Impaired thalamocortical connectivity in humans during general-anesthetic-induced unconsciousness

Sedation Depth During Spinal Anesthesia and the Development of Postoperative Delirium in Elderly Patients Undergoing Hip Fracture Repair

“…The thalamus is the gateway for sensory input, the abnormal processing of which may characterize the hyperarousal of the delirious state. 54 Moreover, the thalamus is thought to play an important role in anesthetic-induced loss of consciousness 55 ; intravenous and volatile anesthetics alter thalamic function, primarily through action at inhibitory g-aminobutyric acid-mediated synapses [56][57][58][59][60] ; and g-aminobutyric acid-mediated tone is reduced with aging. 61 Furthermore, brief exposures of thalamic neurons to propofol may have longer-lasting effects.…”

Cortical and Subcortical Connectivity Changes during Decreasing Levels of Consciousness in Humans: A Functional Magnetic Resonance Imaging Study using Propofol

“…Alternatively, reduced excitatory input to the thalamus from other sites may lead to the observation of reduced local blood flow and metabolism (Tononi and Edelman, 1998;White and Alkire, 2003). Tononi and Edelman propose that activation and deactivation of distributed neural populations in the thalamocortical system is probably not itself a sufficient basis for conscious experience unless activity of the relevant neuronal groups subserving that experience are rapidly and effectively integrated.…”

“…Recently, the picture has been further complicated by evidence from primates showing preservation of resting state networks, coherent system level neural oscillations, during isoflurane anesthesia (Biswal et al, 1995;Gusnard and Raichle, 2001;Vincent et al, 2007). In short, there is substantial evidence that rather than producing global suppression, anesthesia affects the function of discrete networks (White and Alkire, 2003;Laitio et al, 2007).…”

Stable and dynamic cortical electrophysiology of induction and emergence with propofol anesthesia

“…To date, positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies show that there is a complex interplay between and within the thalamus and the cortex. These studies demonstrate that the thalamus is a common site of deactivation during induction by various anesthetic agents (2,3), that there appears to be a disruption of thalamo-cortical and cortico-cortical connectivity (4,5), and that specific regions of association cortices show enhanced deactivation with certain anesthetics (6,7). In parallel with these dynamic interactions, there also appear to be physiologic elements that are invariant and do not change with the loss of consciousness from anesthesia (8,9).…”