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PubMed2006

Humor processing, mentalizing, and executive function in normal aging.

Recent investigations have emphasized the importance of the prefrontal cortex for humor processing. Although the prefrontal cortex is thought to be affected by normal aging, relatively little work has been carried out to investigate the effects of aging on humor processing. In the present investigation participants in three age groups were assessed on a humor comprehension task. They then answered mentalistic and nonmentalistic questions. Executive tasks were also administered. The older group selected significantly fewer correct punchlines from alternatives than the other groups. They were also poorer at answering mentalistic questions, but did not differ significantly for nonmentalistic questions. The findings of the present investigation showed altered in humor processing in normal aging, and this appeared to be related to mentalizing ability.

Adult↗
PubMed2003

Role of executive function in late-life depression.

Late-onset depression has been conceptualized as a neurologic disease. This view has been supported by studies suggesting that late-onset depression is associated with cognitive impairment and neurologic comorbidity that may or may not be clinically evident when depression is first diagnosed. Findings implicating a dysfunction of frontostriatal-limbic pathways in geriatric depression have led to the depression-executive dysfunction (DED) syndrome hypothesis. Subsequent studies suggested that DED has slow, poor, or abnormal response to classical antidepressants. DED is characterized by psychomotor retardation, reduced interest in activities, impaired insight and pronounced behavioral disability. This clinical presentation begs the question whether agents that can selectively activate internal vigilance and therefore improve alertness have beneficial effects on DED. There is early evidence that psychosocial interventions aimed at improving the behavioral deficits of DED patients may also be effective in increasing remission rates and reducing depressive symptoms and disability.

Age of Onset↗
PubMed2003

Behavioral Dyscontrol Scale deficits among traumatic brain injury patients, part II: Comparison to other measures of executive functioning.

The clinical utility of the Behavioral Dyscontrol Scale (BDS) was compared to that of verbal fluency, the Trail Making Test, and the Stroop Color-Word Test, as well as measures of processing speed/cognitive efficiency and manual dexterity. The ability of these measures to classify 49 TBI patients into frontal versus nonfrontal and mild to moderate versus severe groups was examined. The results showed that the Fluid Intelligence Factor of the BDS improved classifications above and beyond traditional executive measures, but was particularly successful at classifying patients who sustained mild injuries. In contrast, traditional executive instruments were successful at lesion location classifications only among the patients with severe injuries. Severity classifications were successful both for traditional measures of processing speed/cognitive efficiency and for the Motor Programming Factor of the BDS, but only among patients with nonfrontal injuries. These results demonstrate that severity of injury may be an important moderator of tests' sensitivity to frontal lobe involvement.

Adult↗
PubMed2006

Interhemispheric connectivity and executive functioning in adults with Tourette syndrome.

The prefrontal cortex (PFC) is relatively smaller, and the corpus callosum (CC) larger, in adults with Tourette syndrome (TS). The authors explored the possible roles of the PFC and the CC in mediating interhemispheric interference and coordination in TS adults. They measured performance on M. Kinsbourne and J. Cook's (1971) verbal-manual interference task and on the bimanual Purdue Pegboard in 38 adults with TS and 34 healthy adults. Compared with controls, TS subjects were impaired on the bimanual Purdue Pegboard. On the dual task, right-hand performance did not differ between groups, but the normally expected left-hand advantage (opposite hemisphere condition) was absent in TS subjects. In the control group only, better left-hand performance accompanied larger PFC volumes but not CC cross-sectional area. PFC dysfunction might have precluded executive control of interference in the TS group.

Adolescent↗
PubMed2004

Executive function is less sensitive to estradiol than spatial memory: performance on an analog of the card sorting test in ovariectomized aged rhesus monkeys.

Functions supported by the frontal lobes are particularly sensitive to the detrimental effects of aging. Recent studies on postmenopausal women find that estrogen replacement therapy benefits performance on tasks dependent on the frontal lobes. To determine whether estrogen has a similar influence in a rhesus monkey model of menopause, we tested five aged, long-term ovariectomized rhesus monkeys in a modified version of the Wisconsin Card Sort test which had been adapted to the nonhuman primate. In this test, monkeys had to select 3-D objects based either on color (blue, red, yellow) or shape (block, tube, cup) and had to be able to switch their response as a function of reinforcement contingencies. The monkeys were treated with placebo and ethinyl estradiol (EE2, 450 ng/kg/day) in alternation with each successive test. Contrary to our hypothesis, estradiol treatment did not affect performance. Because previous studies in the same monkeys [Neurobiol. Aging 23 (2002) 589] had shown that EE2 improves performance on a spatial memory task dependent on the hippocampus, but not on another task dependent upon the frontal lobes (the delayed response), we conclude that executive processes may be less sensitive to the effects of estradiol than hippocampal-dependent tasks.

Age Factors↗
PubMed1998

Central executive function in working memory: event-related brain potential studies.

Visual event-related brain potentials (ERPs) were recorded during a running memory task, in which subjects dynamically revised (updated) memory stores, and a control task not requiring maintenance of a changing memory set but utilising identical stimulus sequences and response patterns. In three experiments, ERPs associated with cognitive processes were isolated through subtraction of control potentials from ERPs acquired during updating. We provide evidence that resultant difference ERPs primarily reflected processing or processing control, as opposed to storage. These findings are consistent both with Baddeley's working memory model, which postulates separate storage and control modules, and Morris and Jones' behavioral evidence for specific involvement of Baddeley's central executive in memory updating. In addition, our ERP data indicate that updating requires processes not suggested by Morris and Jones' behavioural studies; possibly control processes engaged to reduce the effects of proactive interference. Overall the data are consistent with the discovery of an ERP correlate of central executive activity.

Adult↗
PubMed2001

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.

Adult↗
PubMed2005

Processing speed, executive function, and age differences in remembering and knowing.

A group of young (n = 52, M = 23.27 years) and old (n = 52, M = 68.62 years) adults studied two lists of semantically unrelated nouns. For one list a time of 2 s was allowed for encoding, and for the other, 5 s. A recognition test followed where participants classified their responses according to Gardiner's (1988) remember-know procedure. Age differences for remembering and knowing were minimal in the faster 2-s encoding condition. However, in the longer 5-s encoding condition, younger persons produced significantly more remember responses, and older adults a greater number of know responses. This dissociation suggests that in the longer encoding condition, younger adults utilized a greater level of elaborative rehearsal governed by executive processes, whereas older persons employed maintenance rehearsal involving short-term memory. Statistical control procedures, however, found that independent measures of processing speed accounted for age differences in remembering and knowing and that independent measures of executive control had little influence. The findings are discussed in the light of contrasting theoretical accounts of recollective experience in old age.

Adolescent↗
PubMed1997

Relationships between verbal and nonverbal fluency measures: implications for assessment of executive functioning.

This experiment evaluated the relationship between verbal and nonverbal fluency measures commonly employed in neuropsychological assessment. Three fluency measures, the Controlled Oral Word Association Test, the Design Fluency Test, and the Ruff Figural Fluency Test, were administered to a sample of 61 men and 73 women in college. Analyses indicated that scores on the Controlled Oral Word Association Test were significantly correlated with scores on the Fixed but not the Free Condition of the Design Fluency Test. Scores on the Ruff test were significantly more closely correlated with the Fixed versus the Free Condition, although they were also correlated with the total scores on the Design Fluency Test. Differential correlations are discussed in terms of the varying structure inherent in the measures of fluency and their presumed taxing of frontally mediated executive processes.

Adolescent↗
PubMed1996

Verbal fluency in schizophrenia: relationship with executive function, semantic memory and clinical alogia.

To examine whether poor verbal fluency in schizophrenia represents a degraded semantic store or inefficient access to a normal semantic store, 25 normal volunteers and 50 DSM-III-R schizophrenic patients, matched for age, sex and IQ, were recruited. Although schizophrenic patients were impaired on both letter and category fluency, they showed a normal pattern of output in that category was superior to letter fluency, and an improvement in category fluency when a cueing technique was employed (Randolph et al. 1993). These results resemble those found in disorders of frontostriatal systems (Parkinson's and Huntington's disease) and suggest that poor verbal fluency in schizophrenia is because of inefficient access to semantic store. A measure of improvement with cueing was directly related to performance on the Stroop executive task. Of all symptom measures derived from SANS and Manchester Scales, only alogia was related to verbal fluency in that superior improvement correlated inversely with the degree of alogia. It is suggested that both alogia and poor verbal fluency are mediated by the same underlying cognitive abnormality that reflects frontostriatal dysfunction.

Adult↗
PubMed2006

Visuospatial executive function in Turner syndrome: functional MRI and neurocognitive findings.

Turner syndrome is a genetic disorder that results from an abnormal or missing X chromosome in females and is typically associated with impairments in visuospatial, but not verbal, information processing. These visuospatial processing impairments may be exacerbated with increased task demands, such as those engaged during working memory (WM). While previous studies have examined spatial WM function in Turner syndrome, none have directly compared the neural correlates of spatial and verbal WM processes across the encoding, maintenance and retrieval phases. We employed both neurocognitive assessments and functional MRI (fMRI) to examine the neural circuitry underlying both verbal and visuospatial WM functions in individuals with Turner syndrome and normal controls. We furthermore examined the vulnerability of task-related fMRI activation to distracters presented during WM maintenance. Fifteen healthy female volunteers and eight individuals with Turner syndrome performed a delayed-response WM task during fMRI scanning. Neurocognitive tests revealed impaired performance across both verbal and spatial domains in Turner syndrome, with greater impairment on tasks with WM demands. Frontoparietal regions in controls showed significantly sustained levels of activation during visuospatial WM. This sustained activation was significantly reduced in the group with Turner syndrome. Domain-specific activation of temporal regions, in contrast, did not differ between the two groups. Sensory distraction during the WM maintenance phase did not differentially alter frontoparietal activation between the two groups. The results reveal impaired frontoparietal circuitry recruitment during visuospatial executive processing in Turner syndrome, suggesting a significant role for the X chromosome in the development of these pathways.

Adolescent↗
PubMed2005

Visual scanning deficits in schizophrenia and their relationship to executive functioning impairment.

Abnormal visual scanning of faces, objects, and line drawings has been observed in patients with schizophrenia and is thought to reflect neurocognitive impairment. In this study, a simultaneous measurement approach was used to assess whether schizophrenia patients demonstrate restricted visual scanning when confronted with a complex problem-solving stimulus, and whether visual scanning deficits are predictive of inflexible thinking. Thirty-eight schizophrenia patients and 30 comparison participants were presented with Rorschach inkblots while eye movements were monitored and verbal responses to the stimuli were recorded and scored for inflexible thinking using the Rorschach Repetition and Perseveration Scale. Schizophrenia patients demonstrated fewer and longer visual fixations and shorter total scanpath relative to comparison participants but did not differ on mean scanpath length. Among patients, fewer fixations were associated with a higher frequency of verbal perseverations. Correlations between scanning measures and symptoms showed that negative symptoms were related to a minimal scanning or "staring" approach. Results support previous findings of restricted visual scanning in schizophrenia patients, are consistent with previously observed relationships between visual scanning and symptom profiles, and suggest that visual organizational deficits during complex problem-solving tasks may be related to cognitive inflexibility and frontal-executive dysfunction.

Adult↗
PubMed2001

Cortical networks for working memory and executive functions sustain the conscious resting state in man.

The cortical anatomy of the conscious resting state (REST) was investigated using a meta-analysis of nine positron emission tomography (PET) activation protocols that dealt with different cognitive tasks but shared REST as a common control state. During REST, subjects were in darkness and silence, and were instructed to relax, refrain from moving, and avoid systematic thoughts. Each protocol contrasted REST to a different cognitive task consisting either of language, mental imagery, mental calculation, reasoning, finger movement, or spatial working memory, using either auditory, visual or no stimulus delivery, and requiring either vocal, motor or no output. A total of 63 subjects and 370 spatially normalized PET scans were entered in the meta-analysis. Conjunction analysis revealed a network of brain areas jointly activated during conscious REST as compared to the nine cognitive tasks, including the bilateral angular gyrus, the left anterior precuneus and posterior cingulate cortex, the left medial frontal and anterior cingulate cortex, the left superior and medial frontal sulcus, and the left inferior frontal cortex. These results suggest that brain activity during conscious REST is sustained by a large scale network of heteromodal associative parietal and frontal cortical areas, that can be further hierarchically organized in an episodic working memory parieto-frontal network, driven in part by emotions, working under the supervision of an executive left prefrontal network.

Adult↗
PubMed1996

Double dissociations of memory and executive functions in working memory tasks following frontal lobe excisions, temporal lobe excisions or amygdalo-hippocampectomy in man.

Thirty-two neurosurgical patients with unilateral or bilateral frontal lobe excisions, 41 patients with unilateral temporal lobe lesions and 19 patients who had undergone unilateral amygdalo-hippocampectomy were compared with matched controls on a computerized test of spatial working memory. A significant deficit was observed in the frontal lobe group, even at the least challenging level of task difficulty and this impairment was found to relate to the inefficient use of a particular searching strategy shown to improve performance on this task. In contrast, deficits in the temporal lobe group and the amygdalo-hippocampectomy group were only observed at the most difficult level of the task and in neither group could the deficit be related to the inefficient use of any particular searching strategy. In a follow-up study, the three patient groups were compared on analogous computerized tests of visual and verbal working memory. No deficits were observed in the frontal lobe group. By comparison, both the temporal lobe patients and the amygdalo-hippocampectomy group were significantly impaired in the visual working memory condition but not in the verbal working memory condition. These deficits were clearly evident at all levels of task difficulty and were not related to any particular searching strategy. The data are discussed in terms of the relative contributions of "executive' and "mnemonic' mechanisms to the contrasting, material dependent deficits observed in the frontal and temporal lobe groups.

Adult↗
PubMed2002

Acute effects of cigarettes in non-deprived smokers on memory, calculation and executive functions.

To determine whether smoking one or two cigarettes daily has effects on cognitive functions and the blood nicotine level, we examined 20 smokers and 20 nonsmokers as part of a normal daily smoking regimen using psychological tests for memory, calculation and association. Subjects underwent Buschke's selective reminding test, a mental arithmetic task (multiplication between two digits and one digit) and an association task (letter fluency); the duration of each task being 2 min under the condition of pre-smoking, one cigarette smoking and two cigarette smoking sessions, with an inter-session interval of 50 min. The total recall or correct responses were evaluated. The results showed that performance deteriorated in the later sessions in the memory task, whereas it improved in the later sessions in the calculation and association tasks, with no group (smoker-nonsmoker) difference, nor interaction between tasks and groups in each task. Plasma nicotine increased by 10 ng/ml immediately after smoking a cigarette, and 14 ng/ml immediately after smoking two cigarettes, but decreased to the pre-smoking level or slightly higher 10 min after smoking. These findings suggested that a daily dose of nicotine had little effect on the performance related to memory, calculation and mental association.

Adult↗
PubMed1999

Executive functioning in preschool children: performance on A-not-B and other delayed response format tasks.

The A-not-B (AB) task has been hypothesized to measure executive/frontal lobe function; however, the developmental and measurement characteristics of this task have not been investigated. Performances on AB and comparison tasks adapted from developmental and neuroscience literature was examined in 117 preschool children (ages 23-66 months). Age significantly predicted performance on AB, Delayed Alternation, Spatial Reversal, Color Reversal, and Self-Control tasks. A four-factor analytic model best fit task performance data. AB task indices loaded on two factors with measures from the Self-Control and Delayed Alternation tasks, respectively. AB indices did not load with those from the reversal tasks despite similarities in task administration and presumed cognitive demand (working memory). These results indicate that AB is sensitive to individual differences in age-related performance in preschool children and suggest that AB performance is related to both working memory and inhibition processes in this age range.

Child↗