Showing papers by "Gereon R. Fink published in 2006"
TL;DR: The results show that activation of medial prefrontal cortex underlies both the perception of social communication indicated by facial expressions and the feeling of personal involvement indicated by eye gaze and that distinct regions of medial cortex contribute differentially to social cognition.
417 citations
TL;DR: FMRI data provide neural correlates for the different cognitive components involved in the Wisconsin Card Sorting Test and suggest a central role of the right dorsolateral prefrontal cortex in executive working memory operations and cognitive control functions but also suggest a functional dissociation of the rostral and caudal ACC in the implementation of attentional control.
358 citations
TL;DR: For alerting and executive attention, the data indicate a deviant mechanism of cortical control, while ADHD children may have adopted altered strategies for reorienting of attention.
314 citations
TL;DR: This cytoarchitectonic mapping study was to determine whether consistent regions and borders can be found within the cortex of the anterior IPS in a population of 10 post‐mortem human brains and concludes that the human IPS has a more finely grained parcellation than shown in Brodmann's map.
Abstract: Anatomical studies in the macaque cortex and functional imaging studies in humans have demonstrated the existence of different cortical areas within the intraparietal sulcus (IPS). Such functional segregation, however, does not correlate with presently available architectonic maps of the human brain. This is particularly true for the classical Brodmann map, which is still widely used as an anatomical reference in functional imaging studies. The aim of this cytoarchitectonic mapping study was to use previously defined algorithms to determine whether consistent regions and borders can be found within the cortex of the anterior IPS in a population of 10 post-mortem human brains. Two areas, the human intraparietal area 1 (hIP1) and the human intraparietal area 2 (hIP2), were delineated in serial histological sections of the anterior, lateral bank of the human IPS. The region hIP1 is located posterior and medial to hIP2, and the former is always within the depths of the IPS. The latter, on the other hand, sometimes reaches the free surface of the superior parietal lobule. The delineations were registered to standard reference space, and probabilistic maps were calculated, thereby quantifying the intersubject variability in location and extent of both areas. In the future, they can be a tool for analyzing structure-function relationships and a basis for determining degrees of homology in the IPS among anthropoid primates. We conclude that the human IPS has a more finely grained parcellation than shown in Brodmann's map.
270 citations
TL;DR: This paper explored the neural correlates involved in self-other representations by investigating two critical processes: perspective taking and agency, and found evidence for distinct neural substrates underlying representations of the self and others and provide support for the idea that the medial prefrontal cortex crucially contributes to a neural basis of self.
Abstract: Human self-consciousness relies on the ability to distinguish between oneself and others. We sought to explore the neural correlates involved in self-other representations by investigating two critical processes: perspective taking and agency. Although recent research has shed light on the neural processes underlying these phenomena, little is known about how they overlap or interact at the neural level. In a two-factorial functional magnetic resonance imaging (fMRI) experiment, participants played a ball-tossing game with two virtual characters (“avatars”). During an active/agency (ACT) task, subjects threw a ball to one of the avatars by pressing a button. During a passive/nonagency (PAS) task, they indicated which of the other avatars threw the ball. Both tasks were performed from a first-person perspective (1PP), in which subjects interacted from their own perspective, and a third-person perspective (3PP), in which subjects interacted from the perspective of an avatar with another location in space. fMRI analyses revealed overlapping activity in medial prefrontal regions associated with representations of one's own perspective and actions (1PP and ACT), and overlapping activity in temporal-occipital, premotor, and inferior frontal, as well as posterior parietal regions associated with representation of others' perspectives and actions (3PP and PAS). These findings provide evidence for distinct neural substrates underlying representations of the self and others and provide support for the idea that the medial prefrontal cortex crucially contributes to a neural basis of the self. The lack of a statistically significant interaction suggests that perspective taking and agency represent independent constituents of self-consciousness.
243 citations
TL;DR: The amount of top-down information provided by predictive cues influences the neural correlates of reorienting of visuospatial attention by modulating activation of a right fronto-parietal attentional network.
217 citations
TL;DR: This study functionally and anatomically characterize the putative human equivalent to macaque area PIVC by combining functional magnetic resonance imaging (fMRI) of the cortical response to galvanic vestibular stimulation (GVS) with probabilistic cytoarchitectonic maps of the human parietal operculum.
Abstract: The parieto-insular vestibular cortex (PIVC) plays a central role in the cortical vestibular network. Although this region was first defined and subsequently extensively studied in nonhuman primates, there is also ample evidence for a human analogue in the posterior parietal operculum. In this study, we functionally and anatomically characterize the putative human equivalent to macaque area PIVC by combining functional magnetic resonance imaging (fMRI) of the cortical response to galvanic vestibular stimulation (GVS) with probabilistic cytoarchitectonic maps of the human parietal operculum. Our fMRI data revealed a bilateral cortical response to GVS in posterior parieto-insular cortex. Based on the topographic similarity of these activations to primate area PIVC, we suggest that they constitute the functionally defined human equivalent to macaque area PIVC. The locations of these activations were then compared to the probabilistic cytoarchitectonic maps of the parietal operculum (Eickhoff et al. [2005a]: Cereb Cortex, in press; Eickhoff et al. [2005c]: Cereb Cortex, in press), whereby the functionally defined PIVC matched most closely the cytoarchitectonically defined area OP 2. This activation of OP 2 by vestibular stimulation and its cytoarchitectonic features, which are similar to other primary sensory areas, suggest that area OP 2 constitutes the human equivalent of macaque area PIVC.
183 citations
TL;DR: The data show that a 3-week computerised alertness training can improve performance both in alertness and neglect tests and that these behavioural improvements are associated with reactivation in areas associated with alerting and visuospatial attention.
136 citations
TL;DR: The data suggest that STN-DBS ameliorates bladder dysfunction and that this modulation may result from facilitated processing of afferent bladder information.
Abstract: Subthalamic nucleus deep brain stimulation (STN-DBS) is an effective therapy for off-period motor symptoms and dyskinesias in advanced Parkinson's disease. Clinical studies have shown that STN-DBS also ameliorates urinary bladder function in Parkinson's disease patients by delaying the first desire to void and increasing bladder capacity. This study aimed at investigating the effect of STN-DBS on the neural mechanisms underlying cerebral bladder control. Using PET to measure changes in regional cerebral blood flow (rCBF), 11 patients with bilateral STN-DBS were studied during urodynamic bladder filling in STN-DBS ON and OFF condition. A filled bladder led to a significant increase of rCBF in the anterior cingulate cortex, which was further enhanced during STN-DBS OFF. A significant interaction between bladder state and STN-DBS was observed in lateral frontal cortex with increased rCBF when the bladder was filled during STN-DBS OFF. The data suggest that STN-DBS ameliorates bladder dysfunction and that this modulation may result from facilitated processing of afferent bladder information.
129 citations
TL;DR: The data demonstrate that functional asymmetries in auditory processing are modulated by context, and the observed long time constant suggests that this effect results from a "top-down" mechanism.
Abstract: We report evidence for a context- and not stimulus-dependent functional asymmetry in the left and right human auditory midbrain, thalamus, and cortex in response to monaural sounds. Neural activity elicited by left- and right-ear stimulation was measured simultaneously in the cochlear nuclei, inferior colliculi (ICs), medial geniculate bodies (MGBs), and auditory cortices (ACs) in 2 functional magnetic resonance imaging experiments. In experiment 1, pulsed noise was presented monaurally to either ear, or binaurally, simulating a moving sound source. In experiment 2, only monaural sounds were presented. The results show a modulation of the neural responses to monaural sounds by the presence of binaural sounds at a time scale of tens of seconds: In the absence of binaural stimulation, the left and right ICs, MGBs, and ACs responded stronger to stimulation of the contralateral ear. When blocks of binaural stimuli were interspersed in the sound sequence, the contralateral preference vanished in those structures in the right hemisphere. The resulting hemispheric asymmetry was similar to the asymmetry demonstrated for spatial sound processing. Taken together, the data demonstrate that functional asymmetries in auditory processing are modulated by context. The observed long time constant suggests that this effect results from a "top-down" mechanism.
119 citations
TL;DR: It is speculated that the right intraparietal sulcus might be part of two networks working in parallel: one responsible for reorienting attention and the other for the cholinergic modulation of cue reliability.
Journal Article•
TL;DR: It is suggested that combining alertness and spatial attention oriented training procedures might lead to a more stable amelioration of neglect symptoms.
Abstract: Purpose It has been proposed that the right hemisphere alerting network co-activates, either directly or via the brainstem, the spatial attention system in the parietal cortex. The observation that measures of impaired alertness and sustained attention can be used to predict the outcome of neglect might suggest such a relationship, too. The aim of the present study was to investigate the effects of alertness training on hemispatial neglect. Method A three-week computerised alertness training was applied to patients with chronic (> 3 months) stable visuospatial hemineglect. Training effects were investigated both in a single case and in a group of 7 patients by means of neuropsychological tests and functional magnetic resonance imaging (fMRI). Results After the training, the patients showed a significant improvement in a neglect test battery above any natural fluctuation during a three-week baseline phase. Improvements in the neglect tasks were accompanied by an increase of both right and left hemisphere frontal, anterior cingulate and superior parietal activation, areas known to be associated with both alertness and spatial attention. Four weeks after the end of the training, the patients' neglect test performance had mostly returned to baseline. Despite decreases of activation in some of the initially reactivated areas, increases in neural activity bilaterally in frontal areas, in the right anterior cingulate cortex, the right angular gyrus and in the left temporoparietal cortex remained. An Optokinetic Stimulation Training (OKS) in a control group of another 7 neglect patients led to comparable behavioral results. After the training, however, there was a reactivation mainly in posterior parts of both hemispheres suggesting training specific functional reorganization. Conclusion The limited stability of the behavioral and reactivation results over time demonstrates that a three-week alertness or OKS training alone does not result in long lasting behavioral improvements and stable reactivation patterns in every patient. We rather suggest that combining alertness and spatial attention oriented training procedures might lead to a more stable amelioration of neglect symptoms.
TL;DR: The differential modulation of frontocentral event-related potentials suggests that nicotine acts at later stages of target processing, rather than an alteration of perceptual processes, which is suggested in previous work.
TL;DR: It is demonstrated that neural activity in the left supramarginal gyrus underlies motor plans independent from the execution of the movement and thus extend previous neuropsychological and functional imaging data on the role of the left Supramarginals gyrus in higher motor cognition.
TL;DR: A specific role of the right hemisphere, especially of right posterior parietal cortex, in processing spatial aspects of complex actions is suggested to provide a physiological basis for the observed apraxic motor deficits in patients with right hemispheric damage.
Abstract: The left hemispheric dominance for complex motor behavior is undisputed. Clinical observations of complex motor deficits in patients with right hemispheric lesions, however, suggest an additional contribution of the right hemisphere to higher motor control. We assessed, using functional MRI (fMRI), which brain regions are implicated in processing the spatial aspects of complex, object-related actions. Using a blocked, factorial design, 17 healthy volunteers were asked to detect either spatial or sequential errors (factor ERROR) in complex activities of daily living, presented as video sequences with the appropriate object(s) or as pantomimes (factor STIMULUS). Observing complex actions (irrespective of stimulus type) activated a bilateral frontoparietal network. Observing actions with objects (relative to pantomimes) differentially increased neural activity in the fusiform gyrus and inferior occipital cortex bilaterally. Observing pantomimes, i.e., the same actions but without any object, differentially activated right prefrontal cortex, anterior cingulate cortex, the precuneus, and left cerebellum. The left cingulate cortex was differentially activated when subjects assessed the sequencing of actions. By contrast, assessing the spatial configuration of complex actions differentially increased neural activity in right posterior parietal cortex. A significant interaction of ERROR and STIMULUS was revealed for the right inferior parietal cortex only. These findings suggest a specific role of the right hemisphere, especially of right posterior parietal cortex, in processing spatial aspects of complex actions and thus provide a physiological basis for the observed apraxic motor deficits in patients with right hemispheric damage.
TL;DR: The data suggest that the primary visual cortex, higher visual areas, and left intraparietal sulcus represent an object substitution network dedicated to the generation and testing of a perceptual hypotheses as described by the object substitution theory of masking.
Abstract: Four-dot masking is a new form of visual masking that does not involve local contour interactions or spatial superimposition of the target stimulus and the mask (as, e.g., in pattern or metacontrast masking). Rather, the effective masking mechanism is based on object substitution. Object substitution masking occurs when low-level visual information representations are altered before target identification through iterative interaction with high-level visual processing stages has been completed. Interestingly, object substitution interacts with attention processes: Strong masking effects are observed when attentional orientation toward the target location is delayed. In contrast, no masking occurs when attention can be rapidly shifted to and engaged onto the target location. We investigated the neural basis of object substitution masking by studying the interaction of spatial attention and masking processes using functional magnetic resonance imaging. Behavioral data indicated a two-way interaction between the factors Spatial Attention (valid vs. invalid cueing) and Masking (four-dot vs. pattern masking). As expected, spatial attention improved performance more strongly during object substitution masking. Functional correlates of this interaction were found in the primary visual cortex, higher visual areas, and left intraparietal sulcus. A region-of-interest analysis in these areas revealed that the largest blood oxygenation level-dependent signal changes occurred during effective four-dot masking. In contrast, the weakest signal changes in these areas were observed when target visibility was highest. The data suggest that these areas represent an object substitution network dedicated to the generation and testing of a perceptual hypotheses as described by the object substitution theory of masking of Di-Lollo et al. [Competition for consciousness among visual events: The psychophysics of reentrant visual processes. Journal of Experimental Psychology: General, 129, 481–507, 2000].
TL;DR: The data confirm that there are hemifield-specific asymmetries in brain activity during spatial processing of both visual and imagined stimuli, and indicate, however, that these asymmetry are less clear and of a different nature in the latter.
TL;DR: Local on global interference was found for both groups in reaction times and an impairment in the divided attention task was found in both groups, but especially for global targets in NP, consistent with other evidence of difficulty in disengaging attention shown by patients with visuo-spatial neglect.
TL;DR: A 62-year-old man presented with a 36-hour history of painless clonic twitching of his left abdominal muscles and was diagnosed with an idiopathic epilepsia partialis continua of the abdominal muscles.
Abstract: A 62-year-old man presented with a 36-hour history of painless clonic twitching of his left abdominal muscles (video, part 1). After IV administration of 2 mg of clonazepam, the twitching stopped (video, part 2). We diagnosed an idiopathic epilepsia partialis continua (EPC) of the abdominal muscles. In adults, the most common etiologies of EPC include inflammatory …
01 Jan 2006
TL;DR: Using functional magnetic resonance imaging, sex differences in neural activity when subjects distinguished figure from ground in abstract patterns whose component shapes differed in colour, brightness, and symmetry/asymmetry are found.
TL;DR: The 22 contributions in this special issue range from semantic interference and facilitation to empirical studies of neurological patients with aphasic or attentional deficits, from sex differences in the neural mechanisms underlying implicit symmetry processing to studies of the cognitive genetics underlying higher attentional processes, and from delusions to the neural bases of consciousness.