Tomohisa Okada

Attention to emotion modulates fMRI activity in human right superior temporal sulcus

A parallel neural network has been proposed for processing various types of information conveyed by faces including emotion. Using functional magnetic resonance imaging (fMRI), we tested the effect of the explicit attention to the emotional expression of the faces on the neuronal activity of the face-responsive regions. Delayed match to sample procedure was adopted. Subjects were required to match the visually presented pictures with regard to the contour of the face pictures, facial identity, and emotional expressions by valence (happy and fearful expressions) and arousal (fearful and sad expressions). Contour matching of the non-face scrambled pictures was used as a control condition. The face-responsive regions that responded more to faces than to non-face stimuli were the bilateral lateral fusiform gyrus (LFG), the right superior temporal sulcus (STS), and the bilateral intraparietal sulcus (IPS). In these regions, general attention to the face enhanced the activities of the bilateral LFG, the right STS, and the left IPS compared with attention to the contour of the facial image. Selective attention to facial emotion specifically enhanced the activity of the right STS compared with attention to the face per se. The results suggest that the right STS region plays a special role in facial emotion recognition within distributed face-processing systems. This finding may support the notion that the STS is involved in social perception.

Neural Interaction of the Amygdala with the Prefrontal and Temporal Cortices in the Processing of Facial Expressions as Revealed by fMRI

Some involvement of the human amygdala in the processing of facial expressions has been investigated in neuroimaging studies, although the neural mechanisms underlying motivated or emotional behavior in response to facial stimuli are not yet fully understood. We investigated, using functional magnetic resonance imaging (fMRI) and healthy volunteers, how the amygdala interacts with other cortical regions while subjects are judging the sex of faces with negative, positive, or neutral emotion. The data were analyzed by a subtractive method, then, to clarify possible interaction among regions within the brain, several kinds of analysis (i.e., a correlation analysis, a psychophysiological interaction analysis and a structural equation modeling) were performed. Overall, significant activation was observed in the bilateral fusiform gyrus, medial temporal lobe, prefrontal cortex, and the right parietal lobe during the task. The results of subtraction between the conditions showed that the left amygdala, right orbitofrontal cortex, and temporal cortices were predominantly involved in the processing of the negative expressions. The right angular gyrus was involved in the processing of the positive expressions when the negative condition was subtracted from the positive condition. The correlation analysis showed that activity in the left amygdala positively correlated with activity in the left prefrontal cortex under the negative minus neutral subtraction condition. The psychophysiological interaction revealed that the neural responses in the left amygdala and the right prefrontal cortex underwent the condition-specific changes between the negative and positive face conditions. The right amygdaloid activity also had an interactive effect with activity in the right hippocampus and middle temporal gyrus. These results may suggest that the left and right amygdalae play a differential role in effective processing of facial expressions in collaboration with other cortical or subcortical regions, with the left being related with the bilateral prefrontal cortex, and the right with the right temporal lobe.

Differential amygdala response during facial recognition in patients with schizophrenia: an fMRI study

Human lesion or neuroimaging studies suggest that amygdala is involved in facial emotion recognition. Although impairments in recognition of facial and/or emotional expression have been reported in schizophrenia, there are few neuroimaging studies that have examined differential brain activation during facial recognition between patients with schizophrenia and normal controls. To investigate amygdala responses during facial recognition in schizophrenia, we conducted a functional magnetic resonance imaging (fMRI) study with 12 right-handed medicated patients with schizophrenia and 12 age- and sex-matched healthy controls. The experiment task was a type of emotional intensity judgment task. During the task period, subjects were asked to view happy (or angry/disgusting/sad) and neutral faces simultaneously presented every 3 s and to judge which face was more emotional (positive or negative face discrimination). Imaging data were investigated in voxel-by-voxel basis for single-group analysis and for between-group analysis according to the random effect model using Statistical Parametric Mapping (SPM). No significant difference in task accuracy was found between the schizophrenic and control groups. Positive face discrimination activated the bilateral amygdalae of both controls and schizophrenics, with more prominent activation of the right amygdala shown in the schizophrenic group. Negative face discrimination activated the bilateral amygdalae in the schizophrenic group whereas the right amygdala alone in the control group, although no significant group difference was found. Exaggerated amygdala activation during emotional intensity judgment found in the schizophrenic patients may reflect impaired gating of sensory input containing emotion.

Mechanisms underlying fatigue: a voxel-based morphometric study of chronic fatigue syndrome

BackgroundFatigue is a crucial sensation that triggers rest, yet its underlying neuronal mechanisms remain unclear. Intense long-term fatigue is a symptom of chronic fatigue syndrome, which is used as a model to study the mechanisms underlying fatigue.MethodsUsing magnetic resonance imaging, we conducted voxel-based morphometry of 16 patients and 49 age-matched healthy control subjects.ResultsWe found that patients with chronic fatigue syndrome had reduced gray-matter volume in the bilateral prefrontal cortex. Within these areas, the volume reduction in the right prefrontal cortex paralleled the severity of the fatigue of the subjects.ConclusionThese results are consistent with previous reports of an abnormal distribution of acetyl-L-carnitine uptake, which is one of the biochemical markers of chronic fatigue syndrome, in the prefrontal cortex. Thus, the prefrontal cortex might be an important element of the neural system that regulates sensations of fatigue.

Assessment of regional and global left ventricular function by reinjection Tl-201 and rest Tc-99m sestamibi ECG-gated SPECT: Comparison with three-dimensional magnetic resonance imaging

OBJECTIVES The purpose of this study was to test the ability of reinjection thallium-201 and rest technetium-99m sestamibi ECG (electrocardiographic)-gated SPECT (i.e., reinjection-g-SPECT [single-photon emission computed tomography] and MIBI-g-SPECT) to determine regional and global functional parameters. BACKGROUND The ECG-gated perfusion SPECT was reported to provide accurate left ventricular ejection fraction (LVEF) using an automated algorithm. We hypothesized that other various functional data may be obtained using reinjection-g-SPECT and MIBI-g-SPECT. METHODS Reinjection-g-SPECT, MIBI-g-SPECT, and three-dimensional magnetic resonance imaging (3DMRI) were conducted in 20 patients with coronary artery disease. Regional wall motion (RWM) and wall thickening (RWT) were analyzed using semiquantitative visual scoring by each g-SPECT and 3DMRI. The left ventricular end-systolic and end-diastolic volumes (EDV, ESV) and LVEF estimated by reinjection- and MIBI-g-SPECT were compared with the results of 3DMRI. RESULTS A high degree of agreement in RWM and RWT assessment was observed between each g-SPECT and 3DMRI (kappa >.70, p < .001). The LVEF values by reinjection- and MIBI-g-SPECT correlated and agreed well with those by 3DMRI (reinjection: r = .92, SEE = 5.9%, SD of differences = 5.7%; sestamibi: r = .94, SEE = 4.4%, SD of differences = 5.1%). The same also pertained to EDV (reinjection: r = .85, SEE = 18.7 ml, SD of differences = 18.4 ml; sestamibi: r = .92, SEE = 13.1 ml, SD of differences = 13.0 ml) and ESV (reinjection: r = .94, SEE = 10.3 ml, SD of differences = 10.3 ml; sestamibi: r = .97, SEE = 6.7 ml [p < .05 vs. reinjection by F test], SD of differences = 6.6 ml [p < .05 vs. reinjection by F test]). CONCLUSIONS Reinjection- and MIBI-g-SPECT provide clinically satisfactory various functional data. These functional data in combination with the perfusion information will improve diagnostic and prognostic accuracy without an increase in cost or the radiation dose to the patients.

Linking semantic priming effect in functional MRI and event-related potentials.

The aim of this study is to examine the neural substrates involved in semantic priming using a combined event-related functional magnetic resonance imaging (fMRI) and event-related potentials (ERP) study. Twelve subjects were instructed to judge whether the presented target word was a real word or a nonword. Under the related condition, target words were preceded by a semantically related prime word. On the other hand, under the unrelated condition, prime words did not have semantic relatedness with the target word. The reaction time for reaching a judgment was longer under the unrelated condition than under the related condition, indicating that the recognition of target words is promoted by semantic priming under the related condition. In the fMRI results, we found reduced activity in the dorsal and ventral left inferior frontal gyrus, the anterior cingulate, and left superior temporal cortex for related versus unrelated conditions (i.e., the repetition suppression effect). ERP analysis revealed that the amplitude of the N400 component was reduced under the related condition compared with the unrelated condition (i.e., the N400 priming effect). Correlation analysis between the BOLD repetition suppression effect and the N400 priming effect decomposed by independent component analysis (ICA) across subjects showed significant correlation in the left superior temporal gyrus. This finding is consistent with the recent MEG data suggesting that the source of N400 is judged to be the bilateral superior temporal lobe. We discussed this finding herein in relation to the modulation of access to the phonological representation caused by semantic priming.

Localized release of perivascular heparin inhibits intimal proliferation after endothelial injury without systemic anticoagulation

Segmental endothelial desquamation of the common carotid artery was produced in 30 rats using a balloon catheter technique which produces consistent proliferation of intimal smooth muscle cells from 5 to 20 days after injury. Immediately after endothelial injury, 15 animals were treated with periadventitial application of heparin contained in a continuous-release drug-delivery system using the polymer polyvinyl alcohol (PVA) and PVA alone applied in a similar fashion to 15 control rats. Animals were killed at 5, 10 and 20 days, respectively, after surgery by intracardiac perfusion-fixation, and vessels were prepared for light microscopy, scanning electron microscopy, and immunohistochemistry with antibodies directed against actin. At all time periods, there was a significant reduction in intimal cross-sectional area in heparin/PVA-treated vessels compared to control vessels. Scanning electron microscopy showed complete absence of endothelial cells from the luminal surface in both control and treated arteries at all time periods without evidence of significant platelet aggregation. Immunohistochemistry demonstrated the presence of immunoreactive actin in the proliferating myointimal cells. Femoral venous prothrombin time and partial thromboplastin time were unchanged in heparin/PVA-treated animals compared to controls at 1, 5, and 10 days. Continuous-release polymer drug delivery can be used to apply heparin selectively to the adventitial surface of vessels and effect changes in the vessel wall over periods of up to 3 weeks. By this means, smooth muscle proliferation and subsequent vessel narrowing after endothelial injury were inhibited without systemic anticoagulation. This technique may be applicable to both clinical and research applications related to the pathophysiology of arterial injury.

Tactile–visual cross-modal shape matching: a functional MRI study

The process and location of integration of information from different sensory modalities remains controversial. We used functional MRI to investigate the neural representation of cross-modal matching between tactile and visual shape information in eleven normal volunteers. During the scan, patterns of 2D shapes were presented both tactually and visually, simultaneously. Four different matching tasks were performed: tactile-tactile with eyes closed (TT), tactile-tactile with visual input (TTv), visual-visual with tactile input (VVt), and tactile-visual (TV). The TT task activated the contralateral primary sensorimotor area, and the postcentral gyrus, superior parietal lobules, anterior portion of the intraparietal sulcus, secondary somatosensory cortex, thalamus, dorsal premotor area, cerebellum, and supplementary motor area bilaterally, without occipital involvement. Visual matching activated the primary visual cortex and the lingual and fusiform gyri bilaterally. A cross-modal area was identified by subtracting TTv images from TV images, subtracting VVt images from TV images, and then determining common active areas. There was one discrete area that was active bilaterally; the posterior intraparietal sulcus close to the parieto-occipital sulcus. These data suggest that shape information from different sensory modalities may be integrated in the posterior intraparietal sulcus during tactile-visual matching tasks.

Neural correlates underlying mental calculation in abacus experts: a functional magnetic resonance imaging study

Experts of abacus operation demonstrate extraordinary ability in mental calculation. There is psychological evidence that abacus experts utilize a mental image of an abacus to remember and manipulate large numbers in solving problems; however, the neural correlates underlying this expertise are unknown. Using functional magnetic resonance imaging, we compared the neural correlates associated with three mental-operation tasks (numeral, spatial, verbal) among six experts in abacus operations and eight nonexperts. In general, there was more involvement of neural correlates for visuospatial processing (e.g., right premotor and parietal areas) for abacus experts during the numeral mental-operation task. Activity of these areas and the fusiform cortex was correlated with the size of numerals used in the numeral mental-operation task. Particularly, the posterior superior parietal cortex revealed significantly enhanced activity for experts compared with controls during the numeral mental-operation task. Comparison with the other mental-operation tasks indicated that activity in the posterior superior parietal cortex was relatively specific to computation in 2-dimensional space. In conclusion, mental calculation of abacus experts is likely associated with enhanced involvement of the neural resources for visuospatial information processing in 2-dimensional space.

Human limb-specific and non-limb-specific brain representations during kinesthetic illusory movements of the upper and lower extremities

Sensing movements of the upper and lower extremities is important in controlling whole‐body movements. We have shown that kinesthetic illusory hand movements activate motor areas and right‐sided fronto‐parietal cortices. We investigated whether illusions for the upper and lower extremities, i.e. right or left hand or foot, activate the somatotopical sections of motor areas, and if an illusion for each limb engages the right‐sided cortices.