Study Identifies Consistent Brain Changes Across Primates Under Anesthesia
Researchers found that three different anaesthetics — propofol, sevoflurane, and isoflurane — produce similar large-scale changes in brain organisation in marmosets, consistent with patterns previously observed in humans and macaques. The study used functional MRI to show that anaesthesia constrains brain activity to follow underlying structural connectivity more rigidly and collapses the brain's principal functional gradient. These findings suggest there may be universal, drug-independent neural signatures of unconsciousness across primates, with implications for understanding consciousness itself.
A new preprint study published on bioRxiv examined how anaesthesia reshapes large-scale brain organisation in the common marmoset (Callithrix jacchus), a primate species increasingly used as a neuroscience model organism. Using functional MRI, researchers administered three anaesthetics — propofol, sevoflurane, and isoflurane — and found that all three caused brain activity to become increasingly constrained by the brain's underlying structural connectivity. Anaesthesia also induced a collapse of the brain's principal gradient, a key organisational axis of functional connectivity, alongside a breakdown of hierarchical integration across brain regions. These results replicate and extend prior findings from humans and macaques, suggesting the signatures are generalisable across primate species and anaesthetic agents. The convergence across drugs with distinct pharmacological mechanisms strengthens the case that these changes reflect a common neural basis of anaesthetic-induced unconsciousness rather than drug-specific effects. The findings contribute to the broader scientific effort to identify reliable neural correlates of consciousness.
What's missing
The study does not address whether the observed brain changes are specific to unconsciousness or could partly reflect other physiological effects of anaesthesia such as altered respiration or cardiovascular function. It also remains unclear whether these signatures can distinguish gradations of consciousness or predict behavioural responsiveness at the individual level.
What different sources said
- bioRxivCenter
The blueprint of human functional architecture shifts from cognition to anatomy during perturbations of consciousness
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