Much of our waking life is spent in thought that no one asked us to have. Our lab investigates these unguided moments: where spontaneous thoughts come from, how they unfold over time, and what they reveal about the brain’s network organization. This work spans mind-wandering and dreaming, creativity, meditation and introspection, and, more recently, altered states of consciousness through psychedelics. Below is an overview of our main research areas and the studies behind them.
When there is no external task to perform, thoughts often flow in a spontaneous and unconstrained manner. These ‘undirected’ forms of thought are a prevalent aspect of waking mental activity (Christoff, 2012). Our laboratory has begun to examine the neural basis of such spontaneous thought. In an initial fMRI study (Christoff, Ream, & Gabrieli, 2004), we found evidence of considerable contribution from regions in the medial temporal lobe, visual cortex, and the rostrolateral PFC, suggesting that long-term memory, visual imagery, and introspection may form the basis of spontaneous thought. However, despite an upsurge of scientific interest in mind-wandering in subsequent years, studies on this phenomenon were limited to indirect methods – often relying on retrospective reports or using performance errors on a sustained attention task as a proxy for mind-wandering. Recognizing this, we undertook the first investigation of mind-wandering that employed an online experience sampling approach to index this phenomenon during fMRI scanning. This study (Christoff, Gordon, Smallwood, Smith, & Schooler, 2009), which combined objective measures of mind wandering (errors in task performance), subjective self-reports, and brain imaging, suggested that default network regions and executive network regions (e.g., dorsolateral prefrontal cortex, rostrolateral prefrontal cortex, and dorsal anterior cingulate cortex) are concurrently engaged during mind wandering—a finding predicted by behavioural theories of off-task thought.
In subsequent work, we argued that dreaming could be considered a form of mind-wandering or spontaneous thought: the neural substrate of dreaming is highly similar to the default mode network regions strongly implicated in mind wandering, and subjective content reports from both waking ‘daydreams’ and night-time dreaming contain many strong similarities (Fox, Nijeboer, Solomonova, Domhoff, and Christoff, 2013). Expanding on the results of (Christoff et al., 2009), which suggested the involvement of high-level PFC regions in mind wandering, we have highlighted several constructive interactions between metacognition and spontaneous thought processes (Fox and Christoff, 2014). We also published a meta-analytic review of functional neuroimaging research on mind-wandering which revealed activation spanning the default mode network, frontoparietal control network, and other non-DMN regions (Fox et al. 2015).
We have also examined the neural dynamics surrounding the onset of a spontaneous thought. To do this, we have employed the introspective reports of highly-trained meditators (an approach referred to as ‘neurophenomenology’). In an fMRI study in this vein (Ellamil et al. 2016), we demonstrated that the medial temporal lobe subcomponent of the default network, involving regions such as the hippocampus, peaks in activation prior to the onset of a spontaneous thought, while the frontoparietal control network regions, such as dorsolateral prefrontal cortex, peaks following the onset of a spontaneous thought. In an EEG study using the same paradigm (Girn et al. 2017), we found a similar progression of connectivity that begins with default mode network and salience network regions, with the subsequent incorporation of control network regions in the period immediately preceding reports of thought onset.
Dynamic Framework of Thought
Our most recent work has emphasized the limitations of the hitherto dominantly used approach to study spontaneous thought. This approach has typically understood spontaneous thought based on its content – for example, whether it is related or unrelated to one’s current task or immediate environment. In our novel Dynamic Framework of Thought (Christoff et al. 2016), published in Nature Reviews Neuroscience, we have argued that these static content-based measures of thought are unable to capture a core aspect of spontaneous thought: its dynamics. In this framework, we define spontaneous thought as “a mental state, or a sequence of mental states, that arises relatively freely owing to an absence of strong constraints on the contents of each state and on the transitions from one mental state to another.” Our framework shifts the emphasis towards the dynamics of the thinking process and away from the content of a given set of thoughts. To empirically capture dynamic qualities of thought, we have recently introduced a novel experience sampling measure by probing participants with the question: “Is your mind moving about freely?” We have demonstrated that freely moving thought is empirically dissociable from task-unrelatedness (Mills et al., 2017). This finding underscores the importance of using dynamic measures for the study of spontaneous thoughts. This framework explicitly links thought dynamics to fluctuations in the functional interactions of large-scale brain networks and offers a novel way to understand clinically significant alterations in spontaneous thought and their neural basis.
Creativity is manifested in many forms, from artistic creation to scientific discovery, to general problem-solving. Our recent work has revealed different activation patterns for creative idea generation vs. evaluation, spanning default mode network structures as well as high-level metacognitive and executive regions, including RLPFC and DLPFC (Ellamil, Dobson, Beeman, and Christoff, 2012). We have expanded upon these ideas in a recent book chapter that explores how metacognition might facilitate spontaneous thought processes to achieve optimal creative and personal outcomes (Fox and Christoff, 2014). In an additional book chapter, we have also explored potential neural and psychological relationships between psychedelic experience and creativity (Fox, Girn, Parro, and Christoff 2018).
In recent years, cognitive neuroscience has seen an explosion of interest in network-based approaches to the human brain, and the brain is increasingly seen as functioning via the dynamic interaction between networks at multiple spatial and temporal scales. Work in our lab has sought to contribute to our knowledge of functional network organization and dynamics. In a recently published study (Dixon et al. 2017), we utilized dynamic functional connectivity and graph theoretical network neuroscience techniques to demonstrate that the default network (DN) and dorsal attention network (DAN) exhibit variable connectivity across a number of contexts. Our use of these advanced analyses allowed us to obtain evidence against the hitherto strongly held notion that these networks had an intrinsically negative relationship. In addition, we currently have a manuscript that is being revised for resubmission at PNAS (Dixon et al., PNAS) documenting the findings of a study that employed a combination of static and dynamic FC, graph theoretic analyses, and machine learning to precisely characterize the functional organization of the frontoparietal control network and its differential dynamic relationships with the DN and DAN.
Recently, our lab has begun to investigate meditation practitioners. We are interested in the various behavioural improvements that meditation might engender, and particularly in the neural basis for these cognitive and emotional benefits. In one study we have shown that long-term meditation practitioners appear to provide more accurate, reliable introspective reports about their inner experiences (Fox, Zakarauskas, Dixon, Ellamil, Thompson, and Christoff, 2012). Our ongoing work is focusing on meta-analyzing the differences in the brain structure of meditation practitioners that have been found using morphometric neuroimaging (Fox, Nijeboer, Dixon, Floman, Ellamil, Rumak, Sedlmeier, & Christoff, 2014), as well as employing the expert introspective skills of long-term practitioners to investigate the arising of spontaneous thoughts (Ellamil et al., in prep).
Our lab has focused on investigating the dynamic states of consciousness. We are now looking at new methods to change the state of consciousness in order to better understand it. We are using psychedelics, drugs that can alter the mind, as a way to systematically manipulate a mental state in order to unlock the key features of consciousness and develop stronger understandings of individuals’ self-experience.
Psychedelics have been shown previously to be extremely beneficial for the treatment of a variety of different mental health disorders such as depression, PTSD, anxiety, addiction and others (see reviews: Kuypers, 2020; Krediet et al., 2020; Muttoni, Ardissino, & John, 2019; DiVito & Leger, 2020). This could be due to their inherent nature to change the way we think, feel and process our self-experiences.