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Biomedical subjects

T F Münte

Publications and source records attributed to T F Münte.

At least 19 recordsLinked to original sources

[Evidence based treatment of executive dysfunction].

The therapy of executive functions plays an essential role for the functional outcome and the social reintegration. Nevertheless there is a lack of cognitive oriented and evidence-based therapy programs. The purpose of our review is the classification of the present evaluation studies with regard of the principles of evidence based medicine (EbM) and of the content. Besides the EbM criteria the number of participants, the kind and number of interventions, the types of etiology and the standardisation and quality of the outcome parameters are measured. By that, an assessment should be possible, which interventions are successful for what types of dysexecutive syndrome. The present studies belong to three different types of therapy: at first, a therapy form focussing on manipulation and modification of the environment, second, a therapy form using behaviour management and a third form, which is based on practise and cognitive interventions. The heterogeneity of the therapy forms makes different types of evaluation necessary. The evaluation studies reach different classes of evidence. While the cognitive therapy forms reach comparable high evidence classes, the evaluation studies about behaviour management--mostly present as single case studies with individual outcome parameter--reach only low evidence classes. Final, we discuss, which therapy forms are effective using the strong evaluation criteria and at which point further conceptual task and further research is useful.

Cognitive Behavioral Therapy↗

Relationship between hippocampal structure and memory function in elderly humans.

With progressing age, the ability to recollect personal events declines, whereas familiarity-based memory remains relatively intact. It has been hypothesized that age-related hippocampal atrophy may contribute to this pattern because of its critical role for recollection in younger humans and after acute injury. Here, we show that hippocampal volume loss in healthy older persons correlates with gray matter loss (estimated with voxel-based morphometry) of the entire limbic system and shows no correlation with an electrophysiological (event-related potential [ERP]) index of recollection. Instead, it covaries with more substantial and less specific electrophysiological changes of stimulus processing. Age-related changes in another complementary structural measure, hippocampal diffusion, on the other hand, seemed to be more regionally selective and showed the expected correlation with the ERP index of recollection. Thus, hippocampal atrophy in older persons accompanies limbic atrophy, and its functional impact on memory is more fundamental than merely affecting recollection.

Adult↗

Brain potentials related to self-generated and external information used for performance monitoring.

OBJECTIVE: Humans need to supervise and adjust their own behavior by means of an error detection and correction system as well as by using externally available information. The purpose of the present study was to compare the electrophysiological effects related to self-generated internal and to external (feedback) information used for performance monitoring. METHODS: Fourteen young normal subjects learned to associate each of several line-drawings with either a left-hand or right-hand response. In the experiment proper multi-channel ERPs were obtained time-locked to (a) the line-drawings, (b) the button-press, and (c) subsequent feedback stimuli. Feedback was either affirmative, negative, or equivocal. Event-related potentials were quantified and statistically evaluated using standard methodology. RESULTS: Response-locked ERPs showed a typical error-related negativity (ERN) for erroneous responses. ERPs to negative and equivocal feedback stimuli contained a negativity with a more posterior distribution than that of the ERN, which occurred earlier and had a higher peak amplitude in the equivocal condition. Dipole modeling suggests that this feedback-related negativity is generated by medial prefrontal and posterior cingulate cortex areas. CONCLUSIONS: Different brain systems support the use of internal and external information necessary for performance monitoring and modification. SIGNIFICANCE: The flexible use of internal and external information for performance control is a core executive function. The delineation of the corresponding brain correlates will further our understanding of executive dysfunction in neurological disorders.

Adult↗

[Cognitive dysfunction after abdominal surgery in elderly patients].

Elderly patients often suffer from postoperative cognitive deficits (POCD) after serious surgical operations. The reasons for this are not well understood. We investigated the influence of the invasiveness of the operation and the duration of the operation as well as the patient's preoperative physical status on measures of cognitive dysfunction. In a prospective study 59 elderly patients (mean age 69.2 years) were subjected to a neuropsychological test battery and a questionnaire following an abdominal surgical operation. The postoperative recovery with a focus on memory function was assessed using the Wechsler Memory Scale (WMS) seven days after the operation. Self-reported cognitive deficits were studied using the a questionnaire of experienced attention deficits (FEDA) three months after the operation. Postoperative psychological and self-reported test results varied as a function of the invasiveness and the duration of the operation. After more invasive operations patients reported a stronger deficit in activities of daily living and a reduction in drive than after less invasive operations. In addition, the duration of anesthesia influenced the experienced deficits. The self-reported deficits were more strongly influenced by the features of the operation than the psychological test data. The physical status of the patients according to the American Society of Anesthesiologists (ASA) along with the duration of anesthesia as covariate was identified as a good predictor for the cognitive recovery post operation.

Abdomen↗

Dissecting out conscious and unconscious memory (sub)processes within the human medial temporal lobe.

The human medial temporal lobe (MTL) system mediates memories that can be consciously recollected. However, the specific natures of the individual contributions of its various subregions to conscious memory processes remain equivocal. Here we show a functional dissociation between the hippocampus proper and the parahippocampal region in conscious and unconscious memory as revealed by invasive recordings of limbic event-related brain potentials recorded during explicit and implicit word recognition: Only hippocampal and not parahippocampal neural activity exhibits a sensitivity to the implicit versus explicit nature of the recognition memory task. Moreover, only within the hippocampus proper do the neural responses to repeated words differ not only from those to new words but also from each other as a function of recognition success. By contrast parahippocampal (rhinal) responses are sensitive to repetition independent of conscious recognition. These findings thus demonstrate that it is the hippocampus proper among the MTL structures that is specifically engaged during conscious memory processes.

Brain Mapping↗

Developmental dyslexics show altered allocation of attention in visual classification tasks.

OBJECTIVES: Event-related brain potentials (ERPs) were recorded to investigate allocation of attention in adult developmental dyslexics. SUBJECTS AND METHODS: Twelve adult developmental dyslexics and 12 matched normal controls performed three visual choice reaction tasks. In the passive oddball condition, subjects watched two different simple visual stimuli presented with 87.5 and 12.5% probability. In the active oddball condition, participants responded to the low-probability target stimulus. In the active 50/50-condition, both stimuli were presented with 50% probability and a response was required to the target stimulus only. RESULTS: No group differences emerged for performance, P300 latency or laterality and for N200 amplitude, latency or laterality. An enhancement of P300 amplitude with a frontal distribution was found for NoGo (standard)-stimuli in both active conditions for the dyslexic sample. CONCLUSION: Results are discussed in the context of deviances in allocation of attentional resources in dyslexic readers.

Adult↗

Selective loss of timbre perception for keyboard and percussion instruments following a right temporal lesion.

We report the case of a 65-year-old man WDK, who experienced selective loss of timbre perception for keyboard and percussion instruments following a right temporal stroke comprising the anterior superior and medial gyrus and parts of the insular region. Formerly an avid listener to music, the sound of an orchestra appeared to be "flat" to him. WDK and a matched control subject underwent a detailed neuropsychological test battery covering basic auditory function (audiometry and just notable difference for pitch shifts), specific auditory function (recognition of environmental sounds), specific musical functions like discrimination of pitch, interval, contour, rhythm and metre, recognition of familiar melodies, emotional responsiveness, perception of timbre and auditory spectral analysis. While WDK displayed no deficits in primary auditory function, the test battery revealed a selective impairment in the perception of timbre of keyboard and percussion instruments which could be traced to a deficit in discriminating rapid changes of the spectral composition of a tone. Hence, these findings demonstrate the existence of highly specific neural networks underlying isolated aspects of timbre perception in the right anterior temporal lobe.

Acoustic Stimulation↗

Discrepant target detection and action monitoring in obsessive-compulsive disorder.

Obsessive-compulsive disorder (OCD) has been related to altered mechanisms of action monitoring and target detection, and it has been hypothesized that hyperactive striatal-cortical circuits constitute the underlying pathophysiology. This study used event-related brain potentials (ERPs) to explore this hypothesis. A choice reaction time experiment was carried out in a group of OCD patients and a normal comparison group. The P3b component of the ERP to targets was taken as an indicator of the target-evaluation process and the response-locked error-related negativity (ERN) served as an indicator of action monitoring. We hypothesized that the OCD group would show a shortened P3b latency and an amplitude-enhanced ERN. Consistent with our expectations, the P3b latency was shorter and the ERN amplitude was higher in the OCD group. Unexpectedly, we also observed a prolonged ERN latency in the OCD group and a more posterior topography of this component. The data provide partial support for the hypothesis of a hyperactive neural network in OCD. In addition the disorder must involve pathophysiological processes that are presumably related to other aspects of its complex and heterogeneous clinical hallmarks.

Adult↗

Event-related brain potentials to sound omissions differ in musicians and non-musicians.

The mismatch negativity (MMN) component of the auditory event-related brain potential reflects the automatic detection of sound change. MMN to occasionally omitted sounds in a tone series can be used to investigate the time course of temporal integration in the acoustic system. We used MMN to study differences in temporal integration in musicians and non-musicians. In experiment 1, occasionally omitted 'sounds' in an otherwise regular tone series evoked a reliable MMN at interstimulus intervals (SOAs) of 100, 120, 180 and 220 ms in musicians. In non-musicians, MMN was smaller/absent in the 180 and 220 ms SOAs, respectively. In experiment 2, deviance of a tone was induced by presenting tones at a shorter SOA (100 or 130 ms) compared to the standard stimulus (150 ms). Musicians showed a reliable MMN for both deviant SOAs whereas non-musicians showed an MMN only for tones presented 50 ms prior to a standard tone (SOA 100 ms). These results indicate that the temporal window of integration seems to be longer and more precise in musicians compared to musical laypersons and that long-term training is reflected in changes in neural activity.

Acoustic Stimulation↗

An electrophysiological analysis of the time course of conceptual and syntactic encoding during tacit picture naming.

A central question in psycholinguistic research is when various types of information involved in speaking (conceptual/semantic, syntactic, and phonological information) become available during the speech planning process. Competing theories attempt to distinguish between parallel and serial models. Here, we investigated the relative time courses of conceptual and syntactic encoding in a tacit picture-naming task via event-related brain potential (ERP) recordings. Participants viewed pictures and made dual-choice go/no-go decisions based on conceptual features (whether the depicted item was heavier or lighter than 500 g) and syntactic features (whether the picture's German name had feminine or masculine syntactic gender). In support of serial models of speech production, both the lateralized readiness potential, or LRP (related to response preparation), and the N200 (related to response inhibition) measures indicated that conceptual processing began approximately 80 msec earlier than syntactic processing.

Adult↗

Human event-related potentials and distraction during selective listening.

Event-related brain potentials were recorded from healthy human subjects while they attended to one of two auditory stimulus channels (defined by location, left and right of a fixation point, and pitch) in order to detect rare target events. The distracting properties of periodic noise (vs. continuous noise, experiment 1) and backward speech (vs. forward speech, experiment 2) presented from a third speaker located behind the subjects were investigated. A typical attention effect with a larger negativity for attended tones was observed in both experiments. Backward speech led to a significantly reduced target detection rate for the first four stimuli after onset of the distractor accompanied by a reduced event-related brain potential (ERP)-attention effect and a reduced fronto-central N2b component for the target stimuli. This indicates that irrelevant information leads to an attention decrement of about 1 s duration.

Acoustic Stimulation↗

Control of semantic interference in episodic memory retrieval is associated with an anterior cingulate-prefrontal activation pattern.

Prefrontal activation is a consistent finding in functional neuroimaging studies of episodic memory retrieval. In the present study we aimed at a further analysis of prefrontal neural systems involved in the executive control of context-specific properties in episodic memory retrieval using an event-related fMRI design. Nine subjects were asked to learn two 20-item word lists that consisted of concrete nouns assigned to four semantic categories. Ten items of both word lists referred to the same semantic category. Subjects were instructed to determine whether nouns displayed in random order corresponded to the first 20-item target list. The interference evoked by the retrieval of semantically related items of the second list resulted in significantly longer reaction times compared to the noninterference condition. Contrasting the interference against the noninterference retrieval condition demonstrated an activation pattern that comprised a right anterior cingulate and frontal opercular area and a left-lateralized dorsolateral prefrontal region. Trial averaged time series revealed that the PFC areas were selectively activated at the interference condition and did not respond to the familiarity of learned words. These findings suggest a functionally separable role of prefrontal cortical areas mediating processes associated with the executive control of interfering context information in episodic memory retrieval.

Adult↗

Central effects of sildenafil (Viagra) on auditory selective attention and verbal recognition memory in humans: a study with event-related brain potentials.

The purpose of this study was to assess possible central side-effects of sildenafil (Viagra) on attention and memory functions. Sildenafil and placebo were administered in young male subjects in a double-blind balanced cross-over design. Behavioral patterns and event-related brain potentials (ERP) were recorded in a spatial auditory attention and a visual word recognition task. While behavioral patterns did not reveal any overt effects of sildenafil, auditory ERPs were indicative of an enhanced ability to focus attention (amplitude enhancement of Nd-effect) and to select relevant target stimuli in the sildenafil condition (P3 component). In the memory task, CNS-effects of sildenafil were evident in a reduction of a negativity in the 150-250 ms range. No overt effects on behavior were observed. Nevertheless, the data reveal CNS-effects of sildenafil necessitating further studies.

Adult↗

Oxazepam alters action monitoring.

RATIONALE: Oxazepam has been demonstrated to slow reaction times and increase the rate of omission errors in attentional experiments. This suggests that action monitoring might also be impaired. OBJECTIVES: The present study used the event-related brain potential (ERP) technique to investigate this hypothesis. The P3b component to targets was taken as an indicator of the target evaluation process, and the response-locked error-related negativity (ERN) served as an indicator of action monitoring. We hypothesized that the amplitudes of ERN and P3b would be reduced as an effect of oxazepam. METHODS: A simple "oddball" reaction time experiment was conducted in a double-blind crossover study of 30 mg oxazepam versus placebo. In order to investigate variations in attentional allocation, separate experimental runs were undertaken with target frequencies of 50% and 80%. RESULTS: ERN and P3b amplitudes were lower in the 80% target condition than in the 50% condition. Oxazepam did not affect behavioral parameters but was associated with an ERN of lower amplitude than the placebo condition. ERN amplitude variations between target conditions remained unchanged. CONCLUSIONS: Although the intake of 30 mg oxazepam did not impair behavioral performance, measures of the electrophysiological recordings show that action monitoring processes were altered. We argue that this may be related to the anxiolytic properties of the drug and may constitute an important causal factor for behavioral impairments after the intake of oxazepam.

Adult↗

Influence of cerebral lesion volume and lesion distribution on event-related brain potentials in multiple sclerosis.

Neurocognitive involvement in multiple sclerosis (MS) is heterogeneous with some authors suggesting a frontal pattern in patients with predominantly frontal lesions. To assess the relationship between the distribution of lesions and two cognitive components (visual N2, auditory P3a) of the event-related brain potential (ERP) receiving contributions from frontal lobe structures, we performed a combined ERP and magnetic resonance imaging (MRI) study. Thirty-four MS patients were assigned to "low lesion volume, (LLV)"(n = 12),"high lesion volume,(HLV)"(n = 12) and"frontal lesion volume, (FLV)" (n = 10) groups according to lesion volume and distribution on T2-weighted MRI-scans of the brain. ERPs in visual and auditory classification tasks as well as neuropsychological tests were carried out in patients and control subjects (n = 15). The index for automatic feature registration, the N2 component with its mainly frontal contribution in the visual task, was significantly reduced in amplitude in the FLV and HLV groups (both p < 0.01 vs. controls). Moreover its amplitude correlated with lesion volume (r=0.64, p < 0.001). In contrast neither P3a nor P3b subcomponents with a multiple generator nature in the auditory task varied systematically with lesion volume or distribution. Total lesion volume rather than predominant lesion arrangement appears to be the most important factor in neurocognitive changes in MS. This is most consistent with the view that MS lesions lead to partial disconnections within widespread cortical networks which in turn produce a pattern of neuropsychological deficits that reflect total lesion load more than lesion distribution.

Adult↗

Differences in brain potentials to open and closed class words: class and frequency effects.

Closed class (determiners, pronouns, conjunctions, prepositions etc. ) and open class (nouns, verbs, adjectives, adverbs) words have different linguistic functions and have been proposed to be processed by different neural systems. Here, event-related potentials (ERPs) were recorded in young German-speaking subjects while they read closed class and open class words flashed upon a video-screen. In the first experiment closed class words were sorted into four different frequency categories and open class words into three categories. The words were presented in a list with the subjects' task to detect occasional non-words. A centroparietal negativity (N400) with a peak latency of about 400 ms varied in amplitude as a function of frequency in both classes. The N400 in closed class items, however, was considerably smaller than that in open class words of similar frequency. A left anterior negativity (N280/LPN) showed some degree of frequency-sensitivity regardless of word class. Only for the very high frequency closed class words a frontal negativity with an onset of about 400 ms was obtained (N400-700). This N400-700 effect was replicated in the second study, in which medium frequency closed and open class words and very high frequency closed class words were presented at the fifth position of simple German sentences. It is suggested that neither N400 nor the left anterior negativity (N280/LPN) distinguish qualitatively between the two word classes and thus claims about different brain systems involved in the processing of open and closed class words are not substantiated electrophysiologically. The N400-700 effect is possibly related to specific grammatical functions of some closed class items, such as determiners.

Adult↗