Biomedical subjects

Irene Daum

Publications and source records attributed to Irene Daum.

At least 19 recordsLinked to original sources

PubMed2006

Neurocognitive mechanisms of figurative language processing--evidence from clinical dysfunctions.

The interpretation of proverbs has a long tradition in the assessment of abstract thinking, particularly in schizophrenia. Although the usefulness of proverb interpretation as a diagnostic tool has been questioned over the years, the comprehension of non-literal language nevertheless plays an important role in social interactions. Thus, researchers remain interested in the neurocognitive mechanisms mediating comprehension and use of figurative language. The present paper summarizes and evaluates the evidence from behavioral, lesion and imaging studies including data for compromised figurative language processing derived from clinical populations. One main focus is on studies of figurative language comprehension in schizophrenia. Several theoretical explanations proposed to account for the difficulties schizophrenia patients experience when confronted with figurative language will be addressed. An integration of the evidence from different areas of research is attempted and directions for future investigation are outlined.

Comprehension↗

PubMed2006

Frontal positivity discriminates true from false recognition.

Lesion studies have indicated a presumably recollection-based involvement of the prefrontal cortex in the discrimination of true and false recognition. ERP studies of word list recognition, on the other hand, generally did not yield such effects in the time range associated with recollection processes which might relate to variables like study-test shifts of context. The present study aimed to further explore ERP correlates of true and false recognition, using an experimental procedure which emphasized recollection of item-specific information. Young healthy subjects performed a word recognition task, in which items previously presented (targets), semantically related distractors (lures), and unrelated new items (distractors) had to be classified as old or new followed by a remember/know judgment for old items. Items were presented visually during both study and test. Correct old responses to targets elicited significantly more pronounced positive waveforms in comparison to correct rejections of distractors (old/new effect) between 400 and 700 ms after stimulus onset at all left and central electrode positions. A significant old/new effect for false alarms to lures was observed only at the left parietal electrode. ERPs associated with hits and false alarms to lures were similar at parietal but differed at frontal electrode positions. This pattern of results suggests a differential processing of true and false recognition in frontal and posterior brain regions when item-specific recollection is facilitated. Our findings support the assumption of monitoring processes in parallel to the recollection of item-specific information in recognition memory, which might become affected by illusory sensory information generated by posterior areas.

Adult↗

PubMed2006

Time course of cross-hemispheric spatial updating in the human parietal cortex.

In human parietal cortex, the retinal location of a just seen visual stimulus is updated from one hemisphere to the other, when a horizontal eye movement brings the representation of the stimulus into the opposite visual hemifield. The present study aimed to elucidate the time course of this process. Twelve subjects performed an updating task, in which a filled circle was shown before a horizontal saccade, requiring updating of stimulus location, and a control task without visual stimulation before the saccade. Electroencephalogram (EEG) and electrooculogram (EOG) were recorded while subjects performed the tasks and LORETA source analysis was performed on event-related potential (ERP) components. ERP amplitudes were more positive in the updating condition in comparison to the control condition in two latency windows. An early positive wave starting at about 50 ms after saccade offset and originating in the posterior parietal cortex contralateral to saccade direction probably reflects the integration of saccade-related and visual information and thus the updating process. A shift of the representation of the to-be-updated stimulus to the opposite hemisphere is reflected in a later component starting approximately 400 ms after saccade offset, which is related to memory and originates in the PPC ipsilateral to saccade direction and thus contralateral to the spatial location of the updated visual stimulus.

Adolescent↗

PubMed2006

Elevated impulsivity and impaired decision-making cognition in heavy users of MDMA ("Ecstasy").

RATIONALE: In animal studies, the common club drug 3,4-methylendioxymethamphetamine (MDMA, "Ecstasy") consistently caused a prolonged loss of presynaptic serotonergic neurons, and evidence suggests that MDMA consumption may also affect the human serotonergic system. Serotonin (5-HT) has been implicated in the regulation of impulsivity and such executive functions as decision-making cognition. In fact, MDMA users have shown elevated impulsivity in two studies, but little is known about decision making in drug-free MDMA consumers. OBJECTIVE: The aim of this study was to examine the cognitive neurotoxicity of MDMA with regard to behavioral impulsivity and decision-making cognition. METHODS: Nineteen male, abstinent, heavy MDMA users; 19 male, abstinent cannabis users; and 19 male, drug-naïve controls were examined with the Matching Familiar Figures Test (MFFT) as well as with a Go/No-Go Task (GNG) for impulsivity and with a Gambling Task (GT) for executive functioning. RESULTS: MDMA users showed significantly elevated impulsivity in the MFFT Impulsivity score (I-score), but not in commission errors of the GNG, compared with controls. Cannabis users did not yield altered impulsivity compared with controls. In the GT, MDMA users performed significantly worse than cannabis consumers and controls, whereas cannabis users exhibited the same decision-making capacity as controls. In addition, the I-score as well as the decision-making performance was correlated with measures of MDMA intake. The I-score and the decision-making performance were also correlated. CONCLUSION: These results suggest that heavy use of MDMA may elevate behavioral impulsivity and impair decision-making cognition possibly mediated by a selective impairment of the 5-HT system.

Adult↗

PubMed2006

Cognitive function in multiple system atrophy of the cerebellar type.

Dementia represents an exclusion criterion for the diagnosis of multiple system atrophy (MSA), but there have been reports of fronto-executive dysfunction in patients with MSA of the striatonigral type (MSA-P). To study the cognitive profile of MSA, 20 patients with MSA of the cerebellar type (MSA-C) were subjected to an extensive neuropsychological test battery comprising tests for IQ, attention, verbal and visuospatial memory, as well as executive function. There was evidence for impaired verbal memory and verbal fluency. Test performance was not related to the severity of motor disability. Regarding the similar cognitive syndrome of MSA-P, the otherwise subclinical problems in MSA-C result from subcortical rather than from cerebellar dysfunction.

Age of Onset↗

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↗

PubMed2006

Self recognition versus recognition of others by biological motion: viewpoint-dependent effects.

We investigated the influence of viewing angle on performance in recognising the identity of one's own person and familiar individuals such as friends or colleagues from walking patterns. Viewpoint-dependent recognition performance was tested in two groups of twelve persons who knew each other very well. Participants' motion data were acquired by recording their walking patterns in three-dimensional space with the use of a motion capture system. Size-normalised point-light displays of biological motion of these walking patterns, including one's own, were presented to the same group members on a computer screen in frontal view, half-profile view, and profile view. Observers were requested to assign the person's name to the individual gait pattern. No feedback was given. Whereas recognition performance of one's own walking patterns was viewpoint independent, recognition rate for other familiar individuals was better for frontal and half-profile view than for profile view. These findings are discussed in the context of the theory of common coding of motor and visual body representations.

Adult↗

PubMed2006

Creative thinking in adolescents with attention deficit hyperactivity disorder (ADHD).

A widened attentional focus, that is typically associated with ADHD, has been postulated to be accompanied by enhanced creative ability. However, creativity has been only limitedly examined in ADHD. Performance across several creativity measures were investigated in three groups: adolescents with ADHD, those with conduct disorder, and a healthy control sample. The ADHD group exhibited selective cognitive advantages and disadvantages by demonstrating an enhanced ability in overcoming the constraining influence of examples, but a reduced capacity to generate a functional invention during an imagery task. These findings are interpreted with reference to inhibitory control mechanisms and the contextual modulation of creative cognition.

Adolescent↗

PubMed2006

Altered processing of corollary discharge in thalamic lesion patients.

Accumulating evidence suggests that thalamic nuclei relay corollary discharge information of saccadic eye movements, enabling the visual system to update the representation of visual space. The present study aimed to explore the effect of thalamic lesions in humans on updating-related cortical processing. Event-related potentials were recorded while four patients with impairments in using corollary discharge information and 12 healthy control subjects performed a saccadic double-step task. In the experimental condition, which required the use of corollary discharge information, control subjects showed a pronounced positivity over the parietal cortex starting about 150 ms after first saccade onset, reflecting the updating process. In the patients, parietal processing related to updating was altered. Three patients showed evidence of reduced updating event-related potential effects, consistent with a unilateral deficit in using corollary discharge information. In two patients, the event-related potential topography differed significantly from the topography pattern observed in controls. Thalamic damage affects updating-related processing, presumably due to insufficient transfer of saccade-related information to parietal areas. This study thus provides further evidence for thalamic involvement in relaying corollary discharge information related to saccadic eye movements. Our data suggest that integration of corollary discharge and motor information occurs directly before the second saccade in a double-step task.

Adult↗

PubMed2006

Memory deficits in abstinent MDMA (ecstasy) users: neuropsychological evidence of frontal dysfunction.

Chronic administration of the common club drug 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) is associated with long-term depletion of serotonin (5-HT) and loss of 5-HT axons in the brains of rodents and non-human primates, and evidence suggests that recreational MDMA consumption may also affect the human serotonergic system. Moreover, it was consistently shown that abstinent MDMA users have memory deficits. Recently, it was supposed that these deficits are an expression of a temporal or rather hippocampal dysfunction caused by the serotonergic neurotoxicity of MDMA. The aim of this study is to examine the memory deficits of MDMA users neuropsychologically in order to evaluate the role of different brain regions. Nineteen male abstinent MDMA users, 19 male abstinent cannabis users and 19 male drug-naive control subjects were examined with a German version of the Rey Auditory Verbal Learning Test (RAVLT). MDMA users showed widespread and marked verbal memory deficits, compared to drug-naive controls as well as compared to cannabis users, whereas cannabis users did not differ from control subjects in their memory performance. MDMA users revealed impairments in learning, consolidation, recall and recognition. In addition, they also showed a worse recall consistency and strong retroactive interference whereby both measures were previously associated with frontal lobe function. There was a significant correlation between memory performance and the amount of MDMA taken. These results suggest that the memory deficits of MDMA users are not only the result of a temporal or hippocampal dysfunction, but also of a dysfunction of regions within the frontal cortex.

Adult↗

PubMed2005

Cross-modal processing in auditory and visual working memory.

This study aimed to further explore processing of auditory and visual stimuli in working memory. Smith and Jonides (1997) [Smith, E.E., Jonides, J., 1997. Working memory: A view from neuroimaging. Cogn. Psychol. 33, 5-42] described a modified working memory model in which visual input is automatically transformed into a phonological code. To study this process, auditory and the corresponding visual stimuli were presented in a variant of the 2-back task which involved changes from the auditory to the visual modality and vice versa. Brain activation patterns underlying visual and auditory processing as well as transformation mechanisms were analyzed. Results yielded a significant activation in the left primary auditory cortex associated with transformation of visual into auditory information which reflects the matching and recoding of a stored item and its modality. This finding yields empirical evidence for a transformation of visual input into a phonological code, with the auditory cortex as the neural correlate of the recoding process in working memory.

Adult↗

PubMed2005

Post-saccadic updating of visual space in the posterior parietal cortex in humans.

Updating of visual space takes place in the posterior parietal cortex to guarantee spatial constancy across eye movements. However, the timing of updating with respect to saccadic eye movements remains a matter of debate. In the present study, event-related potentials (ERPs) were recorded in 15 volunteers during a saccadic double-step task to elucidate the time course of the updating process. In the experimental condition updating of visual space was required, because both saccade targets had already disappeared before the first saccade was executed. A similar task without updating requirements served as control condition. ERP analysis revealed a significantly larger slow positive wave in the retino-spatial dissonance condition compared to the control condition, starting between 150 and 200 ms after first saccade onset. Source analysis showed an asymmetry with respect to the direction of the first saccade. Whereas the source was restricted to the right PPC in trials with leftward first saccades, left and right PPC were involved in rightward trials. The results of the present study suggest that updating of visual space in a saccadic double-step task occurs not earlier than 150 ms after the onset of the first saccade. We conclude that extraretinal information about the first saccade is integrated with motor information about the second saccade in the inter-saccade interval.

Adult↗

PubMed2005

Visuo-verbal interactions in working memory: evidence from event-related potentials.

Working memory is thought to involve separate modality-specific storage systems. Interactions between these storage systems were investigated using a novel cross-modal 2-back paradigm. 2-back, 1-back and target items were presented either visually as a verbalizable linedrawing or auditorily as a digitized spoken word. ERPs for auditory targets were primarily modulated by the presentation modality of the 2-back item, whereas ERPs for visual targets were largely modulated by presentation modality of the 1-back item. Results indicate that verbalizable pictures are only partially transformed into a phonological code for rehearsal in working memory. Furthermore, results support the idea of a more stable and persistent auditory short-term store as opposed to a more transiently activated visual store for verbalizable material.

Acoustic Stimulation↗

PubMed2005

Recollection and familiarity in negative schizophrenia.

Using the "remember-know" procedure to assess recognition memory, previous studies yielded evidence of impaired recollection but intact familiarity in schizophrenia patients. However, so far, the recognition memory performance of schizophrenia patients has not yet been analysed using the dual-process signal detection model (DPSD) by Yonelinas [Yonelinas, A. P. (2001). Components of episodic memory: The contribution of recollection and familiarity. Philosophical Transactions of Royal Society of London. Series B: Biological Sciences, 356(1413), 1363-1374], which accurately accounts for response and memory bias. Also, clinical symptoms have not yet been taken into account. Based on findings from neuropsychological and neurobiological research we hypothesized that high negative symptoms might be associated with a profile of impaired recollection and spared familiarity. The recognition memory performance of 22 schizophrenia patients scoring higher or lower on the negative symptoms subscale of the Positive and Negative Syndrome Scale (PANSS) was assessed by means of a word list discrimination task. Following the rationale of the dual-process signal detection model, estimates of recollection and familiarity were derived. The recollection estimate, derived by the DPSD model, was lower in patients with more severe negative symptomatology compared with both the patients with lower negative symptoms scores and healthy individuals. Familiarity was not affected if IQ was partialled out. Furthermore, the results yielded increased false alarm rates in patients with negative schizophrenia. The findings confirm an association of negative symptoms and recollection impairment in schizophrenia.

Adult↗

PubMed2005

Structural encoding and recognition of biological motion: evidence from event-related potentials and source analysis.

In the present study, we investigated how different processing stages involved in the perceptual analysis of biological motion (BM) are reflected by modulations in event-related potentials (ERP) in order to elucidate the time course and location of neural processing of BM. Data analysis was carried out using conventional averaging techniques as well as source localization with low resolution brain electromagnetic tomography (LORETA). ERPs were recorded in response to point-light displays of a walking person, an inverted walking person and displays of scrambled motion. Analysis yielded a pronounced negativity with a peak at 180 ms after stimulus onset which was more pronounced for upright walkers than for inverted walkers and scrambled motion. A later negative component between 230 and 360 ms after stimulus onset had a larger amplitude for upright and inverted walkers as compared to scrambled walkers. In the later component, negativity was more pronounced in the right hemisphere revealing asymmetries in BM perception. LORETA analysis yielded evidence for sources specific to BM within the right fusiform gyrus and the right superior temporal gyrus for the second component, whereas sources for BM in the early component were located in areas associated with attentional aspects of visual processing. The early component might reflect the pop-out effect of a moving dot pattern representing the highly familiar form of a human figure, whereas the later component might be associated with the specific analysis of motion patterns providing biologically relevant information.

Adult↗

PubMed2005

Effect of working memory on evaluation-related frontocentral negativity.

Recent results suggest that a negative ERP potential emerges not only on error trials, but is also found after correct responses. There is broad evidence that this component is generated in the anterior cingulate cortex (ACC). The present study aimed to explore the influence of working memory demands on the evaluation process probably reflected by the negative potential. To this purpose, a modified continuous performance task (CPT) was used, with variations of the delay between cues and imperative stimuli. Data were analyzed using conventional averaging techniques as well as source localization with LORETA (low resolution brain electromagnetic tomography). Results suggest a significant effect of working memory delay on the amplitude of the post-response negative ERP component. Its source was located in the anterior cingulate cortex, with the exact location being dependent upon working memory demands. The results support the notion of a general response evaluation system reflected by a post-response negative component. The findings of a working memory dependent modification of this potential suggest a functional link between the medial frontal cortex and the lateral frontal regions primarily involved in working memory processing.

Adult↗

PubMed2005

Attention and memory dysfunctions in mild multiple sclerosis.

This study investigated the relationship between clinical symptoms and cognitive dysfunction in multiple sclerosis. Cognitive dysfunction and visual evoked potentials (VEPs) were studied in patients free of physical disability and mildly to moderately disabled patients with multiple sclerosis (MS). Disability-free patients (EDSS < or = 1.5; n = 13), mildly to moderately disabled patients (EDSS ranging from 2 to 6; n = 13) and a healthy matched control group (n = 16) were examined with respect to attention, verbal and nonverbal memory and early visual processing (VEPs). Disability-free patients showed mild impairments on phasic alertness and divided attention. Deficits were more pronounced in mildly to moderately disabled patients who were additionally impaired with respect to non-verbal memory. Despite adequate visual acuity, one half of all patients showed abnormal VEP latencies for both eyes at the same time. The findings suggest that cognitive deficits are already present in multiple sclerosis even in the absence of physical disability. Even with normal visual acuity, perceptual impairments should be considered as part of the CNS affection.

Adult↗

PubMed2005

Conceptual expansion and creative imagery as a function of psychoticism.

The ability to be creative is often considered a unique characteristic of conscious beings and many efforts have been directed at demonstrating a relationship between creativity and the personality construct of psychoticism. The present study sought to investigate this link explicitly by focusing on discrete facets of creative cognition, namely the originality/novelty dimension and the practicality/usefulness dimension. Based on Eysenck's conceptualisation of psychoticism as being characterised by an overinclusive cognitive style, it was expected that higher levels of psychoticism would accompany a greater degree of conceptual expansion and elevated levels of originality in creative imagery, but would be unrelated to the practicality/usefulness of an idea. These hypotheses were confirmed in 80 healthy participants who were contrasted based on their EPQ psychoticism scale scores. Our findings suggest that the link between psychoticism and creativity is based on associative thinking and broader but weak top-down activation patterns rather than on goal-related thinking.

Adult↗