Biomedical subjects

Thomas F Münte

Publications and source records attributed to Thomas F Münte.

At least 37 records · Page 2Linked to original sources

PubMed2005

Second language interferes with word production in fluent bilinguals: brain potential and functional imaging evidence.

Bilingual individuals need effective mechanisms to prevent interference between their languages. Using event-related brain potentials (ERPs) and functional magnetic resonance imaging (fMRI), we present evidence for interference of phonological information from the nontarget language in German-Spanish bilinguals. A tacit picture-naming task was used in which bilinguals and monolinguals had to make speeded responses based on the first letter of the picture's name in the target language. In one condition, subjects were required to respond when the name began with a vowel and to withhold a response if it started with a consonant. Stimuli had been selected such that in half of the trials, the names in both languages necessitated the same response, whereas in the other half, responses were different for the two languages. For the bilinguals, the language in which the stimuli had to be named was changed after each block. Bilinguals showed phonological interference compared with monolingual performance, which was evident in their performance, ERPs, and fMRI patterns. Nonlanguagespecific brain areas such as the left middle prefrontal cortex were found to be crucial for the control of interference.

Adult↗

PubMed2005

Remember Bach: an investigation in episodic memory for music.

Emotional events are remembered better than nonemotional ones, especially after a long period of time. In this study, we investigated whether emotional music is kept better in episodic long-term memory than less emotional music and to which extent musical structure is important.

Adult↗

PubMed2004

Brain potentials and self-paced random number generation in humans.

Random number generation (RNG) requires executive control. A novel paradigm using the eight drum pads of an electronic drum set as an input device was used to test 15 healthy subjects who engaged in random or ordered number generation (ONG). Brain potentials time-locked to the drum-beats revealed a more negative response during RNG compared to ONG which had a left frontal distribution. Source analysis pointed to Brodmann area 9, which has been reported previously in a PET study and is thought to be engaged in suppression of habitual responses such as counting up in steps of one during RNG. Lateralized readiness potentials reflecting the difference in activation of the contra and ipsilateral motor cortex were smaller during ONG reflecting the ability to preprogram such canonical sequences.

Adult↗

PubMed2004

Target evaluation processing and serum levels of nerve tissue protein S100B in patients with remitted major depression.

Selective attention processes (N2 and P3 components of event-related potentials (ERPs)) have been shown to be impaired in depressed patients but findings have been mixed. Part of this variability might be explained by neurobiological factors. ERPs (Go/Nogo paradigm) were investigated in patients with remitted major depression in relation to S100B. S100B, an astroglial protein with neuroplastic properties, has been shown to be increased in depression. Its pathophysiologic role in depression, however, is not yet sufficiently understood. Patients with increased S100B serum levels (n=6) showed a normal N2- and P3-amplitude in contrast to a reduced N2- and P3-amplitude in patients with normal S100B serum levels (n=6). These findings provide evidence of a correlation between S100B levels and attentional processes in patients with recurrent depression and further substantiate S100B's role as a marker in the course of affective disorders.

Attention↗

PubMed2004

Quantitative MR analyses of the hippocampus: unspecific metabolic changes in aging.

The age-related structural changes of the human hippocampus are not entirely understood. The goal of the present investigation was to understand better the nature of age-related hippocampal changes by a comparative MR-analysis of four complementary aspects of hippocampal integrity: total volume, metabolite concentration, neuron to glial cell ratio and amount of extracellular diffusion space for water. To that end, we applied MR-based methods of manual and computerized (voxel-based morphometry) volumetry, diffusion-weighted imaging and 1H MR spectroscopy to characterize specific age-related hippocampal effects in a group of 22 healthy old adults in comparison with a group of 13 healthy younger adults. Age-related reductions of the hippocampal N-acetyl aspartate to creatine/choline ratio together with only marginal age-related reductions in hippocampal volumes and increases in diffusion parameters suggest that the process of aging affects mainly the metabolic status of the hippocampus with little equivalent age-related changes in hippocampal cell density. The metabolic changes are unspecific as they are not restricted to the hippocampus but equally occur in measures obtained from extrahippocampal temporal lobe regions.

Adult↗

PubMed2004

Functional lesions and human action monitoring: combining repetitive transcranial magnetic stimulation and event-related brain potentials.

OBJECTIVE: Electrophysiological recordings of the error-related negativity (ERN) and functional imaging data point to an involvement of medial frontal cortex (including the anterior cingulate cortex, ACC) and dorsolateral prefrontal cortex (DLPFC) in the detection and correction of performance errors. Here, we studied this network by applying trains of rapid transcranial magnetic stimulation (rTMS) prior to the recording of the ERN. METHODS: Low-frequency (0.9 Hz) rTMS was applied to medial frontal or lateral frontal regions (different sessions) for 60 s immediately before each 3 min ERN recording in 11 healthy young subjects. The ERN was obtained by multichannel recordings in a typical Eriksen flanker task with instructions calling for immediate error correction in case a performance error was detected by the subject. Event-related potentials were quantified and statistically evaluated using standard methodology. RESULTS: Compared to a no-stimulation control condition, medial frontal stimulation led to a small but reliable decrease in the number of corrected errors as well as to an attenuation of the ERN and an increase of the subsequent error-positivity (Pe). No effect on these components was seen after lateral frontal stimulation. No reliable effects on the lateralized readiness potential were observed. CONCLUSIONS: Functional lesions by rTMS appear to interfere with the functions of the medial frontal cortex in error detection and correction.

Adult↗

PubMed2004

An electrophysiological study of errorless learning.

Errorless learning, i.e. learning under conditions that prevent the generation of false memory candidates, has been shown to lead to enhanced memory performance during retrieval compared to errorful, trial-and-error, learning. These two learning methods were implemented in a word-stem completion format and contrasted in young healthy subjects with stimulus-locked and response-locked event-related brain potentials (ERPs) being recorded during memory retrieval. Retrieval accuracy was enhanced for items studied under errorless conditions. Stimulus-locked ERPs showed a modulation of a right frontal effect that differed in amplitude and topography for items learned under errorful and errorless conditions. This effect is interpreted as reflecting post-retrieval processes. In the response-locked ERPs, a typical error-related negativity (ERN) was observed that was most prominent for false alarm trials in the errorless condition, of medium amplitude for hits and false alarms in the errorful condition, smaller for hits in the errorless condition and virtually absent for items correctly or incorrectly classified as new. We propose that the amplitude modulation of the ERN is related to the activity of an internal monitoring device checking the veridicality of a retrieved memory trace.

Adult↗

PubMed2004

Changes in emotional tone and instrumental timbre are reflected by the mismatch negativity.

The present study examined whether or not the brain is capable to preattentively discriminate tones differing in emotional expression or instrumental timbre. In two event-related potential (ERP) experiments single tones (600 ms) were presented which had been rated as happy or sad in a pretest. In experiment 1, 12 non-musicians passively listened to tone series comprising a frequent (standard) single musical tone played by a violin in a certain pitch and with a certain emotional connotation (happy or sad). Among these standard tones deviant tones differing in emotional valence, either in instrumental timbre or in pitch were presented. All deviants generated mismatch negativity (MMN) responses. The MMN scalp topography was similar for all of the three deviants but latency was shorter for pitch deviants than for the other two conditions. The topography of the mismatch responses was indistinguishable. In a second experiment, subjects actively detected the deviant tones by button press. All detected deviants generated P3b waves at parietal leads. These results indicate that the brain is not only able to use simple physical differences such as pitch for rapid preattentive categorization but can also perform similar operations on the basis of more complex differences between tones of the same pitch such as instrumental timbre and the subtle timbral differences associated with different emotional expression. This rapid categorization may serve as a basis for the further fine-grained analysis of musical (and other) sounds with regard to their emotional content.

Acoustic Stimulation↗

PubMed2004

Brain potentials index executive functions during random number generation.

The generation of random sequences is considered to tax different executive functions. To explore the involvement of these functions further, brain potentials were recorded in 16 healthy young adults while either engaging in random number generation (RNG) by pressing the number keys on a computer keyboard in a random sequence or in ordered number generation (ONG) necessitating key presses in the canonical order. Key presses were paced by an external auditory stimulus to yield either fast (1 press/800 ms) or slow (1 press/1300 ms) sequences in separate runs. Attentional demands of random and ordered tasks were assessed by the introduction of a secondary task (key-press to a target tone). The P3 amplitude to the target tone of this secondary task was reduced during RNG, reflecting the greater consumption of attentional resources during RNG. Moreover, RNG led to a left frontal negativity peaking 140 ms after the onset of the pacing stimulus, whenever the subjects produced a true random response. This negativity could be attributed to the left dorsolateral prefrontal cortex and was absent when numbers were repeated. This negativity was interpreted as an index for the inhibition of habitual responses. Finally, in response locked ERPs a negative component was apparent peaking about 50 ms after the key-press that was more prominent during RNG. Source localization suggested a medial frontal source. This effect was tentatively interpreted as a reflection of the greater monitoring demands during random sequence generation.

Adult↗

PubMed2004

Event-related potentials and EMDR treatment of post-traumatic stress disorder.

Ten patients suffering from post-traumatic stress disorder (PTSD) following a severe traumatic event, were assessed with event-related brain potentials (ERPs) in a modified oddball paradigm containing auditory standard, target, and novel tones. ERPs were assessed before and after a treatment session using the eye movement desensitization and reprocessing method. Compared to a control group that underwent sham treatment, ERPs of the patients showed a reduction of the P3a component in the post-treatment recording, suggesting a reduced orienting to novel stimuli and reduced arousal level after the treatment. Moreover, psychometric assessment revealed a marked improvement of the PTSD symptoms after treatment.

Adult↗

PubMed2004

Cognitive changes in short-term hypothyroidism assessed with event-related brain potentials.

Hypothyroidism is a common clinical problem during (131)Iodine-therapy of thyroid cancer. In the present investigation, possible cognitive dysfunction during hypothyroid state was assessed by means of neuropsychological tests and the recording of event-related brain potentials (ERPs). Fifteen patients undergoing therapy for thyroid cancer were examined twice: (1) substituted with thyroid hormones, (2) during hypothyroid state immediately prior to treatment. Standard neuropsychological tests were applied during both sessions and subjects showed a mild-to-moderate impairment in their hypothyroid state. In addition, ERPs were recorded from 19 scalp sites while subjects performed two visual search tasks. The serial task required the effortful one-by-one scanning of several items within a visual array, while the parallel task allowed processing of all stimulus items in parallel and automatically. ERPs showed a marked amplitude decrement and delay of the P3 component known to index the speed of stimulus evaluation and the amount of available processing resources. This effect was present only for the serial search task, while no changes were seen in the parallel search task. These data show that hypothyroidism during (131)Iodine-therapy is associated with clinically relevant cognitive dysfunctions, especially with effortful attention demanding tasks.

Acute Disease↗

PubMed2004

Transcranial magnetic stimulation to the parietal lobes reduces detection of contralateral somatosensory stimuli.

OBJECTIVES: Neglect has been described in patients with lesions of the parietal cortex and has been interpreted as a disorder of the allocation of spatial attention. The persistence of neglect has been linked to poor rehabilitation outcome in patients suffering from acute stroke. Transcranial magnetic stimulation (TMS) applied to the parietal cortex has been shown to induce changes in the perception of stimuli including tactile stimulation of the fingers contra- and ipsilateral to the stimulated hemisphere. MATERIAL AND METHODS: In the current study, eleven normal young subjects performed a detection task for cutaneous electrical stimuli to the left or right forearm that had been precued by a preceding visual warning stimulus. To investigate the role of the parietal cortical areas for attentional processes TMS was applied to frontal and parietal scalp sites of each hemisphere in the cue-target interval before the somatosensory stimulus. RESULTS: Right and left parietal stimulation led to reduced detection sensitivity for near threshold stimuli to the forearm contralateral to the stimulated hemisphere without hemispheric differences. Ipsilateral tactile perception was not influenced by parietal TMS and there was no change in perception after frontal stimulation to left or right scalp sites. CONCLUSION: This pattern of results is consistent with a role of the right and left parietal lobe in the distribution of spatial attention and provides an experimental basis for possible therapeutical application of TMS to improve attentional deficits in stroke patients.

Adult↗

PubMed2003

Tracking of multiple sound sources defined by interaural time differences: brain potential evidence in humans.

Among other cues, interaural time differences (ITD) can be used to compute the location of a sound. To investigate whether ITD can be used for the preattentive detection of sounds coming from a different location than standard sounds (P=0.7, no ITD), left and right 'far' (900 micros ITD, 80 degrees excentricity) and 'near ' (300 micros ITD, 30 degrees ) deviant stimuli (each deviant P=0.075) were presented via headphones. While 15 young healthy subjects passively listened to these sequences, the mismatch negativity (MMN) of the event-related potential was obtained for the deviant sounds. MMN was reliable for all four deviants but larger for the far-lateralized sounds. Moreover, MMN was larger contralateral to the location of the deviant. This indicates a role of preattentive mechanisms in the spatial analysis of auditory scenes.

Adult↗

PubMed2003

Preattentive evaluation of multiple perceptual streams in human audition.

To analyze an auditory scene, the segregation of the input into separate streams of information is necessary. Here, the mismatch negativity (MMN) of the event-related potential was used to trace the number of simultaneously monitored streams in auditory scene analysis. Subjects passively listened to sounds belonging to either one, two, or three auditory streams defined by spatial position and pitch. An MMN was obtained for deviants within either one, two or three auditory streams albeit with a smaller amplitude in the latter condition. Control experiments ruled out that this effect was due to variations in stimulation rate. Thus, a preattentive deviant detection system based on simple auditory features provides the basis for subsequent attentive processing directed to a selected stream.

Acoustic Stimulation↗

PubMed2003

Storage and integration in the processing of filler-gap dependencies: an ERP study of topicalization and wh-movement in German.

We recorded event-related brain potentials (ERPs) during the processing of unambiguous German sentences containing different types of filler-gap dependency. Both topicalization constructions and wh-questions were found to elicit a left-anterior negativity (LAN) prior to the processing of the subcategorizing verb, relative to a gap-free control condition. At the subcategorizing verb, sentences containing a wh-dependency produced a parietal positivity (P600) relative to topicalization structures. These results support the claim that separable parsing processes are involved in the processing of syntactic dependencies, with working memory based processes being reflected in an LAN, and the relative difficulty of integrating the filler with its subcategorizer reflected in a P600. Integration cost but not memory cost was found to be influenced by the type of filler-gap dependency involved.

Adult↗

PubMed2003

Human error monitoring during implicit and explicit learning of a sensorimotor sequence.

During the acquisition of a sensorimotor sequence error monitoring as reflected by the error-related negativity (ERN) of the event-related brain potential was studied in normal human subjects. The central, imperative letter in an Eriksen-like flanker task either followed a repeating sequence or was determined randomly. 'Explicit learners' were informed about the presence of a sequence, whereas 'implicit learners' were not. Both groups learned the sequential structure inherent in the material as indicated by a speed-up in response time for structured compared to random trials. Most importantly, the ERN was larger for explicit compared to implicit learners. Thus, explicitly searching for a sequential regularity led to a more intensive engagement of the error monitoring system as reflected by the ERN.

Adult↗

PubMed2003

Differences in incidental and intentional learning of sensorimotor sequences as revealed by event-related brain potentials.

The present study investigated differences in sequential learning between subjects who were or were not informed of the presence of a repeating sequence (intentional or incidental group, respectively). Subjects had to learn a 16-letter-long repeating sequence that was irregularly disrupted by deviating stimuli. Reaction times indicated that both groups learned the sequential regularities. Intentional learners showed a larger learning effect. Event-related brain potentials (ERPs) recorded during performance of the task showed a reliably enhanced amplitude for the N2b- and P3b-components for deviant letters for intentional learners, but not for incidental learners. These results are discussed in the context of models proposing that different neural structures are involved in implicit and explicit serial learning.

Adult↗

PubMed2003

The fate of sounds in conductors' brains: an ERP study.

Professional music conductors are required to home in on a particular musician but at the same time have to monitor the entire orchestra. It was hypothesized that this unique experience should be reflected by superior auditory spatial processing. Event-related brain potentials were obtained, while conductors, professional pianists, and non-musicians listened to sequences of bandpass-filtered noise-bursts presented in random order from six speakers, three located in front and three to the right of the subjects. In different runs, subjects either attended the centermost or the most peripheral speaker in order to detect slightly deviant noise-bursts. For centrally located speakers, the ERPs showed a typical Nd attention effect for the relevant location with a steep decline for the neighboring speakers in all subject groups. For peripheral speakers, only the conductors showed attentional selectivity, while the Nd effect was of similar size for all three peripheral speakers in the other two groups. These ERP effects were paralleled by an enhanced behavioral selectivity in peripheral auditory space in conductors. Moreover, the pre-attentive monitoring of the entire auditory scene indexed by the mismatch negativity was superior in musicians compared to non-musicians. In conductors, the MMN was followed by a positivity suggesting an attention shift towards the deviant stimuli in this group only.

Acoustic Stimulation↗