Resting-state thalamic dysconnectivity in schizophrenia and relationships with symptoms.

BACKGROUND: Schizophrenia (SZ) is a severe neuropsychiatric disorder associated with disrupted connectivity within the thalamic-cortico-cerebellar network. Resting-state functional connectivity studies have reported thalamic hypoconnectivity with the cerebellum and prefrontal cortex as well as thalamic hyperconnectivity with sensory cortical regions in SZ patients compared with healthy comparison participants (HCs). However, fundamental questions remain regarding the clinical significance of these connectivity abnormalities. METHOD: Resting state seed-based functional connectivity was used to investigate thalamus to whole brain connectivity using multi-site data including 183 SZ patients and 178 matched HCs. Statistical significance was based on a voxel-level FWE-corrected height threshold of p < 0.001. The relationships between positive and negative symptoms of SZ and regions of the brain demonstrating group differences in thalamic connectivity were examined. RESULTS: HC and SZ participants both demonstrated widespread positive connectivity between the thalamus and cortical regions. Compared with HCs, SZ patients had reduced thalamic connectivity with bilateral cerebellum and anterior cingulate cortex. In contrast, SZ patients had greater thalamic connectivity with multiple sensory-motor regions, including bilateral pre- and post-central gyrus, middle/inferior occipital gyrus, and middle/superior temporal gyrus. Thalamus to middle temporal gyrus connectivity was positively correlated with hallucinations and delusions, while thalamus to cerebellar connectivity was negatively correlated with delusions and bizarre behavior. CONCLUSIONS: Thalamic hyperconnectivity with sensory regions and hypoconnectivity with cerebellar regions in combination with their relationship to clinical features of SZ suggest that thalamic dysconnectivity may be a core neurobiological feature of SZ that underpins positive symptoms.

Dynamic functional connectivity analysis reveals transient states of dysconnectivity in schizophrenia.

Schizophrenia is a psychotic disorder characterized by functional dysconnectivity or abnormal integration between distant brain regions. Recent functional imaging studies have implicated large-scale thalamo-cortical connectivity as being disrupted in patients. However, observed connectivity differences in schizophrenia have been inconsistent between studies, with reports of hyperconnectivity and hypoconnectivity between the same brain regions. Using resting state eyes-closed functional imaging and independent component analysis on a multi-site data that included 151 schizophrenia patients and 163 age- and gender matched healthy controls, we decomposed the functional brain data into 100 components and identified 47 as functionally relevant intrinsic connectivity networks. We subsequently evaluated group differences in functional network connectivity, both in a static sense, computed as the pairwise Pearson correlations between the full network time courses (5.4 minutes in length), and a dynamic sense, computed using sliding windows (44 s in length) and k-means clustering to characterize five discrete functional connectivity states. Static connectivity analysis revealed that compared to healthy controls, patients show significantly stronger connectivity, i.e., hyperconnectivity, between the thalamus and sensory networks (auditory, motor and visual), as well as reduced connectivity (hypoconnectivity) between sensory networks from all modalities. Dynamic analysis suggests that (1), on average, schizophrenia patients spend much less time than healthy controls in states typified by strong, large-scale connectivity, and (2), that abnormal connectivity patterns are more pronounced during these connectivity states. In particular, states exhibiting cortical-subcortical antagonism (anti-correlations) and strong positive connectivity between sensory networks are those that show the group differences of thalamic hyperconnectivity and sensory hypoconnectivity. Group differences are weak or absent during other connectivity states. Dynamic analysis also revealed hypoconnectivity between the putamen and sensory networks during the same states of thalamic hyperconnectivity; notably, this finding cannot be observed in the static connectivity analysis. Finally, in post-hoc analyses we observed that the relationships between sub-cortical low frequency power and connectivity with sensory networks is altered in patients, suggesting different functional interactions between sub-cortical nuclei and sensorimotor cortex during specific connectivity states. While important differences between patients with schizophrenia and healthy controls have been identified, one should interpret the results with caution given the history of medication in patients. Taken together, our results support and expand current knowledge regarding dysconnectivity in schizophrenia, and strongly advocate the use of dynamic analyses to better account for and understand functional connectivity differences.

Age-group differences in facets of positive and negative affect.

OBJECTIVES: The higher order structure of Positive Affect (PA) and Negative Affect (NA) is comparable in self-report affect data from younger and older adults. The current study advances this work by comparing the factor structure of facets of PA and NA in older and younger adults using exploratory and confirmatory factor analyses. METHOD: Older (N = 203; M age = 73.5 years, range 65-92) and younger (N = 349; M age = 19.1 years, range 18-30) adults completed the Positive and Negative Affect Schedule-Expanded Form (PANAS-X) (Watson, D., & Clark, L.A. (1999). Manual for the Positive and Negative Affect Schedule -- Expanded Form. Iowa City, IA: The University of Iowa), which measures General PA and NA as well as three facets of PA (Joviality, Self-Assurance, and Attentiveness) and four facets of NA (Fear, Sadness, Guilt, and Hostility). RESULTS: Item-level exploratory factor analyses of the facet scales revealed structures that were similar in older and younger adults; however, older adult solutions were more diffuse and diverged more from the PANAS-X scale structure. The facet of Sadness exhibited the largest age-group difference, relating more to guilt and anxiety in older than younger adults. CONCLUSION: Older adults may discriminate less amongst specific affect terms or may experience greater affective heterogeneity. Further, Sadness may manifest in age-specific ways. The construct variance of Sadness, and how this issue might be related to the assessment of depression in older adults, is discussed.

Evaluation of crude sesquiterpenoid extract of Phellinus fastuosus as a natural preservative.

It has been revealed that the use of synthetic food preservatives has variety of various side effects and hence search of safe and effective natural preservative has become a need. With the afore said objective the present study to screen the possibility of using sesquiterpenoid extract of local folk mushroom Phellinus fastuosus as food preservative was undertaken. Microbial growth inhibition by sesquiterpenoid extract of Phellinus was evaluated in the media with natural ingredient such as milk agar (MA), tomato juice agar (TJA), wheat flour agar (WFA) and pineapple juice agar (PAJA) with the composition with Phellinus extract, sodium benzoate and combinations. Three strains of bacteria and one strain of fungus were used astest organisms. The sesquiterpenoid extract of Phellinus at 0.02% concentration significantly inhibited the growth of all test organisms on natural media and the results were comparable with sodium benzoate. Similarly combination of Phellinus extract and sodium benzoate completely inhibited the growth of all microorganisms in all media, suggesting the possibility of using the Phellinus extract as food preservative.