NeuroImage
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Healthy aging is associated with brain volume reductions that involve the frontal cortex, but also affect other brain regions. We sought to identify an age-related network pattern of MRI gray matter using a multivariate statistical model of regional covariance, the Scaled Subprofile Model (SSM) with voxel based morphometry (VBM) in 29 healthy adults, 23-84 years of age (Group 1). In addition, we evaluated the reproducibility of the age-related gray matter pattern derived from a prior SSM VBM study of 26 healthy adults, 22-77 years of age (Group 2; Alexander et al., 2006) in relation to the current sample and tested the ability of the network analysis to extract an age-related pattern from both cohorts combined. ⋯ The results suggest that healthy aging is associated with a regionally distributed pattern of gray matter atrophy that has reproducible regional features. Whereas the network patterns of atrophy included parietal, temporal, and subcortical regions, involvement of the frontal brain regions showed the most consistently extensive and reliable reductions across samples. Network analysis with SSM VBM can help detect reproducible age-related MRI patterns, assisting efforts in the study of healthy and pathological aging.
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Human functional magnetic resonance imaging (fMRI) evidence suggests the hippocampus is associated with context memory to a greater degree than item memory (where only context memory requires item-in-context binding). A separate line of fMRI research suggests the hippocampus is associated with "remember" responses to a greater degree than "know" or familiarity based responses (where only remembering reflects the subjective experience of specific detail). Previous studies, however, have confounded context memory with remembering and item memory with knowing. ⋯ The analogous pattern of activity that would have supported the remembering hypothesis was never observed in the hippocampus. However, a targeted analysis revealed remembering specific activity in the left inferior parietal cortex. The present results suggest parietal cortex may be associated with subjective remembering while the hippocampus mediates binding.
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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.
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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.
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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.