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Rasmussen T, Filmer HL, Dux PE. On the role of prefrontal and parietal cortices in mind wandering and dynamic thought. Cortex 2024; 178:249-268. [PMID: 39053349 DOI: 10.1016/j.cortex.2024.06.017] [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: 11/08/2023] [Revised: 01/08/2024] [Accepted: 06/27/2024] [Indexed: 07/27/2024]
Abstract
Mind wandering is a common phenomenon in our daily lives and can have both an adaptive and detrimental impact. Recently, a dynamic framework has been proposed to characterise the heterogeneity of internal thoughts, suggesting there are three distinct thought types which can change over time - freely moving, deliberately constrained, and automatically constrained (thoughts). There is currently very little evidence on how different types of dynamic thought are represented in the brain. Previous research has applied non-invasive transcranial direct current stimulation (tDCS) to causally implicate the prefrontal cortex and inferior parietal lobule in mind wandering. However, a more recently developed and nuanced technique, high-definition tDCS (HD-tDCS), delivers more focal stimulation able to target specific brain regions. Therefore, the current study investigated the effect of anodal HD-tDCS applied to the left prefrontal and right inferior parietal cortices (with the occipital cortex included as an active control) on mind wandering, and specifically, the causal neural substrates of the three internal dynamic thought types. This was a single session study using a novel task which allows investigation into how dynamic thoughts are associated with behavioural variability and the recruitment of executive control operations across the three brain regions. There was no evidence to support our hypothesised effect of stimulation reducing task unrelated thought. Furthermore, the hypothesis driven analyses found no evidence of stimulation affecting the dynamic thought types, nor any evidence for our hypothesised effects of stimulation reducing behavioural variability and increasing randomness. There was only evidence for a relationship between these two measures of performance when participants thoughts were freely moving. However, there was evidence from our exploratory analyses that anodal stimulation to the prefrontal cortex decreased freely moving thought and anodal stimulation to the parietal lobule decreased deliberately constrained thought, relative to the sham conditions. The exploratory analyses also suggested stimulation may increase freely moving thought in the occipital cortex. Overall, these findings suggest stimulation does not affect the dynamic thought types, however there is preliminary evidence to support the heterogenous nature of mind wandering, whereby different brain regions may be causally implicated in distinct dynamic thought types.
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Affiliation(s)
- Tara Rasmussen
- School of Psychology, The University of Queensland, Australia.
| | - Hannah L Filmer
- School of Psychology, The University of Queensland, Australia
| | - Paul E Dux
- School of Psychology, The University of Queensland, Australia
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Kucyi A, Kam JWY, Andrews-Hanna JR, Christoff K, Whitfield-Gabrieli S. Recent advances in the neuroscience of spontaneous and off-task thought: implications for mental health. NATURE MENTAL HEALTH 2023; 1:827-840. [PMID: 37974566 PMCID: PMC10653280 DOI: 10.1038/s44220-023-00133-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/25/2023] [Indexed: 11/19/2023]
Abstract
People spend a remarkable 30-50% of awake life thinking about something other than what they are currently doing. These experiences of being "off-task" can be described as spontaneous thought when mental dynamics are relatively flexible. Here we review recent neuroscience developments in this area and consider implications for mental wellbeing and illness. We provide updated overviews of the roles of the default mode network and large-scale network dynamics, and we discuss emerging candidate mechanisms involving hippocampal memory (sharp-wave ripples, replay) and neuromodulatory (noradrenergic and serotonergic) systems. We explore how distinct brain states can be associated with or give rise to adaptive and maladaptive forms of thought linked to distinguishable mental health outcomes. We conclude by outlining new directions in the neuroscience of spontaneous and off-task thought that may clarify mechanisms, lead to personalized biomarkers, and facilitate therapy developments toward the goals of better understanding and improving mental health.
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Affiliation(s)
- Aaron Kucyi
- Department of Psychological and Brain Sciences, Drexel University
| | - Julia W. Y. Kam
- Department of Psychology and Hotchkiss Brain Institute, University of Calgary
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Nejati V, Zamiran B, Nitsche MA. The Interaction of the Dorsolateral and Ventromedial Prefrontal Cortex During Mind Wandering. Brain Topogr 2023:10.1007/s10548-023-00970-z. [PMID: 37202646 DOI: 10.1007/s10548-023-00970-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 05/05/2023] [Indexed: 05/20/2023]
Abstract
BACKGROUND AND AIMS Mind wandering refers to spontaneously occurring, often disruptive thoughts during an ongoing task or resting state. The ventromedial prefrontal cortex (vmPFC) and dorsolateral prefrontal cortex (dlPFC) are two main cortical areas which are involved in this process. This study aimed to explore the interaction of these areas during mind wandering by enhancing specific oscillatory activity of these areas via transcranial alternating current stimulation (tACS) in the theta frequency range. MATERIAL AND METHODS Eighteen healthy adults participated in a randomized, single-blinded, crossover study. tACS (1.5 mA, 6 Hz) was applied in five sessions with one week interval via (1) two channels with synchronized stimulation over the left dlPFC and right vmPFC, (2) the same electrode placement with anti-phase stimulation, (3) stimulation over the left dlPFC only, (4) stimulation over right vmPFC only, and (5) sham stimulation. The return electrodes were placed over the contralateral shoulder in all conditions. The sustained attention to response task (SART) with embedded probes about task-unrelated-thoughts and awareness of these thoughts was performed during intervention. RESULTS Stimulation did not alter SART performance. Right vmPFC stimulation decreased mind wandering and increased awareness of mind wandering. Left dlPFC stimulation and desynchronized stimulation over the dlPFC and vmPFC increased mind wandering compared to the sham stimulation condition. Synchronized stimulation had no effect on mind wandering, but increased awareness of mind wandering. CONCLUSION The results suggest that regional entrainment of the vmPFC decreases mind wandering and increases awareness of mind wandering, whereas regional entrainment of the dlPFC increases mind wandering, but decreases awareness. Under desynchronized stimulation of both areas, the propensity of mind wandering was increased, whereas synchronized stimulation increased the awareness of mind wandering. These results suggest a role of the dlPFC in initiation of mind wandering, whereas the vmPFC downregulates mind wandering, and might exert this function by counteracting respective dlPFC effects via theta oscillations.
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Affiliation(s)
- Vahid Nejati
- Department of Psychology, Shahid Beheshti University Tehran, Tehran, Iran.
| | - Bahar Zamiran
- Department of Psychology, Shahid Beheshti University Tehran, Tehran, Iran
| | - Michael A Nitsche
- Leibniz Research Centre for Working Environment and Human Factors, Department of Psychology and Neurosciences, Dortmund, Germany
- Department of Neurology, University Medical Hospital Bergmannsheil, Bochum, Germany
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Martínez-Pérez V, Andreu A, Sandoval-Lentisco A, Tortajada M, Palmero LB, Castillo A, Campoy G, Fuentes LJ. Vigilance decrement and mind-wandering in sustained attention tasks: Two sides of the same coin? Front Neurosci 2023; 17:1122406. [PMID: 37056308 PMCID: PMC10086236 DOI: 10.3389/fnins.2023.1122406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 03/10/2023] [Indexed: 03/30/2023] Open
Abstract
BackgroundDecrements in performance and the propensity for increased mind-wandering (i.e., task-unrelated thoughts) across time-on-task are two pervasive phenomena observed when people perform vigilance tasks. In the present study, we asked whether processes that lead to vigilance decrement and processes that foster the propensity for mind-wandering (MW) can be dissociated or whether they share a common mechanism. In one experiment, we introduced two critical manipulations: increasing task demands and applying anodal high-definition transcranial direct current stimulation (HD-tDCS) to the left dorsolateral prefrontal cortex.MethodSeventy-eight participants were randomly assigned to one of four groups resulting from the factorial combination of task demand (low, high) and stimulation (anodal, sham). Participants completed the sustained attention to response task (SART), which included thought probes on intentional and unintentional MW. In addition, we investigated the crucial role of alpha oscillations in a novel approach. By assessing pre-post resting EEG, we explored whether participants’ variability in baseline alpha power predicted performance in MW and vigilance decrement related to tDCS or task demands, respectively, and whether such variability was a stable characteristic of participants.ResultsOur results showed a double dissociation, such that task demands exclusively affected vigilance decrement, while anodal tDCS exclusively affected the rate of MW. Furthermore, the slope of the vigilance decrement function and MW rate (overall, intentional and unintentional) did not correlate. Critically, resting state alpha-band activity predicted tDCS-related gains in unintentional MW alone, but not in vigilance decrement, and remained stable after participants completed the task.ConclusionThese results show that when a sustained attention task involving executive vigilance, such as the SART, is designed to elicit both vigilance decrement effects and MW, the processes leading to vigilance decrement should be differentiated from those responsible for MW, a claim that is supported by the double dissociation observed here and the lack of correlation between the measures chosen to assess both phenomena. Furthermore, the results provide the first evidence of how individual differences in alpha power at baseline may be of crucial importance in predicting the effects of tDCS on MW propensity.
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Nawani H, Mittner M, Csifcsák G. Modulation of mind wandering using transcranial direct current stimulation: A meta-analysis based on electric field modeling. Neuroimage 2023; 272:120051. [PMID: 36965860 DOI: 10.1016/j.neuroimage.2023.120051] [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: 11/16/2022] [Revised: 03/03/2023] [Accepted: 03/22/2023] [Indexed: 03/27/2023] Open
Abstract
Mind wandering (MW) is a heterogeneous construct involving task-unrelated thoughts. Recently, the interest in modulating MW propensity via non-invasive brain stimulation techniques has increased. Single-session transcranial direct current stimulation (tDCS) in healthy controls has led to mixed results in modulating MW propensity, possibly due to methodological heterogeneity. Therefore, our aim was to conduct a systematic meta-analysis to examine the influence of left dorsolateral prefrontal cortex (lDLPFC) and right inferior parietal lobule (rIPL) targeted tDCS on MW propensity. Importantly, by computational modeling of tDCS-induced electric fields, we accounted for differences in tDCS-dose across studies that varied strongly in their applied methodology. Fifteen single-session, sham-controlled tDCS studies published until October 2021 were included. All studies involved healthy adult participants and used cognitive tasks combined with MW thought-probes. Heterogeneity in tDCS electrode placement, stimulation polarity and intensity were controlled for by means of electric field simulations, while overall methodological quality was assessed via an extended risk of bias (RoB) assessment. We found that RoB was the strongest predictor of study outcomes. Moreover, the rIPL was the most promising cortical area for influencing MW, with stronger anodal electric fields in this region being negatively associated with MW propensity. Electric field strength in the lDLPFC was not related to MW propensity. We identified several severe methodological problems that could have contributed to overestimated effect sizes in this literature, an issue that needs urgent attention in future research in this area. Overall, there is no reliable evidence for tDCS influencing MW in the healthy. However, the analysis also revealed that increasing neural excitability in the rIPL via tDCS might be associated with reduced MW propensity. In an exploratory approach, we also found some indication that targeting prefrontal regions outside the lDLPFC with tDCS could lead to increased MW propensity.
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Affiliation(s)
- Hema Nawani
- Institute for Psychology, UiT The Arctic University of Norway.
| | | | - Gábor Csifcsák
- Institute for Psychology, UiT The Arctic University of Norway.
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Coulborn S, Fernández-Espejo D. Prefrontal tDCS is unable to modulate mind wandering propensity or underlying functional or effective brain connectivity. Sci Rep 2022; 12:18021. [PMID: 36289366 PMCID: PMC9606118 DOI: 10.1038/s41598-022-22893-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 10/20/2022] [Indexed: 01/24/2023] Open
Abstract
There is conflicting evidence over the ability to modulate mind-wandering propensity with anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (prefrontal tDCS). Here, 20 participants received 20-min of active and sham prefrontal tDCS while in the MRI scanner, in two separate sessions (counterbalanced). In each session, they completed two runs of a sustained attention to response task (before and during tDCS), which included probes recording subjective responses of mind-wandering. We assessed the effects of tDCS on behavioural responses as well as functional and effective dynamics, via dynamic functional network connectivity (dFNC) and dynamic causal modelling analyses over regions of the default mode, salience and executive control networks. Behavioural results provided substantial evidence in support of no effect of tDCS on task performance nor mind-wandering propensity. Similarly, we found no effect of tDCS on frequency (how often) or dwell time (time spent) of underlying brain states nor effective connectivity. Overall, our results suggest that prefrontal tDCS is unable to modulate mind-wandering propensity or influence underlying brain function. This expands previous behavioural replication failures in suggesting that prefrontal tDCS may not lead to even subtle (i.e., under a behavioural threshold) changes in brain activity during self-generated cognition.
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Affiliation(s)
- Sean Coulborn
- School of Psychology, University of Birmingham, Birmingham, UK
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK
- University of California, Berkeley, USA
| | - Davinia Fernández-Espejo
- School of Psychology, University of Birmingham, Birmingham, UK.
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK.
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Self-reported mind wandering reflects executive control and selective attention. Psychon Bull Rev 2022; 29:2167-2180. [PMID: 35672655 DOI: 10.3758/s13423-022-02110-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2022] [Indexed: 11/08/2022]
Abstract
Mind wandering is ubiquitous in everyday life and has a pervasive and profound impact on task-related performance. A range of psychological processes have been proposed to underlie these performance-related decrements, including failures of executive control, volatile information processing, and shortcomings in selective attention to critical task-relevant stimuli. Despite progress in the development of such theories, existing descriptive analyses have limited capacity to discriminate between the theories. We propose a cognitive-model based analysis that simultaneously explains self-reported mind wandering and task performance. We quantitatively compare six explanations of poor performance in the presence of mind wandering. The competing theories are distinguished by whether there is an impact on executive control and, if so, how executive control acts on information processing, and whether there is an impact on volatility of information processing. Across two experiments using the sustained attention to response task, we find quantitative evidence that mind wandering is associated with two latent factors. Our strongest conclusion is that executive control is impaired: increased mind wandering is associated with reduced ability to inhibit habitual response tendencies. Our nuanced conclusion is that executive control deficits manifest in reduced ability to selectively attend to the information value of rare but task-critical events.
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Kam JWY, Mittner M, Knight RT. Mind-wandering: mechanistic insights from lesion, tDCS, and iEEG. Trends Cogn Sci 2022; 26:268-282. [PMID: 35086725 PMCID: PMC9166901 DOI: 10.1016/j.tics.2021.12.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 01/04/2023]
Abstract
Cognitive neuroscience has witnessed a surge of interest in investigating the neural correlates of the mind when it drifts away from an ongoing task and the external environment. To that end, functional neuroimaging research has consistently implicated the default mode network (DMN) and frontoparietal control network (FPCN) in mind-wandering. Yet, it remains unknown which subregions within these networks are necessary and how they facilitate mind-wandering. In this review, we synthesize evidence from lesion, transcranial direct current stimulation (tDCS), and intracranial electroencephalogram (iEEG) studies demonstrating the causal relevance of brain regions, and providing insights into the neuronal mechanism underlying mind-wandering. We propose that the integration of complementary approaches is the optimal strategy to establish a comprehensive understanding of the neural basis of mind-wandering.
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Affiliation(s)
- Julia W Y Kam
- Department of Psychology, University of Calgary, Calgary, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Canada.
| | | | - Robert T Knight
- Department of Psychology, University of California Berkeley, Berkeley, CA, USA; Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, USA
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He F, Li Y, Li C, Fan L, Liu T, Wang J. Repeated anodal high-definition transcranial direct current stimulation over the left dorsolateral prefrontal cortex in mild cognitive impairment patients increased regional homogeneity in multiple brain regions. PLoS One 2021; 16:e0256100. [PMID: 34388179 PMCID: PMC8363005 DOI: 10.1371/journal.pone.0256100] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 07/31/2021] [Indexed: 01/10/2023] Open
Abstract
Transcranial direct current stimulation (tDCS) can improve cognitive function. However, it is not clear how high-definition tDCS (HD-tDCS) regulates the cognitive function and its neural mechanism, especially in individuals with mild cognitive impairment (MCI). This study aimed to examine whether HD-tDCS can modulate cognitive function in individuals with MCI and to determine whether the potential variety is related to spontaneous brain activity changes recorded by resting-state functional magnetic resonance imaging (rs-fMRI). Forty-three individuals with MCI were randomly assigned to receive either 10 HD-tDCS sessions or 10 sham sessions to the left dorsolateral prefrontal cortex (L-DLPFC). The fractional amplitude of low-frequency fluctuation (fALFF) and the regional homogeneity (ReHo) was computed using rs-fMRI data from all participants. The results showed that the fALFF and ReHo values changed in multiple areas following HD-tDCS. Brain regions with significant decreases in fALFF values include the Insula R, Precuneus R, Thalamus L, and Parietal Sup R, while the Temporal Inf R, Fusiform L, Occipital Sup L, Calcarine R, and Angular R showed significantly increased in their fALFF values. The brain regions with significant increases in ReHo values include the Temporal Inf R, Putamen L, Frontal Mid L, Precentral R, Frontal Sup Medial L, Frontal Sup R, and Precentral L. We found that HD-tDCS can alter the intensity and synchrony of brain activity, and our results indicate that fALFF and ReHo analysis are sensitive indicators for the detection of HD-tDCS during spontaneous brain activity. Interestingly, HD-tDCS increases the ReHo values of multiple brain regions, which may be related to the underlying mechanism of its clinical effects, these may also be related to a potential compensation mechanism involving the mobilization of more regions to complete a function following a functional decline.
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Affiliation(s)
- Fangmei He
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, The Key Laboratory of Neuro-informatics and Rehabilitation Engineering of Ministry of Civil Affairs, and Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi, P. R. China
- National Engineering Research Center for Healthcare Devices, Guangzhou, Guangdong, P. R. China
| | - Youjun Li
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, The Key Laboratory of Neuro-informatics and Rehabilitation Engineering of Ministry of Civil Affairs, and Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi, P. R. China
- National Engineering Research Center for Healthcare Devices, Guangzhou, Guangdong, P. R. China
| | - Chenxi Li
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, The Key Laboratory of Neuro-informatics and Rehabilitation Engineering of Ministry of Civil Affairs, and Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi, P. R. China
- National Engineering Research Center for Healthcare Devices, Guangzhou, Guangdong, P. R. China
| | - Liming Fan
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, The Key Laboratory of Neuro-informatics and Rehabilitation Engineering of Ministry of Civil Affairs, and Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi, P. R. China
- National Engineering Research Center for Healthcare Devices, Guangzhou, Guangdong, P. R. China
| | - Tian Liu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, The Key Laboratory of Neuro-informatics and Rehabilitation Engineering of Ministry of Civil Affairs, and Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi, P. R. China
- National Engineering Research Center for Healthcare Devices, Guangzhou, Guangdong, P. R. China
- * E-mail: (JW); (TL)
| | - Jue Wang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, The Key Laboratory of Neuro-informatics and Rehabilitation Engineering of Ministry of Civil Affairs, and Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi, P. R. China
- National Engineering Research Center for Healthcare Devices, Guangzhou, Guangdong, P. R. China
- * E-mail: (JW); (TL)
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