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| Aldous Huxley's "cerebral reducing valve." On the 'inlet' (right) side of the cerebral reducing valve is a vast ocean of all possible perceptual, emotional, and cognitive experiences. On the 'outlet' (left) side is our moment-to-moment stream of experience in normal waking life. Mechanisms inside the valve 'reduce' the character and contents of experience, 'canalizing' the ocean of possible experience into a more limited stream of waking consciousness aimed at maximum biological utility.
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How do psychedelic drugs produce their characteristic range of acute effects in perception, emotion, cognition, and sense of self? How do these effects relate to the clinical efficacy of psychedelic-assisted therapies? Efforts to understand psychedelic phenomena date back more than a century in Western science. In this article I review theories of...
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Context 1
... letter can help unpack the intended 'mind- manifesting' etymology of Osmond's new term psychedelic. Huxley saw the biological function of the brain as a "device" engaged in a continuous process of elimination and inhibition to sustain the "normal self " of everyday waking experience to maximize adaptive fit. Huxley's choice metaphor for visualizing this was the cerebral reducing valve (Figure ...
Similar publications
While psychedelics may have therapeutic potential for treating mental health disorders such as depression, further research is needed to better understand their biological effects and mechanisms of action when considering the development of future novel therapy approaches. Psychedelic research could potentially benefit from the integration of metab...
Background: Microdosing psychedelics – the practice of taking small, sub-hallucinogenic doses of substances like LSD or psilocybin-containing mushrooms – is becoming increasingly popular. Despite its surging popularity, little is known about the effects of this practice. Aims: This research had three main aims. First, we attempted to replicate prev...
Background
While cannabis has a long history of spiritual use, its normalization in Western societies during the last decades has led to more recreational use. This study aimed to explore the characteristics of spiritual cannabis use as compared to recreational use and to the use of psychedelics such as LSD and psilocybin.
Methods
The study employ...
Psilocybin shows efficacy to alleviate depression in human clinical trials for six or more months after only one or two treatments. Another hallucinogenic drug, esketamine, has recently been U.S. Food and Drug Administration (FDA)-approved as a rapid-acting antidepressant. The mechanistic basis for the antidepressant effects of psilocybin and ketam...
Psychedelics like lysergic acid diethylamide (LSD) and psilocybin offer a powerful window into the function of the human brain and mind, by temporarily altering subjective experience through their neurochemical effects. The RElaxed Beliefs Under Psychedelics (REBUS) model postulates that 5-HT2a receptor agonism allows the brain to explore its dynam...
Citations
... From today's perspective, this therapeutic factor can be extended towards not only the primary family group and the individuals' unconscious inner systems of tension or COEX systems (systems of condensed experience) (Grof, 2000), but also to any other autobiographical memories of relational nature. This could be part of the general phenomenon that psychedelics disrupt psychological habits, fixed cognitions and other constraints or 'priors' which limit one's thinking (Carhart-Harris and Friston, 2019;Swanson, 2018). Patients may gain an increased awareness of avoidance tendencies in difficult social situations (Gasser et al., 2015), potentially allowing them to process frightening stimuli in a relatively unconstrained mind (Frecska, 2011), yet still within the supportive framework provided by other group members and therapists. ...
We argue that combining psychedelic substances and group psychotherapy may prove beneficial for increasing group connectedness and interpersonal learning, potentially enhancing prosocial behaviour with direct opportunities to practice newly acquired knowledge about previously maladaptive behavioural patterns. Challenges regarding this approach include a more rigid therapy structure and potential loss of openness from patients, which may be ameliorated by adequate therapeutic training.
... Some researchers have interpreted neurological VHs as resulting from overly strong perceptual predictions which overwhelm sensory prediction error signals (O'Callaghan et al., 2017;Powers et al., 2016). Others have focused on psychedelic VHs and adopted a hierarchical perspective, suggesting that psychedelic hallucinations occur due to a relaxation of high-level perceptual predictions (or Bayesian 'priors'), which has the effect of increasing the influence of bottom-up signalling on perceptual inference (Alonso et al., 2015;Carhart-Harris & Friston, 2019;Swanson, 2018;Timmermann et al., 2018). However, despite accumulating empirical evidence linking perceptual experience to inference and prediction error minimization in both normal (Hardstone et al., 2021) and hallucinatory (Carhart-Harris & Friston 2019;Powers et al., 2016;Schartner & Timmermann, 2020) perception, the computational basis of phenomenological differences between different kinds of VH has remained unclear. ...
... Spontaneous VHs, therefore, correspond closely to the folk-psychological idea of hallucination as perception in the absence of sensory stimulation. In contrast, anecdotal reports of psychedelic complex VHs describe them as frequently being driven by visual 'seeds' from within a perceived scene, bearing similarity to the everyday phenomenon of 'pareidolia' -or 'seeing patterns in noise' (Kometer & Vollenweider, 2018;Preller & Vollenweider, 2018;Swanson, 2018). ...
... Another reason we selected this approach is that it relates to the theorised disruption between (topdown) predictions and (bottom-up) prediction errors, which has been proposed to underlie VHs within PP accounts of perception (Alonso et al., 2015;Carhart-Harris & Friston, 2019;Swanson, 2018;Timmermann et al., 2018). Within this framework, the use of a predetermined target neuron by the Fixed error function can be viewed as simulating the overly strong perceptual predictions thought to be the cause of neurological/CBS VHs (O'Callaghan et al., 2017;Powers et al., 2016). ...
Visual hallucinations (VHs) are perceptions of objects or events in the absence of the sensory stimulation that would normally support such perceptions. Although all VHs share this core characteristic, there are substantial phenomenological differences between VHs that have different aetiologies, such as those arising from neurological conditions, visual loss, or psychedelic compounds. Here, we examine the potential mechanistic basis of these differences by leveraging recent advances in visualising the learned representations of a coupled classifier and generative deep neural network - an approach we call 'computational (neuro)phenomenology'. Examining three aetiologically distinct populations in which VHs occur - neurological conditions (Parkinson's Disease and Lewy Body Dementia), visual loss (Charles Bonnet Syndrome, CBS), and psychedelics - we identify three dimensions relevant to distinguishing these classes of VHs: realism (veridicality), dependence on sensory input (spontaneity), and complexity. By selectively tuning the parameters of the visualisation algorithm to reflect influence along each of these phenomenological dimensions we were able to generate 'synthetic VHs' that were characteristic of the VHs experienced by each aetiology. We verified the validity of this approach experimentally in two studies that examined the phenomenology of VHs in neurological and CBS patients, and in people with recent psychedelic experience. These studies confirmed the existence of phenomenological differences across these three dimensions between groups, and crucially, found that the appropriate synthetic VHs were representative of each group's hallucinatory phenomenology. Together, our findings highlight the phenomenological diversity of VHs associated with distinct causal factors and demonstrate how a neural network model of visual phenomenology can successfully capture the distinctive visual characteristics of hallucinatory experience.
... Additionally, LSD, ayahuasca, and psilocybin induce alpha power reductions within the occipital and parietal cortices, which are important structures for the interpretation of visual stimuli (88). It is believed this reduction explains subjective reports of visual hallucinations as alpha oscillations have been found to play a role in cortical processing of sensory information (92). Finally, under the influence of ayahuasca and LSD, psychedelic effects such as ego dissolution and spiritual feelings have been reported during moments of global decreases in alpha waves (92). ...
... It is believed this reduction explains subjective reports of visual hallucinations as alpha oscillations have been found to play a role in cortical processing of sensory information (92). Finally, under the influence of ayahuasca and LSD, psychedelic effects such as ego dissolution and spiritual feelings have been reported during moments of global decreases in alpha waves (92). Alpha oscillations are correlated with functions in which the DMN plays a major role such as self-reflection; as discussed above, fMRI studies support this association (93). ...
Introduction:
Current treatment options for major depressive disorder (MDD) have limited efficacy and are associated with adverse effects. Recent studies investigating the antidepressant effect of serotonergic psychedelics-also known as classic psychedelics-have promising preliminary results with large effect sizes. In this context, we conducted a review of the putative neurobiological underpinnings of the mechanism of antidepressant action of these drugs.
Methods:
A narrative review was conducted using PubMed to identify published articles evaluating the antidepressant mechanism of action of serotonergic psychedelics.
Results:
Serotonergic psychedelics have serotonin (5HT)2A agonist or partial agonist effects. Their rapid antidepressant effects may be mediated-in part-by their potent 5HT2A agonism, leading to rapid receptor downregulation. In addition, these psychedelics impact brain derived neurotrophic factor and immunomodulatory responses, both of which may play a role in their antidepressant effect. Several neuroimaging and neurophysiology studies evaluating mechanistic change from a network perspective can help us to further understand their mechanism of action. Some, but not all, data suggest that psychedelics may exert their effects, in part, by disrupting the activity of the default mode network, which is involved in both introspection and self-referential thinking and is over-active in MDD.
Conclusion:
The mechanisms of action underlying the antidepressant effect of serotonergic psychedelics remains an active area of research. Several competing theories are being evaluated and more research is needed to determine which ones are supported by the most robust evidence.
... Toutes les substances psychédéliques sont des agonistes des récepteurs sérotoninergiques 5-HT2A. Elles produisent des effets psychotropes connus sous le nom « d'expérience psychédélique » ou trip (voyage) : l'altération -temporaire, mais profonde -de la conscience, impliquant des modifications dans les sphères somatique, perceptive, cognitive, psychologique et affective [33,34]. Les psychédéliques provoquent notamment une altération de la conscience de soi, qui peut mener à une expérience fréquemment décrite par les usagers comme « mystique » 3 . ...
Objectifs--
Les addictions représentent aujourd’hui un enjeu majeur de santé publique. Le constat des résultats limités des traitements proposés incite à envisager de nouvelles modalités thérapeutiques. Cet article propose, par le biais d’une revue de littérature qualitative, d’évaluer la pertinence de l’utilisation de la Thérapie d’Acceptation et d’Engagement comme cadre d’accompagnement de la Psychothérapie Assistée par Psychédéliques, ainsi que la perspective de l’articulation de cette approche dans le champ de l’addictologie.
-- Méthodes --
Après des éléments introductifs portant sur les mécanismes et les prises en charge des addictions, nous aborderons la Psychothérapie Assistée par Psychédéliques et la Thérapie d’Acceptation et d’Engagement. Nous discuterons ensuite leur synergie et leur association, avant de conclure sur les perspectives en addictologie.
-- Résultats --
Les résultats des études suggèrent l’efficacité de ces deux approches utilisées séparément dans différentes indications, dont les addictions. L’efficacité prometteuse de la Psychothérapie Assistée par Psychédéliques repose également sur sa composante psychothérapeutique, nécessaire pour optimiser les effets bénéfiques.
-- Discussion --
Du fait de la synergie de leurs mécanismes d’action, la Thérapie d’Acceptation et d’Engagement semble être particulièrement adaptée à la Psychothérapie Assistée par Psychédéliques. Alors que cette association, récemment employée dans deux recherches sur la dépression résistante n’a pas encore été explorée dans le domaine des addictions, les résultats préliminaires suggérant leur complémentarité ouvrent des perspectives sur leur association au sein d’un cadre thérapeutique en addictologie, et invitent à une réflexion sur la mise en place d’un protocole adapté.
-- Conclusions --
À ce jour, les processus psychologiques de changement impliqués dans la Psychothérapie Assistée par Psychédéliques restent insuffisamment étudiés, nécessitant une compréhension plus approfondie. La Thérapie d’Acceptation et d’Engagement apparaît comme une proposition adéquate pour encadrer la Psychothérapie Assistée par Psychédéliques, qui mériterait d’être testée dans le domaine de l’addictologie, où les processus de flexibilité psychologique – visés aussi bien par les psychédéliques que par cette psychothérapie – sont sous-jacents et de grande importance pour la prise en charge. Dans ce champ encore peu exploré, cette perspective s’inscrit dans la recherche d’une composante psychothérapeutique unificatrice et intégrative, au service d’une vision globale de la prise en charge des troubles de conduites addictives.
-- Mots clés --
AddictionPsychothérapie Assistée par PsychédéliquesThérapie d’Acceptation et d’EngagementFlexibilité Psychologique
-- Abstract --
-- Objectives --
Addictive behaviors are currently considered a major public health concern worldwide. The observation of limited results of existing treatments encourages the search for new therapeutic modalities. This paper examines, through a qualitative literature review, the relevance of using Acceptance and Commitment Therapy (ACT) as a psychotherapeutic framework for Psychedelic-Assisted Psychotherapy (PAP), as well as the perspective of the articulation of this approach in the field of addiction.
-- Methods --
After briefly introducing the current context of addiction, its mechanisms and treatments, we will address both Psychedelic-Assisted Psychotherapy and Acceptance and Commitment Therapy. We will then discuss their synergy and their association, before concluding on perspectives for addictology.
-- Results --
The results of published studies suggest significant efficacy of these two approaches when used separately and for different conditions, including addiction. The promising efficacy of Psychedelic-Assisted Psychotherapy is equally based on its psychotherapeutic component, which is necessary to optimize the beneficial effects.
-- Discussion --
Due to the synergy between their mechanisms of action, ACT seems particularly suited to PAP. While this association, recently used in two recent research studies on treatment-resistant depression, has not yet been explored in the field of addiction, the preliminary results that suggest their complementarity open up perspectives on their association within a therapeutic framework in addictology, and encourage a reflection upon an adapted protocol to implement.
-- Conclusions --
To this day, psychological processes of change involved in PAP remain insufficiently studied and require further understanding. ACT appears as an appropriate proposal for the therapeutic framework of PAP, worthy of future investigation in the field of addiction, where the underlying processes of psychological flexibility – targeted by both psychedelics and this psychotherapeutic approach – play a major role in treatment outcomes. In a field that remains understudied, this perspective participates in the search for a unifying and integrative psychotherapeutic component, in the service of a global overview of the treatment of addiction disorders.
-- Keywords --
AddictionPsychedelic-Assisted PsychotherapyAcceptance and Commitment TherapyPsychological Flexibility
... The neurophysiological correlate of this effect is the modification in oscillatory activity in alphaband, detected in EEG and MEG, particularly in the PCC, a core node of the DMN (Muthukumaraswamy et al., 2013). Specifically, psilocybin reduces alpha power, increases gamma power and causes an overall brain dynamic characterized by increased between-network global functional connectivity, expanded signal diversity, and a larger repertoire of structured neurophysiological activation patterns (Muthukumaraswamy et al., 2013;Schartner et al., 2017;Swanson, 2018). The circuit-level effects of this modification are the disintegration and desegregation of restingstate functional networks, increasing communication between functionally distinct areas and decreasing communication between functionally similar areas -a pattern of compromised modular but enhanced global connectivity which has been subsumed under the entropic brain hypothesis (Carhart-Harris et al., 2014;Carhart-Harris, 2018). ...
Ketamine is an N-methyl-d-aspartate antagonist which is increasingly being researched and used as a treatment for depression. In low doses, it can cause a transitory modification in consciousness which was classically labelled as ‘dissociation’. However, ketamine is also commonly classified as an atypical psychedelic and it has been recently reported that ego dissolution experiences during ketamine administration are associated with greater antidepressant response. Neuroimaging studies have highlighted several similarities between the effects of ketamine and those of serotonergic psychedelics in the brain; however, no unified account has been proposed for ketamine’s multi-level effects – from molecular to network and psychological levels. Here, we propose that the fast, albeit transient, antidepressant effects observed after ketamine infusions are mainly driven by its acute modulation of reward circuits and sub-acute increase in neuroplasticity, while its dissociative and psychedelic properties are driven by dose- and context-dependent disruption of large-scale functional networks. Computationally, as nodes of the salience network (SN) represent high-level priors about the body (‘minimal’ self) and nodes of the default-mode network (DMN) represent the highest-level priors about narrative self-experience (‘biographical’ self), we propose that transitory SN desegregation and disintegration accounts for ketamine’s ‘ dissociative’ state, while transitory DMN desegregation and disintegration accounts for ketamine’s ‘ psychedelic’ state. In psychedelic-assisted psychotherapy, a relaxation of the highest-level beliefs with psychotherapeutic support may allow a revision of pathological self-representation models, for which neuroplasticity plays a permissive role. Our account provides a multi-level rationale for using the psychedelic properties of ketamine to increase its long-term benefits.
... Schachtel's seminal notions on kinesthesia, in a strong tradition of phenomenology, reorients an understanding of the inkblot test: the originating genius of HR's inkblots as a methodology designed to illuminate the processes by which the mind experiences itself and how one mind, including the Rorschach interpreter, apprehends the minds of others (Lipps, 1903(Lipps, , 1907. Despite the minority status of phenomenological psychology in American behavioral science, major developments in psychological science since the 1950s, including the cognitive revolution (Gardner, 1985), the emergence of cognitive neuroscience, phenomenological psychopathology, consciousness studies, and psychedelic science (e.g., Swanson, 2018;Yaden et al., 2021)-including application of 1st, 2nd, and 3rd person perspectiveshave moved phenomenology into the mainstream (Gallagher & Zahavi, 2012). This shift has precipitated a revolution in clinical, social, and personality psychology with implications for Rorschach psychology. ...
This article examines the milieu of Hermann Rorschach's Psychodiagnostics (1921/2021) under development between 1911 and his death in 1922 and explores new evidence about the direction Rorschach's test might have taken after publication of Psychodiagnostics. This includes direct and indirect influences from turn of the century continental philosophy and science and innovative colleagues in the Swiss psychiatric and psychoanalytic societies. The availability of newly translated scholarship, including the correspondence between Ludwig Binswanger and Hermann Rorschach following the 1921 publication of Psychodiagnostics, Binswanger's posthumous 1923 commentary in the International Journal of Psychoanalysis, and recent new translation of Psychodiagnostics, permits a fresh appraisal of the milieu and foundations of Rorschach's development. Understanding these sources and influences opens new vistas in reappraising the nature of Rorschach's “test theory” which Rorschach considered undeveloped at the time of his death. This paper presents new evidence that, under the influence of Rorschach's close colleague, Ludwig Binswanger, the Geisteswissenschaften and phenomenology might have figured prominently in future developments. The paper concludes that Rorschach, preoccupied with considerations of kinesthetic subjectivity in his innovative conceptualization of human movement responses, was a nascent phenomenologist whose untimely death cut short further developments in his theory of the test.
... Many of these themes reflect the known phenomenological features of psilocybin effects as identified in prior research (e.g. Swanson, 2018). Emotional and sensory experiences were the most commonly reported among participants. ...
Recent investigations of naturalistic psychedelic use purport that psychedelic therapies may be useful in criminal justice contexts for reducing recidivism. The present study applies interactionist theories of desistance to critically explore how psychedelic therapies could facilitate agentic self-transformation to support desistance from crime. Psychedelic experience reports written by inmates as part of the “Concord Prison Experiment” (CPE) were collected from the New York Public Library. Reports from 29 participants were then analyzed using a qualitative content analysis that employed both conventional and directed approaches. Participants frequently reported on changes in emotion and sense perception, interactions with other participants, and self-knowledge. Reports of self-knowledge often emerged from cognitive shifts that led to reflexive thought and novel insights regarding crime and criminality. These findings demonstrate how psychedelics can facilitate cognitive shifts in meaning conducive to inspiring desistance from crime. However, shortcomings of the CPE indicate that the social environment can hinder integration, by constraining the potential to enact changes in one’s life or realize meaningful insights through prosocial relationships. The combination of potentially harmful prison environments and the vulnerable states of consciousness generated by psychedelics should preclude investigations among actively incarcerated participants. Without addressing common social and structural barriers to successful reentry such as housing and employment, the efficacy of psychedelic-assisted therapy as a recidivism reducing intervention will be limited. Alternative approaches might explore how psychedelic therapy can address the psychological impacts of incarceration.
... These terms, encountered frequently in psychedelic discourse (Wolfson, 2014;Pink-Hashkes et al., 2017;Swanson, 2018), seldom appear in the psychoanalytic literature. However, the processes are not unfamiliar to analysts. ...
As interest in psychedelics as treatments for psychological problems grows, it is important for psychoanalysts to learn about them. Our patients will come to us to discuss their psychedelic experiences; additionally, psychedelics deserve reconsideration as meaningful collaborators with our field, at both the theoretical and clinical levels. After a brief history of these agents, the paper engages three specific areas: 1) psychedelics’ capacity to evoke egolysis, or ego dissolution, and mystical states; 2) their capacity to support hyperassociative states, free association, and emergence of unconscious material, and 3) the role of set and setting in psychedelic therapy. Drawing from the fields of neuropsychoanalysis, phenomenological research and neuroanthropology, the paper offers a discourse that connects mind and brain and psychedelics in ways meaningful for psychoanalysts.
... These substances elicit an extremely varied array of effects, spanning the entire brain functional hierarchy, from low-level sensory, to mood, and high-level cognitive alterations (Halberstadt, 2015;Nichols, 2016;Preller and Vollenweider, 2016;Kyzar et al., 2017;Vollenweider and Preller, 2020;Inserra et al., 2021;Kelmendi et al., 2022;Kwan et al., 2022;van Elk and Yaden, 2022). Multiple theoretical frameworks are available describing how psychedelics achieve their characteristic effects on brain dynamics and subjective experience (Carhart-Harris, 2018;Swanson, 2018;Doss et al., 2021;Vollenweider and Smallridge, 2022). While there is no universal agreement, perhaps one of the few widely accepted characterizations of the psychedelic state is as one of reduced top-down cognitive control, and increased bottom-up influence of sensory information. ...
Psychedelics are undergoing a major resurgence of scientific and clinical interest. While multiple theories and frameworks have been proposed, there is yet no universal agreement on the mechanisms underlying the complex effects of psychedelics on subjective experience and brain dynamics, nor their therapeutic benefits. Despite being prominent in psychedelic phenomenology and distinct from those elicited by other classes of hallucinogens, the effects of psychedelics on low-level sensory - particularly visual - dimensions of experience, and corresponding brain dynamics, have often been disregarded by contemporary research as 'epiphenomenal byproducts'. Here, we review available evidence from neuroimaging, pharmacology, questionnaires, and clinical studies; we propose extensions to existing models, provide testable hypotheses for the potential therapeutic roles of psychedelic-induced visual hallucinations, and simulations of visual phenomena relying on low-level cortical dynamics. In sum, we show that psychedelic-induced alterations in low-level sensory dimensions 1) are unlikely to be entirely causally reconducible to high-level alterations, but rather co-occur with them in a dialogical interplay, and 2) are likely to play a causally relevant role in determining high-level alterations and therapeutic outcomes. We conclude that reevaluating the currently underappreciated role of sensory dimensions in psychedelic states will be highly valuable for neuroscience and clinical practice, and that integrating low-level and domain-specific aspects of psychedelic effects into existing nonspecific models is a necessary step to further understand how these substances effect both acute and long-term change in the human brain.
... More recently, Robin Carhart-Harris has proposed a model of "cognitive entropy," suggesting that both early experiences of psychosis and psychedelic experiences occur in the same "primitive state" characterized by magical thinking, cognitive looseness, imagination, and flexible, creative thinking (Carhart-Harris, 2013;Carhart-Harris et al., 2014, 2016. As with the leaky filter model, the paradox is resolved; such entropy can either lead to symptoms of psychosis, as new meanings and perceptions come rapidly into view, or allow for productive therapeutic engagement outside of one's usual way of thinking (Swanson, 2018). ...
Experiences of psychedelics and psychosis were deeply entangled in scientific practices in the mid-20th century, from uses of psychedelic drugs that could model psychosis, to detailed phenomenological comparisons of endogenous and drug-induced madness. After the moral panic of the 1960s shut down psychedelic research, however, these two phenomena became disentangled. In the decades following, the science of psychosis transformed, shedding the language of psychoanalysis, and adopting the new scientific veneer of psychiatry. Today, as psychedelic science re-emerges, the research programs surrounding psychosis and psychedelics now stand in stark contrast. Here, I look closely at how these research programs respond to questions related to what is worth measuring, what is worth investigating, and how we ought to respond to these experiences. This comparison reveals radically different assumptions and values that guide each research paradigm and shape clinical practice. While psychedelic research often includes scales that seek to capture experiences of mysticism, meaningfulness, and ego dissolution, research related to psychosis focuses on the measurement of pathological symptoms and functioning. Research into psychosis primarily seeks universal and reductionist causal explanations and interventions, while psychedelic research embraces the importance of set and setting in shaping unique experiences. Responses to psychedelic crisis involve warmth, compassion, and support, while responses to psychotic experiences often involve restraint, seclusion, and weapons. I argue that these differences contain important lessons for psychiatry. However, as psychedelic research struggles to meet regulatory requirements and fit within the paradigm of evidence-based medicine, these differences may quickly dissolve.
