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Santiago Castro-Zaballa

Laboratorio de Neurobiología del Sueño, Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay. Electronic address: scastro@fmed.edu.uy.

4 papers in the library · 53 citations · publishing 2021-2025

Papers

EEG Gamma Band Alterations and REM-like Traits Underpin the Acute Effect of the Atypical Psychedelic Ibogaine in the Rat.

ACS pharmacology & translational science April 9, 2021 Joaquín González, Matias Cavelli, Santiago Castro-Zaballa et al. 26 citations

Ibogaine, a psychedelic alkaloid with anti-addictive potential, produces vivid, dream-like experiences while awake. Analyzing intracranial electroencephalograms in rats, ibogaine-induced wakefulness showed gamma oscillations with greater power than control levels but reduced coherence and complexity. This gamma activity profile resembled that of natural REM sleep, providing biological evidence linking the psychedelic state to REM sleep and advancing understanding of ibogaine's oneirogenic effects.

Ketamine and sleep modulate neural complexity dynamics in cats.

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.

Ketamine and sleep modulate neural complexity dynamics in cats

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.

Cortical high-frequency oscillations (≈ 110 Hz) in cats are state-dependent and enhanced by a subanesthetic dose of ketamine.

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.