Hierarchy in disruption of large-scale networks across altered arousal states

Understanding how anaesthetics act within neural circuits to induce altered arousal states that range from sedation to general anaesthesia is an important question in neuroscience. Studies in laboratory animals demonstrate that anaesthetics including propofol, ether derivatives, and dexmedetomidine induce activity patterns in brainstem arousal nuclei that are similar to natural sleep.^1–3 However, anaesthetic drug action in brainstem arousal nuclei may provide only a partial answer to explain the behavioural and neurophysiological distinctions between anaesthesia-induced states and sleep, because anaesthetics also significantly modulate neuronal activity in other brain regions such as the thalamus and cortex.⁴⁵ Insights into how anaesthetics disrupt networks that sustain consciousness have been constrained by the practical and ethical challenges involved in noninvasively studying human brain activity. Guldenmund and colleagues⁶ used human neuroimaging to study large-scale network disruptions that are associated with dexmedetomidine and propofol sedation, two anaesthetic drugs with different receptor level targets.

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