There are at least two approaches to the definition of consciousness. In the first case, certain aspects of consciousness, called qualia, are considered inaccessible for research from a third person and can only be described through subjective experience. This approach is inextricably linked with the so-called "hard problem of consciousness", that is, the question of why consciousness has...
The evolution of intellectual capacities has brought forth a continuum of consciousness levels subserved by neuronal networks of varying complexity. Brain pathologies, neurodegenerative, and mental diseases affect conscious cognition and behavior. Although impairments in consciousness are among the most devastating consequences of neurological and mental diseases, valid and reliable animal...
Consciousness and its neural mechanisms remain a mystery. Current neuroscientific theories focus predominantly on the external input/stimulus and the associated stimulus-related activity during conscious contents. Despite all progress, we encounter two gaps: (i) a gap between spontaneous and stimulus-related activity; (ii) a gap between neuronal and phenomenal features. A novel, different, and...
Methods used in artificial intelligence (AI) overlap with methods used in computational psychiatry (CP). Hence, considerations from AI ethics are also relevant to ethical discussions of CP. Ethical issues include, among others, fairness and data ownership and protection. Apart from this, morally relevant issues also include potential transformative effects of applications of AI—for instance,...
Consciousness is supported by rich neuronal dynamics to orchestrate behaviors and conscious processing can be disrupted by general anesthetics. Previous studies suggested that dynamic reconfiguration of large-scale functional network is critical for learning and higher-order cognitive function. During altered states of consciousness, how brain functional networks are dynamically changed and...
Cannabis use disorder (CUD) has doubled in prevalence over the past decade as a nation-wide trend toward legalization allows for increased drug accessibility. As a result, marijuana has become the most commonly used illicit drug in the United States particularly among the adolescent population. This is especially concerning since there is greater risk for the harmful side effects of drug use...
(S)-ketamine has been approved as a rapid-acting antidepressant drug (RAAD). Although ketamine has an advantage over classic antidepressants (ADs) due to its rapid action, it remains a controversial drug due to its undesirable effects. Behavioral studies indicate that another enantiomer of ketamine, namely, (R)-ketamine, has been proposed as a safer but still effective RAAD. However, these...
Alcohol use disorder needs more effective treatments because relapse rates remain high. Psychedelics, such as ayahuasca, have been used to treat substance use disorders. Our study aimed to evaluate the effects of ayahuasca on ethanol-induced behavioral sensitization (EIBS). Swiss mice received 2.2 g/kg ethanol or saline IP injections every other day across nine days (D1, D3, D5, D7, and D9),...
Improved understanding of the neurophysiological and neurochemical mechanisms underlying schizophrenia is essential for the identification of biological markers and developing new therapeutic targets. The development of behaviorally faithful, predictive animal models is crucial to this endeavor. We have developed a novel two-hit paradigm designed to recapitulate in rodents the developmental...
Neural populations in the supramarginal gyrus (SMG) of the right hemisphere have been shown to be involved in processing the subjective experience of time, particularly because of their selectivity to specific temporal durations. To directly investigate this relationship, we applied high-frequency transcranial Random Noise Stimulation (hf-tRNS) on the right SMG during a duration judgment task:...
In addiction, apparently causally significant phenomena occur at a huge number of levels; addiction is affected by biomedical, neurological, pharmacological, clinical, social, and politico-legal factors, among many others. In such a complex, multifaceted field of inquiry, it seems very unlikely that all the many layers of explanation will prove amenable to any simple or straightforward,...
Psychedelic drugs acting as 5-hydroxyptryptamine 2A receptor (5-HT2AR) agonists have shown promise as viable treatments of psychiatric disorders, including obsessive-compulsive disorder. The marble burying test is a test of compulsive-like behavior in mice, and psychedelics acting as 5-HT2AR agonists can reduce digging in this test. We assessed the 5-HT2R contribution to the mechanisms of two...
Ayahuasca is a decoction with psychoactive properties, used for millennia for therapeutic and religious purposes by indigenous groups and the population of amazonian countries. As described in this narrative review, it is essentially constituted by β-carbolines and tryptamines, and it has therapeutic effects on behavioral disorders due to the inhibition of the monoamine oxidase enzyme and the...
Serotonin 2A (5-HT2A) receptors are the primary site of action of hallucinogenic drugs and the target of atypical antipsychotics. 5-HT2A receptors are also implicated in executive function, including behavioral flexibility. Previous studies showed that 5-HT2A receptor blockade improved behavioral flexibility in rodent models related to autism spectrum disorder and schizophrenia. The current...
Based on the evidence that meditation is associated with numerous beneficial effects on well-being and reduced stress-related symptoms, mindfulness-based techniques were increasingly implemented into psychotherapeutic programs. However, different meditation styles and the cross-sectional nature of most previous analyses resulted in a great variety of morphometric findings. The present study...
Esketamine was recently licensed by the US Food and Drug Administration (FDA) and European Drug Agency (EDA) for use in treatment resistant depression (TRD), and further research indicates ketamine as a possible treatment in other mental health conditions. While the underlying mechanisms remain unclear, it has been hypothesised that ketamine's acute psychoactive effects may be associated with...
Orexinergic neurons, which are closely associated with narcolepsy, regulate arousal and reward circuits through the activation of monoaminergic neurons. Psychostimulants as well as 5-HT-related compounds have potential in the treatment of human narcolepsy. Previous studies have demonstrated that orexin receptor antagonists as well as orexin deficiencies affect the pharmacological effects of...
Ketamine induces safe and effective anesthesia and displays unusual cataleptic properties that gave rise to the term dissociative anesthesia. Since 1970, clinicians only utilized the drug as an anesthetic or analgesic for decades, but ketamine was found to have rapid acting antidepressant effects in 1990s. Accumulated evidence exhibits NMDAR antagonism may not be the only mechanism of ketamine....
Ketamine, a dissociative anesthetic and psychedelic compound, has revolutionized the field of psychopharmacology by showing robust, and rapid-acting antidepressant activity in patients suffering from major depressive disorder (MDD), suicidal tendencies, and treatment-resistant depression (TRD). Ketamine’s efficacy, however, is transient, and patients must return to the clinic for repeated...
3,4-methylenedioxymethamphetamine (MDMA) recently achieved breakthrough status from the Food and Drug Administration (FDA) for post-traumatic stress disorder (PTSD). However, evidence indicates that exposure to toxic doses of 3,4-methylenedioxymethamphetamine (MDMA) can lead to long-lasting dysregulation of brain monoaminergic neurotransmitters, primarily from studies conducted in young adult...
Post-traumatic stress disorder (PTSD) is a chronic and disabling condition arising after exposure to a severe traumatic event, which affects approximately eight percent of the population. The underlying neurobiology of PTSD, however, has only been partially understood. The exploration of fear memory and its extinction has been the subject to increase our understanding of PTSD. Our previous...
Initiation of ketamine use often occurs in adolescence, yet little is known about long-term consequences when use begins in this developmental period. The current experiments were designed to examine the effects of repeated exposure to ketamine in adolescence on behavior in adulthood. We examined locomotor activity, as well as cognitive function, in animals that received repeated administration...
Discovering that the anesthetic drug ketamine has rapidly acting antidepressant effects in many individuals with major depression is one of the most important findings in clinical psychopharmacology in recent decades. The initial report of these effects in human subjects was based on a foundation of rodent preclinical studies carried out in the 1990s, and subsequent investigation has included...
Inflammatory bone markers may play a role in the antidepressant actions of (R)-ketamine in susceptible mice after chronic social defeat stress (CSDS). In this study, we compared the effects of (R)-ketamine and its final metabolite (2R,6R)-hydroxynorketamine (HNK) in depression-like phenotypes, inflammatory bone markers and bone mineral density (BMD) in CSDS susceptible mice. We measured plasma...
Schizophrenia is a debilitating neurodevelopmental disorder affecting 1% of the global population with heterogeneous symptoms including positive, negative, and cognitive. While treatment for positive symptoms exists, none have been developed to treat negative symptoms. Animal models of schizophrenia are required to test targeted treatments and since patients exhibit reduced effort (breakpoints)...