Abstract
The paraventricular thalamic nucleus (PVT) is a small but highly connected nucleus of the dorsal midline thalamus. The PVT has garnered recent attention as a context-sensitive node within the thalamocortical arousal system that modulates state-dependent motivated behaviors. Once considered related to generalized arousal responses with non-specific impacts on behavior, accumulating evidence bolsters the contemporary view that discrete midline thalamic subnuclei belong to specialized corticolimbic and corticostriatal circuits related to attention, emotions, and cognition. However, the functional connectivity patterns of the human PVT have yet to be mapped. Here, we combined high-quality, high-resolution 7T and 3T resting state MRI data from 121 young adult participants from the Human Connectome Project (HCP) and thalamic subnuclei atlas masks to investigate resting state functional connectivity of the human PVT. The 7T results demonstrated extensive positive functional connectivity with the brainstem, midbrain, ventral and dorsal medial prefrontal cortex (mPFC), anterior and posterior cingulate, ventral striatum, hippocampus, and amygdala. These connections persist upon controlling for functional connectivity of the rest of the thalamus. Whole-brain contrasts provided further evidence that, compared to three nearby midline thalamic subnuclei, functional connectivity of the PVT is strong with the hippocampus, amygdala, ventral and dorsal mPFC, and middle temporal gyrus. These findings suggest that, even during rest, the human PVT is functionally coupled with many regions known to be structurally connected to rodent and non-human primate PVT. Further, cosine similarity analysis results suggested the PVT is integrated into the default mode network (DMN), an intrinsic connectivity network associated with episodic memory and self-referential thought. The current work provides a much-needed foundation for ongoing and future work examining the functional roles of the PVT in humans.
Highlights
The thalamus (Greek for ‘‘inner chamber’’) is well known for its role as a sensory and motor signal relay region
All participants had normal or corrected-to-normal vision. We limited this sample to adults under the age of 36 years, without anatomical anomalies or segmentation problems noted by the Human Connectome Project (HCP) or other known issues noted on the HCP Wiki page1 and with a completed Full NIH Toolbox Battery for optional assessment of neurological and behavioral functioning
The positive functional connectivity map overlapped with the multiple subnuclei of the hypothalamus, including Montreal Neurological Institute (MNI) coordinates corresponding to the lateral hypothalamic area, ventro- and dorsomedial hypothalamic nuclei, supraoptic nucleus, mammillary nucleus, and posterior hypothalamus (Baroncini et al, 2012)
Summary
The thalamus (Greek for ‘‘inner chamber’’) is well known for its role as a sensory and motor signal relay region. Decades of rodent and non-human primate literature have established the PVT as an important stress and reward-related node of the limbic network (Bubser and Deutch, 1999). The posterior PVT has recently been referred to as both a potential ‘‘stressmemory’’ center of the brain (Bhatnagar and Dallman, 1998; Bhatnagar et al, 2000; Fenoglio et al, 2006; Heydendael et al, 2011) and the whole nucleus as the ‘‘traffic light of motivated behaviors’’ (McGinty and Otis, 2020). Given its small size [e.g., ∼7 mm for left paraventricular nucleus (Krauth et al, 2010; Jo et al, 2019)], there is a dearth in our understanding of PVT function in the human brain
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