Alteration of Red Nucleus Microstructure in Depressive Bipolar II Disorder and Unipolar Depression: A Diffusion Kurtosis and Perfusion Imaging Study

Abstract

The red nucleus is an important node of the prefrontal-thalamic-cerebellar circuit, which is related to both cognitive and affective functions. However, the structural and functional changes of the red nucleus in depressive bipolar II disorder (BD-II) or unipolar depression (UD) have rarely been studied. MethodsThirty-five patients with depressive BD-II, 29 patients with UD, and 40 healthy controls underwent diffusion kurtosis imaging (DKI) and three-dimensional arterial spin labeling (3D ASL). Region-of-interest analysis was performed to measure the mean kurtosis (MK), axial kurtosis (Ka), radial kurtosis (Kr), fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Da), radial diffusivity (Dr), and cerebral blood flow (CBF) in the red nucleus. Multivariate analysis of variance (MANOVA) with Bonferroni pairwise comparison tests was performed to compare the DKI parameters and CBF values of the ROIs among patients with depressive BD-II, patients with UD, and HCs, in the left and right red nucleus respectively; Pearson correlation coefficients were then used to assess whether the clinical variables for the patients correlated with their measured DKI or 3D ASL parameters. ResultsCompared with controls, patients with UD exhibited significantly decreased MK and Kr in the left red nucleus; patients with depressive BD-II exhibited significantly decreased MK in the right red nucleus. No significant changes were found in the remaining DKI/3D ASL parameters, and no significant correlations were revealed between the DKI/3D ASL parameters and clinical variables in patients with either depressive BD-II or UD. [29]. This sensitivity to gray matter may enhance examination of the microstructural integrity of the red nucleus. Since the introduction of DKI by Jensen et al. [33], it has shown promising preliminary results for several brain diseases, including temporal lobe epilepsy [34], Parkinson

Microstructural Alterations in Bipolar and Major Depressive Disorders: A Diffusion Kurtosis Imaging Study

“…Third, the findings of neuroimaging studies also suggest differences in cortical thickness, functional connectivity, and cerebral blood flow in the frontal, parietal, and temporal lobes between these two disorders . Three existing diffusion kurtosis imaging (DKI) studies also report lower axial kurtosis (AK) in the right putamen and higher mean diffusivity (MD) in the right caudate nucleus and superior cerebellar peduncle of BD patients than their MDD counterparts . There have also been diffusion tensor imaging (DTI) studies that report lower fractional anisotropy (FA) in the anterior cingulate, corpus callosum, uncinate fasciculus, corticospinal tract, and superior longitudinal fasciculus in BD than MDD .…”

“…As mentioned previously, the observations of the initial DKI studies are suggestive of microstructural differences between BD and MDD . Nevertheless, the existing DKI studies that attempted to identify or distinguish the microstructural alterations in BD and MDD are limited in number and fail to cover the whole brain (ie, the evaluation was limited to the gray matter nuclei and part of the cerebellum) . From the previous DTI and DKI reports of BD and MDD, these disorders can have different DKI characteristics in those areas still unexplored .…”

Stress-induced red nucleus attenuation induces anxiety-like behavior and lymph node CCL5 secretion

“…While multiple brain regions have previously been implicated in anxiety control, the need for anxiety-like behavior and inflammation in these sites remains an open question, based on the findings of electrical recordings 47 , retrograde tracing 48 , or functional imaging experiments 49 , the necessity of any of these sites for generating anxiety-like behavior and inflammation remains an open question. Here, we demonstrated that the red nucleus (RN), which was identified by PRV-based retrograde tracing from CLNs, constitutes a critical hub in the brain circuits that control anxiety-like behavior and inflammation.…”