1
|
Mograbi DC, Rodrigues R, Bienemann B, Huntley J. Brain Networks, Neurotransmitters and Psychedelics: Towards a Neurochemistry of Self-Awareness. Curr Neurol Neurosci Rep 2024; 24:323-340. [PMID: 38980658 DOI: 10.1007/s11910-024-01353-y] [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] [Accepted: 06/17/2024] [Indexed: 07/10/2024]
Abstract
PURPOSE OF REVIEW Self-awareness can be defined as the capacity of becoming the object of one's own awareness and, increasingly, it has been the target of scientific inquiry. Self-awareness has important clinical implications, and a better understanding of the neurochemical basis of self-awareness may help clarifying causes and developing interventions for different psychopathological conditions. The current article explores the relationship between neurochemistry and self-awareness, with special attention to the effects of psychedelics. RECENT FINDINGS The functioning of self-related networks, such as the default-mode network and the salience network, and how these are influenced by different neurotransmitters is discussed. The impact of psychedelics on self-awareness is reviewed in relation to specific processes, such as interoception, body ownership, agency, metacognition, emotional regulation and autobiographical memory, within a framework based on predictive coding. Improved outcomes in emotional regulation and autobiographical memory have been observed in association with the use of psychedelics, suggesting higher-order self-awareness changes, which can be modulated by relaxation of priors and improved coping mechanisms linked to cognitive flexibility. Alterations in bodily self-awareness are less consistent, being potentially impacted by doses employed, differences in acute/long-term effects and the presence of clinical conditions. Future studies investigating the effects of different molecules in rebalancing connectivity between resting-state networks may lead to novel therapeutic approaches and the refinement of existing treatments.
Collapse
Affiliation(s)
- Daniel C Mograbi
- Department of Psychology, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, Brazil.
- Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
| | - Rafael Rodrigues
- Department of Psychology, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Bheatrix Bienemann
- Department of Psychology, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Jonathan Huntley
- Division of Psychiatry, University College London, London, UK
- Wellcome Centre for Human Neuroimaging, University College London, London, UK
| |
Collapse
|
2
|
Bao Z, Burhan A, Frewen P. Transcranial direct current stimulation over medial prefrontal cortex reduced alpha power and functional connectivity during somatic but not semantic self-referential processing. Neuroscience 2024:S0306-4522(24)00279-3. [PMID: 38944148 DOI: 10.1016/j.neuroscience.2024.06.022] [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: 11/20/2023] [Revised: 06/14/2024] [Accepted: 06/22/2024] [Indexed: 07/01/2024]
Abstract
Past self-report and cognitive-behavioural studies of the effects of transcranial direct current stimulation (tDCS) targeting the medial prefrontal cortex (mPFC) on semantic self-referential processing (SRP) have yielded mixed results. Meanwhile, electroencephalography (EEG) studies show that alpha oscillation (8-12 Hz) may be involved during both semantic and somatic SRP, although the effect of tDCS on alpha-EEG during SRP remains unknown. The current study assessed the EEG and subjective effects of 2 mA tDCS over the mPFC while participants were SRP either on semantic (life roles, e.g., "friend") or somatic (outer body, e.g., "arms") self-referential stimuli compared to resting state and an external attention memory task in 52 young adults. Results showed that whereas mPFC-tDCS did not yield significant changes in participants' mood or experienced attention or pleasantness levels during the SRP task, EEG source analysis indicated, compared to sham stimulation, that tDCS reduced alpha power during somatic but not semantic SRP in the posterior cingulate cortex (PCC), and the frontal, parietal, temporal, and somatosensory cortex, and reduced the functional connectivity between the left inferior parietal lobule and the ventral PCC, but only when mPFC-tDCS was applied at the second while not the first experimental session. Our results suggest that while mPFC-tDCS may be insufficient to alter immediate subjective experience during SRP, mPFC-tDCS may modulate the power and functional connectivity of the brain's alpha oscillations during somatic SRP. Future research directions are discussed.
Collapse
Affiliation(s)
- Zhongjie Bao
- Interdisciplinary Program in Neuroscience, Western University, London, ON, Canada
| | - Amer Burhan
- Interdisciplinary Program in Neuroscience, Western University, London, ON, Canada; Ontario Shores Centre for Mental Health Sciences, Whitby, ON, Canada; Department of Psychiatry, Temerty School of Medicine, University of Toronto, Whitby, ON, Canada
| | - Paul Frewen
- Interdisciplinary Program in Neuroscience, Western University, London, ON, Canada; Department of Psychiatry, Schulich School of Medicine and Dentistry, London, ON, Canada.
| |
Collapse
|
3
|
Gu SJ, Aimufua I, Pagliaccio D, Shankman SA, Steinglass JE, Auerbach RP, Walsh BT, Ranzenhofer LM. Self-referential processing in anorexia nervosa. Int J Eat Disord 2024; 57:1234-1244. [PMID: 38436447 PMCID: PMC11093709 DOI: 10.1002/eat.24176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 02/12/2024] [Accepted: 02/12/2024] [Indexed: 03/05/2024]
Abstract
OBJECTIVE Anorexia nervosa (AN) is a serious psychiatric illness associated with significant medical and psychiatric comorbidity and impairment. Theoretical models of AN and self-report studies suggest that negative self-evaluation (i.e., low self-esteem) is related to the development and maintenance of AN. The goal of this study was to extend findings from self-report methodology using a neurocognitive task that probes self-evaluation implicitly and explicitly. METHOD We compared female adolescent and adult patients with AN (n = 35) and healthy controls (HC, n = 38) on explicit (i.e., endorsement of words as self-relevant), implicit (recall, recognition, reaction time), and composite (i.e., valence index, bias score, drift rates) indices of self-evaluation. We applied a drift-diffusion model to compute the drift rates, reflecting participants' decision-making process as to whether words were self-relevant. The association between self-evaluation indices and eating disorder severity was examined. RESULTS There were significant Group × Condition interaction effects for all explicit and implicit measures (all p's ≤ .01), where the AN group endorsed, recalled, and recognized more negative relative to positive words than HC. The AN group had more negative valence index and bias scores, and slower drift rate away from negative words, reflecting more negative self-evaluation. The finding for recall was attenuated when individuals with depression were excluded. Measures of self-evaluation bias were not related to eating disorder severity. DISCUSSION Using a neurocognitive approach that includes explicit and implicit indices of bias, results suggest that patients with AN have more negative self-evaluation. Due to the cross-sectional design, additional studies are needed to further evaluate directionality. PUBLIC SIGNIFICANCE Negative self-evaluation/low self-esteem is thought to contribute to eating disorder symptoms. Findings of this study using a neurocognitive task to probe self-evaluation suggested that individuals with anorexia nervosa have more negative self-evaluation, reflected by endorsing and remembering more negative (than positive) words compared to healthy controls, and doing so faster. Targeting the construct of negative self-evaluation in treatment of AN may be warranted.
Collapse
Affiliation(s)
- Serena J. Gu
- New York State Psychiatric Institute, New York, New York, USA
| | - Ivieosa Aimufua
- New York State Psychiatric Institute, New York, New York, USA
| | - David Pagliaccio
- New York State Psychiatric Institute, New York, New York, USA
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York, USA
| | - Stewart A. Shankman
- Department of Psychiatry and Behavioral Sciences, Northwestern University, Chicago, Illinois, USA
| | - Joanna E. Steinglass
- New York State Psychiatric Institute, New York, New York, USA
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York, USA
| | - Randy P. Auerbach
- New York State Psychiatric Institute, New York, New York, USA
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York, USA
| | - B. Timothy Walsh
- New York State Psychiatric Institute, New York, New York, USA
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York, USA
| | - Lisa M. Ranzenhofer
- New York State Psychiatric Institute, New York, New York, USA
- Department of Psychiatry, Columbia University Irving Medical Center, New York, New York, USA
| |
Collapse
|
4
|
Hu Y, Pan Y, Yue L, Gao X. Self-objectification and eating disorders: the psychopathological and neural processes from psychological distortion to psychosomatic illness. PSYCHORADIOLOGY 2024; 4:kkae003. [PMID: 38666139 PMCID: PMC10946225 DOI: 10.1093/psyrad/kkae003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Revised: 01/30/2024] [Accepted: 02/27/2024] [Indexed: 04/28/2024]
Affiliation(s)
- Yinying Hu
- Department of Applied Psychology, School of Psychology, Shanghai Normal University, Shanghai, Shanghai 200234, China
| | - Yafeng Pan
- Department of Psychology and Behavioral Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
- The State Key Lab of Brain-Machine Intelligence, Zhejiang University, Hangzhou, Zhejaing 310058, China
| | - Liming Yue
- Department of Applied Psychology, School of Psychology, Shanghai Normal University, Shanghai, Shanghai 200234, China
| | - Xiangping Gao
- Department of Applied Psychology, School of Psychology, Shanghai Normal University, Shanghai, Shanghai 200234, China
- Shanghai Institute of Early Childhood Education, Shanghai Normal University, Shanghai, Shanghai 200234, China
| |
Collapse
|
5
|
Jamieson AJ, Harrison BJ, Delahoy R, Schmaal L, Felmingham KL, Phillips L, Davey CG. A brain model of altered self-appraisal in social anxiety disorder. Transl Psychiatry 2023; 13:344. [PMID: 37951951 PMCID: PMC10640593 DOI: 10.1038/s41398-023-02644-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 10/23/2023] [Accepted: 10/30/2023] [Indexed: 11/14/2023] Open
Abstract
The brain's default mode network has a central role in the processing of information concerning oneself. Dysfunction in this self-referential processing represents a key component of multiple mental health conditions, particularly social anxiety disorder (SAD). This case-control study aimed to clarify alterations to network dynamics present during self-appraisal in SAD participants. A total of 38 adolescents and young adults with SAD and 72 healthy control participants underwent a self-referential processing fMRI task. The task involved two primary conditions of interest: direct self-appraisal (thinking about oneself) and reflected self-appraisal (thinking about how others might think about oneself). Dynamic causal modeling and parametric empirical Bayes were then used to explore differences in the effective connectivity of the default mode network between groups. We observed connectivity differences between SAD and healthy control participants in the reflected self-appraisal but not the direct self-appraisal condition. Specifically, SAD participants exhibited greater excitatory connectivity from the posterior cingulate cortex (PCC) to medial prefrontal cortex (MPFC) and greater inhibitory connectivity from the inferior parietal lobule (IPL) to MPFC. In contrast, SAD participants exhibited reduced intrinsic connectivity in the absence of task modulation. This was illustrated by reduced excitatory connectivity from the PCC to MPFC and reduced inhibitory connectivity from the IPL to MPFC. As such, participants with SAD showed changes to afferent connections to the MPFC which occurred during both reflected self-appraisal as well as intrinsically. The presence of connectivity differences in reflected and not direct self-appraisal is consistent with the characteristic fear of negative social evaluation that is experienced by people with SAD.
Collapse
Affiliation(s)
- Alec J Jamieson
- Department of Psychiatry, The University of Melbourne, Parkville, VIC, Australia.
| | - Ben J Harrison
- Department of Psychiatry, The University of Melbourne, Parkville, VIC, Australia
| | - Rebekah Delahoy
- Department of Psychiatry, The University of Melbourne, Parkville, VIC, Australia
| | - Lianne Schmaal
- Orygen, Parkville, VIC, Australia
- Centre for Youth Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Kim L Felmingham
- Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, VIC, Australia
| | - Lisa Phillips
- Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, VIC, Australia
| | - Christopher G Davey
- Department of Psychiatry, The University of Melbourne, Parkville, VIC, Australia.
| |
Collapse
|
6
|
Menon V. 20 years of the default mode network: A review and synthesis. Neuron 2023; 111:2469-2487. [PMID: 37167968 PMCID: PMC10524518 DOI: 10.1016/j.neuron.2023.04.023] [Citation(s) in RCA: 48] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/04/2023] [Accepted: 04/20/2023] [Indexed: 05/13/2023]
Abstract
The discovery of the default mode network (DMN) has revolutionized our understanding of the workings of the human brain. Here, I review developments that led to the discovery of the DMN, offer a personal reflection, and consider how our ideas of DMN function have evolved over the past two decades. I summarize literature examining the role of the DMN in self-reference, social cognition, episodic and autobiographical memory, language and semantic memory, and mind wandering. I identify unifying themes and propose new perspectives on the DMN's role in human cognition. I argue that the DMN integrates and broadcasts memory, language, and semantic representations to create a coherent "internal narrative" reflecting our individual experiences. This narrative is central to the construction of a sense of self, shapes how we perceive ourselves and interact with others, may have ontogenetic origins in self-directed speech during childhood, and forms a vital component of human consciousness.
Collapse
Affiliation(s)
- Vinod Menon
- Department of Psychiatry & Behavioral Sciences and Department of Neurology & Neurological Sciences, Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, USA.
| |
Collapse
|
7
|
Leonards CA, Harrison BJ, Jamieson AJ, Steward T, Lux S, Philipsen A, Davey CG. A distinct intra-individual suppression subnetwork in the brain's default mode network across cognitive tasks. Cereb Cortex 2023; 33:4553-4561. [PMID: 36130087 PMCID: PMC10110429 DOI: 10.1093/cercor/bhac361] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 08/17/2022] [Accepted: 08/18/2022] [Indexed: 11/13/2022] Open
Abstract
Suppression of the brain's default mode network (DMN) during external goal-directed cognitive tasks has been consistently observed in neuroimaging studies. However, emerging insights suggest the DMN is not a monolithic "task-negative" network but is comprised of subsystems that show functional heterogeneity. Despite considerable research interest, no study has investigated the consistency of DMN activity suppression across multiple cognitive tasks within the same individuals. In this study, 85 healthy 15- to 25-year-olds completed three functional magnetic resonance imaging tasks that were designed to reliably map DMN suppression from a resting baseline. Our findings revealed a distinct suppression subnetwork across the three tasks that comprised traditional DMN and adjacent regions. Specifically, common suppression was observed in the medial prefrontal cortex, the dorsal-to-mid posterior cingulate cortex extending to the precuneus, and the posterior insular cortex and parietal operculum. Further, we found the magnitude of suppression of these regions were significantly correlated within participants across tasks. Overall, our findings indicate that externally oriented cognitive tasks elicit common suppression of a distinct subnetwork of the broader DMN. The consistency to which the DMN is suppressed within individuals suggests a domain-general mechanism that may reflect a stable feature of cognitive function that optimizes external goal-directed behavior.
Collapse
Affiliation(s)
- Christine A Leonards
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Ben J Harrison
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Alec J Jamieson
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Trevor Steward
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne, Parkville, Victoria, 3010, Australia
- Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Silke Lux
- Department of Psychiatry and Psychotherapy, University of Bonn, Bonn, 53127, Germany
| | - Alexandra Philipsen
- Department of Psychiatry and Psychotherapy, University of Bonn, Bonn, 53127, Germany
| | - Christopher G Davey
- Department of Psychiatry, The University of Melbourne, Parkville, Victoria, 3010, Australia
| |
Collapse
|
8
|
McAdams CJ, Efseroff B, McCoy J, Ford L, Timko CA. Social Processing in Eating Disorders: Neuroimaging Paradigms and Research Domain Organizational Constructs. Curr Psychiatry Rep 2022; 24:777-788. [PMID: 36417153 PMCID: PMC10373941 DOI: 10.1007/s11920-022-01395-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/29/2022] [Indexed: 11/24/2022]
Abstract
PURPOSE OF REVIEW Social and environmental factors have been related to both symptom expression of disordered eating in individuals and changes in the prevalence of eating disorders (EDs) in populations. Neural differences in processing social information may contribute to EDs. This review assesses the evidence for aberrant neural responses during social processing in EDs. RECENT FINDINGS This review examines how constructs within the social processing domain have been evaluated by neuroimaging paradigms in EDs, including communication, affiliation, and understanding of both oneself and others. Differences related to social processing in EDs include altered processing for self-relevant stimuli, in the context of identity, valence, expectations, and affiliative relationships. Future work is needed to integrate how differences in processing social stimuli relate to alterations in cognitive control and reward as well as specific disordered eating symptoms.
Collapse
Affiliation(s)
- Carrie J McAdams
- Department of Psychiatry, University of Texas at Southwestern Medical School, 6363 Forest Park Rd BL6.204, Dallas, TX, 75390, USA.
| | - Brayden Efseroff
- Department of Psychiatry, University of Texas at Southwestern Medical School, 6363 Forest Park Rd BL6.204, Dallas, TX, 75390, USA
| | - Jordan McCoy
- Department of Psychiatry, University of Texas at Southwestern Medical School, 6363 Forest Park Rd BL6.204, Dallas, TX, 75390, USA
| | - Lauren Ford
- Department of Psychiatry, University of Texas at Southwestern Medical School, 6363 Forest Park Rd BL6.204, Dallas, TX, 75390, USA
| | - C Alix Timko
- Department of Child and Adolescent Psychiatry and Behavioral Health, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, 2716 South Street, Philadelphia, PA, 19146, USA
| |
Collapse
|
9
|
Ljubisavljevic M, Basha J, Ismail FY. The effects of prefrontal vs. parietal cortex transcranial direct current stimulation on craving, inhibition, and measures of self-esteem. Front Neurosci 2022; 16:998875. [DOI: 10.3389/fnins.2022.998875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 10/10/2022] [Indexed: 11/13/2022] Open
Abstract
While prefrontal cortex dysfunction has been implicated in high food cravings, other cortical regions, like the parietal cortex, are potentially also involved in regulating craving. This study explored the effects of stimulating the inferior parietal lobule (IPL) and dorsolateral prefrontal cortex (DLPFC) on food craving state and trait. Transcranial direct current stimulation (tDCS) was administered at 1.5 mA for 5 consecutive days. Participants received 20 min of IPL, DLPFC, or sham stimulation (SHAM) each day which consisted of two rounds of 10-min stimulation, divided by a 10-min mindfulness task break. In addition, we studied inhibition and subjective psychological aspects like body image and self-esteem state and trait. To decompose immediate and cumulative effects, we measured the following on days 1 and 5: inhibition through the Go/No-go task; and food craving, self-esteem, and body appreciation through a battery of questionnaires. We found that false alarm errors decreased in the participants receiving active stimulation in the DLPFC (DLPFC-group). In contrast, false alarm errors increased in participants receiving active stimulation in the IPL (IPL-group). At the same time, no change was found in the participants receiving SHAM (SHAM-group). There was a trending reduction in craving trait in all groups. Momentary craving was decreased in the DLPFC-group and increased in IPL-group, yet a statistical difference was not reached. According to time and baseline, self-esteem and body perception improved in the IPL-group. Furthermore, self-esteem trait significantly improved over time in the DLPFC-group and IPL-group. These preliminary results indicate that tDCS modulates inhibition in frontoparietal areas with opposite effects, enhancing it in DLPFC and impairing it in IPL. Moreover, craving is moderately linked to inhibition, self-esteem, and body appreciation which seem not to be affected by neuromodulation but may rely instead on broader regions as more complex constructs. Finally, the fractionated protocol can effectively influence inhibition with milder effects on other constructs.
Collapse
|