Frequency Dependent Alterations in Regional Homogeneity of Baseline Brain Activity in Schizophrenia

Low frequency oscillations are essential in cognitive function impairment in schizophrenia. While functional connectivity can reveal the synchronization between distant brain regions, the regional abnormalities in task-independent baseline brain activity are less clear, especially in specific frequency bands. Here, we used a regional homogeneity (ReHo) method combined with resting-state functional magnetic resonance imaging to investigate low frequency spontaneous neural activity in the three different frequency bands (slow-5:0.01–0.027 Hz; slow-4:0.027–0.08 Hz; and typical band: 0.01–0.08 Hz) in 69 patients with schizophrenia and 62 healthy controls. Compared with controls, schizophrenia patients exhibited decreased ReHo in the precentral gyrus, middle occipital gyrus, and posterior insula, whereas increased ReHo in the medial prefrontal cortex and anterior insula. Significant differences in ReHo between the two bands were found in fusiform gyrus and superior frontal gyrus (slow-4> slow-5), and in basal ganglia, parahippocampus, and dorsal middle prefrontal gyrus (slow-5> slow-4). Importantly, we identified significant interaction between frequency bands and groups in the inferior occipital gyrus and caudate body. This study demonstrates that ReHo changes in schizophrenia are widespread and frequency dependent

The Changes of Cerebral Morphology Related to Aging in Taiwanese Population

<div><p>A cross-sectional study with the 3-dimensional (3D) MRI reconstruction technique was conducted to investigate cerebral complexity changes related to age differences in native Taiwanese population. In our sample of 85 participants aged between 25 and 81, age was associated with gradual ventricular expansion. A nonlinear quadratic relationship between white matter volume and age was found overall in the brain. Widespread age-related reduction in white matter was detected from late adulthood onwards. However, no significant age-related changes in the cortex and whole brain volume were determined throughout adulthood. These findings provided information in describing brain structural complexity, which might in the future serve as an objective diagnostic index or as a predictive parameter for neurological diseases. Our method then may be used for cross-cultural longitudinal studies to evaluate the effect of disease, environment and aging on the brain.</p> </div

Regression models.

a.<p>ref.: reference group.</p>b.<p>LRT: likelihood ratio test, for testing the non-linear the association between age and dependent variables.</p

Frequency-Specific Alternations in the Amplitude of Low-Frequency Fluctuations in Schizophrenia

Schizophrenia has been associated with abnormal task-related brain activation in sensory and motor regions as well as social cognition network. Recently, two studies investigated temporal correlation between resting-state functional magnetic resonance imaging (R-fMRI) low-frequency oscillations (LFOs) in schizophrenia but reported mixed results. This may be due to the different frequency bands used in these studies. Here we utilized R-fMRI to measure the amplitude of low-frequency fluctuations (ALFF) and fractional ALFF (fALFF) in three different frequency bands (slow-5: 0.01–0.027 Hz; slow-4: 0.027–0.08 Hz; and typical band: 0.01–0.08 Hz) in 69 patients with schizophrenia and 62 healthy controls. We showed that there were significant differences in ALFF/fALFF between the two bands (slow-5 and slow-4) in regions including basal ganglia, midbrain, and ventromedial prefrontal cortex. Importantly, we also identified significant interaction between frequency bands and groups in inferior occipital gyrus, precunus, and thalamus. The results suggest that the abnormalities of LFOs in schizophrenia is dependent on the frequency band and suggest that future studies should take the different frequency bands into account when measure intrinsic brain activity

Three-dimensional reconstruction neuroimages of brain at different structures (vertical view).

<p>Three-dimensional reconstruction neuroimages of brain at different structures (vertical view).</p

The relationship between age and average ventricle volume.

<p>The volume of ventricle  = 0.013× age²−0.74× age+7.23× sex+31.4; male  = 1, female  = 0.</p

The relationship between age and average white matter volume.

<p>The volume of white matter  = −0.09× age²+9.85× age+41.76× sex+152.56; male  = 1, female  = 0.</p

The relationship between age and average whole brain volume.

<p>The whole brain volume  = 1008.13+146.08× sex; male  = 1, female  = 0.</p

The main effect for frequency band on ReHo.

<p>Hot colors represent higher ReHo in the slow-4 band than in the slow-5 band, whereas blue cold colors represent lower ReHo. The results were obtained by a two-way repeated-measures ANOVA.</p