The structural connectivity mapping of the intralaminar thalamic nuclei

Abstract

The intralaminar nuclei of the thalamus play a pivotal role in awareness, conscious experience, arousal, sleep, vigilance, as well as in cognitive, sensory, and sexual processing. Nonetheless, in humans, little is known about the direct involvement of these nuclei in such multifaceted functions and their structural connections in the brain. Thus, examining the versatility of structural connectivity of the intralaminar nuclei with the rest of the brain seems reasonable. Herein, we attempt to show the direct structural connectivity of the intralaminar nuclei to diencephalic, mesencephalic, and cortical areas using probabilistic tracking of the diffusion data from the human connectome project. The intralaminar nuclei fiber distributions span a wide range of subcortical and cortical areas. Moreover, the central medial and parafascicular nucleus reveal similar connectivity to the temporal, visual, and frontal cortices with only slight variability. The central lateral nucleus displays a refined projection to the superior colliculus and fornix. The centromedian nucleus seems to be an essential component of the subcortical somatosensory system, as it mainly displays connectivity via the medial and superior cerebellar peduncle to the brainstem and the cerebellar lobules. The subparafascicular nucleus projects to the somatosensory processing areas. It is interesting to note that all intralaminar nuclei have connections to the brainstem. In brief, the structural connectivity of the intralaminar nuclei aligns with the structural core of various functional demands for arousal, emotion, cognition, sensory, vision, and motor processing. This study sheds light on our understanding of the structural connectivity of the intralaminar nuclei with cortical and subcortical structures, which is of great interest to a broader audience in clinical and neuroscience research.

Re-awakening the brain: Forcing transitions in disorders of consciousness by external in silico perturbation

“…This higher coupling and communication of the thalamus with other brain areas might explain the broadcasting of the local stimulation in the thalamus at the global level dynamics, as revealed in our results. Furthermore, published evidence indicates that the thalamus possesses distinctive nuclei characterized by different projection patterns, target cortical regions, and specialized functions [129][130][131]. This construct has been supported empirically, in which DBS in intralaminar nuclei reversed general anesthesia [132][133][134], anterior thalamus showed improvements in epilepsy patients [135,136]s and central thalamus regulated arousal levels in healthy non-human primates [137].…”

Distinct roles of two thalamostriatal systems in learning processes of visual discrimination in common marmosets

“…In addition, the thalamostriatal systems provide sparsely their axonal collaterals to some cortical areas in rodents, including the collaterals from the Pf to the frontal, motor, and insular cortical areas 61 and those from the CL to the motor cortex 62 . Structural connectivity analysis of the human brain reports the distribution of axonal collaterals originating from the CM/Pf complex to the somatosensory cortical areas 63 , although the distribution of collaterals in the marmoset brain has not yet been fully investigated. These collaterals may affect some behavioral responses, such as the acquisition or switching of sensory cue-dependent decision making we tested herein.…”

In-vivo parcellation of human subcortex by multi-modal MRI

“…These cortico-SGM circuits play crucial roles in brain function 24 and have been studied extensively in animal models using invasive techniques [25][26][27][28][29] . Very recently, thalamic nuclei-specific connectivity to cortical, subcortical, and brainstem sites were mapped using atlas-to-MRI registration of a microscopic stereotactic atlas 30 of the human thalamus 31 . Subnuclei of the thalamus 32 and amygdala 33 have been explored by manual delineation of histological scans combined with ex-vivo structural MRI.…”