Human brain mapping
-
Human brain mapping · Dec 2008
Spatial nonuniformity of the resting CBF and BOLD responses to sevoflurane: in vivo study of normal human subjects with magnetic resonance imaging.
Pulsed arterial spin labeling magnetic resonance imaging (MRI) was performed to investigate the local coupling between resting regional cerebral blood flow (rCBF) and BOLD (blood oxygen level dependent) signal changes in 22 normal human subjects during the administration of 0.25 MAC (minimum alveolar concentration) sevoflurane. Two states were compared with subjects at rest: anesthesia and no-anesthesia. Regions of both significantly increased and decreased resting-state rCBF were observed. ⋯ The slope of the linear regression line for AC, where rCBF was increased by sevoflurane, was markedly smaller than the slope for those ROIs where rCBF was decreased by sevoflurane, indicating a bigger change in BOLD per unit change in rCBF in regions where rCBF was increased by sevoflurane. These results suggest that it would be inaccurate to use a global quantitative model to describe coupling across all brain regions and in all anesthesia conditions. The observed spatial nonuniformity of rCBF and BOLD signal changes suggests that any interpretation of BOLD fMRI data in the presence of an anesthetic requires consideration of these insights.
-
Human brain mapping · Dec 2008
Representation of UV-B-induced thermal and mechanical hyperalgesia in the human brain: a functional MRI study.
Surrogate models of pain and hyperalgesia allow the investigation of underlying mechanisms in healthy volunteers. Here, we investigated brain activation patterns during mechanical and heat hyperalgesia in an inflammatory human pain model using functional magnetic resonance imaging. Heat and mechanical hyperalgesia were induced on the right forearm by UV-B application in 14 healthy subjects. ⋯ We conclude that different types of hyperalgesia in a human surrogate model of inflammatory pain produce different brain activation patterns. This is partly due to a differential processing of thermal and mechanical pain and an interaction of sensitization and modality in the caudal portion of the IFC. Finally, the data provide evidence for the existence of a common "sensitization network" consisting of ACC, bilateral anterior insula, and parts of the IFC.
-
Human brain mapping · Dec 2008
Differential contributions of the anterior temporal and medial temporal lobe to the retrieval of memory for person identity information.
Although previous studies have suggested the importance of the bilateral anterior temporal (ATL) and medial temporal lobes (MTL) in the retrieval of person identity information, there is little evidence concerning how these regions differentially contribute to the process. Here we investigated this question using functional magnetic resonance imaging (fMRI). Before scanning, subjects learned associations among faces (F), names (N), and job titles (as a form of person-related semantics, S). ⋯ In addition, activity in bilateral ATL was significantly correlated with reaction time for HSFN, whereas we found no significant correlation between activity in the right MTL and reaction time in any condition. The present findings suggest that the left ATL may mediate associations between names and person-related semantic information, whereas the right ATL mediates the association between faces and person-related semantic information in memory for person identity information. In addition, activation of the right MTL region implies that this area may contribute to a more general relational processing of associative components, including memory for person identity information.