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G.R. Fink

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21 papers
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21

YNICL Journal 2018 Journal Article

Network connectivity of motor control in the ageing brain

  • J. Michely
  • L.J. Volz
  • F. Hoffstaedter
  • M. Tittgemeyer
  • S.B. Eickhoff
  • G.R. Fink
  • C. Grefkes

Older individuals typically display stronger regional brain activity than younger subjects during motor performance. However, knowledge regarding age-related changes of motor network interactions between brain regions remains scarce. We here investigated the impact of ageing on the interaction of cortical areas during movement selection and initiation using dynamic causal modelling (DCM). We found that age-related psychomotor slowing was accompanied by increases in both regional activity and effective connectivity, especially for 'core' motor coupling targeting primary motor cortex (M1). Interestingly, younger participants within the older group showed strongest connectivity targeting M1, which steadily decreased with advancing age. Conversely, prefrontal influences on the motor system increased with advancing age, and were inversely correlated with reduced parietal influences and core motor coupling. Interestingly, higher net coupling within the prefrontal-premotor-M1 axis predicted faster psychomotor speed in ageing. Hence, as opposed to a uniform age-related decline, our findings are compatible with the idea of different age-related compensatory mechanisms, with an important role of the prefrontal cortex compensating for reduced coupling within the core motor network.

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YNICL Journal 2018 Journal Article

Test-retest variability of resting-state networks in healthy aging and prodromal Alzheimer's disease

  • K. Conwell
  • B. von Reutern
  • N. Richter
  • J. Kukolja
  • G.R. Fink
  • O.A. Onur

In recent years, changes in resting-state networks (RSN), identified by functional magnetic resonance imaging (fMRI), have gained increasing attention as potential biomarkers and trackers of neurological disorders such as Alzheimer's disease (AD). Intersession reliability of RSN is fundamental to this approach. In this study, we investigated the test-retest reliability of three memory related RSN (i.e., the default mode, salience, and executive control network) in 15 young, 15 healthy seniors (HS), and 15 subjects affected by mild cognitive impairment (MCI) with positive biomarkers suggestive of incipient AD (6 females each). FMRI was conducted on three separate occasions. Independent Component Analysis decomposed the resting-state data into RSNs. Comparisons of variation in functional connectivity between groups were made applying different thresholds in an explorative approach. Intersession test-retest reliability was evaluated by intraclass correlation coefficient (ICC) comparisons. To assess the effect of gray matter volume loss, motion, cerebrospinal fluid based biomarkers and the time gap between sessions on intersession variation, the former four were correlated separately with the latter. Data showed that i) young subjects ICCs (relative to HS/MCI-subjects) had higher intersession reliability, ii) stringent statistical thresholds need to be applied to prevent false-positives, iii) both HS and MCI-subjects (relative to young) showed significantly more clusters of intersession variation in all three RSN, iv) while intersession variation was highly correlated with head motion, it was also correlated with biomarkers (especially phospho-tau), the time gap between sessions and local GMV. Results indicate that time gaps between sessions should be kept constant and that head motion must be taken into account when using RSN to assess aging and neurodegeneration. In patients with prodromal AD, re-test reliability may be increased by accouting for overall disease burden by including biomarkers of neuronal injury (especially phospho-tau) in statistical analyses. Local atrophy however, does not seem to play a major role in regards to reliability, but should be used as covariate depending on the research question.

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YNICL Journal 2017 Journal Article

Time-dependent functional role of the contralesional motor cortex after stroke

  • L.J. Volz
  • M. Vollmer
  • J. Michely
  • G.R. Fink
  • J.C. Rothwell
  • C. Grefkes

After stroke, movements of the paretic hand rely on altered motor network dynamics typically including additional activation of the contralesional primary motor cortex (M1). The functional implications of contralesional M1 recruitment to date remain a matter of debate. We here assessed the role of contralesional M1 in 12 patients recovering from a first-ever stroke using online transcranial magnetic stimulation (TMS): Short bursts of TMS were administered over contralesional M1 or a control site (occipital vertex) while patients performed different motor tasks with their stroke-affected hand. In the early subacute phase (1–2weeks post-stroke), we observed significant improvements in maximum finger tapping frequency when interfering with contralesional M1, while maximum grip strength and speeded movement initiation remained unaffected. After >3months of motor recovery, disruption of contralesional M1 activity did not interfere with performance in any of the three tasks, similar to what we observed in healthy controls. In patients with mild to moderate motor deficits, contralesional M1 has a task- and time-specific negative influence on motor performance of the stroke-affected hand. Our results help to explain previous contradicting findings on the role of contralesional M1 in recovery of function.

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YNICL Journal 2017 Journal Article

Young adolescents with autism show abnormal joint attention network: A gaze contingent fMRI study

  • E. Oberwelland
  • L. Schilbach
  • I. Barisic
  • S.C. Krall
  • K. Vogeley
  • G.R. Fink
  • B. Herpertz-Dahlmann
  • K. Konrad

Behavioral research has revealed deficits in the development of joint attention (JA) as one of the earliest signs of autism. While the neural basis of JA has been studied predominantly in adults, we recently demonstrated a protracted development of the brain networks supporting JA in typically developing children and adolescents. The present eye-tracking/fMRI study now extends these findings to adolescents with autism. Our results show that in adolescents with autism JA is subserved by abnormal activation patterns in brain areas related to social cognition abnormalities which are at the core of ASD including the STS and TPJ, despite behavioral maturation with no behavioral differences. Furthermore, in the autism group we observed increased neural activity in a network of social and emotional processing areas during interactions with their mother. Moreover, data indicated that less severely affected individuals with autism showed higher frontal activation associated with self-initiated interactions. Taken together, this study provides first-time data of JA in children/adolescents with autism incorporating the interactive character of JA, its reciprocity and motivational aspects. The observed functional differences in adolescents ASD suggest that persistent developmental differences in the neural processes underlying JA contribute to social interaction difficulties in ASD.

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YNIMG Journal 2016 Journal Article

Look into my eyes: Investigating joint attention using interactive eye-tracking and fMRI in a developmental sample

  • E. Oberwelland
  • L. Schilbach
  • I. Barisic
  • S.C. Krall
  • K. Vogeley
  • G.R. Fink
  • B. Herpertz-Dahlmann
  • K. Konrad

Joint attention, the shared attentional focus of at least two people on a third significant object, is one of the earliest steps in social development and an essential aspect of reciprocal interaction. However, the neural basis of joint attention (JA) in the course of development is completely unknown. The present study made use of an interactive eye-tracking paradigm in order to examine the developmental trajectories of JA and the influence of a familiar interaction partner during the social encounter. Our results show that across children and adolescents JA elicits a similar network of “social brain” areas as well as attention and motor control associated areas as in adults. While other-initiated JA particularly recruited visual, attention and social processing areas, self-initiated JA specifically activated areas related to social cognition, decision-making, emotions and motivational/reward processes highlighting the rewarding character of self-initiated JA. Activation was further enhanced during self-initiated JA with a familiar interaction partner. With respect to developmental effects, activation of the precuneus declined from childhood to adolescence and additionally shifted from a general involvement in JA towards a more specific involvement for self-initiated JA. Similarly, the temporoparietal junction (TPJ) was broadly involved in JA in children and more specialized for self-initiated JA in adolescents. Taken together, this study provides first-time data on the developmental trajectories of JA and the effect of a familiar interaction partner incorporating the interactive character of JA, its reciprocity and motivational aspects.

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YNIMG Journal 2016 Journal Article

Movement-related phase locking in the delta–theta frequency band

  • S. Popovych
  • N. Rosjat
  • T.I. Toth
  • B.A. Wang
  • L. Liu
  • R.O. Abdollahi
  • S. Viswanathan
  • C. Grefkes

Movements result from a complex interplay of multiple brain regions. These regions are assembled into distinct functional networks depending on the specific properties of the action. However, the nature and details of the dynamics of this complex assembly process are unknown. In this study, we sought to identify key markers of the neural processes underlying the preparation and execution of motor actions that always occur irrespective of differences in movement initiation, hence the specific neural processes and functional networks involved. To this end, EEG activity was continuously recorded from 18 right-handed healthy participants while they performed a simple motor task consisting of button presses with the left or right index finger. The movement was performed either in response to a visual cue or at a self-chosen, i. e. , non-cued point in time. Despite these substantial differences in movement initiation, dynamic properties of the EEG signals common to both conditions could be identified using time–frequency and phase locking analysis of the EEG data. In both conditions, a significant phase locking effect was observed that started prior to the movement onset in the δ–θ frequency band (2–7Hz), and that was strongest at the electrodes nearest to the contralateral motor region (M1). This phase locking effect did not have a counterpart in the corresponding power spectra (i. e. , amplitudes), or in the event-related potentials. Our finding suggests that phase locking in the δ–θ frequency band is a ubiquitous movement-related signal independent of how the actual movement has been initiated. We therefore suggest that phase-locked neural oscillations in the motor cortex are a prerequisite for the preparation and execution of motor actions.

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YNICL Journal 2014 Journal Article

Apraxia, pantomime and the parietal cortex

  • E. Niessen
  • G.R. Fink
  • P.H. Weiss

Apraxia, a disorder of higher motor cognition, is a frequent and outcome-relevant sequel of left hemispheric stroke. Deficient pantomiming of object use constitutes a key symptom of apraxia and is assessed when testing for apraxia. To date the neural basis of pantomime remains controversial. We here review the literature and perform a meta-analysis of the relevant structural and functional imaging (fMRI/PET) studies. Based on a systematic literature search, 10 structural and 12 functional imaging studies were selected. Structural lesion studies associated pantomiming deficits with left frontal, parietal and temporal lesions. In contrast, functional imaging studies associate pantomimes with left parietal activations, with or without concurrent frontal or temporal activations. Functional imaging studies that selectively activated parietal cortex adopted the most stringent controls. In contrast to previous suggestions, current analyses show that both lesion and functional studies support the notion of a left-hemispheric fronto-(temporal)-parietal network underlying pantomiming object use. Furthermore, our review demonstrates that the left parietal cortex plays a key role in pantomime-related processes. More specifically, stringently controlled fMRI-studies suggest that in addition to storing motor schemas, left parietal cortex is also involved in activating these motor schemas in the context of pantomiming object use. In addition to inherent differences between structural and functional imaging studies and consistent with the dedifferentiation hypothesis, the age difference between young healthy subjects (typically included in functional imaging studies) and elderly neurological patients (typically included in structural lesion studies) may well contribute to the finding of a more distributed representation of pantomiming within the motor-dominant left hemisphere in the elderly.

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YNIMG Journal 2010 Journal Article

Animated brain: A functional neuroimaging study on animacy experience

  • Natacha S. Santos
  • B. Kuzmanovic
  • N. David
  • A. Rotarska-Jagiela
  • S.B. Eickhoff
  • J.N. Shah
  • G.R. Fink
  • G. Bente

Previous research used animated geometric figures to investigate social cognitive processes involved in ascribing mental states to others (e. g. mentalizing). The relationship between animacy perception and brain areas commonly involved in social cognition, as well as the influence of particular motion patterns on animacy experience, however, remains to be further elucidated. We used a recently introduced paradigm for the systematic variation of motion properties, and employed functional magnetic resonance imaging to identify the neural mechanisms underlying animacy experience. Based on individual ratings of increased animacy experience the following brain regions of the “social neural network” (SNN), known to be involved in social cognitive processes, were recruited: insula, superior temporal gyrus, fusiform gyrus, parahippocampal gyrus and the ventromedial prefrontal cortex bilaterally. Decreased animacy experience was associated with increased neural activity in the inferior parietal and inferior frontal gyrus, key constituents of the human “mirror neuron system” (hMNS). These findings were corroborated when analyses were based on movement patterns alone, irrespective of subjective experience. Additionally to the areas found for increased animacy experience, an increase in interactive movements elicited activity in the amygdala and the temporal pole. In conclusion, the results suggest that the hMNS is recruited during a low-level stage of animacy judgment representing a basic disposition to detect the salience of movements, whereas the SNN appears to be a high-level processing component serving evaluation in social and mental inference.

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YNIMG Journal 2009 Journal Article

Single-trial P3 amplitude and latency informed event-related fMRI models yield different BOLD response patterns to a target detection task

  • T. Warbrick
  • A. Mobascher
  • J. Brinkmeyer
  • F. Musso
  • N. Richter
  • T. Stoecker
  • G.R. Fink
  • N.J. Shah

Using single-trial parameters as a regressor in the General Linear Model (GLM) is becoming an increasingly popular method for informing fMRI analysis. However, the parameter used to characterise or to differentiate brain regions involved in the response to a particular task varies across studies (e. g. ERP amplitude, ERP latency, reaction time). Furthermore, the way in which the single-trial information is used in the fMRI analysis is also important. For example, the single-trial parameters can be used as regressors in the GLM or to modify the duration of the events modelled in the GLM. The aim of this study was to investigate the BOLD response to a target detection task when including P3 amplitude, P3 latency and reaction time parameters in the GLM. Simultaneous EEG-fMRI was recorded from fifteen subjects in response to a visual choice reaction time task. Including P3 amplitude as a regressor in the GLM yielded activation in left central opercular cortex, left postcentral gyrus, left insula, left middle frontal gyrus, left insula and left parietal operculum. Using P3 latency and reaction time as an additional regressor yielded no additional activation in comparison with the conventional fMRI analysis. However, when P3 latency or reaction time was used to determine the duration of events at a single-trial level, additional activation was observed in the left postcentral gyrus, left precentral gyrus, anterior cingulate cortex and supramarginal gyrus. Our findings suggest that ERP amplitudes and latencies can yield different activation patterns when used to modify relevant aspects of the GLM.

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YNIMG Journal 2007 Journal Article

Visuospatial working memory and changes of the point of view in 3D space

  • D. Schmidt
  • B.J. Krause
  • P.H. Weiss
  • G.R. Fink
  • N.J. Shah
  • M.-A. Amorim
  • H.-W. Müller
  • A. Berthoz

We used functional magnetic resonance imaging to explore the brain mechanisms of changing point of view (PoV) in a visuospatial memory task in 3D space. Eye movements were monitored and BOLD signal changes were measured while subjects were presented with 3D images of a virtual environment. Subjects were required to encode the position of a lamp in the environment and, after changing the PoV (angular difference varied from 0° to 180° in 45° steps), to decide whether the lamp position had been changed too or not. Performance data and a scan-path analysis based on eye movement support the use of landmarks in the environment for coding lamp position and increasing spatial updating costs with increasing changes of PoV indicating allocentric coding strategies during all conditions (0°- to 180°-condition). Subtraction analysis using SPM revealed that a parieto–temporo–frontal network including left medial temporal areas was activated during this 3D visuospatial task, independent of angular difference. The activity of the left parahippocampal area and the left lingual gyrus (but not the hippocampus) correlated with increasing changes of the PoV between encoding and retrieval, emphasizing their specific role in spatial scene memory and allocentric coding. The results suggest that these areas are involved in a continuous matching process between internal representations of the environment and the external status quo. In addition, hippocampal activation correlated with performance was found indicating successful recall of spatial information. Finally, in a prefrontal area comprising, the so-called “deep” frontal eye field, activation was correlated with the amount of saccadic eye movements confirming its role in oculomotor processes.

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YNIMG Journal 2005 Journal Article

Linking retinotopic fMRI mapping and anatomical probability maps of human occipital areas V1 and V2

  • A.M. Wohlschläger
  • K. Specht
  • C. Lie
  • H. Mohlberg
  • A. Wohlschläger
  • K. Bente
  • U. Pietrzyk
  • T. Stöcker

Using functional MRI, we characterized field sign maps of the occipital cortex and created three-dimensional maps of these areas. By averaging the individual maps into group maps, probability maps of functionally defined V1 or V2 were determined and compared to anatomical probability maps of Brodmann areas BA17 and BA18 derived from cytoarchitectonic analysis (Amunts, K. , Malikovic, A. , Mohlberg, H. , Schormann, T. , Zilles, K. , 2000. Brodmann's areas 17 and 18 brought into stereotaxic space—where and how variable? NeuroImage 11, 66–84). Comparison of areas BA17/V1 and BA18/V2 revealed good agreement of the anatomical and functional probability maps. Taking into account that our functional stimulation (due to constraints of the visual angle of stimulation achievable in the MR scanner) only identified parts of V1 and V2, for statistical evaluation of the spatial correlation of V1 and BA17, or V2 and BA18, respectively, the a priori measure κ was calculated testing the hypothesis that a region can only be part of functionally defined V1 or V2 if it is also in anatomically defined BA17 or BA18, respectively. κ = 1 means the hypothesis is fully true, κ = 0 means functionally and anatomically defined visual areas are independent. When applying this measure to the probability maps, κ was equal to 0. 84 for both V1/BA17 and V2/BA18. The data thus show a good correspondence of functionally and anatomically derived segregations of early visual processing areas and serve as a basis for employing anatomical probability maps of V1 and V2 in group analyses to characterize functional activations of early visual processing areas.

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YNIMG Journal 2002 Journal Article

The Influence of Explicit Instructions and Stimulus Material on Lateral Frontal Responses to an Encoding Task

  • P.C. Fletcher
  • N. Palomero-Gallagher
  • O. Zafiris
  • G.R. Fink
  • L.K. Tyler
  • K. Zilles

In this functional magnetic resonance imaging study, we explored the effects of both stimulus material and encoding task demands on activation in lateral prefrontal cortex (PFC). Two factors were manipulated: material type and task instructions. Subjects encoded words or abstract figures (factor 1: stimulus type) and were required to make either a meaning-based or a form-based (letter or shape) decision about each stimulus (factor 2: task instructions). Abstract figures engendered significantly higher levels of right PFC activity than did words. This effect was seen for meaning-based and form-based processing tasks and was significantly greater for the former. We did not observe a differential response of left lateral PFC to verbal and pictorial material. A double dissociation, however, was found within left PFC. A ventrolateral region (within left inferior frontal gyrus) showed the highest levels of activity when words were processed according to their meaning whereas activity in a more dorsolateral region (within left middle frontal gyrus) was greatest when words were processed according to their form (constituent letters). We have therefore observed a main effect of material type in producing lateralized activation of frontal lobes, although the strength of this effect is sensitive to the nature of the task that subjects are asked to perform. Left-side lateral PFC activity is also sensitive to task instructions but this effect was specific to verbal material. The complex patterns of frontal effect counsel against any simple dichotomy of frontal function at the level of either material or task type.

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YNIMG Journal 2001 Journal Article

Mind Reading: Neural Mechanisms of Theory of Mind and Self-Perspective

  • K. Vogeley
  • P. Bussfeld
  • A. Newen
  • S. Herrmann
  • F. Happé
  • P. Falkai
  • W. Maier
  • N.J. Shah

Human self-consciousness as the metarepresentation of ones own mental states and the so-called theory of mind (TOM) capacity, which requires the ability to model the mental states of others, are closely related higher cognitive functions. We address here the issue of whether taking the self-perspective (SELF) or modeling the mind of someone else (TOM) employ the same or differential neural mechanisms. A TOM paradigm was used and extended to include stimulus material that involved TOM and SELF capacities in a two-way factorial design. A behavioral study in 42 healthy volunteers showed that TOM and SELF induced differential states of mind: subjects assigned correctly first or third person pronouns when providing responses to the stimuli. Following the behavioral study, we used functional magnetic resonance imaging (fMRI) in eight healthy, right-handed males to study the common and differential neural mechanisms underlying TOM and SELF. The main factor TOM led to increased neural activity in the anterior cingulate cortex and left temporopolar cortex. The main factor SELF led to increased neural activity in the right temporoparietal junction and in the anterior cingulate cortex. A significant interaction of both factors TOM and SELF was observed in the right prefrontal cortex. These divergent neural activations in response to TOM and SELF suggest that these important differential mental capacities of human self-consciousness are implemented at least in part in distinct brain regions.

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v2026.09.13