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Michael Erb

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42 papers
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42

YNIMG Journal 2021 Journal Article

Evidence for modulation of EEG microstate sequence by vigilance level

  • Marina Krylova
  • Sarah Alizadeh
  • Igor Izyurov
  • Vanessa Teckentrup
  • Catie Chang
  • Johan van der Meer
  • Michael Erb
  • Nils Kroemer

The momentary global functional state of the brain is reflected in its electric field configuration and cluster analytical approaches have consistently shown four configurations, referred to as EEG microstate classes A to D. Changes in microstate parameters are associated with a number of neuropsychiatric disorders, task performance, and mental state establishing their relevance for cognition. However, the common practice to use eye-closed resting state data to assess the temporal dynamics of microstate parameters might induce systematic confounds related to vigilance levels. Here, we studied the dynamics of microstate parameters in two independent data sets and showed that the parameters of microstates are strongly associated with vigilance level assessed both by EEG power analysis and fMRI global signal. We found that the duration and contribution of microstate class C, as well as transition probabilities towards microstate class C were positively associated with vigilance, whereas the sign was reversed for microstate classes A and B. Furthermore, in looking for the origins of the correspondence between microstates and vigilance level, we found Granger-causal effects of vigilance levels on microstate sequence parameters. Collectively, our findings suggest that duration and occurrence of microstates have a different origin and possibly reflect different physiological processes. Finally, our findings indicate the need for taking vigilance levels into consideration in resting-sate EEG investigations.

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YNICL Journal 2019 Journal Article

CACNA1C risk variant affects microstructural connectivity of the amygdala

  • Katharina Koch
  • Sophia Stegmaier
  • Lena Schwarz
  • Michael Erb
  • Mara Thomas
  • Klaus Scheffler
  • Dirk Wildgruber
  • Vanessa Nieratschker

Deficits in perception of emotional prosody have been described in patients with affective disorders at behavioral and neural level. In the current study, we use an imaging genetics approach to examine the impact of CACNA1C, one of the most promising genetic risk factors for psychiatric disorders, on prosody processing on a behavioral, functional and microstructural level. Using functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) we examined key areas involved in prosody processing, i.e. the amygdala and voice areas, in a healthy population. We found stronger activation to emotional than neutral prosody in the voice areas and the amygdala, but CACNA1C rs1006737 genotype had no influence on fMRI activity. However, significant microstructural differences (i.e. mean diffusivity) between CACNA1C rs1006737 risk allele carriers and non carriers were found in the amygdala, but not the voice areas. These modifications in brain architecture associated with CACNA1C might reflect a neurobiological marker predisposing to affective disorders and concomitant alterations in emotion perception.

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YNIMG Journal 2019 Journal Article

Tuned to voices and faces: Cerebral responses linked to social anxiety

  • Benjamin Kreifelts
  • Kathrin N. Eckstein
  • Thomas Ethofer
  • Ariane Wiegand
  • Sarah Wächter
  • Carolin Brück
  • Michael Erb
  • Martin Lotze

Voices and faces are the most common sources of threat in social anxiety (SA) where the fear of negative evaluation and social exclusion is the central element. SA itself is spectrally distributed among the general population and its clinical manifestation, termed social anxiety disorder, is one of the most common anxiety disorders. While heightened cerebral responses to angry or contemptuous facial or vocal expressions are well documented, it remains unclear if the brain of socially anxious individuals is generally more sensitive to voices and faces. Using functional magnetic resonance imaging, we investigated how SA affects the cerebral processing of voices and faces as compared to various other stimulus types in a study population with greatly varying SA (N = 50, 26 female). While cerebral voice-sensitivity correlated positively with SA in the left temporal voice area (TVA) and the left amygdala, an association of face-sensitivity and SA was observed in the right fusiform face area (FFA) and the face processing area of the right posterior superior temporal sulcus (pSTSFA). These results demonstrate that the increase of cerebral responses associated with social anxiety is not limited to facial or vocal expressions of social threat but that the respective sensory and emotion processing structures are also generally tuned to voices and faces.

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YNIMG Journal 2018 Journal Article

The human body odor compound androstadienone increases neural conflict coupled to higher behavioral costs during an emotional Stroop task

  • Jonas Hornung
  • Lydia Kogler
  • Michael Erb
  • Jessica Freiherr
  • Birgit Derntl

The androgen derivative androstadienone (AND) is a substance found in human sweat and thus may act as human chemosignal. With the current experiment, we aimed to explore in which way AND affects interference processing during an emotional Stroop task which used human faces as target and emotional words as distractor stimuli. This was complemented by functional magnetic resonance imaging (fMRI) to unravel the neural mechanism of AND-action. Based on previous accounts we expected AND to increase neural activation in areas commonly implicated in evaluation of emotional face processing and to change neural activation in brain regions linked to interference processing. For this aim, a total of 80 healthy individuals (oral contraceptive users, luteal women, men) were tested twice on two consecutive days with an emotional Stroop task using fMRI. Our results suggest that AND increases interference processing in brain areas that are heavily recruited during emotional conflict. At the same time, correlation analyses revealed that this neural interference processing was paralleled by higher behavioral costs (response times) with higher interference related brain activation under AND. Furthermore, AND elicited higher activation in regions implicated in emotional face processing including right fusiform gyrus, inferior frontal gyrus and dorsomedial cortex. In this connection, neural activation was not coupled to behavioral outcome. Furthermore, despite previous accounts of increased hypothalamic activation under AND, we were not able to replicate this finding and discuss possible reasons for this discrepancy. To conclude, AND increased interference processing in regions heavily recruited during emotional conflict which was coupled to higher costs in resolving emotional conflicts with stronger interference-related brain activation under AND. At the moment it remains unclear whether these effects are due to changes in conflict detection or resolution. However, evidence most consistently suggests that AND does not draw attention to the most potent socio-emotional information (human faces) but rather highlights representations of emotional words.

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YNICL Journal 2017 Journal Article

Face-name association task reveals memory networks in patients with left and right hippocampal sclerosis

  • Silke Klamer
  • Monika Milian
  • Michael Erb
  • Sabine Rona
  • Holger Lerche
  • Thomas Ethofer

We aimed to identify reorganization processes of episodic memory networks in patients with left and right temporal lobe epilepsy (TLE) due to hippocampal sclerosis as well as their relations to neuropsychological memory performance. We investigated 28 healthy subjects, 12 patients with left TLE (LTLE) and 9 patients with right TLE (RTLE) with hippocampal sclerosis by means of functional magnetic resonance imaging (fMRI) using a face-name association task, which combines verbal and non-verbal memory functions. Regions-of-interest (ROIs) were defined based on the group results of the healthy subjects. In each ROI, fMRI activations were compared across groups and correlated with verbal and non-verbal memory scores. The face-name association task yielded activations in bilateral hippocampus (HC), left inferior frontal gyrus (IFG), left superior frontal gyrus (SFG), left superior temporal gyrus, bilateral angular gyrus (AG), bilateral medial prefrontal cortex and right anterior temporal lobe (ATL). LTLE patients demonstrated significantly less activation in the left HC and left SFG, whereas RTLE patients showed significantly less activation in the HC bilaterally, the left SFG and right AG. Verbal memory scores correlated with activations in the left and right HC, left SFG and right ATL and non-verbal memory scores with fMRI activations in the left and right HC and left SFG. The face-name association task can be employed to examine functional alterations of hippocampal activation during encoding of both verbal and non-verbal material in one fMRI paradigm. Further, the left SFG seems to be a convergence region for encoding of verbal and non-verbal material.

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YNIMG Journal 2016 Journal Article

Neurobiology of knowledge and misperception of lyrics

  • Claudia Beck Lidén
  • Oliver Krüger
  • Lena Schwarz
  • Michael Erb
  • Bernd Kardatzki
  • Klaus Scheffler
  • Thomas Ethofer

We conducted two functional magnetic resonance imaging (fMRI) experiments to investigate the neural underpinnings of knowledge and misperception of lyrics. In fMRI experiment 1, a linear relationship between familiarity with lyrics and activation was found in left-hemispheric speech-related as well as bilateral striatal areas which is in line with previous research on generation of lyrics. In fMRI experiment 2, we employed so called Mondegreens and Soramimi to induce misperceptions of lyrics revealing a bilateral network including middle temporal and inferior frontal areas as well as anterior cingulate cortex (ACC) and mediodorsal thalamus. ACC activation also correlated with the extent to which misperceptions were judged as amusing corroborating previous neuroimaging results on the role of this area in mediating the pleasant experience of chills during music perception. Finally, we examined the areas engaged during misperception of lyrics using diffusion-weighted imaging (DWI) to determine their structural connectivity. These combined fMRI/DWI results could serve as a neurobiological model for future studies on other types of misunderstanding which are events with potentially strong impact on our social life.

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YNIMG Journal 2015 Journal Article

Multimodal effective connectivity analysis reveals seizure focus and propagation in musicogenic epilepsy

  • Silke Klamer
  • Sabine Rona
  • Adham Elshahabi
  • Holger Lerche
  • Christoph Braun
  • Jürgen Honegger
  • Michael Erb
  • Niels K. Focke

Dynamic causal modeling (DCM) is a method to non-invasively assess effective connectivity between brain regions. ‘Musicogenic epilepsy’ is a rare reflex epilepsy syndrome in which seizures can be elicited by musical stimuli and thus represents a unique possibility to investigate complex human brain networks and test connectivity analysis tools. We investigated effective connectivity in a case of musicogenic epilepsy using DCM for fMRI, high-density (hd-) EEG and MEG and validated results with intracranial EEG recordings. A patient with musicogenic seizures was examined using hd-EEG/fMRI and simultaneous ‘256-channel hd-EEG’/‘whole head MEG’ to characterize the epileptogenic focus and propagation effects using source analysis techniques and DCM. Results were validated with invasive EEG recordings. We recorded one seizure with hd-EEG/fMRI and four auras with hd-EEG/MEG. During the seizures, increases of activity could be observed in the right mesial temporal region as well as bilateral mesial frontal regions. Effective connectivity analysis of fMRI and hd-EEG/MEG indicated that right mesial temporal neuronal activity drives changes in the frontal areas consistently in all three modalities, which was confirmed by the results of invasive EEG recordings. Seizures thus seem to originate in the right mesial temporal lobe and propagate to mesial frontal regions. Using DCM for fMRI, hd-EEG and MEG we were able to correctly localize focus and propagation of epileptic activity and thereby characterize the underlying epileptic network in a patient with musicogenic epilepsy. The concordance between all three functional modalities validated by invasive monitoring is noteworthy, both for epileptic activity spread as well as for effective connectivity analysis in general.

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YNICL Journal 2015 Journal Article

The impact of isolated lesions on white-matter fiber tracts in multiple sclerosis patients

  • Amgad Droby
  • Vinzenz Fleischer
  • Marco Carnini
  • Hilga Zimmermann
  • Volker Siffrin
  • Joachim Gawehn
  • Michael Erb
  • Andreas Hildebrandt

Infratentorial lesions have been assigned an equivalent weighting to supratentorial plaques in the new McDonald criteria for diagnosing multiple sclerosis. Moreover, their presence has been shown to have prognostic value for disability. However, their spatial distribution and impact on network damage is not well understood. As a preliminary step in this study, we mapped the overall infratentorial lesion pattern in relapsing-remitting multiple sclerosis patients (N = 317) using MRI, finding the pons (lesion density, 14.25/cm(3)) and peduncles (13.38/cm(3)) to be predilection sites for infratentorial lesions. Based on these results, 118 fiber bundles from 15 healthy controls and a subgroup of 23 patients showing lesions unilaterally at the predilection sites were compared using diffusion tensor imaging to analyze the impact of an isolated infratentorial lesion on the affected fiber tracts. Fractional anisotropy, mean diffusion as well as axial and radial diffusivity were investigated at the lesion site and along the entire fiber tract. Infratentorial lesions were found to have an impact on the fractional anisotropy and radial diffusivity not only at the lesion site itself but also along the entire affected fiber tract. As previously found in animal experiments, inflammatory attack in the posterior fossa in multiple sclerosis impacts the whole affected fiber tract. Here, this damaging effect, reflected by changes in diffusivity measures, was detected in vivo in multiple sclerosis patients in early stages of the disease, thus demonstrating the influence of a focal immune attack on more distant networks, and emphasizing the pathophysiological role of Wallerian degeneration in multiple sclerosis.

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YNIMG Journal 2012 Journal Article

Biological motion processing: The left cerebellum communicates with the right superior temporal sulcus

  • Arseny A. Sokolov
  • Michael Erb
  • Alireza Gharabaghi
  • Wolfgang Grodd
  • Marcos S. Tatagiba
  • Marina A. Pavlova

The cerebellum is thought to be engaged not only in motor control, but also in the neural network dedicated to visual processing of body motion. However, the pattern of connectivity within this network, in particular, between the cortical circuitry for observation of others' actions and the cerebellum remains largely unknown. By combining functional magnetic resonance imaging (fMRI) with functional connectivity analysis and dynamic causal modelling (DCM), we assessed cerebro-cerebellar connectivity during a visual perceptual task with point-light displays depicting human locomotion. In the left lateral cerebellum, regions in the lobules Crus I and VIIB exhibited increased fMRI response to biological motion. The outcome of the connectivity analyses delivered the first evidence for reciprocal communication between the left lateral cerebellum and the right posterior superior temporal sulcus (STS). Through communication with the right posterior STS that is a key node not only for biological motion perception but also for social interaction and visual tasks on theory of mind, the left cerebellum might be involved in a wide range of social cognitive functions.

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YNIMG Journal 2012 Journal Article

Cerebral integration of verbal and nonverbal emotional cues: Impact of individual nonverbal dominance

  • Heike Jacob
  • Benjamin Kreifelts
  • Carolin Brück
  • Michael Erb
  • Franziska Hösl
  • Dirk Wildgruber

Emotional communication is essential for successful social interactions. Emotional information can be expressed at verbal and nonverbal levels. If the verbal message contradicts the nonverbal expression, usually the nonverbal information is perceived as being more authentic, revealing the “true feelings” of the speaker. The present fMRI study investigated the cerebral integration of verbal (sentences expressing the emotional state of the speaker) and nonverbal (facial expressions and tone of voice) emotional signals using ecologically valid audiovisual stimulus material. More specifically, cerebral activation associated with the relative impact of nonverbal information on judging the affective state of a speaker (individual nonverbal dominance index, INDI) was investigated. Perception of nonverbally expressed emotions was associated with bilateral activation within the amygdala, fusiform face area (FFA), temporal voice area (TVA), and the posterior temporal cortex as well as in the midbrain and left inferior orbitofrontal cortex (OFC)/left insula. Verbally conveyed emotions were linked to increased responses bilaterally in the TVA. Furthermore, the INDI correlated with responses in the left amygdala elicited by nonverbal and verbal emotional stimuli. Correlation of the INDI with the activation within the medial OFC was observed during the processing of communicative signals. These results suggest that individuals with a higher degree of nonverbal dominance have an increased sensitivity not only to nonverbal but to emotional stimuli in general.

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YNIMG Journal 2012 Journal Article

Where in the brain is nonliteral language? A coordinate-based meta-analysis of functional magnetic resonance imaging studies

  • Alexander M. Rapp
  • Dorothee E. Mutschler
  • Michael Erb

An increasing number of studies have investigated non-literal language, including metaphors, idioms, metonymy, or irony, with functional magnetic resonance imaging (fMRI). However, key questions regarding its neuroanatomy remain controversial. In this work, we used coordinate-based activation-likelihood estimations to merge available fMRI data on non-literal language. A literature search identified 38 fMRI studies on non-literal language (24 metaphor studies, 14 non-salient stimuli studies, 7 idiom studies, 8 irony studies, and 1 metonymy study). Twenty-eight studies with direct comparisons of non-literal and literal studies were included in the main meta-analysis. Sub-analyses for metaphors, idioms, irony, salient metaphors, and non-salient metaphors as well as studies on sentence level were conducted. Studies reported 409 activation foci, of which 129 (32%) were in the right hemisphere. These meta-analyses indicate that a predominantly left lateralised network, including the left and right inferior frontal gyrus; the left, middle, and superior temporal gyrus; and medial prefrontal, superior frontal, cerebellar, parahippocampal, precentral, and inferior parietal regions, is important for non-literal expressions.

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YNIMG Journal 2011 Journal Article

Task-specific activity and connectivity within the mentalizing network during emotion and intention mentalizing

  • Bijoy Atique
  • Michael Erb
  • Alireza Gharabaghi
  • Wolfgang Grodd
  • Silke Anders

Mentalizing, i. e. the process of inferring another person's mental state, is thought to be primarily subserved by three brain regions, the VMPFC (ventromedial prefrontal cortex), precuneus and TPJ (temporo-parietal junction). However, it is still unclear what the exact roles of these regions in mentalizing are. Here, we compare activity within, and functional connectivity between, the VMPFC, precuneus and TPJ during two different mentalizing tasks. Specifically, we examine whether inferring another person's emotion (“emotion mentalizing”) and inferring another person's intention (“intention mentalizing”) activate similar or distinct subregions within the VMPFC, precuneus and TPJ, and whether these different kinds of mentalizing are associated with different patterns of functional connectivity between these regions. Our results indicate that emotion mentalizing and intention mentalizing activate partly distinct subregions of the right and left TPJ that can be spatially separated across participants. These subregions also showed different patterns of functional connectivity with the VMPFC: a more anterior region of the right and left TPJ, which was more strongly activated during emotion mentalizing, showed stronger functional connectivity with the VMPFC, particularly during emotion mentalizing, than a more posterior region that was more strongly activated during intention mentalizing. Critically, this double dissociation became evident only when the fine-scale distribution of activity within activated regions was analysed, and despite the fact that there was also a significant overlap of activity during the two tasks. Our findings provide first evidence that different neural modules might have evolved within the TPJ that show distinct patterns of functional connectivity and might subserve slightly different subfunctions of mentalizing.

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YNIMG Journal 2011 Journal Article

Voxel-based morphometry studies of personality: Issue of statistical model specification—effect of nuisance covariates

  • Xiaochen Hu
  • Michael Erb
  • Hermann Ackermann
  • Jason A. Martin
  • Wolfgang Grodd
  • Susanne M. Reiterer

There are an increasing number of studies on the localization of personality using voxel-based morphometry. Due to the complex analytic challenge in volumetric studies, the specification and treatment of the nuisance covariate (such as age, gender, and global measures) is currently not consistent. Here, we present a study in which we conducted voxel-based morphometry with Five-Factor Model (FFM) of personality traits (extraversion, neuroticism, openness to experience, agreeableness, and conscientiousness) that aimed to test the influence of NC specification in the determination of the results. In this study, 62 healthy subjects underwent MRI investigation and completed a German version of the FFM personality questionnaire. Voxel-based morphometry was used to investigate the correlation between the FFM personality traits and subtle brain structure. Different NC combinations were used during the model specification. Significant clusters were found only under the condition of some of the NC combinations but not under the others. In addition, we use the structure equation modeling (automated specification search from AMOS) to narrow down the possible choices of NC combinations according to a set of goodness-of-fit indices to identify well-fitted statistic models. As a final step, theoretical implications of the results are discussed, before accepting the selected model.

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YNIMG Journal 2010 Journal Article

The contribution of mesiofrontal cortex to the preparation and execution of repetitive syllable productions: An fMRI study

  • Bettina Brendel
  • Ingo Hertrich
  • Michael Erb
  • Axel Lindner
  • Axel Riecker
  • Wolfgang Grodd
  • Hermann Ackermann

Clinical data indicate that the brain network of speech motor control can be subdivided into at least three functional–neuroanatomical subsystems: (i) planning of movement sequences (premotor ventrolateral–frontal cortex and/or anterior insula), (ii) preparedness for/initiation of upcoming verbal utterances (supplementary motor area, SMA), and (iii) on-line innervation of vocal tract muscles, i. e. , motor execution (corticobulbar system, basal ganglia, cerebellum). Using an event-related design, this functional magnetic resonance imaging (fMRI) study sought to further delineate the contribution of SMA to pre-articulatory processes of speech production (preceding the innervation of vocal tract muscles) during an acoustically paced syllable repetition task forewarned by a tone signal. Hemodynamic activation across the whole brain and the time courses of the responses in five regions of interest (ROIs) were computed. First, motor preparation was associated with a widespread bilateral activation pattern, encompassing brainstem structures, SMA, insula, premotor ventrolateral–frontal areas, primary sensorimotor cortex (SMC), basal ganglia, and the superior cerebellum. Second, calculation of the time courses of BOLD (“blood oxygenation level-dependent”) signal changes revealed the warning stimulus to elicit synchronous onset of hemodynamic activation in these areas. However, during 4-s intervals of syllable repetitions SMA and cerebellum showed opposite temporal activation patterns in terms of a shorter (SMA) and longer (cerebellum) latency of the entire BOLD response—as compared to SMC, indicating different pacing mechanisms during the initial and the ongoing phase of the task. Nevertheless, the contribution of SMA was not exclusively restricted to the preparation/initiation of verbal responses since the extension of mesiofrontal activation varied with task duration.

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YNIMG Journal 2009 Journal Article

Visual features of an observed agent do not modulate human brain activity during action observation

  • Luca Turella
  • Michael Erb
  • Wolfgang Grodd
  • Umberto Castiello

Recent neuroimaging evidence in macaques has shown that the neural system underlying the observation of hand actions performed by others (i. e. , “action observation system”) is modulated by whether the observed action is performed by a person in full view or an isolated hand (i. e. , type of view manipulation). Although a human homologue of such circuit has been identified, whether in humans the neural processes involved in this capacity are modulated by the type of view remains unknown. Here we used functional magnetic resonance imaging (fMRI) to investigate whether the “action observation system”, with specific reference to the ventral premotor cortex, responds differentially depending on type of view. We also tested this manipulation within regions of the human brain showing overlapping activity for both the observation and the execution of action (“mirror” regions). To this end, the same subjects were requested to observe grasping actions performed under the two types of view (observation conditions) or to perform a grasping action (execution condition). Results from whole-brain analyses indicate that overlapping activity for action observation and execution was evident in a broad network of areas including parietal, premotor and temporal cortices. Activity within such network was evident for both the observation of a person in full view or an isolated hand, but it was not modulated by the type of view. Similarly, results from region of interest (ROI) analyses, performed within the ventral premotor cortex, did confirm that this area responded in a similar fashion following the observation of either an isolated hand or an entire model acting. These findings offer novel insights on what the “action observation” and the “mirror” systems visually code and how the processing underlying such coding may vary across species. Further, they support the hypothesis that action goal is amongst the main determinants for the revelation of action observation activity, and to the existence of a broad system involved in the simulation of action.

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YNIMG Journal 2007 Journal Article

Audiovisual integration of emotional signals in voice and face: An event-related fMRI study

  • Benjamin Kreifelts
  • Thomas Ethofer
  • Wolfgang Grodd
  • Michael Erb
  • Dirk Wildgruber

In a natural environment, non-verbal emotional communication is multimodal (i. e. speech melody, facial expression) and multifaceted concerning the variety of expressed emotions. Understanding these communicative signals and integrating them into a common percept is paramount to successful social behaviour. While many previous studies have focused on the neurobiology of emotional communication in the auditory or visual modality alone, far less is known about multimodal integration of auditory and visual non-verbal emotional information. The present study investigated this process using event-related fMRI. Behavioural data revealed that audiovisual presentation of non-verbal emotional information resulted in a significant increase in correctly classified stimuli when compared with visual and auditory stimulation. This behavioural gain was paralleled by enhanced activation in bilateral posterior superior temporal gyrus (pSTG) and right thalamus, when contrasting audiovisual to auditory and visual conditions. Further, a characteristic of these brain regions, substantiating their role in the emotional integration process, is a linear relationship between the gain in classification accuracy and the strength of the BOLD response during the bimodal condition. Additionally, enhanced effective connectivity between audiovisual integration areas and associative auditory and visual cortices was observed during audiovisual stimulation, offering further insight into the neural process accomplishing multimodal integration. Finally, we were able to document an enhanced sensitivity of the putative integration sites to stimuli with emotional non-verbal content as compared to neutral stimuli.

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YNIMG Journal 2007 Journal Article

Neural correlates of metaphor processing in schizophrenia

  • Tilo T.J. Kircher
  • Dirk T. Leube
  • Michael Erb
  • Wolfgang Grodd
  • Alexander M. Rapp

Objective: A main feature of schizophrenic thought and language disturbance is concretism, the inability to understand the figurative meaning of proverbs and metaphors. Although this is routinely tested during clinical interview, its neural basis is unknown. Method: We investigated processing of metaphoric sentences with functional magnetic resonance imaging (fMRI) in 12 patients with schizophrenia and 12 control subjects. Stimuli consisted of 60 novel short sentences with either metaphoric or literal meaning presented visually, intersparsed by a low level baseline (grey background). Subjects read these sentences silently and judged by button press whether they had a positive or negative connotation. Results: Reading metaphors in contrast to literal sentences revealed signal changes in the left inferior frontal gyrus in the control subjects (BA 45/47) and an area 3 cm dorsal to that in the patients (BA 45). Only activation in this area was negatively correlated with the severity of concretism rated with the PANSS. Comparison between groups for the contrast metaphors vs. low level baseline revealed stronger signal changes in the control group in the right superior/middle temporal gyrus (BA 39) and the left inferior frontal gyrus (BA 45) in the patients. Conclusions: The results in the control subjects are in line with studies showing an involvement of the left inferior frontal and right lateral temporal cortex during context processing. Failure to recruit these areas in the patients may underlie schizophrenic concretism.

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YNIMG Journal 2006 Journal Article

Cerebral pathways in processing of affective prosody: A dynamic causal modeling study

  • Thomas Ethofer
  • Silke Anders
  • Michael Erb
  • Cornelia Herbert
  • Sarah Wiethoff
  • Johanna Kissler
  • Wolfgang Grodd
  • Dirk Wildgruber

This study was conducted to investigate the connectivity architecture of neural structures involved in processing of emotional speech melody (prosody). 24 subjects underwent event-related functional magnetic resonance imaging (fMRI) while rating the emotional valence of either prosody or semantics of binaurally presented adjectives. Conventional analysis of fMRI data revealed activation within the right posterior middle temporal gyrus and bilateral inferior frontal cortex during evaluation of affective prosody and left temporal pole, orbitofrontal, and medial superior frontal cortex during judgment of affective semantics. Dynamic causal modeling (DCM) in combination with Bayes factors was used to compare competing neurophysiological models with different intrinsic connectivity structures and input regions within the network of brain regions underlying comprehension of affective prosody. Comparison on group level revealed superiority of a model in which the right temporal cortex serves as input region as compared to models in which one of the frontal areas is assumed to receive external inputs. Moreover, models with parallel information conductance from the right temporal cortex were superior to models in which the two frontal lobes accomplish serial processing steps. In conclusion, connectivity analysis supports the view that evaluation of affective prosody requires prior analysis of acoustic features within the temporal and that transfer of information from the temporal cortex to the frontal lobes occurs via parallel pathways.

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YNIMG Journal 2006 Journal Article

Exploring the visual world: The neural substrate of spatial orienting

  • Marc Himmelbach
  • Michael Erb
  • Hans-Otto Karnath

Inspecting the visual environment, humans typically direct their attention across space by means of voluntary saccadic eye movements. Neuroimaging studies in healthy subjects have identified the superior parietal cortex and intraparietal sulcus as important structures involved in visual search. However, in apparent contrast, spatial disturbance of free exploration typically is observed after damage of brain structures located far more ventrally. Lesion studies in such patients disclosed the inferior parietal lobule (IPL) and temporo-parietal junction (TPJ), the superior temporal gyrus (STG) and insula, as well as the inferior frontal gyrus (IFG) of the right hemisphere. Here we used functional magnetic resonance imaging to investigate the involvement of these areas in active visual exploration in the intact brain. We conducted a region of interest analysis comparing free visual exploration of a dense stimulus array with the execution of stepwise horizontal and vertical saccades. The comparison of BOLD responses revealed significant signal increases during exploration in TPJ, STG, and IFG. This result calls for a reappraisal of the previous thinking on the function of these areas in visual search processes. In agreement with lesion studies, the data suggest that these areas are part of the network involved in human spatial orienting and exploration. The IPL dorsally of TPJ seem to be of minor importance for free visual exploration as these areas appear to be equally involved in the execution of spatially predetermined saccades.

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YNIMG Journal 2004 Journal Article

To act or not to act. Neural correlates of executive control of learned motor behavior

  • Friedhelm Hummel
  • Ralf Saur
  • Simone Lasogga
  • Christian Plewnia
  • Michael Erb
  • Dirk Wildgruber
  • Wolfgang Grodd
  • Christian Gerloff

Successful behavior requires contextual modulation of learned “programs”, that is, the retrieval or nonretrieval (inhibition) of behavioral elements depending on situative context. Here we report neural correlates of these elementary aspects of behavior as identified with functional magnetic resonance imaging (fMRI). Inhibition of a “ready-to-go” behavioral program was represented in the brain by reduction of net synaptic activity in the cerebro-cerebellar pathway. The metabolic correlate of inhibition was a multifocal (premotor, primary sensorimotor, superior parietal, cingulate cortex, and cerebellum) decrease of the blood oxygenation level-dependent (BOLD) signal to below the resting state (negative BOLD) with a concomitant decrease of motor cortical excitability. The reverse was true for retrieval. We propose that contextual modulation of learned behavioral programs depends on an interplay of focal increases and decreases of neural activity and that the inhibitory changes are reflected by negative BOLD responses in an extended cerebro-cerebellar network of sensorimotor structures.

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YNIMG Journal 2003 Journal Article

From will to action: sequential cerebellar contributions to voluntary movement

  • Ernst Hülsmann
  • Michael Erb
  • Wolfgang Grodd

The cerebellum is known to be involved in numerous motor related functions, but recent observations suggest that it also performs fundamental operations on nonmotor functions such as perception and cognition. Assuming that the cerebellum has to be consulted in a limited window of time, cerebellar activation should occur in a time-dependent manner in respect to the corresponding telencephalic areas. This hypothesis was tested by combining a simple motor task with the demand of a self-paced delay using event-related functional magnetic resonance imaging. Evaluation with a time-shifted canonical hemodynamic response function revealed spatially and temporally separated cerebral and cerebellar activation accompanying the entire process—from conscious planning to final motor output—within a time frame of 6 s. The cerebral activations spread from the anterior cingulate cortex through the supplementary motor and premotor area to the primary motor and sensory cortices. This cascade was temporally in parallel with cerebellar activations propagating from the neo- to the spinocerebellum. An early lateral cerebellar recruitment 3 s prior movement onset confirms its involvement in cognitive processing. A later medial activation occurring close to movement onset most probably reflects spinocerebellar kinesthetic feedback. Between these two points a striking lateromedial succession was found, which is in line with the hypothesis of the existence of multiple internal models residing in the cerebellum, each communicating with its own corresponding telencephalic region.

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YNIMG Journal 2003 Journal Article

Physiological self-regulation of regional brain activity using real-time functional magnetic resonance imaging (fMRI): methodology and exemplary data

  • Nikolaus Weiskopf
  • Ralf Veit
  • Michael Erb
  • Klaus Mathiak
  • Wolfgang Grodd
  • Rainer Goebel
  • Niels Birbaumer

A brain–computer interface (BCI) based on real-time functional magnetic resonance imaging (fMRI) is presented which allows human subjects to observe and control changes of their own blood oxygen level-dependent (BOLD) response. This BCI performs data preprocessing (including linear trend removal, 3D motion correction) and statistical analysis on-line. Local BOLD signals are continuously fed back to the subject in the magnetic resonance scanner with a delay of less than 2 s from image acquisition. The mean signal of a region of interest is plotted as a time-series superimposed on color-coded stripes which indicate the task, i. e. , to increase or decrease the BOLD signal. We exemplify the presented BCI with one volunteer intending to control the signal of the rostral–ventral and dorsal part of the anterior cingulate cortex (ACC). The subject achieved significant changes of local BOLD responses as revealed by region of interest analysis and statistical parametric maps. The percent signal change increased across fMRI-feedback sessions suggesting a learning effect with training. This methodology of fMRI-feedback can assess voluntary control of circumscribed brain areas. As a further extension, behavioral effects of local self-regulation become accessible as a new field of research.

Details DOI

YNIMG Journal 1999 Journal Article

Dynamical Cluster Analysis of Cortical fMRI Activation

  • Axel Baune
  • Friedrich T. Sommer
  • Michael Erb
  • Dirk Wildgruber
  • Bernd Kardatzki
  • Günther Palm
  • Wolfgang Grodd

Localized changes in cortical blood oxygenation during voluntary movements were examined with functional magnetic resonance imaging (fMRI) and evaluated with a new dynamical cluster analysis (DCA) method. fMRI was performed during finger movements with eight subjects on a 1. 5-T scanner using single-slice echo planar imaging with a 107-ms repetition time. Clustering based on similarity of the detailed signal time courses requires besides the used distance measure no assumptions about spatial location and extension of activation sites or the shape of the expected activation time course. We discuss the basic requirements on a clustering algorithm for fMRI data. It is shown that with respect to easy adjustment of the quantization error and reproducibility of the results DCA outperforms the standardk-means algorithm. In contrast to currently used clustering methods for fMRI, likek-means or fuzzyk-means, DCA extracts the appropriate number and initial shapes of representative signal time courses from data properties during run time. With DCA we simultaneously calculate a two-dimensional projection of cluster centers (MDS) and data points for online visualization of the results. We describe the new DCA method and show for the well-studied motor task that it detects cortical activation loci and provides additional information by discriminating different shapes and phases of hemodynamic responses. Robustness of activity detection is demonstrated with respect to repeated DCA runs and effects of different data preprocessing are shown. As an example of how DCA enables further analysis we examined activation onset times. In areas SMA, M1, and S1 simultaneous and sequential activation (in the given order) was found.

Details DOI
v2026.09.13