NeuroImage
-
Using a whole-cortex magnetoencephalograph, magnetic field changes were recorded to describe brain activities related to simultaneous visual and olfactory processing and to detect odor-related influences on verbal information processing. Words had to be either shallowly (nonsemantic) or deeply (semantic) encoded by healthy young subjects, each of these tasks under two different kinds of olfactory stimulation. After each encoding phase, word recognition performance was tested. ⋯ Lorig (1999, Neurosci. Biobehav. Rev. 23, 391-398).
-
Voxel-based morphometry (VBM) may afford a more rapid and extensive survey of gray matter abnormalities in schizophrenia than manually drawn region of interest (ROI) analysis, the current gold standard in structural MRI. Unfortunately, VBM has not been validated by comparison with ROI analyses, nor used in first-episode patients with schizophrenia or affective psychosis, who lack structural changes associated with chronicity. An SPM99-based implementation of VBM was used to compare a group of 16 patients with first-episode schizophrenia and a group of 18 normal controls and, as a further comparison, 16 first-episode patients with affective psychosis. ⋯ With this statistical correction, the insula showed, bilaterally, the same pattern of differences in affective disorder subjects as that in schizophrenic subjects, whereas both left STG and left hippocampus showed statistical differences between affectives and schizophrenics, indicating the abnormalities specific to first-episode schizophrenia. These findings suggest both the promise and utility of VBM in evaluating gray matter abnormalities. They further suggest the importance of comparing VBM findings with more traditional ROI analyses until the reasons for the differences between methods are determined.
-
Although pathological muscle pain involves a significantly larger population than any other pain condition, the central mechanisms are less explored than those of cutaneous pain. The aims of the study were to establish the pain matrix for muscle pain in the full head volume and, further, to explore the possibility of a functional segregation to nonpainful and painful stimuli within the area of the parasylvian cortex corresponding to the secondary somatosensory area. Additionally, we speculate that a randomization of nonpainful and painful stimuli may target specific structures related to stimulus salience. ⋯ Individual analysis suggests separate representations within the area bounded by the upper bank of the Sylvian fissure (SF) and the circular sulcus of insula (CSI). Nonpainful stimulation activated the superficial parietal operculum adjoining the SF, while the painful condition additionally targeted the deeper parietal operculum bordering the CSI. Randomization of stimuli of different intensities likely introduces cognitive components that engage neural substrates servicing the appreciation of stimulus salience in the context of affect-laden pain imposition.
-
Comparative Study Clinical Trial
Patterns of cerebral atrophy in dementia with Lewy bodies using voxel-based morphometry.
Previous cross-sectional MRI studies based on region-of-interest analyses have shown that increased cerebral atrophy is a feature of both Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). Relative preservation of the hippocampus and temporal lobe structures in DLB compared to AD has been reported in region-of-interest-based studies. Recently, image processing techniques such as voxel-based morphometry (VBM) have been developed to provide an unbiased, visually informative, and comprehensive means of studying patterns of cerebral atrophy. ⋯ Regional gray matter volume loss was observed bilaterally in the temporal and frontal lobes and insular cortex of patients with DLB compared to control subjects. Comparison of dementia groups showed preservation of the medial temporal lobe, hippocampus, and amygdala in DLB relative to AD. Significant gray matter loss was also observed in the thalamus of AD patients compared to DLB.
-
Motor imagery is a state of mental rehearsal of single movements or movement patterns and has been shown to recruit motor networks overlapping with those activated during movement execution. We wished to examine whether the brain areas subserving control of sequential processes could be delineated by pure mental imagery, their activation levels reflecting the processing demands of a sequential task. We studied six right-handed volunteers (39.0 +/- 14 years) with H(2)(15)O positron emission tomography (PET) while they continuously mentally pursued with their right hand one of five sequences differing in complexity (i.e., increases in sequence length, single-finger repetitions, and reversals). ⋯ Activation decreases occurred in bilateral prefrontal and right temporo-occipital cortex. Activation increases that correlated with sequence complexity were observed only in specific areas of the activated network, notably in left PMd, right superior parietal cortex, and right cerebellar vermis (P < 0.05, corrected). In conclusion, our study, by varying the sequence structure of imagined finger movements, identified task-related activity changes in parietopremotor-cerebellar structures, reflecting their role in mediating sequence control.