NeuroImage
-
To examine the functional association between brain and autonomic activities accompanying decision-making, we simultaneously recorded regional cerebral blood flow using (15)O-water positron emission tomography and event-related brain potentials (ERPs) time-locked to feedback of reward and punishment, as well as cardiovascular parameters, during a stochastic decision-making task. We manipulated the uncertainty of outcomes in the task; specifically, we compared a condition with high predictability of reward/punishment (contingent-reward condition) and a condition with low predictability of reward/punishment (random-reward condition). The anterior cingulate cortex (ACC) was commonly activated in both conditions. ⋯ Activation of these brain regions correlated with a positive component of ERPs locked to feedback signals (feedback-related positivity), which showed an association with behavioral decision-making in the contingent-reward condition. Furthermore, cardiovascular responses were attenuated in the random-reward condition, where continuous attention and contingency monitoring were needed, and such attenuation of cardiovascular responses was mediated by vagal activity that was governed by the rostral ACC. These findings suggest that the prefrontal-striatal network provides a neural basis for decision-making and modulation over the peripheral autonomic activity accompanying decision-making.
-
This work examines the influence of changes in baseline activity on the intrinsic functional connectivity fMRI (fc-fMRI) in humans. Baseline brain activity was altered by inducing anesthesia (sevoflurane end-tidal concentration 1%) in human volunteers and fc-fMRI maps between the pre-anesthetized and anesthetized conditions were compared across different brain networks. ⋯ The results indicate that, while fc-fMRI patterns did not significantly differ (p<0.005; 20-voxel cluster threshold) in sensory cortex and in the DMN between the pre- and anesthetized conditions, fc-fMRI in high-order cognitive regions (i.e. memory and pain circuits) was significantly altered by anesthesia. These findings provide further evidence that fc-fMRI reflects intrinsic brain properties, while also demonstrating that 0.5 MAC sevoflurane anesthesia preferentially modulates higher-order connections.
-
Randomized Controlled Trial
Xenon-induced changes in CNS sensitization to pain.
Electrophysiological investigations of the spinal cord in animals have shown that pain sensitizes the central nervous system via glutamate receptor dependent long-term potentiation (LTP) related to an enhancement of pain perception. To expand these findings, we used functional magnetic resonance (fMRI), blood oxygen level dependent (BOLD) and perfusion imaging in combination with repeated electrical stimulation in humans. Specifically we monitored modulation of somatosensory processing during inhibition of excitatory transmission by ocular application of the glutamate receptor antagonist xenon. ⋯ Moreover, effects of xenon on behavioral, fMRI and perfusion data scaled with stimulus intensity. The dependence of pain sensitization on sufficient pre-activation reflects a multistage process which is characteristic for glutamate receptor related processes of LTP. This study demonstrates how LTP related processes known from the cellular level can be investigated at the brain systems level.
-
Neuroticism is associated with the experience of negative affect and the development of affective disorders. While evidence exists for a modulatory role of neuroticism on task induced brain activity, it is unknown how neuroticism affects brain connectivity, especially the crucial coupling between the amygdala and the prefrontal cortex. Here we investigate this relation between functional connectivity and personality in response to negative facial expressions. ⋯ Our results therefore suggest that high neurotic participants display stronger self-referential processing in response to negative emotional faces. Second, in line with previous reports on ACC function, the negative correlation between amygdala-ACC connectivity and neuroticism scores might indicate that those high in neuroticism display diminished control function of the ACC over the amygdala. These connectivity patterns might be associated with vulnerability to developing affective disorders such as depression and anxiety.
-
The objective of this study was to delineate a common functional network that underlies autobiographical, episodic, and semantic memory retrieval. We conducted an event-related fMRI study in which we utilized the same pictorial stimuli, but manipulated retrieval demands to extract autobiographical, episodic, or semantic memories. To assess this common network, we first examined the functional connectivity of regions identified by a previous analysis of task-related activity that were active across all three tasks. ⋯ Activity in inferior frontal and middle temporal cortex bilaterally, left temporoparietal junction, and anterior and posterior cingulate gyri was positively correlated with the seeds, whereas activity in posterior occipito-temporo-parietal regions was negatively correlated. These findings support the idea that a common neural network underlies the retrieval of declarative memories regardless of memory content. This proposed network consists of increased activity in regions that represent internal processes of memory retrieval and decreased activity in regions that mediate attention to external stimuli.