Capacity for consciousness under ketamine anaesthesia is selectively associated with activity in posteromedial cortex in rats
A. Arena, Bjørn E. Juel, R. Comolatti, S. Thon, J. Storm
Neuroscience of Consciousness 2022 DOI: 10.1093/nc/niac004 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational study Peer reviewed |
|---|---|
| Sample size | 6 |
| Population | Rats |
| Intervention | Ketamine anaesthesia |
| Dose | minimal dose needed to induce behavioural unresponsiveness and twice this dose |
| Topics | Esketamine Ketamine |
| Key findings | Activity in the posteromedial cortex correlates with the capacity for consciousness, as assessed by PCIST, during different depths of ketamine anaesthesia in rats, independently of behaviour. |
Abstract
Abstract It remains unclear how specific cortical regions contribute to the brain’s overall capacity for consciousness. Clarifying this could help distinguish between theories of consciousness. Here, we investigate the association between markers of regionally specific (de)activation and the brain’s overall capacity for consciousness. We recorded electroencephalographic responses to cortical electrical stimulation in six rats and computed Perturbational Complexity Index state-transition (PCIST), which has been extensively validated as an index of the capacity for consciousness in humans. We also estimated the balance between activation and inhibition of specific cortical areas with the ratio between high and low frequency power from spontaneous electroencephalographic activity at each electrode. We repeated these measurements during wakefulness, and during two levels of ketamine anaesthesia: with the minimal dose needed to induce behavioural unresponsiveness and twice this dose. We found that PCIST was only slightly reduced from wakefulness to light ketamine anaesthesia, but dropped significantly with deeper anaesthesia. The high-dose effect was selectively associated with reduced high frequency/low frequency ratio in the posteromedial cortex, which strongly correlated with PCIST. Conversely, behavioural unresponsiveness induced by light ketamine anaesthesia was associated with similar spectral changes in frontal, but not posterior cortical regions. Thus, activity in the posteromedial cortex correlates with the capacity for consciousness, as assessed by PCIST, during different depths of ketamine anaesthesia, in rats, independently of behaviour. These results are discussed in relation to different theories of consciousness.
Comparable studies
Other preclinical and animal studies on ketamine, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| mTOR-Dependent Synapse Formation Underlies the Rapid Antidepressant Effects of NMDA Antagonists Rats | 2010 | Observational study | |
| Activation of Glutamatergic Neurotransmission by Ketamine: A Novel Step in the Pathway from NMDA Receptor Blockade to Dopaminergic and Cognitive Disruptions Associated with the Prefrontal Cortex Conscious rats | 1997 | Dose-response study with microdialysis and behavioral testing | |
| NMDAR inhibition-independent antidepressant actions of ketamine metabolites Mice | 2016 | Preclinical study | |
| The dissociative anaesthetics, ketamine and phencyclidine, selectively reduce excitation of central mammalian neurones by N‐methyl‐aspartate Spinal neurons in decerebrate or pentobarbitone-anaesthetized cats and rats | 1983 | Experimental study | |
| R-ketamine: a rapid-onset and sustained antidepressant without psychotomimetic side effects Mice | 2015 | Experimental study |
Citations in the library
Cited by 7
- An integrative, multiscale view on neural theories of consciousness. Neuron May 15, 2024
- Exploring effects of anesthesia on complexity, differentiation, and integrated information in rat EEG. Neuroscience of Consciousness 2024
- Psilocybin for disorders of consciousness: A case-report study. Clinical Neurophysiology May 1, 2025
- Ketamine-Induced Unresponsiveness Shows a Harmonic Shift from Global to Localised Functional Organisation bioRxiv (Cold Spring Harbor Laboratory) June 25, 2024
- Effects of ketamine and propofol on muscarinic plateau potentials in rat neocortical pyramidal cells. PLoS One 2025
and 2 more in the library
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