TY - JOUR
T1 - Connectome harmonic decomposition tracks the presence of disconnected consciousness during ketamine-induced unresponsiveness
AU - Van Maldegem, Milan
AU - Vohryzek, Jakub
AU - Atasoy, Selen
AU - Alnagger, Naji
AU - Cardone, Paolo
AU - Bonhomme, Vincent
AU - Vanhaudenhuyse, Audrey
AU - Demertzi, Athena
AU - Jaquet, Oceane
AU - Bahri, Mohamed Ali
AU - Nunez, Pablo
AU - Kringelbach, Morten L.
AU - Stamatakis, Emmanuel A.
AU - Luppi, Andrea I.
N1 - Publisher Copyright:
© 2025 The Author(s)
PY - 2025/4
Y1 - 2025/4
N2 - Background: Ketamine, in doses suitable to induce anaesthesia in humans, gives rise to a unique state of unresponsiveness accompanied by vivid experiences and sensations, making it possible to disentangle the correlated but distinct concepts of conscious awareness and behavioural responsiveness. This distinction is often overlooked in the study of consciousness. Methods: The mathematical framework of connectome harmonic decomposition (CHD) was used to view functional magnetic resonance imaging (fMRI) signals during ketamine-induced unresponsiveness as distributed patterns across spatial scales. The connectome harmonic signature of this particular state was mapped onto signatures of other states of consciousness for comparison. Results: An increased prevalence of fine-grained connectome harmonics was found in fMRI signals obtained during ketamine-induced unresponsiveness, indicating higher granularity. After statistical assessment, the ketamine sedation harmonic signature showed alignment with signatures of LSD-induced (fixed effect =0.0113 [0.0099, 0.0127], P<0.001) or ketamine-induced (fixed effect =0.0087 [0.0071, 0.0103], P<0.001) psychedelic states, and misalignment with signatures seen in unconscious individuals owing to propofol sedation (fixed effect =–0.0213 [–0.0245, –0.0181], P<0.001) or brain injury (fixed effect =–0.0205 [–0.0234, –0.0178], P<0.001). Conclusions: The CHD framework, which only requires resting-state fMRI data and can be applied retrospectively, has the ability to track alterations in conscious awareness in the absence of behavioural responsiveness on a group level. This is possible because of ketamine's unique property of decoupling these two facets, and is important for consciousness and anaesthesia research.
AB - Background: Ketamine, in doses suitable to induce anaesthesia in humans, gives rise to a unique state of unresponsiveness accompanied by vivid experiences and sensations, making it possible to disentangle the correlated but distinct concepts of conscious awareness and behavioural responsiveness. This distinction is often overlooked in the study of consciousness. Methods: The mathematical framework of connectome harmonic decomposition (CHD) was used to view functional magnetic resonance imaging (fMRI) signals during ketamine-induced unresponsiveness as distributed patterns across spatial scales. The connectome harmonic signature of this particular state was mapped onto signatures of other states of consciousness for comparison. Results: An increased prevalence of fine-grained connectome harmonics was found in fMRI signals obtained during ketamine-induced unresponsiveness, indicating higher granularity. After statistical assessment, the ketamine sedation harmonic signature showed alignment with signatures of LSD-induced (fixed effect =0.0113 [0.0099, 0.0127], P<0.001) or ketamine-induced (fixed effect =0.0087 [0.0071, 0.0103], P<0.001) psychedelic states, and misalignment with signatures seen in unconscious individuals owing to propofol sedation (fixed effect =–0.0213 [–0.0245, –0.0181], P<0.001) or brain injury (fixed effect =–0.0205 [–0.0234, –0.0178], P<0.001). Conclusions: The CHD framework, which only requires resting-state fMRI data and can be applied retrospectively, has the ability to track alterations in conscious awareness in the absence of behavioural responsiveness on a group level. This is possible because of ketamine's unique property of decoupling these two facets, and is important for consciousness and anaesthesia research.
KW - connectome harmonics
KW - consciousness
KW - dissociative anaesthesia
KW - functional MRI
KW - ketamine dreams
KW - unresponsiveness
UR - http://www.scopus.com/inward/record.url?scp=85217417870&partnerID=8YFLogxK
U2 - 10.1016/j.bja.2024.12.036
DO - 10.1016/j.bja.2024.12.036
M3 - Journal article
C2 - 39933965
AN - SCOPUS:85217417870
SN - 0007-0912
VL - 134
SP - 1088
EP - 1104
JO - British Journal of Anaesthesia
JF - British Journal of Anaesthesia
IS - 4
ER -