with frontal lobe lesions overestimated their ability to order words accurately. On the less semantically interrelated lists, metamemory judgment in patients with frontal lesions did not correlate with their performance. These results indicate that both temporal order judgment and metacognitive decisions about temporal order judgment are subserved by the prefrontal cortex and further clarifies the role of the frontal lobes in behavioral monitoring.     

Differentiating among prefrontal substrates in psychopathy: Neuropsychological test findings.

Frontal lobe and consequent executive dysfunction have long been related to psychopathy. More recently, there have been suggestions that specific regions of frontal cortex, rather than all of frontal cortex, may be implicated in psychopathy. To examine this issue, the authors presented 25 individuals with psychopathy and 30 comparison individuals with measures preferentially indexing the orbitofrontal cortex (OFC; object alternation task), dorsolateral prefrontal cortex (DLPFC; spatial alternation task), and anterior cingulate cortex (ACC; number-Stroop reading and counting tasks). The individuals with psychopathy showed significant impairment on the measure preferentially sensitive to OFC functioning. In contrast, the 2 groups did not show impairment on the measures preferentially sensitive to the functioning of the DLPFC or ACC. These results are interpreted with reference to executive dysfunction accounts of the disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Midlife aging, open-ended planning, and laboratory measures of executive function.

The frontal lobes show early signs of structural and functional change in the course of adult aging. The 1st study of the current article examined whether midlife aging influences open-ended planning, a skill that is particularly sensitive to frontal lobe damage. There were no midlife declines in the ability to carry out variants of the T. Shallice and P. Burgess (1991) Six Elements and Multiple Errands Tests. Younger adults were more likely to break individual task rules. In a 2nd experiment, middle-aged adults performed worse than young adults did on laboratory executive tests sensitive to frontal lobe damage—Self-Ordered Pointing and the Wisconsin Card Sorting Test (N. M. Fristoe, T. A. Salthouse, & J. L. Woodard, 1997). In spite of changes in novel executive test performance, real-world executive skills appear to be spared in midlife aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dopamine-dependent frontostriatal planning deficits in early Parkinson's disease.

Three groups of medicated and nonmedicated patients at different stages of Parkinson's disease and a group of neurosurgical patients with localized frontal lobe excisions were assessed on 2 novel tests of planning and spatial working memory. Results demonstrate that, like other tests of frontal lobe dysfunction, planning and spatial working memory are vulnerable in nonmedicated patients with mild Parkinson's disease and suggest that certain aspects of the planning impairment in these patients may be ameliorated by dopaminergic therapy. Specifically, with medication there was an improvement in accuracy of planning, but not in latency, in a series of problems based on the Tower of London test of planning. The results in terms of the frontostriatal, dopamine-dependent nature of some of the cognitive deficits found in early Parkinson's disease versus the apparent dopamine-independent nature of deficits in other cognitive processes are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Frequency judgements of abstract designs by patients with diencephalic, temporal lobe or frontal lobe lesions

Patients with diencephalic, temporal lobe or frontal lobe lesions were compared with healthy controls on a frequency judgement task. The three patient groups were disproportionately impaired at estimating how often a series of abstract designs had been presented relative to controls. Diencephalic and temporal lobe patients did not differ from each other. It is argued that the results may reflect a 'core' memory deficit in the temporal lobe patients. The impairment in the frontal patients may reflect their difficulty in making an organised search in memory for multiple traces of an item, while the deficit shown by the diencephalic patients (particularly those with Korsakoff syndrome) may be due to the combined effects of a generally poor memory and superimposed frontal pathology.     

Neuropsychological correlates of short-term memory distractor tasks among patients with surgical repair of anterior communicating artery aneurysms.

The relative utility of the visual consonant trigram (VCT) and release from proactive inhibition (PI) versions of the short-term memory (STM) distractor task in investigating the separate but related cognitive realms of memory and executive frontal lobe functioning were explored in patients with anterior communicating artery (ACoA) aneurysms n?=?24. Compared with normal controls n?=?19, ACoA patients were impaired on clinical measures of memory and on measures of executive functioning, including concept formation and fluent word generation. Furthermore, ACoA patients were impaired on the VCT task but not on the release-from PI task, indicating a differential sensitivity of these tasks to the impairment manifested by ACoA patients. Regression modeling indicated that the VCT and release-from-PI tasks were closely associated with clinical memory tests, although the release-from-PI-task was also associated with fluency, an executive functioning domain. In general, our results fail to support the broad generalization that impaired performance on STM distractor tasks is necessarily symptomatic of frontal lobe dysfunction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence for executive dysfunction in autism

A group of young people with autism (ranging in ability from high functioning to moderately learning disabled), and ability-matched control groups of (i) non-autistic individuals with moderate learning disabilities, and (ii) normally developing children, were presented with two tests of executive function: the Intra-dimensional/Extra-dimensional set-shifting task and the Tower of London planning task. These tests were graded in difficulty and included internal control measures. On each task, the autistic group was differentially impaired with respect to both control groups. Moreover, this impairment was specific to the stages of each task which placed greatest demands upon executive control. This evidence for executive dysfunction in autism is discussed in the context of Norman and Shallice's (Centre for Human Information Processing Technical Report 99, 1980) "Supervisory Attentional System" model of frontal function.     

On the relative importance of "psychopathic" personality and alcoholism on neuropsychological measures of frontal lobe dysfunction.

Previous research indicated that certain behaviors associated with "psychopathic" personality may derive in part from dysfunction in the frontal lobe of the cerebral cortex (Gorenstein, 1982). However, the effects of substance abuse provide an alternative explanation for frontal lobe deficits in a psychopathic population. Hare (1984) demonstrated that psychopaths in a prison population did not appear to have frontal lobe impairments, but he did not attempt a replication of Gorenstein's study. In the present study we attempted such a replication and examined the relative effects of psychopathic personality and alcoholism on several measures of frontal lobe impairment. Results did not support a significant relation between frontal lobe impairment and psychopathic personality, nor do they provide support for a significant relation between frontal lobe impairment and level of general alcoholism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Positive mood and executive function: Evidence from Stroop and fluency tasks.

Contrasting predictions have been made about the effects of positive mood states on the performance of frontal lobe tests that tap executive functions such as inhibition, switching, and strategy use. It has been argued that positive mood is likely to improve some cognitive processes, particularly those dependent on the frontal cortex and anterior cingulate of the brain. However, there is some evidence that happy mood may impair executive functioning. The current experiments investigated the effects of positive mood on Stroop and fluency tests, which are frequently used to assess executive function. Positive mood impaired performance on a switching condition of the Stroop test, but improved performance on a creative uses test of fluency. The effect of positive mood on an executive task may therefore depend on whether a task is inherently motivating or is impaired by diffuse semantic activation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Verbal fluency deficits in patients with schizophrenia: Semantic fluency is differentially impaired as compared with phonologic fluency.

Patients with schizophrenia show deficits in phonologic (ability to name words that begin with a specific letter, e.g., F) and semantic (ability to name members of a category, e.g., "animals" fluency.) Whereas the former deficit has been presumed to reflect a dysfunction of the frontal lobe, the latter has been linked to frontal and temporoparietal brain areas. These 2 verbal fluency measures were studied in a sample of 27 schizophrenia patients and 24 normal controls who were matched on age and a putative measure of premorbid intellectual ability. A 2-min production task of switching between letters and between categories measured demand for flexibility. On switching and nonswitching tasks controls produced more words during semantic versus phonologic fluency. Conversely, schizophrenia patients produced more words for letters than for categories, suggesting dysfunction of the frontal and temporoparietal areas of the brain. Furthermore, the greater impairment of semantic fluency may be related to a breakdown of semantic information processing beyond "executive" search and retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Are there cognitive subtypes in adult attention deficit/hyperactivity disorder?

There has been increasing knowledge of the treatment, diagnosis, and demographics of adults with residual attention deficit/hyperactivity disorder (ADHD). However, less is known about the neuropsychological functioning in adults with residual ADHD. In comparing the clinical neuropsychological test performance of a group of adult clinic patients with residual ADHD (N = 30) with that of normal controls (N = 10), we found the patients performed worse on the Trail Making Test, a visual continuous performance test, and the "Brown-Peterson" Auditory Consonant Trigrams Test, but not on any other neuropsychological measures. This pattern indicated a deficit in the area of executive control type functioning, a functional deficit that could be linked to dysregulation of frontal lobe brain systems. Of equal interest was that patients diagnosed with ADHD/hyperactive impulsive type (ADHD+) and patients diagnosed with ADHD/inattentive type (ADHD-) had different types of executive system deficits. ADHD+ was associated with relative deficiency on the Wisconsin Card Sorting Test. ADHD- was associated with relative deficiency on the "Brown-Peterson" Auditory Consonant Trigrams Test, a measure of working memory, as well as less olfactory identification on a smell identification test. The data are discussed in terms of recent localization theories of frontal lobe function. The preliminary data suggest that the different cognitive weaknesses of ADD subtypes may be linked to dysregulation of separate frontal brain regions and/or neurotransmitter systems.     

Cognitive impairment following frontal lobe damage and its relevance to human amnesia.

Whether frontal lobe pathology can account for some of the cognitive impairment oberved in amnesic patients with Korsakoff's syndrome was investigated. Various cognitive and memory tests were given to patients with circumscribed frontal lobe lesions, patients with Korsakoff's syndrome, non-Korsakoff amnesic patients, and control Ss. Patients with frontal lobe lesions were not amnesic. Nevertheless, they exhibited 2 deficits that were also exhibited by patients with Korsakoff's syndrome but not by other amnesic patients: (a) impairment on the Wisconsin Card Sorting Test and (b) impairment on the Initiation and Perseveration subscale of the Dementia Rating Scale. Thus, frontal lobe pathology can explain some of the cognitive deficits observed in patients with Korsakoff's syndrome. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Loss of control" in alcoholism and drug addiction: A neuroscientific interpretation.

Considerable neurological evidence indicates that the prefrontal cortex mediates complex "executive" functions including behavioral autonomy and self-control. Given that impairments of self-control are characteristic of alcoholism and other drug addictions, frontal lobe dysfunction may play a significant role in such compulsive behaviors. Consistent with this idea, recent research using brain imaging, neuropsychological testing, and other techniques has revealed that the frontal lobes are particularly vulnerable to the acute and chronic effects of addictive drugs, especially alcohol and cocaine. Evidence implicating a hyperdopaminergic mechanism of acute and chronic drug-induced frontal lobe dysfunction and interactions with premorbid factors and stress are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A study of performance on tests from the CANTAB battery sensitive to frontal lobe dysfunction in a large sample of normal volunteers: implications for theories of executive functioning and cognitive aging. Cambridge Neuropsychological Test Automated Battery

Several tests from the CANTAB neuropsychological test battery previously shown to be sensitive to frontal lobe dysfunction were administered to a large group of normal volunteers (N = 341) ranging in age from 21 to 79 years. The main tests included a computerized form of the Tower of London test of planning, a self-ordered spatial working memory task, and a test of attentional set formation and shifting. A computerized form of the Corsi spatial span task was also given. Age-related graded declines in performance were seen, sometimes in a discontinuous manner, especially for the attentional set shifting task (at the extradimensional shift stage). Patterns of deficits reminiscent of frontal lobe or basal ganglia damage were observed in the oldest age group (74-79). However, overall the data were only partially consistent with the hypothesis that frontal lobe functions are the most sensitive to effects of aging. Factor analyses showed that performance in the executive tests was not simply related to a measure of fluid intelligence, and their performance had a factor loading structure distinct from that for the CANTAB tests of visual memory and learning previously administered to the same sample. Finally, only limited support was found for the hypothesis that cognitive aging depends on slowed information processing.     

Frontal lobe dysfunctions in Korsakoff's syndrome and chronic alcoholism: Continuity or discontinuity?

The effect of long-term heavy alcohol consumption on brain functions is still under debate. The authors investigated a sample of 17 Korsakoff amnesics, 23 alcoholics without Korsakoff's syndrome, and 21 controls with peripheral nerve diseases, matched for intelligence and education. Executive functions were examined for word fluency, the modified Wisconsin Card Sorting Test, an alternate response task, and an "n-back" working memory task. Korsakoff amnesics, but not alcoholics, showed a marked memory impairment. They also scored lower in each of the executive tasks--the alcoholics only in the alternate response task. This task also correlated with the years of the alcohol dependency. First, the authors conclude that Korsakoff's syndrome is associated not only with a memory impairment but also with a global executive deficit. Second, the decline in the ability to alternate between different responses argues for a restricted neurotoxic effect of alcohol on some frontal lobe areas (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A neuropsychological investigation into frontal lobe involvement in dementia of the Alzheimer type.

Studied frontal lobe involvement in dementia of the Alzheimer type (DAT) using 4 neuropsychological tests (verbal fluency, delayed alternation, subject-ordered pointing, and the Wisconsin Card Sorting Test) in 25 patients suffering from DAT and 12 age-matched normal controls. The first 3 tasks demonstrated that a frontal lobe impairment is present at all stages of the disease and is related to disease severity. Results offer information regarding the frontal component in DAT by providing neuropsychological support for the findings of an anterior pathology as reflected in blood flow and metabolism studies. The need for suitable frontal tasks with minimal memory involvement in the study of dementia is emphasized, and the delayed alternation task is recommended. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Meta-Analytic Review of Verbal Fluency Deficits in Huntington's Disease.

A meta-analysis of 30 studies with 1,511 participants was conducted to estimate and compare the magnitude of deficits on tests of phonemic and semantic fluency for patients with Huntington's disease (HD) relative to healthy control participants. As has been found for patients with focal frontal cortical lesions (but not for patients with focal temporal cortical lesions), symptomatic HD patients were comparably impaired on tests of phonemic and semantic fluency (rs=.71 and .73, respectively). However, in contrast to patients with focal frontal lobe injuries, fluency deficits did not qualify as differential deficits relative to verbal intelligence or psychomotor speed. Therefore, for patients with HD, deficits on tests of phonemic and semantic fluency do not appear to reflect executive dysfunction but a more generalized cognitive impairment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)