Jiri Horacek

• National Institute of Mental Health

Background Recent studies intensively explore psilocybin’s antidepressant potential, but variables like previous experience, repeated use, setting, and sex remain underexplored. This study examines acute and long-term effects of psilocybin in healthy individuals. Methods A double-blind, placebo-controlled, cross-over study included 40 healthy part...

Background/Objectives: Cancer- or chemotherapy-related cognitive deficit is a common side effect occurring in patients with Hodgkin lymphoma. No previous study compared the influence of different types of treatment on the onset and development of chemotherapy cognitive impairment in longitudinal design. The aim of this study was to assess whether a...

Background COVID-19 vaccine hesitancy (CVH) has become a critical public health issue, with attitudes toward vaccines emerging as a broader social issue. Public debates surrounding vaccines have expanded beyond health considerations to include issues of trust, misinformation, and societal values, making CVH a complex challenge that requires multifa...

UNSTRUCTURED People worldwide are currently confronted with a number of environmental and socio-political stressors, which act as a potent source of subjective uncertainty. The uncertainty arising in response to volatility and unpredictability of adversities is amplified by their (mis) representation in media news. While the causal effect of media...

People worldwide are confronted with environmental and sociopolitical stressors that act as potent sources of subjective uncertainty. The uncertainty arising in response to the volatility and unpredictability of adversities is amplified by their representation or misrepresentation in media news. While the causal effect of media news on vicarious tr...

In this study, we explore the intricate landscape of brain connectivity in the early stages of schizophrenia, focusing on the patterns of hyper- and hypoconnectivity. Despite existing literature’s support for altered functional connectivity (FC) in schizophrenia, inconsistencies and controversies persist regarding specific dysconnections. Leveragin...

Rationale: Mescaline is a classical psychedelic compound with a phenylethylamine structure that primarily acts on serotonin 5-HT2A/C receptors, but also binds to 5-HT1A and 5-HT2B receptors. Despite being the first psychedelic ever isolated and synthesized, the precise role of different serotonin receptor subtypes in its behavioral pharmacology is...

Background Recent studies have intensively explored the potential antidepressant effects of psilocybin. However, important variables such as previous experience, repeated administration, setting and sex remain underexplored. This study describes the acute psilocybin experience and long-term effects in a small sample of healthy individuals. Methods...

While one may be immediately captivated by visual artwork, the profound experience typically unfolds through intentional meaning-making over time. Contemporary neuro-cognitive models of aesthetic experience emphasize the role of reflection and knowledge assimilation. Studies on symbolic cultural forms like narratives in texts or movies highlight th...

BACKGROUND Detrimental effects of misinformation were observed during the COVID-19 pandemic. Presently, amid Russia’s military aggression in Ukraine, another wave of misinformation is spreading on the internet and impacting our daily lives, with many citizens and politicians embracing Russian propaganda narratives. Despite the lack of an objective...

Background Detrimental effects of misinformation were observed during the COVID-19 pandemic. Presently, amid Russia’s military aggression in Ukraine, another wave of misinformation is spreading on the web and impacting our daily lives, with many citizens and politicians embracing Russian propaganda narratives. Despite the lack of an objective conne...

The relationship between personality and brain activity has been an increasingly popular topic of neuroscientific research. However, the limitations of both personality measures and neu-roimaging, as well as methodological issues, continue to pose challenges to its understanding. The naturalistic viewing condition has been shown to enhance individu...

Schizophrenia (SCHZ) notably impacts various human perceptual modalities, including vision. Prior research has identified marked abnormalities in perceptual organization in SCHZ, predominantly attributed to deficits in bottom-up processing. Our study introduces a novel paradigm to differentiate the roles of top-down and bottom-up processes in visua...

Background The main aim of the present study is to determine the role of metabolites observed using proton magnetic resonance spectroscopy (1H-MRS) in obsessive-compulsive disorder (OCD). As the literature describing biochemical changes in OCD yields conflicting results, we focused on accurate metabolite quantification of total N-acetyl aspartate (...

Background: Cancer-related cognitive impairment (CRCI) is one of the most serious side effects of cancer that negatively impacts the quality of life of cancer patients and survivors. There is evidence of CRCI in Hodgkin lymphoma patients (HL); however, there is a lack of studies examining the presence of cognitive deficits before starting any treat...

Objectives NREM parasomnias also known as disorders of arousal (DOA) are characterised by abnormal motor and autonomic activation during arousals primarily from slow wave sleep. Dissociative state between sleep and wake is likely responsible for clinical symptoms of DOA. We therefore investigated potential dissociation outside of parasomnic events...

Background: Cancer-related cognitive impairment (CRCI) is one of the most serious side effects of cancer that negatively impact the quality of life of cancer patients and survivors. There is evidence of CRCI in Hodgkin lymphoma patients (HL); however, there is a lack of studies examining the presence of cognitive deficits before starting any treatm...

Introduction Psilocybin is one of the most extensively studied psychedelic drugs with a broad therapeutic potential. Despite the fact that its psychoactivity is mainly attributed to the agonism at 5-HT2A receptors, it has high binding affinity also to 5-HT2C and 5-HT1A receptors and indirectly modulates the dopaminergic system. Psilocybin and its a...

Psilocybin is investigated as a fast-acting antidepressant used in conjunction with psychotherapy. Intact cognitive functions, including memory, are one of the basic conditions of effective psychedelic-assisted therapy. While cognitive and memory processing is attenuated on various domains during psilocybin intoxication, the effect of psilocybin on...

Cancer treatment brings about a phenomenon not fully clarified yet, termed chemobrain. Its strong negative impact on patients' well‐being makes it a trending topic in current research, interconnecting many disciplines from clinical oncology to neuroscience. Clinical and animal studies have often reported elevated concentrations of proinflammatory c...

Introduction: N-2-methoxy-benzylated (“NBOMe”) analogues of phenethylamine are a group of new psychoactive substances (NPS) with reported strong psychedelic effects in sub-milligram doses linked to a number of severe intoxications, including fatal ones. In our present work, we provide a detailed investigation of pharmacokinetics and acute behaviour...

Chemotherapy-related cognitive impairment (CRCI) is a well-documented side effect of cancer treatment in various types of tumors including Hodgkin's lymphoma (HL). However, a longitudinal study evaluating the cognitive performance of HL patients has been completely lacking. The aim of the study was to determine the presence of CRCI in HL patients b...

Interval timing plays an essential role in various types of behavior including perception and production of music. However, subjectively perceived intervals may substantially differ from their objective durations. One of the phenomena, the filled duration illusion (FDI), is well described in the literature; however, there are still many questions t...

Sparse linear regression methods including the well-known LASSO and the Dantzig selector have become ubiquitous in the engineering practice, including in medical imaging. Among other tasks, they have been successfully applied for the estimation of neuronal activity from functional magnetic resonance data without prior knowledge of the stimulus or a...

Background Low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) diminishes auditory hallucinations (AHs). The aims of our study were a) to assess the efficacy of LF-rTMS in a randomized, sham-controlled double-blind alignment, b) to identify the electrophysiological changes accompanying the LF-rTMS, and c) to identify the influence...

The human brain represents a complex computational system, the function and structure of which may be measured using various neuroimaging techniques focusing on separate properties of the brain tissue and activity. We capture the organization of white matter fibers acquired by diffusion-weighted imaging using probabilistic diffusion tractography. B...

Psilocybin is a classical serotoninergic psychedelic that induces cognitive disruptions similar to psychosis. Gamma activity is affected in psychosis and is tightly related to cognitive processing. The 40 Hz auditory steady-state responses (ASSR) are frequently used as indicators to test the ability to generate gamma activity. Based on previous lit...

Functional connectivity analysis is a common approach to the characterization of brain function. While studies of functional connectivity have predominantly focused on resting‐state fMRI, naturalistic paradigms, such as movie watching, are increasingly being used. This ecologically valid, yet relatively unconstrained acquisition state has been show...

Graph-theoretical approaches are increasingly used to study the brain and may enhance our understanding of its asymmetries. In this paper, we hypothesize that the structure of the left hemisphere is, on average, more modular. To this end, we analyzed resting-state functional magnetic resonance imaging data of 90 healthy subjects. We computed functi...

Sparse linear regression methods including the well-known LASSO and the Dantzig selector have become ubiquitous in the engineering practice, including in medical imaging. Among other tasks, they have been successfully applied for the estimation of neuronal activity from functional magnetic resonance data without prior knowledge of the stimulus or a...

BACKGROUND Due to the COVID-19 pandemic, the Czech population experienced a second lockdown lasting for about half a year, restricting free movement, and imposing social isolation. It is not known whether the impact of the long lockdown resulted in habituation to the adverse situation or in the traumatization of the Czech population, and whether th...

Background: Due to the COVID-19 pandemic, the Czech population experienced a second lockdown lasting for about half a year, restricting free movement, and imposing social isolation. It is not known whether the impact of the long lockdown resulted in habituation to the adverse situation or in the traumatization of the Czech population, and whether...

The heritable component of schizophrenia (SCH) as a polygenic trait is represented by numerous variants from a heterogeneous group of genes each contributing a relatively small effect. Various SNPs have already been found and analyzed in genes encoding the NMDAR subunits. However, less is known about genetic variations of genes encoding the AMPA an...

Several studies suggest that EEG parameters, reflecting top-down processes in the brain, may predict cognitive performance, e.g. short-term memory (STM) capacity. According to Lisman and Idart’s model, STM capacity is predicted by theta and gamma EEG waves and their ratio. This model suggests that the more periods of gamma band waves fit into one p...

Increased frontal midline theta activity generated by the anterior cingulate cortex (ACC) is induced by conflict processing in the medial frontal cortex (MFC). There is evidence that theta band transcranial alternating current stimulation (θ-tACS) modulates ACC function and alters inhibitory control performance during neuromodulation. Multi-electri...

Objective Ketamine has been shown to be effective in treatment of episodes of major depressive disorder (MDD). This controlled study aimed to analyse the predictive and discriminative power of heart rate (HR) and heart rate variability (HRV) for ketamine treatment in MDD. Methods In 51 patients, HR and HRV were assessed at baseline before and duri...

Functional magnetic resonance imaging (fMRI) techniques and electroencephalography (EEG) were used to investigate sleep with a focus on impaired arousal mechanisms in disorders of arousal (DOAs). With a prevalence of 2–4% in adults, DOAs are significant disorders that are currently gaining attention among physicians. The paper describes a simultane...

Serotonergic agonist psilocybin is a psychedelic with antidepressant potential. Sleep may interact with psilocybin’s antidepressant properties like other antidepressant drugs via induction of neuroplasticity. The main aim of the study was to evaluate the effect of psilocybin on sleep architecture on the night after psilocybin administration. Regard...

One of the major neuropeptide groups in insects is adipokinetic hormone/red pigment-concentrating hormone (AKH/RPCH) family of peptides. AKH had improving effects on depression and anxiety in animal models and it may be a new treatment choice in these disorders. Aim of this study was to investigate effects of Anax imperator AKH (Ani-AKH), Libellula...

This study analyzes how people's attitudes to the European refugee crisis (ERC) correspond to selected psychological state and trait measures and impact the neural processing of media images of refugees. From a large pool of respondents, who filled in an online xenophobia questionnaire, we selected two groups (total N = 38) with the same socio-demo...

The rapid antidepressant effect of ketamine has become a breakthrough in the research and treatment of depression. Although predictive and modulating factors of the response to ketamine are broadly studied, little is known about optimal concurrent medication protocols. Concerning gamma-aminobutyric acid neurotransmission being a shared target for b...

Introduction: Deficits in neurocognitive mechanisms such as inhibition control and cognitive flexibility have been suggested to mediate the symptoms in obsessive–compulsive disorder (OCD). These mechanisms are proposedly controlled by the “affective” and “executive” orbitofronto-striato-thalamo-cortical (CSTC) circuits with well-documented morpholo...

Although the neurocognitive deficit is the best-recognized indicator of Alzheimer’s disease (AD), psychotic and other noncognitive symptoms are the prime cause of institutionalization. BACE1 is the rate-limiting enzyme in the production of Aβ of AD, and one of the promising therapeutic targets in countering the cognitive decline and amyloid patholo...

In the last years, there has been a considerable increase of research into the neuroimaging correlates of inter-individual temperament and character variability—an endeavour for which the term ‘personality neuroscience’ was coined. Among other neuroimaging modalities and approaches, substantial work focuses on functional connectivity in resting sta...

The approximate knowledge of the hemodynamic response to neuronal activity is widely used in statistical testing of effects of external stimulation, but has also been applied to estimate the neuronal activity directly from functional magnetic resonance data without knowing the stimulus timing. To this end, sparse linear regression methods have been...

Background: Cannabis, and specifically one of its active compounds delta-9-tetrahydrocannabinol in recreational doses, has a variety of effects on cognitive processes. Most studies employ resting state functional magnetic resonance imaging techniques to assess the stationary effects of cannabis and to-date one report addressed the impact of delta-...

Objective Previous studies have demonstrated the efficacy of reduction of prefrontal theta cordance (RC) after 1week of treatment in the prediction of antidepressant response. Our study aimed to compare the ability of RC in the prediction of response to various treatments. Methods In total, 167 inpatients with MDD were treated with various antidep...

Studies of consciousness have traditionally been based mainly upon the perceptual domains of consciousness. However, there is another side of consciousness, represented by various types of intrinsic conscious experiences. Even though intrinsic experiences can represent up to 50% of our conscious experiences, they are still largely neglected in cons...

Despite the substantial knowledge accumulated by past research, the exact mechanisms of the pathogenesis of schizophrenia and causal treatments still remain unclear. Deficits of cognition and information processing in schizophrenia are today often viewed as the primary and core symptoms of this devastating disorder. These deficits likely result fro...

The aim of the presented work was to develop a highly sensitive, accurate and rapid analytical method for the determination of concentration levels of tryptophan and its metabolites of kynurenine catabolic pathway, as well as neurotransmitters and their metabolites in complex biological matrices (brain tissue and blood plasma). The developed analyt...

Obsessive-compulsive disorder (OCD) is a chronic psychiatric illness and 1 of the most common anxiety disorders with the prevalence of 3%. Although its pathogenesis remains unclear, the traditional model focused on alternations in the serotonin system. Selective serotonin reuptake inhibitors provide the most effective treatment; however, as much as...

Objectives: To evaluate the coherence values of the cortical bands in patients with first episode schizophrenia and schizoaffective disorder during the performance of a mental arithmetic task. Method: We analysed EEG coherence in the resting state and subsequently while counting down from 200 in steps of 7 in 32 first episode schizophrenia patie...

Background The underlying symptomatology of obsessive–compulsive disorder (OCD) can be viewed as an impairment in both cognitive and behavioral inhibition, regarding difficult inhibition of obsessions and behavioral compulsions. Converging results from neuroimaging and electroencephalographic (EEG) studies have identified changes in activities thro...

The elusive relationship between the mental domain and the physical brain, known as the mind-body problem, is still a hot topic of discussion among philosophers and neuroscientists. Rather than solving this problem, our pilot study addresses the question as to whether personality features could influence intuitions of the mind-body problem, or more...

The current evidence of cognitive disturbances and brain alterations in schizophrenia does not provide the plausible explanation of the underlying mechanisms. Neuropsychological studies outlined the cognitive profile of patients with schizophrenia, that embodied the substantial disturbances in perceptual and motor processes, spatial functions, verb...

Aims: This study aimed to assess possible changes in functional connectivity (FC) of hippocampus and other brain regions involved in spatial navigation. Methods: Thirty-three healthy participants completed two resting state functional magnetic resonance (rsfMRI) measurements (3T Siemens Prisma scanner) at the baseline and after 3 months. For this...

This includes Supplementary Tables 1-3. Supplementary Table 1 represents a complete list of all significant left/right hippocampal FCs identified in the baseline TEST session and is supplementary to Table 1 (see Results: Resting State fMRI/Baseline Hippocampal FC). Supplementary Table 2 demonstrates the simple intervention effects in functional con...

The adipokinetic and red pigment‐concentrating hormone (AKH/RPCH) family of peptides controls fat, carbohydrate and protein metabolism in insects. In our previous study, we showed that AKH possesses antidepressant, anxiolytic, and analgesic effects, causes hyperlocomotion and exerts neuroprotective effects and increased brain neurotrophic factors i...

The regional distribution of white matter (WM) abnormalities in schizophrenia remains poorly understood, and reported disease effects on the brain vary widely between studies. In an effort to identify commonalities across studies, we perform what we believe is the first ever large-scale coordinated study of WM microstructural differences in schizop...

Infection during the prenatal or neonatal stages of life is considered one of the major risk factors for the development of mental diseases such as schizophrenia or autism. However, the impacts of such an immune challenge on adult behavior are still not clear. In our study, we used a model of early postnatal immune activation by the application of...

Objective Time-course of ketamine effect was assessed in depressive patients by QEEG to elucidate changes associated with treatment and to assess potential predictors of response. Methods The analysis was completed from data of two double-blind, cross-over, placebo-controlled studies, assessing the effect of ketamine infusion (0.54 mg/kg) in 51 in...

Background The auditory verbal hallucinations (AVH) prevalence among patients diagnosed with schizophrenia is more than 70% (Hugdahl et al, 2008). The brain mechanisms of AVH are not yet clarified. In the currect study, we explore the specific brain connections that are usually associated with perception and reception of the speech, being present i...

There is a vibrant debate about consequences of mobile devices on our cognitive capabilities. Use of technology guided navigation has been linked with poor spatial knowledge and wayfinding in both virtual and real world experiments. Our goal was to investigate how the attention people pay to the GPS aid influences their navigation performance. We d...

Rationale: Disruption of auditory event-related evoked potentials (ERPs) P300 and mismatch negativity (MMN), electrophysiological markers of attentive and pre-attentive cognitive processing, is repeatedly described in psychosis and schizophrenia. Similar findings were observed in a glutamatergic model of psychosis, but the role of serotonergic 5-H...

Introduction.-Studies in adults show that approximately 30-60% of individuals diagnosed with bipolar disorder (BD) retrospectively report the onset of their illness in childhood. Objectives.-To determine psychopathology, cognitive functions and identify early markers in EEG cortical sources, cortical connec-tivity and event-related potentials (ERPs...

In this review, we deal with two central questions of consciousness how and why, and we outline their possible future development. The question how refers to the empirical endeavor to reveal the neural correlates and mechanisms that form consciousness. On the other hand, the question why generally refers to the “hard problem” of consciousness, whic...

Chronic methamphetamine (METH) abuse has been shown to elicit strong neurotoxic effects. Yet, with an increasing number of children born to METH abusing mothers maturing into adulthood, one important question is how far do the neurotoxic effects of METH alter various neurotransmitter systems in the adult METH-exposed offspring. The purpose of this...

Rationale: Self-report studies indicate that cannabis could increase sexual desire in some users. We hypothesized that intoxication increases activation of brain areas responsive to visual erotica, which could be useful in the treatment of hypoactive sexual desire disorder, a condition marked by a lack of sexual desire. Objectives: The aim of th...

One of the biggest problems in automated diagnosis of psychiatric disorders from medical images is the lack of sufficiently large samples for training. Sample size is especially important in the case of highly heterogeneous disorders such as schizophrenia, where machine learning models built on relatively low numbers of subjects may suffer from poo...

Background: Latent toxoplasmosis, the life-long presence of dormant stages of Toxoplasma in immunoprivileged organs and of anamnestic IgG antibodies in blood, affects about 30% of humans. Infected subjects have an increased incidence of various disorders, including schizophrenia. Several studies, as well as the character of toxoplasmosis-associate...

Existing theories of empathic response to visual art works postulate the primacy of automatic embodied reaction to images based on mirror neuron mechanisms. Arguing for a more inclusive concept of empathy-related response and integrating four distinct bodies of literature, we discuss contextual, and personal factors which modulate empathic response...

OBJECTIVES The serotonergic hallucinogen psilocybin, has profound effects on the human mind, which can be characterized by alteration in perception, thinking disorder and strong emotional salience. The character of the altered state of consciousness induced by hallucinogens is hardly predictable; while an important role has the environment in which...

The endocannabinoid system (ECS), which is composed of the cannabinoid receptors types 1 and 2 (CB1 and CB2) for marijuana’s psychoactive ingredient Δ⁹-tetrahydrocannabinol (Δ⁹-THC), the endogenous ligands (AEA and 2-AG) and the enzymatic systems involved in their biosynthesis and degradation, recently emerged as important modulator of emotional an...

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder with 1–3% prevalence. OCD is characterized by recurrent thoughts (obsessions) and repetitive behaviors (compulsions). The pathophysiology of OCD remains unclear, stressing the importance of pre-clinical studies. The aim of this article is to critically review a proposed animal model...

Review paper highlights the connection between psyche and the body's immune defense mechanisms and summarizes new findings on the relations between nervous and immune systems. The article also briefly describes the outcome of authors' own original works on the relationship between infections and schizophrenia, and their notice about possible immuno...

Repetitive transcranial magnetic stimulation (rTMS) has been demonstrated to have efficacy in the treatment of unipolar depression but limited research has explored the efficacy of rTMS in bipolar depression. Therefore, we conducted a comparative clinical trial evaluating clinical responses to prefrontal bilateral and unilateral rTMS in patients su...