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Memory deficits in long-term survivors of childhood brain tumors may primarily reflect general cognitive dysfunctions.

BACKGROUND: To analyze the impact of potential predictors on memory performance in survivors of childhood brain tumors and to examine whether deficits in memory after radiotherapy (RT) should be considered part of a more global mental dysfunction. PROCEDURE: We studied 126 patients with brain tumors diagnosed before the age of 15 years and treated January 1970 through February 1997 in Eastern Denmark. Sixty-nine of the 126 patients had received RT. In addition to working memory and long-term memory (LTM), general intelligence (IQ) was assessed. RESULTS: The mean test scores in nearly all memory tests were lower than expected from available norms. In multiple linear regression, treatment with RT, hemisphere tumor location, and hydrocephalus treated with a shunt at the time of diagnosis were found to be significant risk factors for memory deficits. When IQ was included as a covariate, RT did not significantly predict memory performance, while shunt and tumor location remained significant for several but not all tests. CONCLUSION: These results suggest that in patients treated with RT, memory deficits primarily reflect a general cognitive dysfunction, and it is likely that these intelligence deficits may compromise the chances of success of special memory training. In contrast, memory deficits in non-irradiated patients may to some degree reflect specific cognitive dysfunctions being most pronounced for patients treated with a shunt and for patients with hemispheric tumors.

Adolescent↗

Cognitive complexity and cognitive-affective integration: related or separate domains of adult development?

This study used a latent variable approach to describe two broad domains of adult development and their interrelations. One domain was cognitive complexity, defined by crystallized intelligence, fluid intelligence, and reflective cognition: the other domain was cognitive-affective integration, operationalized in terms of integrated and defensive coping. It was hypothesized that these 2 domains are related to each other and that they imply different developmental correlates. Structural relations among the latent variables supported a model in which integrated coping showed positive relations with crystallized intelligence and reflective cognition, whereas defensive coping showed negative relations to these cognitive factors. Age and education were significant predictors of the cognitive complexity factors, whereas evaluations of the climate in one's current family and family of origin were related to the factors of cognitive-affective integration.

Adaptation, Psychological↗

Event-related potentials associated with sound discrimination versus novelty detection in children.

In children, deviant sounds in an oddball paradigm elicit a mismatch negativity (MMN) indexing discrimination of sound change and late difference negativity (LDN) with unknown functional significance. Salient sounds elicit an ERP index if orienting, P3a, and a late negative component, Nc. We compared children's responses elicited by moderate sound changes and novel sounds to examine the relationships between MMN and LDN, and LDN and Nc. Two components of the Nc, the Nc1 and Nc2, were identified. The scalp topography of LDN differed from those of the MMN and Nc1. Children's early P3a appeared mature but late P3a lacked frontal predominance. The findings suggested that LDN is not linked with either the sensory or attentional processing. It might reflect cognitive, albeit preattentive, processing of sound change. The Nc1 appears to reflect cognitive attentive processing of salient stimuli and the Nc2 might reflect reorienting after distraction.

Adolescent↗

A componential investigation of the relation between structural modelling and cognitive accounts of human judgement.

Structural modelling and cognitive process approaches have developed rather different accounts of human judgement and decision making. Two hypotheses to explain these differences were evaluated in the context of a judgement task, and formulated in terms of predictions concerning measurement of attribute importance. First, following suggestions made by Billings and Marcus (1983), it was argued that measures of judgement behaviour based on structural modelling reflect cognitive activity late in the judgement process, whereas measures derived from cognitive process approaches reflect cognitive activity early in the process. A new componential judgement task was developed which not only provided estimates of attribute importance based on structural modelling, but also two sets of cognitive process measures based on cognitive components assumed to occur early and late in the judgement process. A greater degree of convergence between approaches was predicted when the cognitive approach was based on activity in the component occurring later in the judgement process. Second, it was argued that in previous research subjects have had unlimited time to make their judgements, reducing the need for attribute importance to provide the dominant basis for determining processing strategy. The present experiment introduced a time pressure condition and, on the basis of previous research, predicted that this would increase the amount of information processing based on attribute importance, thereby increasing the convergence between estimates of attribute importance derived from the two approaches. The first, but not the second hypothesis was supported and the results were discussed in terms of their implications for understanding previous differences between the two approaches to human judgement.

Accounting↗

The dimensional complexity of the EEG during cognitive tasks reflects the impaired information processing in schizophrenic patients.

The aim of the present study was to investigate whether schizophrenic patients show a different change of the dimensional complexity of the EEG, as represented by the Grassberger-Procaccia correlation dimension D(2,) under cognitive challenge compared to normal control subjects. With respect to results reported in the literature, it was expected that the complexity of the signal under cognitive challenge is higher in schizophrenic patients than in normal control subjects reflecting the impaired information processing abilities of the patients. Eighty-seven schizophrenic and 30 matched control subjects performed two different types of the continuous performance task. The results revealed differences between schizophrenic patients and control subjects for the performance as well as the complexity measures. Schizophrenic patients produced more omission errors than normal subjects did. For the EEG complexity measure no differences occurred under the baseline condition. In contrast, during the first minute under task conditions the control subjects showed a decrease of the dimension while no changes were found for the schizophrenic group. These results occurred for both types of the cognitive task but they reached clear significance only in one of them. The results are interpreted as reflecting the ability of normal subjects to adapt their information processing system to the cognitive challenge and to focus their attention on the task while schizophrenic subjects do not show this adaptation to the task.

Adult↗

Monitoring the source of memory in detoxified alcoholics.

The ability to monitor the source of remembered information and related reflective cognitive processes was examined in normal volunteers and detoxified alcoholics. Normal volunteers were very accurate judges of whether remembered events were presented as stimuli or were self-generated, even when memory was tested 2 days later. In contrast, a subgroup of otherwise cognitively unimpaired alcoholics demonstrated impairments in the ability to track the source of remembered knowledge and were also less able to inhibit intrusion errors in recalling information from memory. These findings provide preliminary evidence of an impairment in cognitive control functions in certain alcoholics. This conclusion is supported by associated findings indicating that, among alcoholics, performance on explicit memory tasks that required reflective cognitive operations were positively correlated with glucose utilization rates in left prefrontal, temporal, and posterior orbital frontal cortical regions.

Adult↗

Cognitive style in adults: task alternatives, task strategy, and time estimation.

Increasing the number of task alternatives in a match-to-sample problem led to longer decision times in cognitively reflective but not in cognitively impulsive adults. Impulsives, as compared to reflectives, were found to verbalize less "thinking out loud" coded verbal behavior, to endorse less motivation for success and more motivation for speed, and to consistently underestimate time (i.e., periods of 10, 20, & 60 seconds). The present results suggest a latency-related response inhibition deficit in cognitively impulsive adults. The potential of a cognitive-behavioral treatment strategy is considered.

Adolescent↗

Left and right temporal lobe epileptics: a controlled investigation of some psychological differences.

Twenty-two young adults with clinically and electroencephalographically diagnosed temporal lobe epilepsy were selected from an outpatient neurology source; 11 with focal epileptic activity in the right temporal lobe and 11 with left temporal lobe involvement were included. All patients had normal intelligence and comparable educational and socioeconomic backgrounds. Matched nonepileptic controls were also tested. Subjects were given psychological tests assessing differences in cognitive style and affect communication. Greater reliance on the ear ipsilateral to discharge focus in a dichotic listening paradigm was discovered, confirming appropriate lateralization assignment. Left lateralized patients exhibited a more reflective cognitive style than controls; right lateralized patients were more impulsive. Previously confirmed associations between impulsivity and externalized aggressive responses suggest the hypothesis that externalization of aggressive responses may occur more often among right lateralized patients. Left lateralized patients exhibited a more reflective cognitive style than controls; right lateralized patients were more impulsive. Previously confirmed associations between impulsivity and externalized aggressive responses suggest the hypothesis that externalization of aggressive responses may occur more often among right lateralized patients. Left lateralized patients made more atypical assignments of affect labels to emotionally evocative descriptions. Right laterlized patients tended to assign affect labels as controls. A greater potential for disturbance in the verbal communication of affect among left laterlized patients is suggested.

Adolescent↗

Ontogeny of selective attention effects on event-related potentials in attention-deficit hyperactivity disorder and normal boys.

A longitudinal study of young attention-deficit hyperactivity disorder (ADHD) boys has found clear evidence for developmental abnormalities in event-related potential (ERP) waves that reflect cognitive processes associated with selective attentional tasks. Boys alternated attention to auditory or visual modalities in a train of stimuli, in an attempt to detect target stimuli in the attended modality. Results suggest that ADHD boys' attentional difficulties are due to insufficient facilitation of responses to the attended stimuli and not to an inability to block ignored stimuli. Abnormalities in ERPs reflecting cognitive processes associated with both interchannel selection mechanisms (processing negativity) and intrachannel selection mechanisms (P3b) were found. The degree of abnormality in the P3b responses to target stimuli in ADHD boys (lower than normal boys) was found to increase with age. It is suggested that the abnormally low P36 response to attended target stimuli found in ADHD boys may be due in part to insufficient LC noradrenergic activity normally triggered by attended task-relevant or novel stimuli.

Arousal↗

Phase-locking and amplitude modulations of EEG alpha: Two measures reflect different cognitive processes in a working memory task.

It has been demonstrated in numerous experiments that oscillatory EEG responses in the alpha frequency band (8-12 Hz) increase with memory load during the retention interval in working memory tasks. However, the findings diverge with respect to which measurement of alpha activity is influenced by memory processes. Here, we differentiate between evoked and total alpha activity in order to separate effects of phase-locking and amplitude modulation. We present data from a delayed-matching-to-sample task (S1-S2 paradigm) for which we compared EEG alpha responses between a perception and a memory condition. Increased total alpha activity was found in the retention interval for the memory as compared to the perception condition. Evoked alpha activity, however, did not differentiate between memory and perception conditions but, instead, was increased for the more complex condition of processing non-Kanizsa figures as compared to Kanizsa figures. Thus, our results demonstrate a functional differentiation between evoked and total alpha activity. While alpha phase locking seemed to be influenced mainly by task complexity, alpha amplitude clearly reflected memory demands in our paradigm.

Adult↗

The reflection of cognitive tasks in EEG and MRI and a method of its visualization.

Up until recently, neurology was dominated by localisatory thinking. Language and other so-called "centers" were considered to be centers of command controlling the respective functions. Today, there is general agreement that, instead, for every brain function numerous brain regions must act together. For the exploration of these manifold topographic cooperations produced by cognitive tasks, coherence of long-term EEG periods proved to be a proficient parameter for the representation of functionally essential connections. Because of the unequivocal meaningfulness of absolute coherence values, instead, only the signs of significant differences between coherence values during cognitive tasks and periods of EEG at rest before and after the task were considered for all possible electrode pairings and charted on schematic maps of the brain. In addition, the signs of significant changes of amplitude were entered. This procedure was performed for each of 6 frequency bands and for the 19 electrodes of the 10/20 system, thus yielding 171 possible plus or minus values for coherence and 19 for amplitude, respectively. The positions of the electrodes were marked by an MRI contrast medium. After the EEG, MRI examination was performed. The MRI data were segmented and the cortex was mapped onto a plane using a method similar to cartography. The exact electrode positions are registered from a similarly obtained map of the scalp and the electrode position pattern is used as basis for the coherence graphs. A detailed map of the cortex based on the segmented MRI data with the electrode positions marked is provided as a reference enabling allocation of the electrodes to the cortical structures. The usefulness of this procedure is demonstrated with a single subject by means of different cognitive tasks including musical thinking.

Aged↗

Pupillary responses on the visual backward masking task reflect general cognitive ability.

Cognitive processing efficiency requires both an ability to attend to task-relevant stimuli with quickness and accuracy, also while filtering distracting or task-irrelevant stimuli. This study investigated cognitive processing efficiency by using pupillary responses as an index of attentional allocation to relevant target and irrelevant masks on a visual backward masking task. The relationship between attentional allocation on this task and general cognitive ability on the scholastic aptitude test (SAT) was examined in college students (n=67). A principle components analysis of the pupillary response waveform isolated a late component that appeared to index the attentional demands associated with processing masks on the backward masking task. This pupillary response index of wasteful resource allocation to the mask accounted for significant variance in SAT scores over and above that accounted for by socio-economic status and target detection accuracy scores. Consistent with the neural efficiency hypothesis, individuals who allocated more resources to processing irrelevant information performed more poorly on cognitive ability tests.

Adult↗

The event-related P300 potential analysis of cognitive human brain aging: a review.

Event-related P300 potentials are closely reflecting cognitive functions such as stimulus evaluation time (P300 latency) and task relevance (P300 amplitude). Hence, both their potential clinical application for detecting slight cognitive disturbances and an increasing interest in the aging of cognitive human brain functions resulted in a growing number of studies on age-related P300 changes. Although there are converging lines of evidence that aging results in prolongations of P300 latencies, reductions of P300 amplitudes and a more equipotential P300 scalp distribution, the amount of these changes and the best fit for the P300-age interactions, respectively, remain still controversial. In general, these P300 alterations obviously reflect only minor cognitive changes during normal aging. For their clinical application, however, it is necessary to obtain an age-matched normative database. Furthermore, the increased P300 variability in the elderly has to be reduced--as far as possible--by appropriate simple P300 paradigms which should be preferentially applied in longitudinal analyses to differentiate normal from pathological aging of cognitive functions. Finally, additional cross-correlational analyses between the P300 and morphological as well as neurobiochemical data are needed. By these means, our knowledge about age-related changes of cognitive brain functions should be considerably enlarged.

Adolescent↗

Auditory P300, CT scans and cognitive state in Binswanger's disease.

The P300 component of evoked potential can reflect cognitive state in dementia patients. The purpose of this study was to investigate the value of P300 as an indicator of cognition in Binswanger's disease (BD) and to explore the possible causes of dementia in BD patients. P300 was measured at Cz site in 21 patients with BD and 21 controls matched with age, sex, handedness, and education. This measurement included P300 latency and amplitude. All patients were also given WAIS-RC test and scanned with computerized tomography (CT), and were treated with hyperbaric oxygenation (HBO). The relationships among P300, CT and WAIS-RC score were studied. BD patients had significantly prolonged P300 latency and a tendency of low amplitude P300, but the amplitude difference was not significant compared with controls. P300 latency was found to be negatively correlated with WARS-RC scale, and positively correlated with the change of white matter low attenuation (WMLA). WMLA was also correlated with WAIS-RC score. Treatment with HBO reduced P300 latency and had effect on the cognitive part of P300 but had no effect on CT changes. The significant association between neurophysiological and neuropsychological measurement suggests that P300 measurement reflects a disrupted aspect of cognitive function in BD patients, and it may be a useful means to assess the degree of subcortical cognitive deterioration and the effect of therapy. White matter lesion in BD is concerned to the occurrence of dementia by disturbing axonal conduction.

Aged↗

Early contingent negative variation (CNV) shows a small symmetrical negativity in a somatosensory paradigm.

The influence of sensory modulation on the early stage of information processing was investigated with a somatosensory contingent negative variation (CNV) paradigm. Whether or not even a somatosensory input as well as auditory or visual stimulus to one hemisphere elicits the symmetrical "early CNV" was also examined. Eleven normal individuals (3 males, 8 females) performed a conventional CNV paradigm with a click sound as the warning stimulus (WS) and a red light flash as the imperative stimulus (IS). Nine individuals (5 males, 4 females) did the somatosensory CNV paradigm with paired electrical stimuli as WS and IS. The subjects were instructed to press a button in response to IS as fast as possible. The early CNV amplitude was smaller and P300 latency was longer in somatosensory paradigm than conventional paradigm. In addition, the latency of P100 in a somatosensory paradigm was longer than that of N100 in a conventional paradigm. These findings suggest that the initiation of early detection, reflected by P100, the initiation of cognition, reflected by P300, and orienting response, reflected by early CNV, are delayed in a somatosensory CNV paradigm. Furthermore, all event-related potentials (ERPs) evoked by somatosensory stimuli showed a bilateral symmetry.

Adult↗