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Kesner L. A hole in a piece of cardboard and predictive brain: the incomprehension of modern art in the light of the predictive coding paradigm. Philos Trans R Soc Lond B Biol Sci 2024; 379:20220417. [PMID: 38104613 PMCID: PMC10725754 DOI: 10.1098/rstb.2022.0417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 07/13/2023] [Indexed: 12/19/2023] Open
Abstract
Incomprehension of and resistance to contemporaneous art have been constant features in the development of modern art. The predictive coding framework can be used to analyse this response by outlining the difference between the misunderstanding of (i) contemporary conceptual/minimalist art and (ii) early modern avant-garde art and by elucidating their underlying cognitive mechanisms. In both of these cases, incomprehension and its behavioural consequences are tied to the failure of the optimal prediction error (PE) minimization that is involved in the perception of such art works. In the case of contemporary conceptual/minimalist art the failure stems from the fact that the encounter results in non-salient visual sensations and generates no PE. In early modern avant-garde art, the occasional inability of viewers to recognize pictorial content using new pictorial conventions reflected the absence of suitable priors to explain away ambiguous sensory data. The capacity to recognize pictorial content in modernist painting, as a prerequisite for a satisfying encounter with such works and ultimately a wider acceptance of new artistic styles, required an updating of a number of expectations in order to optimize the fit between priors and sensations, from low-level perceptual priors to the development of higher-level, culturally determined expectations. This article is part of the theme issue 'Art, aesthetics and predictive processing: theoretical and empirical perspectives'.
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Affiliation(s)
- Ladislav Kesner
- Center for Advanced Study of Brain and Consciousness, National Institute of Mental Health, Klecany 25067, Czech Republic
- Art History, Masaryk University Brno, Brno 60200, Czech Republic
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2
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Wehrman J, Sanders R, Wearden J. What came before: Assimilation effects in the categorization of time intervals. Cognition 2023; 234:105378. [PMID: 36706494 DOI: 10.1016/j.cognition.2023.105378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 01/15/2023] [Accepted: 01/16/2023] [Indexed: 01/26/2023]
Abstract
Assimilation is the process by which one judgment tends to approach some aspect of another stimulus or judgment. This effect has been known for over half a century in various domains such as the judgment of weight or sound intensity. However, the assimilation of judgments of durations have been relatively unexplored. In the current article, we present the results of five experiments in which participant s were required to judge the duration of a visual stimulus on each trial. In each experiment, we manipulated the pattern of durations they experienced in order to systematically separate the effects of the objective and subjective duration of stimuli on subsequent judgments. We found that duration judgments were primarily driven by prior judgments, with little, if any, effect of the prior objective stimulus duration. This is in contrast to the findings previously reported in regards to non-temporal judgments. We propose two mechanist explanations of this effect; a representational account in which judgments represent the speed of an underlying pacemaker, and an assimilation account in which judgment is based in prior experience. We further discuss results in terms of predictive coding, in which the previous rating is representative of a prior expectation, which is modified by current experience.
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3
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Nutt D, Spriggs M, Erritzoe D. Psychedelics therapeutics: What we know, what we think, and what we need to research. Neuropharmacology 2023; 223:109257. [PMID: 36179919 DOI: 10.1016/j.neuropharm.2022.109257] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 09/07/2022] [Accepted: 09/11/2022] [Indexed: 12/14/2022]
Abstract
Psychedelic therapy is perhaps the most exciting new development in psychiatry. Not only does it offer a radical new approach to treatment where mainstream approaches have proven ineffective, but the growing evidence for transdiagnostic efficacy is eliciting a re-think of current diagnostic and symptom-specific approaches to psychiatry. This excitement has led to a massive investment in this field with many tens of new pharmaceutical companies being set up to research the effects of known psychedelics and develop new patentable molecules. Whilst this enthusiasm is to be welcomed, it is important that new research is properly grounded in established facts and reflects current knowledge. In this commentary we lay out the knowledge framework that should be taken into account by all innovative researchers in this field.
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Affiliation(s)
- David Nutt
- Centres for Neuropsychopharmacology and Psychedelic Research, Division of Psychiatry, Department of Brain Sciences, Imperial College London, London, UK
| | - Meg Spriggs
- Centres for Neuropsychopharmacology and Psychedelic Research, Division of Psychiatry, Department of Brain Sciences, Imperial College London, London, UK
| | - David Erritzoe
- Centres for Neuropsychopharmacology and Psychedelic Research, Division of Psychiatry, Department of Brain Sciences, Imperial College London, London, UK.
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4
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Calder AE, Hasler G. Towards an understanding of psychedelic-induced neuroplasticity. Neuropsychopharmacology 2023; 48:104-112. [PMID: 36123427 PMCID: PMC9700802 DOI: 10.1038/s41386-022-01389-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/10/2022] [Accepted: 07/12/2022] [Indexed: 12/20/2022]
Abstract
Classic psychedelics, such as LSD, psilocybin, and the DMT-containing beverage ayahuasca, show some potential to treat depression, anxiety, and addiction. Importantly, clinical improvements can last for months or years after treatment. It has been theorized that these long-term improvements arise because psychedelics rapidly and lastingly stimulate neuroplasticity. The focus of this review is on answering specific questions about the effects of psychedelics on neuroplasticity. Firstly, we review the evidence that psychedelics promote neuroplasticity and examine the cellular and molecular mechanisms behind the effects of different psychedelics on different aspects of neuroplasticity, including dendritogenesis, synaptogenesis, neurogenesis, and expression of plasticity-related genes (e.g., brain-derived neurotrophic factor and immediate early genes). We then examine where in the brain psychedelics promote neuroplasticity, particularly discussing the prefrontal cortex and hippocampus. We also examine what doses are required to produce this effect (e.g., hallucinogenic doses vs. "microdoses"), and how long purported changes in neuroplasticity last. Finally, we discuss the likely consequences of psychedelics' effects on neuroplasticity for both patients and healthy people, and we identify important research questions that would further scientific understanding of psychedelics' effects on neuroplasticity and its potential clinical applications.
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Affiliation(s)
- Abigail E. Calder
- grid.8534.a0000 0004 0478 1713University Center for Psychiatric Research, University of Fribourg, Fribourg, Switzerland
| | - Gregor Hasler
- University Center for Psychiatric Research, University of Fribourg, Fribourg, Switzerland.
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5
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Rygvold TW, Hatlestad-Hall C, Elvsåshagen T, Moberget T, Andersson S. Long term potentiation-like neural plasticity and performance-based memory function. Neurobiol Learn Mem 2022; 196:107696. [PMID: 36368635 DOI: 10.1016/j.nlm.2022.107696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 09/23/2022] [Accepted: 10/30/2022] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Experience-dependent modulation of the visual evoked potential (VEP) has emerged as a promising non-invasive proxy for assaying long term potentiation (LTP)-like plasticity in the cerebral cortex. LTP is considered the principal candidate mechanism underlying learning and memory. There is, however, a paucity of evidence exploring associations between LTP-like plasticity and performance-based learning and memory. The present study aimed to explore the relationship between VEP-plasticity and higher-order learning and memory in healthy adults. METHOD Visual and verbal learning and memory was assessed using the Aggie Figures Learning Test (AFLT) and the Rey Auditory Verbal Learning Test (RAVLT). The study included 111 healthy adults (61.1% females; mean age 37.6 years, range 17-71) who underwent a VEP paradigm employing visual high-frequency stimulation to induce a change in visual evoked responses recorded by scalp EEG. In addition, a more comprehensive neuropsychological assessment was administered. RESULTS Several significant moderate age-corrected positive correlations were found between modulation of the later VEP components (N1 and P1-N1 peak-to-peak) and both visual and verbal learning and memory performance. Further, there were significant differences in learning and memory performance between participants showing a higher degree of modulation (>1 SD above mean) compared to participants showing a lower degree of modulation. No significant associations were found between VEP-plasticity and other neurocognitive domains. CONCLUSIONS The current results suggest that LTP-like plasticity indexed by VEP modulation reflect processes specific to learning and memory. Future research is needed to further delineate the complex relationship between neural plasticity and learning and memory, specifically concerning possible clinical implications in populations with deficits in learning and memory function.
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Affiliation(s)
- Trine Waage Rygvold
- Department of Psychology, Faculty of Social Sciences, University of Oslo, Oslo, Norway
| | | | | | - Torgeir Moberget
- Department of Psychology, Faculty of Social Sciences, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital, Oslo, Norway
| | - Stein Andersson
- Department of Psychology, Faculty of Social Sciences, University of Oslo, Oslo, Norway
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6
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Dias JW, McClaskey CM, Rumschlag JA, Harris KC. Sensory tetanisation to induce long-term-potentiation-like plasticity: A review and reassessment of the approach. Eur J Neurosci 2022; 56:6115-6140. [PMID: 36227258 PMCID: PMC9772088 DOI: 10.1111/ejn.15847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 09/02/2022] [Accepted: 10/05/2022] [Indexed: 12/29/2022]
Abstract
There is great interest in developing non-invasive approaches for studying cortical plasticity in humans. High-frequency presentation of auditory and visual stimuli, or sensory tetanisation, can induce long-term-potentiation-like (LTP-like) changes in cortical activity. However, contrasting effects across studies suggest that sensory tetanisation may be unreliable. We review these contrasting effects, conduct our own study of auditory and visual tetanisation, and perform meta-analyses to determine the average effect of sensory tetanisation across studies. We measured auditory-evoked amplitude changes in a group of younger (18-29 years of age) and older (55-83 years of age) adults following tetanisation to 1 and 4 kHz tone bursts and following a slow-presentation control. We also measured visual-evoked amplitude changes following tetanisation to horizontal and vertical sign gradients. Auditory and visual response amplitudes decreased following tetanisation, consistent with some studies but contrasting with others finding amplitude increases (i.e. LTP-like changes). Older adults exhibited more modest auditory-evoked amplitude decreases, but visual-evoked amplitude decreases like those of younger adults. Changes in response amplitude were not specific to tetanised stimuli. Importantly, slow presentation of auditory tone bursts produced response amplitude changes approximating those observed following tetanisation in younger adults. Meta-analyses of visual and auditory tetanisation studies found that the overall effect of sensory tetanisation was not significant across studies or study sites. The results suggest that sensory tetanisation may not produce reliable changes in cortical responses and more work is needed to determine the validity of sensory tetanisation as a method for inducing human cortical plasticity in vivo.
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Affiliation(s)
- James W Dias
- Department of Otolaryngology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Carolyn M McClaskey
- Department of Otolaryngology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Jeffrey A Rumschlag
- Department of Otolaryngology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Kelly C Harris
- Department of Otolaryngology, Medical University of South Carolina, Charleston, South Carolina, USA
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7
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Kleeva DF, Rebreikina AB, Soghoyan GA, Kostanian DG, Neklyudova AN, Sysoeva OV. Generalization of sustained neurophysiological effects of short-term auditory 13-Hz stimulation to neighboring frequency representation in humans. Eur J Neurosci 2021; 55:175-188. [PMID: 34736295 PMCID: PMC9299826 DOI: 10.1111/ejn.15513] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 10/23/2021] [Accepted: 10/29/2021] [Indexed: 11/30/2022]
Abstract
A fuller understanding of the effects of auditory tetanization in humans would inform better language and sensory learning paradigms, however, there are still unanswered questions. Here, we probe sustained changes in the event-related potentials (ERPs) to 1020Hz and 980Hz tones following a rapid presentation of 1020Hz tone (every 75 ms, 13.3Hz, tetanization). Consistent with the previous studies (Rygvold, et al., 2021, Mears & Spencer 2012), we revealed the increase in the P2 ERP component after tetanization. Contrary to other studies (Clapp et al., 2005; Lei et al., 2017) we did not observe the expected N1 increase after tetanization even in the experimental sequence identical to Clapp. et al., 2005. We detected a significant N1 decrease after tetanization. Expanding previous research, we showed that P2 increase and N1 decrease is not specific to the stimulus type (tetanized 1020Hz and non-tetanized 980Hz), suggesting the generalizability of tetanization effect to the not-stimulated auditory tones, at least to those of the neighboring frequency. The ERPs tetanization effects were observed for at least 30 min - the most prolonged interval examined, consistent with the duration of long-term potentiation, LTP. In addition, the tetanization effects were detectable in the blocks where the participants watched muted videos, an experimental setting that can be easily used in children and other challenging groups. Thus, auditory 13-Hz stimulation affects brain processing of tones including those of neighboring frequencies.
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Affiliation(s)
- D F Kleeva
- Center for Cognitive Research, Sirius University of Science and Technology, Sochi, Russia.,Center for Bioelectric Interfaces, National Research University "Higher School of Economics", Moscow, Russia
| | - A B Rebreikina
- Center for Cognitive Research, Sirius University of Science and Technology, Sochi, Russia.,Laboratory of Human Higher Nervous Activity, Institute of Higher Nervous Activity and Neurophysiology of RAS, Moscow, Russia
| | - G A Soghoyan
- Center for Cognitive Research, Sirius University of Science and Technology, Sochi, Russia.,Center for Bioelectric Interfaces, National Research University "Higher School of Economics", Moscow, Russia.,V. Zelman Center for Neurobiology and Brain Restoration, Skolkovo Institute of Science and Technology 121205, Moscow, Russia
| | - D G Kostanian
- Center for Cognitive Research, Sirius University of Science and Technology, Sochi, Russia.,Laboratory of Human Higher Nervous Activity, Institute of Higher Nervous Activity and Neurophysiology of RAS, Moscow, Russia
| | - A N Neklyudova
- Center for Cognitive Research, Sirius University of Science and Technology, Sochi, Russia.,Laboratory of Human Higher Nervous Activity, Institute of Higher Nervous Activity and Neurophysiology of RAS, Moscow, Russia
| | - O V Sysoeva
- Center for Cognitive Research, Sirius University of Science and Technology, Sochi, Russia.,Laboratory of Human Higher Nervous Activity, Institute of Higher Nervous Activity and Neurophysiology of RAS, Moscow, Russia
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8
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Spriggs MJ, Douglass HM, Park RJ, Read T, Danby JL, de Magalhães FJC, Alderton KL, Williams TM, Blemings A, Lafrance A, Nicholls DE, Erritzoe D, Nutt DJ, Carhart-Harris RL. Study Protocol for "Psilocybin as a Treatment for Anorexia Nervosa: A Pilot Study". Front Psychiatry 2021; 12:735523. [PMID: 34744825 PMCID: PMC8563607 DOI: 10.3389/fpsyt.2021.735523] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/15/2021] [Indexed: 01/14/2023] Open
Abstract
Background: Anorexia nervosa (AN) is a serious and life-threatening psychiatric condition. With a paucity of approved treatments, there is a desperate need for novel treatment avenues to be explored. Here, we present (1) an overview of the ways through which Public Patient Involvement (PPI) has informed a trial of psilocybin-assisted therapy for AN and (2) a protocol for a pilot study of psilocybin-assisted therapy in AN currently underway at Imperial College London. The study aims to assess the feasibility, brain mechanisms and preliminary outcomes of treating anorexia nervosa with psilocybin. Methods: (1) PPI: Across two online focus groups, eleven individuals with lived experience of AN were presented with an overview of the protocol. Their feedback not only identified solutions to possible barriers for future participants, but also helped the research team to better understand the concept of "recovery" from the perspective of those with lived experience. (2) Protocol: Twenty female participants [21-65 years old, body mass index (BMI) 15 kg/m2 or above] will receive three oral doses of psilocybin (up to 25 mg) over a 6-week period delivered in a therapeutic environment and enveloped by psychological preparation and integration. We will work with participant support networks (care teams and an identified support person) throughout and there will be an extended remote follow-up period of 12 months. Our two-fold primary outcomes are (1) psychopathology (Eating Disorder Examination) across the 6-month follow-up and (2) readiness and motivation to engage in recovery (Readiness and Motivation Questionnaire) across the 6-week trial period. Neurophysiological outcome measures will be: (1) functional magnetic resonance imaging (fMRI) brain changes from baseline to 6-week endpoint and (2) post-acute changes in electroencephalography (EEG) activity, including an electrophysiological marker of neuronal plasticity. Discussion: The results of this pilot study will not only shed light on the acceptability, brain mechanisms, and impression of the potential efficacy of psilocybin as an adjunct treatment for AN but will be essential in shaping a subsequent Randomised Control Trial (RCT) that would test this treatment against a suitable control condition. Clinical Trial Registration: identifier: NCT04505189.
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Affiliation(s)
- Meg J. Spriggs
- Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Hannah M. Douglass
- Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Rebecca J. Park
- OxBREaD Research Group, Department of Psychiatry, University of Oxford, Oxford, United Kingdom
| | - Tim Read
- Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Jennifer L. Danby
- Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, United Kingdom
| | | | - Kirsty L. Alderton
- Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Tim M. Williams
- Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Allan Blemings
- Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Adele Lafrance
- School of Rural and Northern Health, Laurentian University, Sudbury, ON, Canada
| | - Dasha E. Nicholls
- Division of Psychiatry, Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - David Erritzoe
- Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - David J. Nutt
- Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Robin L. Carhart-Harris
- Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, United Kingdom
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9
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Murphy RJ, Sumner RL, Evans W, Menkes D, Lambrecht I, Ponton R, Sundram F, Hoeh N, Ram S, Reynolds L, Muthukumaraswamy S. MDLSD: study protocol for a randomised, double-masked, placebo-controlled trial of repeated microdoses of LSD in healthy volunteers. Trials 2021; 22:302. [PMID: 33892777 PMCID: PMC8062934 DOI: 10.1186/s13063-021-05243-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 03/31/2021] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND Regular ingestion of sub-hallucinogenic doses of psychedelics, referred to as "microdosing", has gained increasing popularity and attention in the press and in online forums, with reported benefits across multiple cognitive and emotional domains. Rigorously controlled studies to date, however, have been limited in scope and have failed to produce results comparable to those reported in the grey literature. METHODS Eighty healthy male participants will receive 14 doses of placebo or 10 μg lysergic acid diethylamide orally every 3rd day over a 6-week treatment protocol. A battery of personality, creativity, mood, cognition, and EEG plasticity measures, as well as resting-state fMRI imaging, will be administered at baseline and at the end of the protocol. Creativity, mood, and plasticity measures will additionally be assessed in the acute phase of the first dose. Daily functioning will be monitored with questionnaires and a wearable sleep and activity tracker. DISCUSSION This study will rigorously examine the claims presented in the microdosing grey literature by pairing a comparable dosing protocol with objective measures. Potential therapeutic implications include future clinical trials to investigate microdosed psychedelics as a standalone treatment or as an augmentation of psychotherapy in the treatment of depression, addiction, eating disorders, obsessive-compulsive disorders, and palliative care. TRIAL REGISTRATION ACTRN12621000436875 . Registered on 19 February 2021.
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Affiliation(s)
- Robin J Murphy
- School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland, 1023, New Zealand.
| | - Rachael L Sumner
- School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland, 1023, New Zealand
| | - William Evans
- Mana Health, 7 Ruskin St, Parnell, Auckland, 1052, New Zealand
| | - David Menkes
- Department of Psychological Medicine, Faculty of Medical and Health Sciences, Waikato Clinical Campus, Peter Rothwell Academic Centre, University of Auckland, Pembroke Street, Hamilton, 3240, New Zealand
| | - Ingo Lambrecht
- Regional Cancer & Blood Service, Auckland District Health Board, 2 Park Road, Grafton, Auckland, 1023, New Zealand
| | - Rhys Ponton
- School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland, 1023, New Zealand
| | - Frederick Sundram
- Department of Psychological Medicine, Faculty of Medical and Health Sciences, University of Auckland, 2 Park Road, Grafton, Auckland, 1023, New Zealand
| | - Nicholas Hoeh
- Department of Psychological Medicine, Faculty of Medical and Health Sciences, University of Auckland, 22-30 Park Avenue, Grafton, Auckland, 1023, New Zealand
| | - Sanya Ram
- School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland, 1023, New Zealand
| | - Lisa Reynolds
- Department of Psychological Medicine, Faculty of Medical and Health Sciences, University of Auckland, 22-30 Park Avenue, Grafton, Auckland, 1023, New Zealand
| | - Suresh Muthukumaraswamy
- School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland, 1023, New Zealand
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10
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Adams NE, Hughes LE, Rouse MA, Phillips HN, Shaw AD, Murley AG, Cope TE, Bevan-Jones WR, Passamonti L, Street D, Holland N, Nesbitt D, Friston K, Rowe JB. GABAergic cortical network physiology in frontotemporal lobar degeneration. Brain 2021; 144:2135-2145. [PMID: 33710299 PMCID: PMC8370432 DOI: 10.1093/brain/awab097] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 12/31/2020] [Accepted: 01/03/2021] [Indexed: 11/23/2022] Open
Abstract
The clinical syndromes caused by frontotemporal lobar degeneration are heterogeneous, including the behavioural variant frontotemporal dementia (bvFTD) and progressive supranuclear palsy. Although pathologically distinct, they share many behavioural, cognitive and physiological features, which may in part arise from common deficits of major neurotransmitters such as γ-aminobutyric acid (GABA). Here, we quantify the GABAergic impairment and its restoration with dynamic causal modelling of a double-blind placebo-controlled crossover pharmaco-magnetoencephalography study. We analysed 17 patients with bvFTD, 15 patients with progressive supranuclear palsy, and 20 healthy age- and gender-matched controls. In addition to neuropsychological assessment and structural MRI, participants undertook two magnetoencephalography sessions using a roving auditory oddball paradigm: once on placebo and once on 10 mg of the oral GABA reuptake inhibitor tiagabine. A subgroup underwent ultrahigh-field magnetic resonance spectroscopy measurement of GABA concentration, which was reduced among patients. We identified deficits in frontotemporal processing using conductance-based biophysical models of local and global neuronal networks. The clinical relevance of this physiological deficit is indicated by the correlation between top-down connectivity from frontal to temporal cortex and clinical measures of cognitive and behavioural change. A critical validation of the biophysical modelling approach was evidence from parametric empirical Bayes analysis that GABA levels in patients, measured by spectroscopy, were related to posterior estimates of patients’ GABAergic synaptic connectivity. Further evidence for the role of GABA in frontotemporal lobar degeneration came from confirmation that the effects of tiagabine on local circuits depended not only on participant group, but also on individual baseline GABA levels. Specifically, the phasic inhibition of deep cortico-cortical pyramidal neurons following tiagabine, but not placebo, was a function of GABA concentration. The study provides proof-of-concept for the potential of dynamic causal modelling to elucidate mechanisms of human neurodegenerative disease, and explains the variation in response to candidate therapies among patients. The laminar- and neurotransmitter-specific features of the modelling framework, can be used to study other treatment approaches and disorders. In the context of frontotemporal lobar degeneration, we suggest that neurophysiological restoration in selected patients, by targeting neurotransmitter deficits, could be used to bridge between clinical and preclinical models of disease, and inform the personalized selection of drugs and stratification of patients for future clinical trials.
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Affiliation(s)
- Natalie E Adams
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Laura E Hughes
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK.,MMRC Cognition and Brain Sciences Unit, Cambridge CB2 7EF, UK
| | - Matthew A Rouse
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Holly N Phillips
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK
| | | | - Alexander G Murley
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK.,Cambridge University Hospitals, Cambridge, CB2 0QQ, UK
| | - Thomas E Cope
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK.,MMRC Cognition and Brain Sciences Unit, Cambridge CB2 7EF, UK.,Cambridge University Hospitals, Cambridge, CB2 0QQ, UK
| | - W Richard Bevan-Jones
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK.,Cambridge University Hospitals, Cambridge, CB2 0QQ, UK
| | - Luca Passamonti
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK.,Cambridge University Hospitals, Cambridge, CB2 0QQ, UK
| | - Duncan Street
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK.,Cambridge University Hospitals, Cambridge, CB2 0QQ, UK
| | - Negin Holland
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK.,Cambridge University Hospitals, Cambridge, CB2 0QQ, UK
| | - David Nesbitt
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK.,MMRC Cognition and Brain Sciences Unit, Cambridge CB2 7EF, UK.,Cambridge University Hospitals, Cambridge, CB2 0QQ, UK
| | - Karl Friston
- Wellcome Centre for Human Neuroimaging, University College London, London WC1N 3AR, UK
| | - James B Rowe
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK.,MMRC Cognition and Brain Sciences Unit, Cambridge CB2 7EF, UK.,Cambridge University Hospitals, Cambridge, CB2 0QQ, UK
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11
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Sumner RL, Spriggs MJ, Shaw AD. Modelling thalamocortical circuitry shows that visually induced LTP changes laminar connectivity in human visual cortex. PLoS Comput Biol 2021; 17:e1008414. [PMID: 33476341 PMCID: PMC7853500 DOI: 10.1371/journal.pcbi.1008414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 02/02/2021] [Accepted: 10/05/2020] [Indexed: 11/19/2022] Open
Abstract
Neuroplasticity is essential to learning and memory in the brain; it has therefore also been implicated in numerous neurological and psychiatric disorders, making measuring the state of neuroplasticity of foremost importance to clinical neuroscience. Long-term potentiation (LTP) is a key mechanism of neuroplasticity and has been studied extensively, and invasively in non-human animals. Translation to human application largely relies on the validation of non-invasive measures of LTP. The current study presents a generative thalamocortical computational model of visual cortex for investigating and replicating interlaminar connectivity changes using non-invasive EEG recording of humans. The model is combined with a commonly used visual sensory LTP paradigm and fit to the empirical EEG data using dynamic causal modelling. The thalamocortical model demonstrated remarkable accuracy recapitulating post-tetanus changes seen in invasive research, including increased excitatory connectivity from thalamus to layer IV and from layer IV to II/III, established major sites of LTP in visual cortex. These findings provide justification for the implementation of the presented thalamocortical model for ERP research, including to provide increased detail on the nature of changes that underlie LTP induced in visual cortex. Future applications include translating rodent findings to non-invasive research in humans concerning deficits to LTP that may underlie neurological and psychiatric disease. The brain’s ability to learn and form memories is governed by neuroplasticity. One of the major mechanisms of neuroplasticity is long-term potentiation (LTP). To study LTP in detail necessitates implanting electrodes in the brain of non-human animals. However, to translate this knowledge to humans requires a non-invasive method. Neural mass models use mathematical equations to describe the brain’s neural architecture and function over time. Fitting these models to real data, using methods such as dynamic causal modelling (DCM), helps to elucidate the connectivity and major channel changes that could have plausibly caused the observed effects in electroencephalography data recorded non-invasively from the scalp. The current study presents a thalamocortical model of the neural architecture of the visual system combined with a thalamic compartment. The model is able to represent the basic transfer of visual information to the cortex, mediated by major receptor types. We combined the thalamocortical model with a visual processing task that uses black and white grating images to induce and measure LTP in visual cortex. We hypothesised that the changes in the model would be consistent with what is seen in animal invasive recordings. The model demonstrated remarkable accuracy in recapitulating changes to neural architecture consistent with the induction of LTP in visual cortex. Additionally, the result demonstrated specificity to the visual input that induced LTP. Future applications include translating animal findings that are beginning to determine how disordered LTP may underlie neurological and psychiatric disease (for example depression, schizophrenia, autism, and dementia).
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Affiliation(s)
- Rachael L. Sumner
- School of Pharmacy, University of Auckland, Auckland, New Zealand
- * E-mail:
| | - Meg J. Spriggs
- Centre for Psychedelic Research, Department of Medicine, Imperial College London, London, United Kingdom
| | - Alexander D. Shaw
- Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, United Kingdom
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12
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Kaertner LS, Steinborn MB, Kettner H, Spriggs MJ, Roseman L, Buchborn T, Balaet M, Timmermann C, Erritzoe D, Carhart-Harris RL. Positive expectations predict improved mental-health outcomes linked to psychedelic microdosing. Sci Rep 2021; 11:1941. [PMID: 33479342 PMCID: PMC7820236 DOI: 10.1038/s41598-021-81446-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 12/28/2020] [Indexed: 12/20/2022] Open
Abstract
Psychedelic microdosing describes the ingestion of near-threshold perceptible doses of classic psychedelic substances. Anecdotal reports and observational studies suggest that microdosing may promote positive mood and well-being, but recent placebo-controlled studies failed to find compelling evidence for this. The present study collected web-based mental health and related data using a prospective (before, during and after) design. Individuals planning a weekly microdosing regimen completed surveys at strategic timepoints, spanning a core four-week test period. Eighty-one participants completed the primary study endpoint. Results revealed increased self-reported psychological well-being, emotional stability and reductions in state anxiety and depressive symptoms at the four-week primary endpoint, plus increases in psychological resilience, social connectedness, agreeableness, nature relatedness and aspects of psychological flexibility. However, positive expectancy scores at baseline predicted subsequent improvements in well-being, suggestive of a significant placebo response. This study highlights a role for positive expectancy in predicting positive outcomes following psychedelic microdosing and cautions against zealous inferences on its putative therapeutic value.
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Affiliation(s)
- L S Kaertner
- Centre for Psychedelic Research, Division of Psychiatry, Imperial College London, London, UK.
| | - M B Steinborn
- Departmant of Psychology, Julius-Maximilans-University Würzburg, Würzburg, Germany
| | - H Kettner
- Centre for Psychedelic Research, Division of Psychiatry, Imperial College London, London, UK
| | - M J Spriggs
- Centre for Psychedelic Research, Division of Psychiatry, Imperial College London, London, UK
| | - L Roseman
- Centre for Psychedelic Research, Division of Psychiatry, Imperial College London, London, UK
| | - T Buchborn
- Centre for Psychedelic Research, Division of Psychiatry, Imperial College London, London, UK
| | - M Balaet
- Computational, Cognitive and Clinical Neuroimaging Laboratory, Imperial College London, London, UK
| | - C Timmermann
- Centre for Psychedelic Research, Division of Psychiatry, Imperial College London, London, UK
| | - D Erritzoe
- Centre for Psychedelic Research, Division of Psychiatry, Imperial College London, London, UK
| | - R L Carhart-Harris
- Centre for Psychedelic Research, Division of Psychiatry, Imperial College London, London, UK
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13
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Experience-dependent modulation of the visual evoked potential: Testing effect sizes, retention over time, and associations with age in 415 healthy individuals. Neuroimage 2020; 223:117302. [DOI: 10.1016/j.neuroimage.2020.117302] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 08/12/2020] [Accepted: 08/18/2020] [Indexed: 12/20/2022] Open
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14
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Sumner RL, McMillan R, Spriggs MJ, Campbell D, Malpas G, Maxwell E, Deng C, Hay J, Ponton R, Sundram F, Muthukumaraswamy SD. Ketamine improves short-term plasticity in depression by enhancing sensitivity to prediction errors. Eur Neuropsychopharmacol 2020; 38:73-85. [PMID: 32763021 DOI: 10.1016/j.euroneuro.2020.07.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 06/02/2020] [Accepted: 07/16/2020] [Indexed: 12/17/2022]
Abstract
Major depressive disorder negatively impacts the sensitivity and adaptability of the brain's predictive coding framework. The current electroencephalography study into the antidepressant properties of ketamine investigated the downstream effects of ketamine on predictive coding and short-term plasticity in thirty patients with depression using the auditory roving mismatch negativity (rMMN). The rMMN paradigm was run 3-4 h after a single 0.44 mg/kg intravenous dose of ketamine or active placebo (remifentanil infused to a target plasma concentration of 1.7 ng/mL) in order to measure the neural effects of ketamine in the period when an improvement in depressive symptoms emerges. Depression symptomatology was measured using the Montgomery-Asberg Depression Rating Scale (MADRS); 70% of patients demonstrated at least a 50% reduction their MADRS global score. Ketamine significantly increased the MMN and P3a event related potentials, directly contrasting literature demonstrating ketamine's acute attenuation of the MMN. This effect was only reliable when all repetitions of the post-deviant tone were used. Dynamic causal modelling showed greater modulation of forward connectivity in response to a deviant tone between right primary auditory cortex and right inferior temporal cortex, which significantly correlated with antidepressant response to ketamine at 24 h. This is consistent with the hypothesis that ketamine increases sensitivity to unexpected sensory input and restores deficits in sensitivity to prediction error that are hypothesised to underlie depression. However, the lack of repetition suppression evident in the MMN evoked data compared to studies of healthy adults suggests that, at least within the short term, ketamine does not improve deficits in adaptive internal model calibration.
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Affiliation(s)
| | | | - Meg J Spriggs
- Centre for Psychedelic Research, Department of Medicine, Imperial College London, UK; Brain Research New Zealand; School of Psychology, University of Auckland, New Zealand
| | - Doug Campbell
- Department of Anaesthesia and Perioperative Medicine, Auckland District Health Board, New Zealand
| | - Gemma Malpas
- Department of Anaesthesia and Perioperative Medicine, Auckland District Health Board, New Zealand
| | - Elizabeth Maxwell
- Department of Anaesthesia and Perioperative Medicine, Auckland District Health Board, New Zealand
| | - Carolyn Deng
- Department of Anaesthesia and Perioperative Medicine, Auckland District Health Board, New Zealand
| | - John Hay
- Department of Anaesthesia and Perioperative Medicine, Auckland District Health Board, New Zealand
| | - Rhys Ponton
- School of Pharmacy, University of Auckland, New Zealand
| | - Frederick Sundram
- Department of Psychological Medicine, University of Auckland, New Zealand
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15
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Kirk IJ, Spriggs MJ, Sumner RL. Human EEG and the mechanisms of memory: investigating long-term potentiation (LTP) in sensory-evoked potentials. J R Soc N Z 2020. [DOI: 10.1080/03036758.2020.1780274] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Ian J. Kirk
- Cognitive Neuroscience Research Group, School of Psychology, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, University of Auckland, Auckland, New Zealand
- Brain Research New Zealand, New Zealand
| | - Meg J. Spriggs
- Centre for Psychedelic Research, Division of Brain Sciences, Centre for Psychiatry, Imperial College London, London, UK
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16
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Sumner RL, Spriggs MJ, Muthukumaraswamy SD, Kirk IJ. The role of Hebbian learning in human perception: a methodological and theoretical review of the human Visual Long-Term Potentiation paradigm. Neurosci Biobehav Rev 2020; 115:220-237. [PMID: 32562886 DOI: 10.1016/j.neubiorev.2020.03.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 03/02/2020] [Accepted: 03/12/2020] [Indexed: 11/17/2022]
Abstract
Long-term potentiation (LTP) is one of the most widely studied forms of neural plasticity, and is thought to be the principle mechanism underlying long-term memory and learning in the brain. Sensory paradigms utilising electroencephalography (EEG) and sensory stimulation to induce LTP have allowed translation from rodent and primate invasive research to non-invasive human investigations. This review focusses on visual sensory LTP induced using repetitive visual stimulation, resulting in changes in the visually evoked response recorded at the scalp with EEG. Across 15 years of use and replication in humans several major paradigm variants for eliciting visual LTP have emerged. The application of different paradigms, and the broad implementation of visual LTP across different populations combines to provide a rich and sensitive account of Hebbian LTP, and potentially non-Hebbian plasticity mechanisms. This review will conclude with a discussion of how these findings have advanced existing theories of perceptual learning by positioning Hebbian learning both alongside and within other major theories such as Predictive Coding and The Free Energy Principle.
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Affiliation(s)
| | - Meg J Spriggs
- Centre for Psychedelic Research, Division of Brain Sciences, Centre for Psychiatry, Imperial College London, UK
| | | | - Ian J Kirk
- Brain Research, New Zealand; School of Psychology, University of Auckland, New Zealand
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17
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Maddaluno O, Guidali G, Zazio A, Miniussi C, Bolognini N. Touch anticipation mediates cross-modal Hebbian plasticity in the primary somatosensory cortex. Cortex 2020; 126:173-181. [DOI: 10.1016/j.cortex.2020.01.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/15/2019] [Accepted: 01/07/2020] [Indexed: 12/28/2022]
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18
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GABA-ergic Dynamics in Human Frontotemporal Networks Confirmed by Pharmaco-Magnetoencephalography. J Neurosci 2020; 40:1640-1649. [PMID: 31915255 DOI: 10.1523/jneurosci.1689-19.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 11/25/2019] [Accepted: 12/25/2019] [Indexed: 12/15/2022] Open
Abstract
To bridge the gap between preclinical cellular models of disease and in vivo imaging of human cognitive network dynamics, there is a pressing need for informative biophysical models. Here we assess dynamic causal models (DCM) of cortical network responses, as generative models of magnetoencephalographic observations during an auditory oddball roving paradigm in healthy adults. This paradigm induces robust perturbations that permeate frontotemporal networks, including an evoked 'mismatch negativity' response and transiently induced oscillations. Here, we probe GABAergic influences in the networks using double-blind placebo-controlled randomized-crossover administration of the GABA reuptake inhibitor, tiagabine (oral, 10 mg) in healthy older adults. We demonstrate the facility of conductance-based neural mass mean-field models, incorporating local synaptic connectivity, to investigate laminar-specific and GABAergic mechanisms of the auditory response. The neuronal model accurately recapitulated the observed magnetoencephalographic data. Using parametric empirical Bayes for optimal model inversion across both drug sessions, we identify the effect of tiagabine on GABAergic modulation of deep pyramidal and interneuronal cell populations. We found a transition of the main GABAergic drug effects from auditory cortex in standard trials to prefrontal cortex in deviant trials. The successful integration of pharmaco- magnetoencephalography with dynamic causal models of frontotemporal networks provides a potential platform on which to evaluate the effects of disease and pharmacological interventions.SIGNIFICANCE STATEMENT Understanding human brain function and developing new treatments require good models of brain function. We tested a detailed generative model of cortical microcircuits that accurately reproduced human magnetoencephalography, to quantify network dynamics and connectivity in frontotemporal cortex. This approach identified the effect of a test drug (GABA-reuptake inhibitor, tiagabine) on neuronal function (GABA-ergic dynamics), opening the way for psychopharmacological studies in health and disease with the mechanistic precision afforded by generative models of the brain.
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19
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Burgess JD, Major BP, McNeel C, Clark GM, Lum JAG, Enticott PG. Learning to Expect: Predicting Sounds During Movement Is Related to Sensorimotor Association During Listening. Front Hum Neurosci 2019; 13:215. [PMID: 31333431 PMCID: PMC6624421 DOI: 10.3389/fnhum.2019.00215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 06/11/2019] [Indexed: 11/13/2022] Open
Abstract
Sensory experiences, such as sound, often result from our motor actions. Over time, repeated sound-producing performance can generate sensorimotor associations. However, it is not clear how sensory and motor information are associated. Here, we explore if sensory prediction is associated with the formation of sensorimotor associations during a learning task. We recorded event-related potentials (ERPs) while participants produced index and little finger-swipes on a bespoke device, generating novel sounds. ERPs were also obtained as participants heard those sounds played back. Peak suppression was compared to assess sensory prediction. Additionally, transcranial magnetic stimulation (TMS) was used during listening to generate finger-motor evoked potentials (MEPs). MEPs were recorded before and after training upon hearing these sounds, and then compared to reveal sensorimotor associations. Finally, we explored the relationship between these components. Results demonstrated that an increased positive-going peak (e.g., P2) and a suppressed negative-going peak (e.g., N2) were recorded during action, revealing some sensory prediction outcomes (P2: p = 0.050, ηp2 = 0.208; N2: p = 0.001, ηp2 = 0.474). Increased MEPs were also observed upon hearing congruent sounds compared with incongruent sounds (i.e., associated to a finger), demonstrating precise sensorimotor associations that were not present before learning (Index finger: p < 0.001, ηp2 = 0.614; Little finger: p < 0.001, ηp2 = 0.529). Consistent with our broad hypotheses, a negative association between the MEPs in one finger during listening and ERPs during performance of the other was observed (Index finger MEPs and Fz N1 action ERPs; r = −0.655, p = 0.003). Overall, data suggest that predictive mechanisms are associated with the fine-tuning of sensorimotor associations.
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Affiliation(s)
- Jed D Burgess
- Cognitive Neuroscience Unit, School of Psychology, Deakin University, Geelong, VIC, Australia
| | - Brendan P Major
- Cognitive Neuroscience Unit, School of Psychology, Deakin University, Geelong, VIC, Australia
| | - Claire McNeel
- Cognitive Neuroscience Unit, School of Psychology, Deakin University, Geelong, VIC, Australia
| | - Gillian M Clark
- Cognitive Neuroscience Unit, School of Psychology, Deakin University, Geelong, VIC, Australia
| | - Jarrad A G Lum
- Cognitive Neuroscience Unit, School of Psychology, Deakin University, Geelong, VIC, Australia
| | - Peter G Enticott
- Cognitive Neuroscience Unit, School of Psychology, Deakin University, Geelong, VIC, Australia
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20
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Sumner RL, McMillan R, Spriggs MJ, Campbell D, Malpas G, Maxwell E, Deng C, Hay J, Ponton R, Kirk IJ, Sundram F, Muthukumaraswamy SD. Ketamine Enhances Visual Sensory Evoked Potential Long-term Potentiation in Patients With Major Depressive Disorder. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2019; 5:45-55. [PMID: 31495712 DOI: 10.1016/j.bpsc.2019.07.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/29/2019] [Accepted: 07/01/2019] [Indexed: 12/15/2022]
Abstract
BACKGROUND The rapid-acting clinical effects of ketamine as a novel treatment for depression along with its complex pharmacology have made it a growing research area. One of the key mechanistic hypotheses for how ketamine works to alleviate depression is by enhancing long-term potentiation (LTP)-mediated neural plasticity. METHODS The objective of this study was to investigate the plasticity hypothesis in 30 patients with depression noninvasively using visual LTP as an index of neural plasticity. In a double-blind, active placebo-controlled crossover trial, electroencephalography-based LTP was recorded approximately 3 to 4 hours following a single 0.44-mg/kg intravenous dose of ketamine or active placebo (1.7 ng/mL remifentanil) in 30 patients. Montgomery-Åsberg Depression Rating Scale scores were used to measure clinical symptoms. Visual LTP was measured as a change in the visually evoked potential following high-frequency visual stimulation. Dynamic causal modeling investigated the underlying neural architecture of visual LTP and the contribution of ketamine. RESULTS Montgomery-Åsberg Depression Rating Scale scores revealed that 70% of participants experienced 50% or greater reduction in their depression symptoms within 1 day of receiving ketamine. LTP was demonstrated in the N1 (p = .00002) and P2 (p = 2.31 × 10-11) visually evoked components. Ketamine specifically enhanced P2 potentiation compared with placebo (p = .017). Dynamic causal modeling replicated the recruitment of forward and intrinsic connections for visual LTP and showed complementary effects of ketamine indicative of downstream and proplasticity modulation. CONCLUSIONS This study provides evidence that LTP-based neural plasticity increases within the time frame of the antidepressant effects of ketamine in humans and supports the hypothesis that changes to neural plasticity may be key to the antidepressant properties of ketamine.
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Affiliation(s)
- Rachael L Sumner
- School of Pharmacy, University of Auckland, Auckland, New Zealand.
| | - Rebecca McMillan
- School of Pharmacy, University of Auckland, Auckland, New Zealand
| | - Meg J Spriggs
- School of Psychology, University of Auckland, Auckland, New Zealand; Brain Research New Zealand, Aukland, New Zealand; Centre for Psychedelic Research, Department of Medicine, Imperial College London, London, United Kingdom
| | - Doug Campbell
- Department of Anaesthesia and Perioperative Medicine, Auckland District Health Board, Auckland, New Zealand
| | - Gemma Malpas
- Department of Anaesthesia and Perioperative Medicine, Auckland District Health Board, Auckland, New Zealand
| | - Elizabeth Maxwell
- Department of Anaesthesia and Perioperative Medicine, Auckland District Health Board, Auckland, New Zealand
| | - Carolyn Deng
- Department of Anaesthesia and Perioperative Medicine, Auckland District Health Board, Auckland, New Zealand
| | - John Hay
- Department of Anaesthesia and Perioperative Medicine, Auckland District Health Board, Auckland, New Zealand
| | - Rhys Ponton
- School of Pharmacy, University of Auckland, Auckland, New Zealand
| | - Ian J Kirk
- School of Psychology, University of Auckland, Auckland, New Zealand; Brain Research New Zealand, Aukland, New Zealand
| | - Frederick Sundram
- Department of Psychological Medicine, University of Auckland, Auckland, New Zealand
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21
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Spriggs MJ, Thompson CS, Moreau D, McNair NA, Wu CC, Lamb YN, McKay NS, King ROC, Antia U, Shelling AN, Hamm JP, Teyler TJ, Russell BR, Waldie KE, Kirk IJ. Human Sensory LTP Predicts Memory Performance and Is Modulated by the BDNF Val 66Met Polymorphism. Front Hum Neurosci 2019; 13:22. [PMID: 30828292 PMCID: PMC6384276 DOI: 10.3389/fnhum.2019.00022] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 01/18/2019] [Indexed: 12/16/2022] Open
Abstract
Background: Long-term potentiation (LTP) is recognised as a core neuronal process underlying long-term memory. However, a direct relationship between LTP and human memory performance is yet to be demonstrated. The first aim of the current study was thus to assess the relationship between LTP and human long-term memory performance. With this also comes an opportunity to explore factors thought to mediate the relationship between LTP and long-term memory. The second aim of the current study was to explore the relationship between LTP and memory in groups differing with respect to brain-derived neurotrophic factor (BDNF) Val66Met; a single-nucleotide polymorphism (SNP) implicated in memory function. Methods: Participants were split into three genotype groups (Val/Val, Val/Met, Met/Met) and were presented with both an EEG paradigm for inducing LTP-like enhancements of the visually-evoked response, and a test of visual memory. Results: The magnitude of LTP 40 min after induction was predictive of long-term memory performance. Additionally, the BDNF Met allele was associated with both reduced LTP and reduced memory performance. Conclusions: The current study not only presents the first evidence for a relationship between sensory LTP and human memory performance, but also demonstrates how targeting this relationship can provide insight into factors implicated in variation in human memory performance. It is anticipated that this will be of utility to future clinical studies of disrupted memory function.
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Affiliation(s)
- Meg J Spriggs
- Faculty of Science, School of Psychology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Brain Research New Zealand, Auckland, New Zealand.,Psychedelic Research Group, Division of Brain Sciences, Centre for Psychiatry, Imperial College London, London, United Kingdom
| | - Chris S Thompson
- Faculty of Science, School of Psychology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - David Moreau
- Faculty of Science, School of Psychology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Nicolas A McNair
- Faculty of Science, School of Psychology, University of Auckland, Auckland, New Zealand.,School of Psychology, University of Sydney, Sydney, NSW, Australia
| | - C Carolyn Wu
- Faculty of Science, School of Psychology, University of Auckland, Auckland, New Zealand.,Department of Psychology, University of Trier, Trier, Germany
| | - Yvette N Lamb
- Faculty of Science, School of Psychology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Nicole S McKay
- Faculty of Science, School of Psychology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Rohan O C King
- Faculty of Science, School of Psychology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Ushtana Antia
- Faculty of Medical and Health Sciences, School of Pharmacy, University of Auckland, Auckland, New Zealand.,Boston Scientific, Mascot, NSW, Australia
| | - Andrew N Shelling
- Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Department of Obstetrics & Gynaecology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Jeff P Hamm
- Faculty of Science, School of Psychology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | | | - Bruce R Russell
- Faculty of Medical and Health Sciences, School of Pharmacy, University of Auckland, Auckland, New Zealand.,School of Pharmacy, University of Otago, Dunedin, New Zealand
| | - Karen E Waldie
- Faculty of Science, School of Psychology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Ian J Kirk
- Faculty of Science, School of Psychology, University of Auckland, Auckland, New Zealand.,Centre for Brain Research, University of Auckland, Auckland, New Zealand.,Brain Research New Zealand, Auckland, New Zealand
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22
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Auditory predictions shape the neural responses to stimulus repetition and sensory change. Neuroimage 2019; 186:200-210. [DOI: 10.1016/j.neuroimage.2018.11.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 11/04/2018] [Accepted: 11/07/2018] [Indexed: 01/22/2023] Open
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23
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Sumner RL, Spriggs MJ, McMillan RL, Sundram F, Kirk IJ, Muthukumaraswamy SD. Neural plasticity is modified over the human menstrual cycle: Combined insight from sensory evoked potential LTP and repetition suppression. Neurobiol Learn Mem 2018; 155:422-434. [PMID: 30172951 DOI: 10.1016/j.nlm.2018.08.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 08/18/2018] [Accepted: 08/29/2018] [Indexed: 01/18/2023]
Abstract
In healthy women, fluctuations in hormones including progesterone and oestradiol lead to functional changes in the brain over the course of each menstrual cycle. Though considerable attention has been directed towards understanding changes in human cognition over the menstrual cycle, changes in underlying processes such as neural plasticity have largely only been studied in animals. In this study we explored predictive coding and repetition suppression via the roving mismatch negativity paradigm as a model of short-term plasticity (Garrido, Kilner, Kiebel, et al., 2009), and Hebbian learning via visual sensory long-term potentiation (LTP) as a model of long-term plasticity (Teyler et al., 2005). Electroencephalography (EEG) was recorded in 20 females during their early follicular and mid-luteal phases. Event-related potential (ERP) analyses were complemented with dynamic causal modelling (DCM) to characterise changes in the underlying neural architecture. More sustained variability in the ERP response to a change in tone during the luteal phase are interpreted as a delayed habituation of the P3a component in the luteal relative to the follicular phase. The additional increased forward connection strength over tone repetitions compared to the follicular phase suggests that, in this phase, females may be less efficient when processing deviations from predicted sensory input (error). In contrast, there appears to be no reliable change in sensory LTP. This suggests that predictive coding, but not Hebbian plasticity is modified in the mid-luteal compared to the follicular phase, at least at the days of the menstrual cycle tested. This finding implicates the human menstrual cycle in complex changes in neural plasticity and provides further evidence for the importance of considering the menstrual cycle when including females in electrophysiological research.
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Affiliation(s)
- R L Sumner
- School of Pharmacy, The University of Auckland, Auckland, New Zealand.
| | - M J Spriggs
- School of Psychology, The University of Auckland, Auckland, New Zealand; Brain Research New Zealand, New Zealand
| | - R L McMillan
- School of Pharmacy, The University of Auckland, Auckland, New Zealand
| | - F Sundram
- Department of Psychological Medicine, The University of Auckland, Auckland, New Zealand
| | - I J Kirk
- School of Psychology, The University of Auckland, Auckland, New Zealand; Brain Research New Zealand, New Zealand
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