Long-term efficacy and safety of aripiprazole in patients with schizophrenia, schizophreniform disorder, or schizoaffective disorder: 26-week prospective study

AIMS

To date there have been no reports of long-term efficacy of aripiprazole in Asian populations. The aim of the present study was therefore to investigate the long-term efficacy, safety and tolerability of aripiprazole in a large number of patients with schizophrenia, schizophreniform disorder, or schizoaffective disorder in Korea.

METHODS

This study was a prospective, multicenter, single-group, 26-week open study of patients with schizophrenia, schizophreniform disorder, or schizoaffective disorder. A total of 300 Korean patients participated in the study. The primary efficacy measure was the Positive and Negative Syndrome Scale (PANSS) total score, and secondary efficacy measures included the PANSS positive and negative subscales, Clinical Global Impression-Severity of Illness (CGI-S). Tolerability and safety were assessed by monitoring the frequency and severity of treatment-emergent adverse events, extrapyramidal symptoms (EPS), vital signs, weight, and laboratory tests.

RESULTS

Aripiprazole produced rapid and significant improvements on all efficacy measures. As evidenced by PANSS total score, PANSS positive subscales and the CGI-S scores, first-episode drug-naive patients demonstrated significantly greater efficacy relative to patients who had previously experienced one or more episodes of relapse. Aripiprazole was associated with significant decrease of serum prolactin level. The subjects showed mild weight gain.

CONCLUSION

Aripiprazole is an effective antipsychotic in the long-term treatment of both positive and negative symptoms. This study extends the findings of previous long-term studies, and has found that there is no significant difference with regard to ethnicity in response to aripiprazole.

Impairment of source memory in patients with obsessive-compulsive disorder: equivalent current dipole analysis

We examined memory performance and cortical source localization of old/new effects in a source memory task in obsessive-compulsive disorder (OCD) patients by employing an equivalent current dipole (ECD) model using EEG and a realistic head model. Event-related potentials (ERPs) were recorded while 14 OCD patients and 14 age-, sex-, handedness-, and educational level-matched healthy control subjects performed recognition tasks for spoken words (items) or for the voice of the speaker of spoken words (sources). In the item memory task, both groups showed ERP old/new effects at 300-700 ms. In the source memory task, the controls showed ERP old/new effects at 400-700 ms, whereas the OCD patients did not. Compared with the controls, the OCD patients showed significantly lower source accuracy and prolonged reaction times to the old words with accurate voice judgments. There were no differences between the OCD and control groups with regard to the locations of the ERP generators elicited by source correct and correct rejection conditions. The OCD patients showed significantly altered hemispheric asymmetry of ECD power in the frontal lobe during source memory retrieval, compared with the controls. These results indicate that OCD patients have preserved item memory about content, but impaired source memory about context.

Taq1A polymorphism in the dopamine D2 receptor gene as a predictor of clinical response to aripiprazole

We investigated whether the clinical response to aripiprazole differed according to the Taq1A polymorphism in the dopamine D2 receptor (DRD2) gene. In this 26-week, prospective, open-label, double-blind, parallel-group study, 90 patients with schizophrenia, schizoaffective disorder, or schizophreniform disorder were recruited and divided into two groups according to their DRD2 genotype (A1A1, n=14; A1A2+A2A2, n=76). The efficacy assessment included Positive and Negative Syndrome Scale (PANSS) scores and Clinical Global Impression (CGI) scores. Extrapyramidal symptoms were assessed using the Simpson-Angus Scale (SAS), Abnormal Involuntary Movement Scale (AIMS), and Barnes Akathisia Rating Scale (BAS). Plasma prolactin levels were also measured. Patients with the A1A1 genotype showed a more favorable therapeutic response to aripiprazole when assessed using the PANSS ratio. The changes in the SAS score from baseline to week 4 also differed according to the genotype group. There were no significant differences in the changes in the CGI, AIMS, and BAS scores or plasma prolactin level between the two genotype groups. The results suggest an association between the DRD2 Taq1A polymorphism status and the variation in the clinical response to aripiprazole.

Structural abnormalities of the right inferior colliculus in schizophrenia

Although structural and functional neuroimaging studies of schizophrenia have suggested that impaired connectivity in the extensive network of cortical and subcortical areas is involved in its pathophysiology, there were no studies have investigated the structural integrity of the lower sensory brain areas including the inferior (IC) and the superior (SC) colliculus. The IC plays an important role in mediating auditory gating processes and inhibitory neural transmission, while the SC is a key structure in a distributed network mediating saccadic eye movements and shifts of attention, both of which have been linked to the pathophysiology of schizophrenia. We compared the morphologies of the IC and SC, which are involved in the early stage processing of visual and auditory stimuli, in patients with schizophrenia (N=28) and healthy controls (N=34) using high-resolution magnetic resonance imaging. Subjects with schizophrenia had a significantly smaller right IC, compared with controls. The reduced IC volume suggests that a structural abnormality of the IC in patients with schizophrenia may be involved in the auditory cognitive dysfunction of schizophrenia.

Surface-based functional magnetic resonance imaging analysis of partial brain echo planar imaging data at 1.5 T

Surface-based functional magnetic resonance imaging (fMRI) analysis is more sensitive and accurate than volume-based analysis for detecting neural activation. However, these advantages are less important in practical fMRI experiments with commonly used 1.5-T magnetic resonance devices because of the resolution gap between the echo planar imaging data and the cortical surface models. We expected high-resolution segmented partial brain echo planar imaging (EPI) data to overcome this problem, and the activation patterns of the high-resolution data could be different from the low-resolution data. For the practical applications of surface-based fMRI analysis using segmented EPI techniques, the effects of some important factors (e.g., activation patterns, registration and local distortions) should be intensively evaluated because the results of surface-based fMRI analyses could be influenced by them. In this study, we demonstrated the difference between activations detected from low-resolution EPI data, which were covering whole brain, and high-resolution segmented EPI data covering partial brain by volume- and surface-based analysis methods. First, we compared the activation maps of low- and high-resolution EPI datasets detected by volume- and surface-based analyses, with the spatial patterns of activation clusters, and analyzed the distributions of activations in occipital lobes. We also analyzed the high-resolution EPI data covering motor areas and fusiform gyri of human brain, and presented the differences of activations detected by volume- and surface-based methods.

Selective impairment in visual perception of biological motion in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is associated with a variety of well-documented cognitive deficits such as deficits in memory and executive functioning, but little is known about basic perceptual concomitants of OCD. This study investigated global, configural processing in OCD using dynamic (moving) and static stimuli with minimal demands on cognitive function. Twenty OCD patients and 16 age- and education-matched healthy control subjects were tested on four perceptual tasks: two motion tasks involved detection and discrimination of human activity portrayed by point-light animations ("biological" motion). The other two tasks involved detection of coherent, translational motion defined by random-dot cinematograms and detection of static global shape defined by spatially distributed contours. OCD patients exhibited impaired performance on biological motion tasks; in contrast, their performance on tasks of coherent motion detection and global form perception were comparable to those of healthy controls. These results indicate that OCD patients have a specific deficit in perceiving biological motion signals, whereas their perception of non-biological coherent motion and static global shape is intact. Because efficient social interactions depend on accurate and rapid perception of subtle socially relevant cues, deficits in biological motion perception may compromise social functioning in people with OCD.

Prospective outcome of early intervention for individuals at ultra-high-risk for psychosis

AIM

Based on previous reports of second-generation antipsychotic agents having a beneficial effect on prodromal symptoms, we investigated the effectiveness and tolerability of atypical antipsychotic therapies in individuals at high risk for developing psychosis.

METHODS

We examined prodromal symptoms and functioning in individuals at ultra-high-risk for psychosis using an uncontrolled prospective design with pre- and post-treatment measures.

RESULTS

Of the 27 subjects taking antipsychotics during the study period, 15 took part in at least one follow-up assessment. Overall Comprehensive Assessment of At-Risk Mental States scores significantly improved at the last evaluation point, with a medium-size effect of Cohen's d = 0.54 (95% confidence interval, -0.02 to 1.08) (mean follow-up period = 8.8; SD = 8.3 months). Depression and anxiety symptoms were markedly reduced, and global and social functioning also significantly improved. Of the 27 subjects, two (7.4%) converted to psychosis and 16 (59.3%) experienced at least one treatment-emergent adverse event, but no subjects exhibited serious adverse events.

CONCLUSIONS

The results of this study support treating high-risk individuals with antipsychotics to reduce prodromal symptoms with adequate safety.

Neuropsychological correlates of N400 anomalies in patients with schizophrenia: A preliminary report

We investigated N400 anomalies and their relationship with neuropsychological disturbance of schizophrenia. Twelve patients with schizophrenia and 12 normal controls, matched for age, sex, education and handedness underwent both the neuropsychological test and the electrophysiological recordings employing semantic violation sentence paradigm. The patients with schizophrenia showed a reduced N400 amplitude and worse performance in the frontal lobe function test compared to healthy participants. Furthermore, statistically significant positive correlations were found between N400 amplitude and neuropsychological performances on the Stroop Task and Wisconsin Card Sorting Test in patients with schizophrenia. Our results suggest the possibility that N400 anomalies reflect the disturbed integrity of the fronto-temporal network in schizophrenia evidenced by neuropsychological deficits. In addition, we concluded that the N400 amplitude is a candidate for an endophenotype marker of schizophrenia by revealing its relationship to neuropsychological deficits.

The emotional characteristics of schizotypy

OBJECTIVE

The aim of this study was to investigate the relationship between emotional traits and schizotypal symptoms and to establish a hypothetical model for the causal relationship between them.

METHODS

Schizotypal symptoms were assessed using the Schizotypal Personality Questionnaire (SPQ), and a total of seven emotional traits considered to be potential risk factors for schizotypy were categorized as emotional disturbances, emotional attenuators or emotional amplifiers. A total of 502 undergraduate students completed the SPQ and other scales.

RESULTS

The result of the present study suggested that the high levels of emotional disturbance in individuals who are prone to schizotypy or psychosis are amplified by their intensity and fluctuation. However, if their emotion attenuating abilities function well, these disturbances can be controlled and the schizotypal symptoms and progression to psychosis can be contained. Discriminant analysis showed that 69.0% of the subjects with many schizotypal symptoms and 80.7% of the subjects with few schizotypal symptoms were correctly classified.

CONCLUSION

The present study suggests the possibility of using emotional traits to identify the risk factors for psychosis.

Social functioning deficits in young people at risk for schizophrenia

OBJECTIVE

Impairment in social functioning is a central feature of schizophrenia and is known to be evident before the onset of psychosis, acting as a potential vulnerability marker. The aim of the present study was to test the hypothesis that social impairment is simultaneously a state and trait marker of risk for schizophrenia and schizophrenia-related disorder.

METHOD

Social functioning was examined in three groups: ultra-high-risk subjects (UHR, n =32), genetic high-risk subjects (GHR, n =32), and age- and IQ-matched healthy controls (HC, n =30). Social functioning was assessed using the Social Functioning Scale (SFS), and prodromal symptoms were assessed in high-risk subjects using the Comprehensive Assessment of At-Risk Mental States (CAARMS).

RESULTS

Both the UHR and GHR groups exhibited significantly impaired social functioning compared with the HC group, and the UHR group was more impaired than the GHR group. In the UHR group, duration of prodromal symptoms was related to impaired 'interpersonal behaviour'. Positive and negative symptoms were not significantly associated with social functioning, whereas disorganized and general symptoms were significantly correlated with poor 'independence-competence' in UHR individuals.

CONCLUSION

The findings support the hypothesis that impairment in social functioning is both a trait and state marker of risk for schizophrenia and other psychotic disorders, implying that social impairment constitutes a mediating vulnerability indicator of psychotic disorders including schizophrenia.

Effect of electrolyzed water for reduction of foodborne pathogens on lettuce and spinach

The ability of electrolyzed water (EW) to inactivate foodborne pathogens on the surfaces of lettuce and spinach was investigated. Lettuce and spinach leaves were inoculated with a cocktail of 3 strains each of Escherichia col O157:H7, Salmnonella Typhimurium, and Listeria monocytogenes and treated with acidic electrolyzed water (AC-EW), alkaline electrolyzed water (AK-EW), alkaline electrolyzed water followed by acidic electrolyzed water (sequential treatment, AK-EW + AC-EW), deionized water followed by acidic electrolyzed water (sequential treatment, DW + AC-EW), and deionized water (control, DW) for 15, 30 s, and 1, 3, and 5 min at room temperature (22 +/- 2 degrees C). For all 3 pathogens, the same pattern of microbial reduction on lettuce and spinach were apparent. The relative efficacy of reduction was AC-EW > DW + AC-EW approximately = AK-EW + AC-EW > AK-EW > control. After a 3-min treatment of AC-EW, the 3 tested pathogens were reduced below the detection limit (0.7 log). DW + AC-EW and AK-EW + AC-EW produced the same levels of reduction after 5 min when compared to the control. AK-EW did not reduce levels of pathogens even after a 5-min treatment on lettuce and spinach. Results suggest that AC-EW treatment was able to significantly reduce populations of the 3 tested pathogens from the surfaces of lettuce and spinach with increasing time of exposure.

Probable case of neuroleptic malignant syndrome following administration of antituberculotic drugs in a chlorpromazine-treated patient

Neuroleptic malignant syndrome (NMS), a potentially fatal adverse reaction to neuroleptics, is known to occur more often in the initial stage of antipsychotic treatment. We describe a patient with chronic schizophrenia who, in a few days after the addition of antituberculotic drugs to his antipsychotic regimen, developed probable NMS without pyrexia. We reasoned that rifampin, a strong hepatic enzyme inducer, decreased the plasma chlorpromazine concentration of the patient, with the result of cholinergic hyperactivity and finally, the symptoms of NMS. Therefore, physicians should be aware of drug interactions and the likelihood of NMS, and consider antipsychotic dose adjustment when prescribing drugs that may influence pharmacokinetic properties of antipsychotics in a patient with schizophrenia receiving long-term antipsychotic treatment.

Cavum septum pellucidum in subjects at ultra-high risk for psychosis: compared with first-degree relatives of patients with schizophrenia and healthy volunteers

OBJECTIVE

The cavum septum pellucidum (CSP) is a space between the two leaflets of the septum pellucidum, and is a putative marker of disturbance in early brain development. We examined whether CSP was present more frequently in subjects at ultra-high risk (UHR) for psychosis compared to first-degree relatives of patients with schizophrenia (genetic high risk, GHR) and healthy controls (HC).

METHODS

We evaluated CSP in 87 subjects (30 UHR, 23 GHR, and 34 HC) according to a published grading system using high-resolution magnetic resonance imaging (MRI) with 0.45-mm slice thickness. We also assessed two other criteria: presence of CSP on at least one MRI slice, and abnormally large CSP (i.e., > or =6 mm in length). Correlational analysis between CSP measures and clinical symptoms was also examined.

RESULTS

Based on the grading scale, the UHR group exhibited a significantly higher incidence of abnormal CSP (grades 2, 3, and 4) compared to the HC group, but there were no significant differences in the incidence of abnormal CSP between the UHR and GHR or the GHR and HC groups. There were no significant differences among the groups in the presence of CSP on at least one MRI slice or abnormally large CSP based on the length of CSP. In addition, no significant correlations between CSP measures and clinical symptoms were found.

CONCLUSION

These findings suggest that abnormal CSP might be associated with susceptibility to psychosis, although the CSP itself might be a normal anatomical variant. Further studies using a larger sample are needed to clarify issues on neurodevelopmental perspective in subjects at high risk for psychosis.

Microwave dielectric properties of (A2+(1/3)B5+(2/3))0.5Ti0(0.5)O2 (A2+ = Zn, Mg, B5+ = Nb, Ta) ceramics

Dielectric properties of (A(2+)(1/3)B(5+)(2/3))(0.5)Ti0(0.5)O(2) (A(2+) = Zn, Mg, B(5+) = Nb, Ta) ceramics were investigated at microwave frequencies. A single phase with tetragonal rutile structure was obtained through the entire compositions. Dielectric properties were strongly dependent on the structural characteristics. The specimens with B(5+) = Nb showed a larger dielectric constant than those with B(5+) = Ta due to the decrease of bond valence. Quality factors (Qf) of the specimens with B(5+) = Ta were larger than those with B(5+) = Nb. Temperature coefficient of the resonant frequencies (TCF) of (Zn(1/3)Nb(2/3) )0(0.5)Ti0(0.5)O(2) was larger than that of (Mg(1/3)Ta(2/3))0(0.5)Ti0(0.5)O(2). These results could be attributed to the changes of the temperature coefficient of dielectric constant and the degree of oxygen octahedral distortion.

Dysfunction in configural face processing in patients with schizophrenia

BACKGROUND

Face recognition has important implications for patients with schizophrenia, who exhibit poor interpersonal and social skills. Previous reports have suggested that patients with schizophrenia have deficits in their ability to recognize faces, and because face recognition relies heavily on information about the configuration of faces, we hypothesized that patients with schizophrenia would have specific problems in processing configural information.

METHODS

We measured the performance of 20 patients with schizophrenia and 20 normal subjects in a face-discrimination task, using upright and inverted pairs of face photographs that differed in featural or configural information.

RESULTS

The patients with schizophrenia showed disproportionately poorer performance in discriminating configural compared with featural face sets.

CONCLUSION

The result suggests that the face-recognition deficit in schizophrenic patients is due to specific impairments in configural processing of faces.

Correlation between the in vitro ATP-based chemosensitivity assay and HER2/neu expression in women with breast cancer

Several in vitro chemosensitivity tests have been developed to predict the chemotherapeutic response of tumours prior to initiation of individualized treatment for breast cancer. This study investigated whether the in vitro chemosensitivity response of cell lines derived from breast cancer patients was affected by HER2/neu expression. We cultured breast cancer cell lines from 50 patients and the adenosine triphosphatebased chemotherapy response assay (ATPCRA) was performed with 5-fluorouracil, gemcitabine, docetaxel, doxorubicin, methotrexate, vinorelbine and paclitaxel. 5-fluorouracil combined a high median cell death rate (32.4%) with the narrowest range of cytotoxic effects (7.3-65.7%). In addition, gemcitabine showed significantly greater activity in HER2/neupositive patients. In contrast, docetaxel was significantly less effective in HER2/neu-positive patients. No significant correlation was found between the other agents and HER2/neu expression. The use of the ATP-CRA test for metastatic tissue from patients with recurrent disease might be a useful approach to determine the most effective chemotherapy regimen.

Impact of coexistent schizotypal personality traits on frontal lobe function in obsessive-compulsive disorder

OBJECTIVE

This study was a post-hoc analysis of the results from a neuropsychological battery which was conducted to investigate the frontal lobe difference between obsessive-compulsive disorder (OCD) patients with and without schizotypal personality trait (SPT), especially dorsolateral prefrontal and medial frontal functions.

METHODS

Fifty-five OCD patients were divided into two groups according to their Personality Disorder Questionnaire-4+ scores. Patients with OCD with SPT (n=17) and OCD without SPT (n=38) were compared to 52 schizophrenia patients and 67 healthy subjects. Two neuropsychological tasks, the Wisconsin Card Sorting Test (WCST) and verbal fluency tests which are considered to reflect dorsolateral and medial frontal functions, were selected for an analysis.

RESULTS

OCD with SPT patients and patients with schizophrenia performed significantly worse than controls in both the WCST and verbal fluency tasks, whereas OCD without SPT patients showed no deficits in the same tasks. Moreover, we found no statistically significant difference in either task between patients having OCD with SPT and patients with schizophrenia.

CONCLUSION

This study indicate that OCD with SPT may have distinct patterns of neurocognitive deficit that differ from those of OCD without SPT, especially in terms of frontal lobe function.

Deficit of theory of mind in individuals at ultra-high-risk for schizophrenia

BACKGROUND

Although a deficit in social cognition is regarded as an early indicator of schizophrenia, few studies have investigated social cognition in ultra-high-risk (UHR) individuals.

METHODS

Our investigation involved subjects at UHR for psychosis (N=33) and an age- and IQ-matched healthy control (HC) group (N=36). Two types of theory of mind (ToM) tasks and a neuropsychological test battery were measured.

RESULTS

Compared to the HC group, the UHR group performed significantly worse for ToM tasks, with the effect size at an intermediate level (0.64-0.68). Furthermore, the UHR group showed impaired performance in the executive and working memory tests, but not verbal memory tests. These deficits for ToM tests observed in the UHR group were significantly correlated with set-shifting tasks.

CONCLUSIONS

Deficits in social cognition may be modest at the prodromal stage of schizophrenia and may be attributed to prefrontal dysfunction. To prevent or delay transition to psychosis, there is a need for specific preventive strategies targeting social functioning for the UHR group.

Voxel-based morphometry study of gray matter abnormalities in obsessive-compulsive disorder

To examine regional abnormalities in the brains of patients with obsessive-compulsive disorder (OCD), we assessed the gray matter (GM) density using voxel-based morphometry (VBM). We compared magnetic resonance images (MRIs) acquired from 71 OCD patients and 71 age- and gender-matched normal controls and examined the relationship between GM density and various clinical variables in OCD patients. We also investigated whether GM density differs among the subtypes of OCD compared to healthy controls. We detected significant reduction of GM in the inferior frontal gyrus, the medial frontal gyrus, the insula, the cingulate gyrus, and the superior temporal gyrus of OCD patients. A significant increase in GM density was observed in the postcentral gyrus, the thalamus, and the putamen. Some of these regions, including the insular and postcentral gyrus, were also associated with the severity of obsessive- compulsive symptoms. These findings indicate that the frontal-subcortical circuitry is dysfunctional in OCD, and suggest that the parietal cortex may play a role in the pathophysiology of this disease.

Artificial shifting of fMRI activation localized by volume- and surface-based analyses

Spatial smoothing is an important post-processing procedure that is used to increase the signal-to-noise ratio (SNR) of blood oxygenation level-dependent signals (BOLD) in common functional magnetic resonance imaging (fMRI) applications. However, recent studies have shown that smoothing artificially shifts probabilistic local maxima of fMRI activations. In this study, we show shifting of the localization of functional centers in hand motor areas of the cerebral cortex by three-dimensional isotropic Gaussian kernel smoothing or two-dimensional heat kernel smoothing in volume- and surface-based fMRI analyses. Activation maps derived from smoothed echo planar imaging (EPI) data by volume- and surface-based analyses were assigned to the nodes of individual cortical surface models, and local maxima in the primary motor area (M1) and the primary somatosensory cortex (S1) were compared with those derived from non-smoothed risk map analysis, which is commonly used in presurgical applications. For each analysis, the Euclidean and geodesic distances between the correlation coefficients of local maxima derived from smoothed and non-smoothed EPI data were measured. The results show that the correlation coefficients derived from the volume- and surface-based analyses were about 29.4% and 42.9% higher for smoothed than for non-smoothed risk map analyses, and show minimum shifting of localizations by 12.1 mm and 6.9 mm on average in Euclidean distance, respectively, and about 9.5 mm and 5.7 mm on average in geodesic distance, respectively.

Potential vulnerability markers within the affective domain in subjects at genetic and clinical high risk for schizophrenia

BACKGROUND

Relative to ample high-risk studies on neurocognitive function, only a few high-risk studies have examined affective functioning components as possible vulnerability markers. In this study, we comprehensively assessed baseline affective functioning in subjects at clinical high risk (CHR) and genetic high risk (GHR) for schizophrenia, and healthy controls (HC), and compared the results to elucidate possible vulnerability markers in the affective domain.

METHODS

We studied 3 groups of subjects: those with CHR (n = 28) or GHR (n = 28) and a HC group (n = 24). Affective-process- and affective-content-related functioning were assessed using 5 emotion-related scales.

RESULTS

In affective process, CHR subjects showed impairments in emotional awareness and mood repair, with some trend of impaired emotional expressivity as well as aggression control relative to either HC or GHR subjects, whereas GHR subjects showed only a trend of impairment in mood repair. In affective content, CHR subjects had less positive and more negative affect scores than the other 2 groups.

CONCLUSIONS

These results correspond to previous findings of prodrome studies of schizophrenia and chronic schizophrenia and suggest that impaired mood repair and emotional awareness, as well as less positive and more negative affect may be potential candidates of vulnerability markers.

Neural correlates of cognitive inflexibility during task-switching in obsessive-compulsive disorder

A deficit in cognitive flexibility is acknowledged as a cognitive trait for obsessive-compulsive disorder (OCD). However, no investigations to date have used a cognitive activation paradigm to specify the neural correlates of this deficit in OCD. The objective of this study was to clarify how abnormal brain activities relate to cognitive inflexibility in OCD, using a task-switching paradigm. A task-switching paradigm which has two kinds of task-set was applied to 21 patients with OCD and 21 healthy subjects of matching age, IQ and sex, during an event-related functional magnetic resonance imaging experiment. Compared with the healthy subjects, patients with OCD exhibited a significantly higher error rate in task-switch trials (P < 0.05). Healthy controls showed significant activation in various areas, including dorsal frontal-striatal regions, during task-switching, whereas patients with OCD showed no activation in these areas. Significant differences were also observed in the dorsal frontal-striatal regions and ventromedial prefrontal and right orbitofrontal cortexes between patients with OCD and healthy controls. Correlation analysis indicated that the activations of orbitofrontal cortex were related with the performance in both groups and also with the activation of anterior cingulate cortex in the OCD group. These findings replicate previous studies of cognitive inflexibility in OCD and provide neural correlates related to a task-switching deficit in OCD. The results suggest that impaired task-switching ability in OCD patients might be associated with an imbalance in brain activation between dorsal and ventral frontal-striatal circuits.

Terahertz electromagnetic wave transmission through random arrays of single rectangular holes and slits in thin metallic sheets

We report on the observation of terahertz transparency in random arrays of the single rectangular holes and slits with the areal coverage of only 12%. The terahertz transparency occurs at the fundamental shape resonance of the rectangular holes and confirms the theoretical predictions of earlier works of García-Vidal et al. [Phys. Rev. Lett. 95, 103901 (2005)] on single rectangular holes and of Ruan and Qiu [Phys. Rev. Lett. 96, 233901 (2006)] on random arrays of holes.

Shape deformity of the corpus striatum in obsessive-compulsive disorder

Volumetric changes of striatal structures based on magnetic resonance imaging (MRI) have been inconsistent in patients with obsessive-compulsive disorder (OCD) due to methodological limitations. The purpose of this study was to investigate shape deformities of the corpus striatum in patients with OCD. We performed 3-D shape deformation analysis of the caudate nucleus, the putamen, and the globus pallidus in 36 patients with OCD and 36 healthy normal subjects. Shape analysis showed deformity of the striatal structures, especially the caudate nucleus. Outward deformities in the superior, anterior portion of the bilateral caudate were observed in patients with OCD. In addition, an outward deformity in the inferior, lateral portion of the left putamen was also detected. These results suggest that patients with OCD have shape deformities of the corpus striatum, especially the caudate nucleus, compared with healthy normal subjects, and that shape analysis may provide an important complement to volumetric MRI studies in investigating the pathophysiology of OCD.