The neural substrates of affective face recognition in patients with Hwa-Byung and healthy individuals in Korea.

Hwa-Byung (HB) is a Korean culture-bound psychiatric syndrome caused by the suppression of anger. HB patients have various psychological and somatic symptoms, such as chest discomfort, a sensation of heat, and the sensation of having an epigastric mass. In this study, we measured brain activity in HB patients and healthy individuals in response to affective facial stimuli. Using functional magnetic resonance imaging (fMRI), the current study measured neural responses to neutral, sad, and angry facial stimuli in 12 healthy individuals and 12 patients with HB. In response to all types of facial stimuli, HB patients showed increased activations in the lingual gyrus and fusiform gyrus compared with healthy persons, but they showed relatively lower activation in the thalamus. We also found that patients with HB showed lower activity in response to the neutral condition in the right ACC than healthy controls. The current study indicates that the suppression of affect results in aberrant function of the brain regions of the visual pathway, and functional impairment in the ACC may contribute to the pathophysiology of HB.

Evaluation of the somatotopic organization of corticospinal tracts in the internal capsule and cerebral peduncle: results of diffusion-tensor MR tractography.

OBJECTIVE: We have used diffusion tensor tractography (DTT) for the evaluation of the somatotopic organization of corticospinal tracts (CSTs) in the posterior limb of the internal capsule (PLIC) and cerebral peduncle (CP). MATERIALS AND METHODS: We imaged the brains of nine healthy right-handed subjects. We used a spin-echo echo-planar imaging (EPI) sequence with 12 diffusion-sensitized directions. DTT was calculated with an angular threshold of 35 degrees and a fractional anistropy (FA) threshold of 0.25. We determined the location of the CSTs by using two regions of interest (ROI) at expected areas of the pons and expected areas of the lateral half of the PLIC, in the left hemisphere of the brain. Fiber tracts crossing these two ROIs and the precentral gyrus (PCG) were defined as CSTs. Four new ROIs were then defined for the PCG, from the medial to lateral direction, as ROI 1 (medial) to ROI 4 (lateral). Finally, we defined each fiber tract of the CSTs between the pons and each ROI in the PCG by using two ROIs methods. RESULTS: In all subjects, the CSTs were organized along the long axis of the PLIC, and the hand fibers were located anterior to the foot fibers. The CSTs showed transverse orientation in the CP, and the hand fibers were located usually medial to the foot fibers. CONCLUSION: Corticospinal tracts are organized along the long axis of the PLIC and the horizontal direction of the CP.

Hepatocyte-like cells from human mesenchymal stem cells engrafted in regenerating rat liver tracked with in vivo magnetic resonance imaging.

Cell transplantation using hepatocytes derived from stem cells has been regarded as a possible alternative treatment for various hepatic disorders. Recently, mesenchymal stem cells (MSCs) from the bone marrow have shown the potential to differentiate into hepatocytes in in vitro and in vivo conditions. Noninvasive imaging techniques allowing in vivo assessment of the location of cells are of great value for experimental studies in which these cells are transplanted. We labeled human mesenchymal stem cells (hMSCs) with green fluorescence protein (GFP) and superparamagnetic iron oxide (SPIO) using a transfection agent (GenePORTER). Cellular labeling was evaluated with magnetic resonance (MR) imaging of labeled suspensions, and Prussian blue staining for iron assessment. hMSCs labeled with SPIO and GFP were injected into the portal veins of immunosuppressed, hepatic-damaged rats. MR imaging findings were compared histologically. To identify the differentiation of hMSCs into hepatocytes and to trace the hepatocytes with molecular imaging, we observed the potential of SPIO and GFP double-labeled hMSCs to differentiate into hepatocyte-like cells in the regenerating rat liver. Serial MR imaging showed the possible detection of transplanted cells in the early period of transplantation. Our results indicate that magnetic labeling of hMSCs with SPIO may enable cellular MR imaging and tracking in experimental in vivo settings.

Diminished rostral anterior cingulate activity in response to threat-related events in posttraumatic stress disorder.

BACKGROUND: Previous brain imaging studies have reported hyperactivation of the amygdala and hypoactivation of the anterior cingulate in posttraumatic stress disorder (PTSD) patients, which is believed to be an underlying neural mechanism of the PTSD symptoms. The current study specifically focuses on the abnormal activity of the rostral anterior cingulate, using a paradigm which elicits an unexpected processing conflict caused by salient emotional stimuli. METHODS: Twelve survivors (seven men and five women) of the Taegu subway fire in 2003, who later developed PTSD, agreed to participate in this study. Twelve healthy volunteers (seven men and five women) were recruited for comparison. Functional brain images of all participants were acquired using functional magnetic resonance imaging while performing a same-different judgment task, which was modified to elicit an unexpected emotional processing conflict. RESULTS: PTSD patients, compared to comparison subjects, showed a decreased rostral anterior cingulate functioning when exposed to situations which induce an unexpected emotional processing conflict. Moreover, PTSD symptom severity was negatively correlated to the level of decrease in the rostral anterior cingulate activity. CONCLUSIONS: The results of this study provide evidence that the rostral anterior cingulate functioning is impaired in PTSD patients during response-conflict situations that involve emotional stimuli.

Distinction of reactive joint fluid from pyogenic abscess by diffusion-weighted imaging.

It is difficult to distinguish reactive joint fluid from infectious joint fluid by conventional MR images. In this presented case, we successfully distinguished these two conditions using diffusion-weighted imaging.