A temporal sequence of thalamic activity unfolds at transitions in behavioral arousal state

Abstract

Awakening from sleep reflects a profound transformation in neural activity and behavior. The thalamus is a key controller of arousal state, but whether its diverse nuclei exhibit coordinated or distinct activity at transitions in behavioral arousal state is unknown. Using fast fMRI at ultra-high field (7 Tesla), we measured sub-second activity across thalamocortical networks and within nine thalamic nuclei to delineate these dynamics during spontaneous transitions in behavioral arousal state. We discovered a stereotyped sequence of activity across thalamic nuclei and cingulate cortex that preceded behavioral arousal after a period of inactivity, followed by widespread deactivation. These thalamic dynamics were linked to whether participants subsequently fell back into unresponsiveness, with unified thalamic activation reflecting maintenance of behavior. These results provide an outline of the complex interactions across thalamocortical circuits that orchestrate behavioral arousal state transitions, and additionally, demonstrate that fast fMRI can resolve sub-second subcortical dynamics in the human brain.

Cortico–subcortical spatiotemporal dynamics in Parkinson’s disease can be modulated by transcranial alternating current stimulation

“…Moreover, the connectivity between the thalamus and cortical sensory regions decreases with age [65]. In addition, the thalamocortical activity has demonstrated high spatiotemporal dynamics to flexibly change brain states [66] and plays a critical role in the regulation of adaptive sensory functions [67]. In the relationship between the thalamus and VN, visual deprivation disrupts the thalamocortical network in the visual-spatial integration task [68].…”

“…To flexibly adjust to changing environmental demands, the thalamus structurally and functionally connects to multiple cortical networks, forming different thalamocortical activity patterns [62, 63], even before birth [64]. Moreover, the connectivity between the thalamus and cortical sensory regions decreases with age [65]. In addition, the thalamocortical activity has demonstrated high spatiotemporal dynamics to flexibly change brain states [66] and plays a critical role in the regulation of adaptive sensory functions [67].…”

Resting-state fMRI signals contain spectral signatures of local hemodynamic response timing

“…Improvements in the temporal resolution of BOLD fMRI have also sparked interest in detecting neural sequences at subsecond timescales, which are highly relevant for many studies of cognition. Recent studies have leveraged fast fMRI to detect rapid sequences of neural events related to visual sequence detection (76), auditory dynamics (77), and changes in arousal state (22). As we continue to identify these rapid neural sequences, it will become even more crucial to consider how the hemodynamic response varies across regions to determine whether a given sequence represents regional differences in neuronal or in hemodynamic timing.…”

“…Advances in acquisition technology now allow high-resolution whole brain fMRI data to be acquired at fast (<500 ms) rates (14)(15)(16)(17)(18)(19), suggesting that fMRI could provide a unique tool to noninvasively track temporal sequences of neural activity (20) across the entire brain. Indeed, recent studies have revealed highly structured temporal dynamics using fMRI and suggest that fMRI can enable whole-brain mapping of temporal sequences (21)(22)(23)(24)(25). Furthermore, hemodynamic signals have been shown to contain more information about fast and high-frequency activity than previously thought (21,(26)(27)(28)(29).…”

Brain Connectivity Changes in Meditators and Novices during Yoga Nidra: A Novel fMRI Study

“…The supplementary motor area (SMA) and the postcentral gyrus (PCG) regions that are involved in motor planning and control are activated as expected as the instructions involve scanning of body parts. Other areas include the thalamus and brainstem, crucial for the relay of sensory and motor signals 50 . Activations in the anterior cingulate cortex (ACC) well-known for its role in both cognition and emotion is notable.…”