The European journal of neuroscience
March 1, 2022
Claudia Pascovich, Santiago Castro-Zaballa, Pedro A M Mediano et al.
16 citations
Neural complexity, measured by the Lempel-Ziv (LZ) compression algorithm, is lowest during NREM sleep and similar during REM sleep and wakefulness in cats with intracranial electrodes. Under subanaesthetic doses of ketamine (5, 10, and 15 mg/kg), complexity follows an inverted U-shaped curve in some electrodes, primarily in prefrontal cortex, rising at low doses and falling as doses approach anaesthetic levels. The variability in the ketamine dose-response curve across cats and cortices was larger than across sleep stages, highlighting differential local dynamics. These results replicate findings in humans and other species, showing neural complexity is sensitive to changes in conscious state.
bioRxiv Preprint Server
June 25, 2021
Claudia Pascovich, Santiago Castro-Zaballa, Pedro A.M. Mediano et al.
7 citations
preprint
Neural complexity, measured by the Lempel-Ziv compression algorithm, is lowest during NREM sleep and similar during REM sleep and wakefulness in cats with intracranial electrodes. Under subanesthetic doses of ketamine (5, 10, and 15 mg/kg), complexity follows an inverted U-shaped curve in some electrodes, especially in prefrontal cortex, rising at low doses and falling as doses approach anesthetic levels. Variability in the ketamine dose-response across cats and cortices is larger than sleep-stage differences, revealing distinct local dynamics. These results replicate findings in humans and other species, showing neural complexity is sensitive to conscious state changes and dose-dependent ketamine effects.
Behavioural brain research
January 5, 2025
Santiago Castro-Zaballa, Joaquín González, Matías Cavelli et al.
4 citations
In cats, high-frequency oscillations (HFO, >100 Hz) in the brain's electrical activity are linked to breathing during wakefulness but not during sleep. A sub-anesthetic dose of ketamine increases the power of these HFO, and they remain tied to the inhalation phase of respiration. The enhanced HFO appear to originate in the olfactory bulb and travel to the prefrontal cortex. Blocking the nostrils reduces the ketamine-enhanced HFO in both regions. Auditory stimulation does not affect these oscillations. The findings suggest that ketamine's enhancement of respiration-coupled HFO may disrupt cortical information processing, potentially contributing to its neuropsychiatric effects.
Journal of cognitive neuroscience
May 27, 2026
Alejandro Chandia-Jorquera, Sean D van Mil, Mar Estarellas et al.
3 citations
Pure awareness, a state of minimal phenomenal experience, can be reliably studied through transcendental meditation. In 33 experienced TM practitioners compared to controls doing mental counting, TM produced significantly greater intensity and temporal variability of pure awareness, unrelated to years of practice. Using EEG and multivariate classification, a double dissociation emerged: temporal entropy and aperiodic dynamics best distinguished TM from counting, while low-frequency functional connectivity best distinguished TM from its own baseline. These differences reflected distributed neural patterns, not localized effects. TM showed little carryover into rest, unlike counting. The findings characterize pure awareness electrophysiologically and support neurophenomenology as a framework for studying minimal experience.