Metabolic Activity of Red Nucleus and Its Correlation with Cerebral Cortex and Cerebellum: A Study Using a High-Resolution Semiconductor PET System

Abstract

The red nucleus (RN) is a pair of small gray matter structures located in the midbrain and involved in muscle movement and cognitive functions. This retrospective study aimed to investigate the metabolism of human RN and its correlation to other brain regions. Methods:We developed a high-resolution semiconductor PET system to image small brain structures. Twenty patients without neurologic disorders underwent whole-brain scanning after injection of 400 MBq of 18 F-FDG. The individual brain 18 F-FDG PET images were spatially normalized to generate a surface projection map using a 3-dimensional stereotactic surface projection technique. The correlation between the RN and each voxel on the cerebral and cerebellar cortices was estimated with Pearson product-moment correlation analysis. Results: Both right and left RNs were visualized with higher uptake than that in the background midbrain. The maximum standardized uptake values of RN were 7.64 ± 1.92; these were higher than the values for the dentate nucleus but lower than those for the caudate nucleus, putamen, and thalamus. The voxel-by-voxel analysis demonstrated that the right RN was correlated more with ipsilateral association cortices than contralateral cortices, whereas the left RN was equally correlated with ipsilateral and contralateral cortices. The left RN showed a stronger correlation with the motor cortices and cerebellum than the right RN did. Conclusion: Although nonspecific background activity around RNs might have influenced the correlation patterns, these metabolic relationships suggested that RN cooperates with association cortices and limbic areas to conduct higher brain functions. Ther ed nucleus (RN) is a pair of small gray matter structures located in the midbrain. The RN sends efferent axons to the contralateral spinal cord, forming a route known as the rubrospinal tract (1). The rubrospinal tract mainly controls limb musculature, whereas the pyramidal tract can act on the whole musculature (1). A recent anatomic study indicated that a significant amount of rubrospinal tract is present in the human brain (2). Because neuronal activity of the RN in Parkinson disease is known to be increased during passive and voluntary movements (3), the RN may play a role in the coordination of muscular movement. Cognitive symptoms, such as intellectual fatigability, decreased verbal fluency, and discrete memory impairment, have been reported in relation to RN infarction (4).Using 3-T MR imaging, Nioche et al. reported a cognitive role of the RN, probably related to salience detection and executive control (5). During the brain resting state, the RN displayed strong functional coherence with associative prefrontal, insular, temporal, and parietal cortices; the thalamus; and the hypothalamus but not with the sensorimotor cortex (5). 18 F-FDG PET has been used for correlational analyses of regional metabolic rates to characterize relations among different brain regions (6,7). In general, regional functional correlation of the resting brain can be better demonst...

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“…Functional neuroimaging studies suggest that the RN is functionally connected to brain areas related to WM, including prefrontal cortical areas (BA 45; BA 46; BA 47), the insula, the hippocampus (BA 11 and precuneus) and the occipital cortex [51]. In addition, a recent study [52] using high resolution PET showed very similar results to the study [51] and suggested that the right RN showed strong ipsilateral metabolic correlations with association cortices, while the left RN showed a more bilateral pattern of connectivity with the cerebral cortex [52]. These findings suggest that the RN shows strong connectivity with cortical areas that are either part of the “core” WM network [15] or had shown activity during visuospatial WM tasks, and several of them showed activity and connectivity effects in our healthy sample.…”

Corticospinal vs Rubrospinal Revisited: An Evolutionary Perspective for Sensorimotor Integration

“…It is known that the RN in humans receives afferents from the dentate nucleus of cerebellum and the cerebral cortex (Habas and Cabanis, 2007); however, new techniques like diffusion tensor imaging (DTI) provide anatomical information about several regions of the cerebral cortex that connect to the RN, including the prefrontal, sensorimotor, premotor lateral and medial prefrontal, and cingulate cortices. Also, the RN has anatomical connections to the thalamus, paracentral lobule, precentral gyrus, and superior frontal gyrus, and is less connected to the caudal middle frontal gyrus, inferior and superior parietal lobules, and middle temporal gyrus (Hirata et al, 2015;Milardi et al, 2016).…”

“…The human RN plays a critical role in motor control and is involved in the regulation of muscle tension, motor responses, motor learning, and sensory discrimination (Liu et al, 2000). Recently, it has been associated with cognitive functions related to salience detection, executive control (Hirata et al, 2015;Cacciola et al, 2019), and emotion processing (Zhang et al, 2015).…”

Dynamical Role of Pivotal Brain Regions in Parkinson Symptomatology Uncovered with Deep Learning

“…The Substantia Nigra (pars compacta) along with the nigrostriatal dopaminergic pathways are also likely compromised in PD [34]. Cognitive symptoms, such as intellectual fatigability, decreased verbal fluency, and discrete memory impairment, have been reported in relation to Red Nucleus deficits [35,36]. Finally, increased activity in the Subthalamic Nucleus activity was reported during decisions requiring high cognitive burden and when linking cognitive and motor processes [37].…”