Results 1 - 10
of
807
FMRI visualization of brain activity during a monetary incentive delay task
- NEUROIMAGE 12
, 2010
"... Comparative studies have implicated striatal and mesial forebrain circuitry in the generation of autonomic, endocrine, and behavioral responses for incentives. Using blood oxygen level-dependent functional magnetic resonance imaging, we sought to visualize functional activation of these regions in 1 ..."
Abstract
-
Cited by 178 (18 self)
- Add to MetaCart
Comparative studies have implicated striatal and mesial forebrain circuitry in the generation of autonomic, endocrine, and behavioral responses for incentives. Using blood oxygen level-dependent functional magnetic resonance imaging, we sought to visualize functional activation of these regions in 12 normal volunteers as they anticipated and responded for monetary incentives. Both individual and group analyses of time-series data revealed significant activation of striatal and mesial forebrain structures (including insula, caudate, putamen, and mesial prefrontal cortex) during trials involving both monetary rewards and punishments. In addition to these areas, during trials involving punishment, group analysis revealed activation foci in the anterior cingulate and thalamus. These
Dissociable executive functions in the dynamic control of behavior: inhibition, error detection, and correction
- Neuroimage
, 2002
"... The present study employed event-related fMRI and EEG to investigate the biological basis of the cognitive control of behavior. Using a GO/NOGO task optimized to produce response inhibitions, frequent commission errors, and the opportunity for subsequent behavioral correction, we identified distinct ..."
Abstract
-
Cited by 159 (4 self)
- Add to MetaCart
(Show Context)
The present study employed event-related fMRI and EEG to investigate the biological basis of the cognitive control of behavior. Using a GO/NOGO task optimized to produce response inhibitions, frequent commission errors, and the opportunity for subsequent behavioral correction, we identified distinct cortical areas associated with each of these specific executive processes. Two cortical systems, one involving right prefrontal and parietal areas and the second regions of the cingulate, underlay inhibitory control. The involvement of these two systems was predicated upon the difficulty or urgency of the inhibition and each was employed to different extents by high- and low-absentminded subjects. Errors were associated with medial activation incorporating the anterior cingulate and pre-SMA while behavioral alteration subsequent to errors was associated with both the anterior cingulate and the left prefrontal cortex. Furthermore, the EEG data demonstrated that successful response inhibition depended upon the timely activation of cortical areas as predicted by race models of response selection. The results highlight how higher cognitive functions responsible for behavioral control can result from the dynamic interplay of distinct cortical systems. © 2002 Elsevier Science (USA)
Puzzlingly high correlations in fMRI studies of emotion, personality, and social cognition. Perspect Psychol Sci
, 2009
"... ABSTRACT—Functional magnetic resonance imaging (fMRI) studies of emotion, personality, and social cognition have drawn much attention in recent years, with high-profile studies frequently reporting extremely high (e.g.,>.8) cor-relations between brain activation andpersonalitymeasures. We show th ..."
Abstract
-
Cited by 148 (0 self)
- Add to MetaCart
(Show Context)
ABSTRACT—Functional magnetic resonance imaging (fMRI) studies of emotion, personality, and social cognition have drawn much attention in recent years, with high-profile studies frequently reporting extremely high (e.g.,>.8) cor-relations between brain activation andpersonalitymeasures. We show that these correlations are higher than should be expected given the (evidently limited) reliability of both fMRI and personality measures. The high correlations are all the more puzzling because method sections rarely contain much detail about how the correlationswere obtained.We surveyed authors of 55 articles that reported findings of this kind to determine a few details on how these correlations were computed. More than half acknowledged using a strategy that computes separate correlations for individual voxels and reports means of only those voxels exceeding chosen thresh-
The common neural basis of autobiographical memory, prospection, navigation, theory of mind, and the default mode: A quantitative meta-analysis
- Journal of Cognitive Neuroscience
, 2009
"... & A core brain network has been proposed to underlie a number of different processes, including remembering, prospection, navigation, and theory of mind [Buckner, R. L., & Carroll, D. C. Self-projection and the brain. Trends in Cognitive Sciences, 11, 49–57, 2007]. This purported network— me ..."
Abstract
-
Cited by 129 (8 self)
- Add to MetaCart
(Show Context)
& A core brain network has been proposed to underlie a number of different processes, including remembering, prospection, navigation, and theory of mind [Buckner, R. L., & Carroll, D. C. Self-projection and the brain. Trends in Cognitive Sciences, 11, 49–57, 2007]. This purported network— medial prefrontal, medial-temporal, and medial and lateral parietal regions—is similar to that observed during defaultmode processing and has been argued to represent selfprojection [Buckner, R. L., & Carroll, D. C. Self-projection and the brain. Trends in Cognitive Sciences, 11, 49–57, 2007] or
A hybrid approach to the skull stripping problem in MRI
- NeuroImage
, 2004
"... We present a novel skull-stripping algorithm based on a hybrid approach that combines watershed algorithms and deformable surface models. Our method takes advantage of the robustness of the former as well as the surface information available to the latter. The algorithm first localizes a single whit ..."
Abstract
-
Cited by 127 (11 self)
- Add to MetaCart
(Show Context)
We present a novel skull-stripping algorithm based on a hybrid approach that combines watershed algorithms and deformable surface models. Our method takes advantage of the robustness of the former as well as the surface information available to the latter. The algorithm first localizes a single white matter voxel in a T1-weighted MRI image, and uses it to create a global minimum in the white matter before applying a watershed algorithm with a preflooding height. The watershed algorithm builds an initial estimate of the brain volume based on the three-dimensional connectivity of the white matter. This first step is robust, and performs well in the presence of intensity nonuniformities and noise, but may erode parts of the cortex that abut bright nonbrain structures such as the eye sockets, or may remove parts of the cerebellum. To correct these inaccuracies, a surface deformation process fits a smooth surface to the masked volume, allowing the incorporation of geometric constraints into the skullstripping procedure. A statistical atlas, generated from a set of accurately segmented brains, is used to validate and potentially correct the segmentation, and the MRI intensity values are locally re-estimated at the boundary of the brain. Finally, a high-resolution surface deformation is performed that accurately matches the outer boundary of the brain, resulting in a robust and automated procedure. Studies by our group and others outperform other publicly available skullstripping tools.
Conceptual processing during the conscious resting state. A functional MRI study
- J. Cogn. Neurosci
, 1999
"... n Localized, task-induced decreases in cerebral blood �ow are a frequent �nding in functional brain imaging research but remain poorly understood. One account of these phenomena postulates processes ongoing during conscious, resting states that are interrupted or inhibited by task performance. Psych ..."
Abstract
-
Cited by 120 (6 self)
- Add to MetaCart
(Show Context)
n Localized, task-induced decreases in cerebral blood �ow are a frequent �nding in functional brain imaging research but remain poorly understood. One account of these phenomena postulates processes ongoing during conscious, resting states that are interrupted or inhibited by task performance. Psychological evidence suggests that conscious humans are engaged almost continuously in adaptive processes involving semantic knowledge retrieval, representation in awareness, and directed manipulation of represented knowledge for organization, problem-solving, and planning. If interruption of such “conceptual” processes accounts for task-induced deactivation, tasks that also engage these conceptual processes should not cause deactivation. Furthermore, comparisons between conceptual and nonconceptual tasks should show activation during conceptual tasks of the same brain areas that are “deactivated ” relative to rest.
Activation of cortical and cerebellar motor areas during executed and imagined hand movements: An fMRI study
- Journal of Cognitive Neuroscience
, 1999
"... Brain activation during executed (EM) and imagined move-ments (IM) of the right and left hand was studied in 10 healthy right-handed subjects using functional magnetic resonance imagining (fMRI). Low electromyographic (EMG) activity of the musculi ºexor digitorum superªcialis and high vividness of ..."
Abstract
-
Cited by 108 (2 self)
- Add to MetaCart
(Show Context)
Brain activation during executed (EM) and imagined move-ments (IM) of the right and left hand was studied in 10 healthy right-handed subjects using functional magnetic resonance imagining (fMRI). Low electromyographic (EMG) activity of the musculi ºexor digitorum superªcialis and high vividness of the imagined movements were trained prior to image acquisition. Regional cerebral activation was measured by fMRI during EM and IM and compared to resting conditions. Anatomically se-lected regions of interest (ROIs) were marked interactively over the entire brain. In each ROI activated pixels above a t value of 2.45 (p < 0.01) were counted and analyzed. In all subjects the supplementary motor area (SMA), the premotor cortex (PMC), and the primary motor cortex (M1) showed signiªcant activation during both EM and IM; the somatosen-sory cortex (S1) was signiªcantly activated only during EM. Ipsilateral cerebellar activation was decreased during IM com-pared to EM. In the cerebellum, IM and EM differed in their foci of maximal activation: Highest ipsilateral activation of the cerebellum was observed in the anterior lobe (Larsell lobule H IV) during EM, whereas a lower maximum was found about 2-cm dorsolateral (Larsell lobule H VII) during IM. The prefron-tal and parietal regions revealed no signiªcant changes during both conditions. The results of cortical activity support the hypothesis that motor imagery and motor performance possess similar neural substrates. The differential activation in the cere-bellum during EM and IM is in accordance with the assumption that the posterior cerebellum is involved in the inhibition of movement execution during imagination.
A parametric manipulation of factors affecting task-induced deactivation in functional neuroimaging
- Journal of Cognitive Neuroscience
, 2003
"... & Task-induced deactivation (TID) refers to a regional decrease in blood flow during an active task relative to a ‘‘resting’ ’ or ‘‘passive’ ’ baseline. We tested the hypothesis that TID results from a reallocation of processing resources by parametrically manipulating task difficulty within thr ..."
Abstract
-
Cited by 102 (5 self)
- Add to MetaCart
(Show Context)
& Task-induced deactivation (TID) refers to a regional decrease in blood flow during an active task relative to a ‘‘resting’ ’ or ‘‘passive’ ’ baseline. We tested the hypothesis that TID results from a reallocation of processing resources by parametrically manipulating task difficulty within three factors: target discriminability, stimulus presentation rate, and short-term memory load. Subjects performed an auditory target detection task during functional magnetic resonance imaging (fMRI), responding to a single target tone or, in the short-term memory load conditions, to target sequences. Seven task conditions (a common version and two additional levels for each of the three factors) were each alternated with ‘‘rest’ ’ in a block design. Analysis of covariance identified brain regions in which TID occurred. Analyses of variance identified seven regions (left anterior cingulate/superior frontal gyrus, left middle frontal gyrus, right anterior cingulate gyrus, left and right posterior cingulate gyrus, left posterior parieto-occipital cortex, and right precuneus) in which TID magnitude varied across task levels within a factor. Follow-up tests indicated that for each of the three factors, TID magnitude increased with task difficulty. These results suggest that TID represents reallocation of processing resources from areas in which TID occurs to areas involved in task performance. Short-term memory load and stimulus rate also predict suppression of spontaneous thought, and many of the brain areas showing TID have been linked with semantic processing, supporting claims that TID may be due in part to suspension of spontaneous semantic processes that occur during ‘‘rest’’ (Binder et al., 1999). The concept that the typical ‘‘resting state’ ’ is actually a condition characterized by rich cognitive activity has important implications for the design and analysis of neuroimaging studies. &
The neural basis of financial risk taking.
- Neuron,
, 2005
"... Summary Investors systematically deviate from rationality when making financial decisions, yet the mechanisms responsible for these deviations have not been identified. Using event-related fMRI, we examined whether anticipatory neural activity would predict optimal and suboptimal choices in a finan ..."
Abstract
-
Cited by 98 (6 self)
- Add to MetaCart
(Show Context)
Summary Investors systematically deviate from rationality when making financial decisions, yet the mechanisms responsible for these deviations have not been identified. Using event-related fMRI, we examined whether anticipatory neural activity would predict optimal and suboptimal choices in a financial decision-making task. We characterized two types of deviations from the optimal investment strategy of a rational risk-neutral agent as risk-seeking mistakes and risk-aversion mistakes. Nucleus accumbens activation preceded risky choices as well as risk-seeking mistakes, while anterior insula activation preceded riskless choices as well as risk-aversion mistakes. These findings suggest that distinct neural circuits linked to anticipatory affect promote different types of financial choices and indicate that excessive activation of these circuits may lead to investing mistakes. Thus, consideration of anticipatory neural mechanisms may add predictive power to the rational actor model of economic decision making.
Regional homogeneity approach to fMRI data analysis
- NeuroImage
, 2004
"... Kendall’s coefficient concordance (KCC) can measure the similarity of a number of time series. It has been used for purifying a given cluster in functional MRI (fMRI). In the present study, a new method was developed based on the regional homogeneity (ReHo), in which KCC was used to measure the simi ..."
Abstract
-
Cited by 88 (9 self)
- Add to MetaCart
(Show Context)
Kendall’s coefficient concordance (KCC) can measure the similarity of a number of time series. It has been used for purifying a given cluster in functional MRI (fMRI). In the present study, a new method was developed based on the regional homogeneity (ReHo), in which KCC was used to measure the similarity of the time series of a given voxel to those of its nearest neighbors in a voxel-wise way. Six healthy subjects performed left and right finger movement tasks in event-related design; five of them were additionally scanned in a rest condition. KCC was compared among the three conditions (left finger movement, right finger movement, and the rest). Results show that bilateral primary motor cortex (M1) had higher KCC in either left or right finger movement condition than in rest condition. Contrary to prediction and to activation pattern, KCC of ipsilateral M1 is significantly higher than contralateral M1 in unilateral finger movement conditions. These results support the previous electrophysiologic findings of increasing ipsilateral M1 excitation during unilateral movement. ReHo can consider as a complementary method to model-driven method, and it could help reveal the complexity of the human brain function. More work is needed to understand the neural mechanism underlying ReHo.
