Filip Tyls

Filip Tyls

Filip Tyls

Filip Tylš (1985, Praha) je psychiatr a neurovědec působící v Národním Ústavu Duševního Zdraví (Klecany), kde se věnuje výzkumu účinků psychedelických látek. Absolvoval 1.LF UK (2012, MUDr.) a získal specializaci v elektroenefalografii (EEG, 2013), od roku 2014 je frekventantem výcviku v Gestalt psychoterapii (terapie zaměřená na přítomný okamžik) a příležitostně učí na 3.LF UK. Je zakládajícím členem České Psychedelické společnosti (CZEPS, 2015). Jeho hlavní vědecký zájem je studium neurobiologie změněných stavu vědomí vyvolaných psychedeliky, jejich terapeutického i seberozvojového využití. V rámci doktorandského studia na 3. LF UK se věnuje translačním farmakologicky indukovaným modelům akutní psychozy a neurobiologii změněného stavu vědomí. Studuje fenomenologické koreláty intoxikace a také vliv psychedelických látek na EEG aktivitu mozku. Je součástí řešitelského týmu pilotní studie podávání psilocybinu lidským subjektům (psychedelický sitter). Je autorem několika tuzemských a zahraničních publikací (např. přehledová práce Psilocybin – summary of knowledge) a populárně-vědeckých textů.


TITLE (POSTER): Psilocybin-induced psychosis in humans and in rats – Translational quantitative EEG study

Introduction
Psilocybin and its active metabolite psilocin are classical tryptamine hallucinogens. The neurochemical basis of their effects is related to the stimulation of serotonin 5-HT1A a 5-HT2A/C receptors. Intoxication induces significant alterations in perception, thought disturbance and emotional processing – effects that mimic psychotic symptoms. Although these symptoms are only partially transferable to rats, the brain activity assessed by quantitative EEG (QEEG) has translational validity. The objective of the study was to compare changes in QEEG induced by psilocybin during the resting state in humans and by psilocin during behavioral inactivity in freely moving rats.

Methods
In a double blind placebo-controlled design, 20 healthy volunteers were administered an oral dose of psilocybin (0,26 mg/kg) and were subjected to resting-state EEG recordings at baseline and at the intoxication peak (90 minutes after ingestion). The effect of intoxication was evaluated on EEG power spectra, coherence and on current density using sLORETA (standardized low-resolution brain electromagnetic tomography). In the animal part of the study, we measured quantitative EEG in freely moving rats after administration of psilocin. 14 electrodes (12 active)were stereotactically implanted to the surface of the rats’ cor¬tex and were fixed to the rat’s skull with dental cement. Behavioral activity was co-registered along with the EEG. Only signals corresponding to inactivity were used in the fur¬ther analysis. Data was transformed by Fast Fourier Transformation (FFT) and spectral and coherence analyses were performed.

Results
Psilocybin in humans induced a decrement in relative alpha spectral power and strongly increased high beta and gamma power. LORETA localized the alpha decrease to the occipital lobe and posterior midline structures, while the increases in fast activity were most pronounced in large fronto-temporo-occipital areas. Furthermore, decreased EEG coherences in theta, alpha and beta bands were observed, mainly between the frontal and temporal areas. Psilocin in rats decreased the relative spectral power in theta band and caused increases in higher frequencies (beta and gamma) in rats. A broadband decrement in EEG coherences was observed with the most significant changes observable in lower frequencies.

Discussion
The decrement of basic alpha activity in posterior midline structures in humans after psilocybin administration are related to a characteristic feature of altered states of consciousness – the transformative experience of ego-dissolution.  The strong activation of large association brain areas (increase in gamma) might be an underlying process of perceptual and cognitive changes. Disconnection is one of the core neurobiological features underlying psychosis. Both animal and human data showed several parallels – a decrease in basic brain activity (alpha in human, theta in rats) and disconnection of long projections. Therefore our results confirmed the translational validity of animal EEG during behavioral inactivity and resting state EEG in humans.