Ketamine and sleep modulate neural complexity dynamics in cats.
Claudia Pascovich, Santiago Castro-Zaballa, Pedro A. M. Mediano, Daniel Bor, Andrés Canales-Johnson, Pablo Torterolo, Tristan A Bekinschtein
European Journal of Neuroscience March 1, 2022 DOI: 10.1111/ejn.15646 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational study Peer reviewed |
|---|---|
| Sample size | 5 |
| Population | Cats implanted with intracranial electrodes |
| Intervention | Ketamine |
| Dose | 5, 10, and 15 mg/kg i.m. |
| Topics | Ketamine Esketamine |
| Keywords | Cats Complexity Cortex Local field potential Psychedelics Sleep Thalamus |
| Citations | 16 |
| Key findings | LZ complexity was lowest in NREM sleep and followed an inverted U-shaped curve with increasing ketamine doses, primarily in prefrontal cortex. |
Abstract
There is increasing evidence that the level of consciousness can be captured by neural informational complexity: for instance, complexity, as measured by the Lempel Ziv (LZ) compression algorithm, decreases during anaesthesia and non-rapid eye movement (NREM) sleep in humans and rats, when compared with LZ in awake and REM sleep. In contrast, LZ is higher in humans under the effect of psychedelics, including subanaesthetic doses of ketamine. However, it is both unclear how this result would be modulated by varying ketamine doses, and whether it would extend to other species. Here, we studied LZ with and without auditory stimulation during wakefulness and different sleep stages in five cats implanted with intracranial electrodes, as well as under subanaesthetic doses of ketamine (5, 10, and 15 mg/kg i.m.). In line with previous results, LZ was lowest in NREM sleep, but similar in REM and wakefulness. Furthermore, we found an inverted U-shaped curve following different levels of ketamine doses in a subset of electrodes, primarily in prefrontal cortex. However, it is worth noting that the variability in the ketamine dose-response curve across cats and cortices was larger than that in the sleep-stage data, highlighting the differential local dynamics created by two different ways of modulating conscious state. These results replicate previous findings, both in humans and other species, demonstrating that neural complexity is highly sensitive to capture state changes between wake and sleep stages while adding a local cortical description. Finally, this study describes the differential effects of ketamine doses, replicating a rise in complexity for low doses, and further fall as doses approach anaesthetic levels in a differential manner depending on the cortex.
Comparable studies
Other observational and cohort studies on ketamine, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Taming the Ketamine Tiger Volunteers from a prison population | 2010 | Observational study | n = 20 |
| Increased spontaneous MEG signal diversity for psychoactive doses of ketamine, LSD and psilocybin Humans | 2017 | Observational study | |
| Disruption of Frontal–Parietal Communication by Ketamine, Propofol, and Sevoflurane Surgical patients undergoing induction of anesthesia with intravenous ketamine | 2013 | Observational cohort | n = 30 |
| Do the dissociative side effects of ketamine mediate its antidepressant effects? Treatment-resistant inpatients with major depressive disorder or bipolar disorder | 2014 | Observational cohort | n = 108 |
| Concomitant BDNF and sleep slow wave changes indicate ketamine-induced plasticity in major depressive disorder Patients with treatment-resistant major depressive disorder | 2012 | Observational cohort | n = 30 |
Citations in the library
Cited by 5
- Canalization and plasticity in psychopathology Neuropharmacology December 27, 2022
- Breathwork-induced psychedelic experiences modulate neural dynamics. Cerebral Cortex August 1, 2024
- Psychedelics and schizophrenia: Distinct alterations to Bayesian inference. Neuroimage November 1, 2022
- The entropic brain today Brain December 12, 2025
- A critical review of brain entropy as a biomarker of the psychedelic state. Neuroscience & Biobehavioral Reviews July 1, 2026
Cites 23
- 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 Journal of Neuroscience April 15, 1997
- A Theoretically Based Index of Consciousness Independent of Sensory Processing and Behavior Science Translational Medicine August 14, 2013
- The entropic brain: a theory of conscious states informed by neuroimaging research with psychedelic drugs Frontiers in Human Neuroscience 2014
- Ketamine and Ketamine Metabolite Pharmacology: Insights into Therapeutic Mechanisms Pharmacological Reviews June 26, 2018
- Increased spontaneous MEG signal diversity for psychoactive doses of ketamine, LSD and psilocybin Scientific Reports April 19, 2017
and 18 more in the library