Processing of sensory, painful and vestibular stimuli in the thalamus

Abstract

Objectives The thalamus plays an important role in the mediation and integration of various stimuli (e.g., somatosensory, pain, and vestibular). Whether a stimulus-specific and topographic organization of the thalamic nuclei exists is still unknown. The aim of our study was to define a functional, in vivo map of multimodal sensory processing within the human thalamus. Methods Twenty healthy individuals (10 women, 21–34 years old) participated. Defined sensory stimuli were applied to both hands (innocuous touch, mechanical pain, and heat pain) and the vestibular organ (galvanic stimulation) during 3 T functional MRI. Results Bilateral thalamic activations could be detected for touch, mechanical pain, and vestibular stimulation within the left medio-dorsal and right anterior thalamus. Heat pain did not lead to thalamic activation at all. Stimuli applied to the left body side resulted in stronger activation patterns. Comparing an early with a late stimulation interval, the mentioned activation patterns were far more pronounced within the early stimulation interval. Conclusions The right anterior and ventral-anterior nucleus and the left medio-dorsal nucleus appear to be important for the processing of multimodal sensory information. In addition, galvanic stimulation is processed more laterally compared to mechanical pain. The observed changes in activity within the thalamic nuclei depending on the stimulation interval suggest that the stimuli are processed in a thalamic network rather than a distinct nucleus. In particular, the vestibular network within the thalamus recruits bilateral nuclei, rendering the thalamus an important integrative structure for vestibular function.

Simultaneous cortical, subcortical, and brainstem mapping of sensory activation

“…While right-foot activity aligned with the VPL when compared to the Saranathan thalamic atlas (Saranathan et al 2021), right-hand and left-hand activity were medial to the VPL, aligning more closely with the pulvinar region (Figure 2, Figure 3). Though not expected based on our knowledge of the dorsal column pathway, this finding does align with previous studies that observed pulvinar involvement during non-painful sensory processing (Golaszewski et al 2006;Charyasz et al 2023;Habig et al 2023). In a study of hand and foot motor activity, Errante and colleagues (2023) also saw that hand activity was medial to foot activity and had more pulvinar involvement, consistent with our results.…”

“…The thalamus and cerebellum have also been independently studied. In the thalamus, the ventral posterolateral nucleus has been linked to processing of tactile stimuli (Gilman 2002; Charyasz et al 2023; Habig et al 2023). In the cerebellum, upper and lower extremity movements have been observed to activate lobules V/VI/VIIIa/VIIIb and I-IV/V/VIIIb/XI, respectively (Grodd et al 2001; Ashida et al 2019).…”

Changes of cerebral functional connectivity induced by foot reflexology in a RCT

“…Similarly, only the contralateral part of the supplementary motor area (SMA) was affected—the SMA responding both to motor and sensory tasks 32 . Concerning the connectivity with the left thalamus, which is implicated in motor and sensory features, a study have demonstrated that stimuli applied to the left side of the body led to responses in some left and right nuclei of the thalamus 33 .…”

Electrical stimulation of the peripheral and central vestibular system

“…In addition, imaging studies have shown that GVS activates regions of the cerebellum, thalamus, and cortical areas (i.e. PIVC, 3aV, and 2v) associated with self-motion processing [7 ▪▪ ,50 ▪ ,51,52 ▪ ,53]. Interestingly, bilateral vestibulopathy patients demonstrate reduced resting state brain activity in several of these core cortical vestibular regions, that can be increased via GVS (Fig.…”

“…The central vestibular network described above [7 ▪▪ ,50 ▪ ,51,52 ▪ ,53] has been revealed by neuroimaging studies contrasting BOLD signal during GVS with various control conditions. Complementary to this approach, iEBS can disrupt neural activity within specific nodes of the central vestibular pathways.…”