Voxel-based morphometry is a method for detecting group differences in the density or volume of brain matter. The authors reviewed the literature on use of voxel-based morphometry in schizophrenia imaging research to examine the capabilities of this method for clearly identifying specific structural differences in patients with schizophrenia, compared with healthy subjects. The authors looked for consistently reported results of relative deficits in gray and white matter in schizophrenia and evaluated voxel-based morphometry methods in order to propose a future strategy for using voxel-based morphometry in schizophrenia research.
The authors reviewed all voxel-based morphometry studies of schizophrenia that were published to May 2004 (15 studies). The studies included a total of 390 patients with a diagnosis of schizophrenia and 364 healthy volunteers.
Gray and white matter deficits in patients with schizophrenia, relative to healthy comparison subjects, were reported in a total of 50 brain regions. Deficits were reported in two of the 50 regions in more than 50% of the studies and in nine of the 50 regions in one study only. The most consistent findings were of relative deficits in the left superior temporal gyrus and the left medial temporal lobe. Use of a smaller smoothing kernel (4-8 mm) led to detection of a greater number of regions implicated in schizophrenia.
This review implicates the left superior temporal gyrus and the left medial temporal lobe as key regions of structural difference in patients with schizophrenia, compared to healthy subjects. The diversity of regions reported in voxel-based morphometry studies is in part related to the choice of variables in the automated process, such as smoothing kernel size and linear versus affine transformation, as well as to differences in patient groups. Voxel-based morphometry can be used as an exploratory whole-brain approach to identify abnormal brain regions in schizophrenia, which should then be validated by using region-of-interest analyses.
"In modulated images, the total volume of gray matter is the same as in the original images as modulation scales by the same amount of expansion or contraction that is applied during normalization. The modulated gray matter volumes were smoothed with a Gaussian kernel of 8 mm full width at half maximum (FWHM), which is the optimal kernel for detecting morphometric differences in small as well as larger neural structures (Honea et al., 2005; White et al., 2001). No outliers were identified via a homogeneity check, thus the normalized, modulated, and smoothed gray matter segments of all 125 subjects were included in the statistical analyses. "
"While the handful of previous fMRI studies of facial emotion perception in relatives did not report abnormalities in these regions, an fMRI study of language processing in schizophrenia and relatives reported reduced fusiform activation in both groups compared to controls (Li et al., 2007). Moreover, structural MRI studies indicate that both patients (Honea et al., 2005) and relatives (Goghari et al., 2011) have reduced fusiform grey matter volumes, particularly for the left hemisphere. Our finding of left hemisphere hypoactivation converges with these findings, and provides additional evidence that temporo-occipital lobe abnormalities in schizophrenia are associated with the genetic liability to the disorder. "
"In addition, not only do the current results agree with that of prior research in finding deficiencies in facial expressions of emotion specific to negative emotions in schizophrenia, but there is evidence of the brain-based nature of this deficit. Neuroanatomical anomalies are consistently reported in schizophrenia, and some of the more focal neuroanatomical anomalies tend to occur in frontal and temporal structures (Honea et al., 2005; Torres et al., 2013) implicated in facial emotion recognition (Nakamura et al., 2014), and deficient facial emotion recognition in schizophrenia has been linked to anomalous activation of these areas (Baird et al., 1999). While the nature of these findings may vary with disorder subtype (Pinkham et al., 2015), several studies have found hypoactivation specifically in response to the negatively valenced emotions (Ji et al., 2015; Phillips et al., 1999) measured behaviorally in the current study. "
[Show abstract][Hide abstract] ABSTRACT: Facial emotion recognition has been found to be impaired in schizophrenia, although overall results have been inconclusive. A new set of facial emotion stimuli with Chinese faces was developed, using static and dynamic avatars, the identification of which were subsequently validated in 562 healthy control subjects. This test was then used to identify facial emotion recognition accuracy in 44 patients with schizophrenia and 41 healthy controls. Overall, patients identified facial emotions significantly worse than healthy controls (p = 0.018) with a significant main effect for type of emotion (p = 0.016). Patients performed significantly worse in fear (p = 0.029) and sadness (p = 0.037), and marginally worse in anger (p = 0.052). No significant differences were evident in contempt (p = 0.254) or happiness (p = 0.943). Regarding error rates of misattribution, patients overidentified contempt (p = 0.035) and sadness (p = 0.01), but not anger, fear, or happiness. Conclusion, patients of Chinese ethnicity with schizophrenia may have significantly greater difficulties identifying negative, but not positive emotions.
The Journal of nervous and mental disease 07/2015; 203(9). DOI:10.1097/NMD.0000000000000358 · 1.69 Impact Factor
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