The Bored Brain: Insular Cortex and the Default Mode Network

The bored brain: insular cortex and the default mode network. James Danckert and Julia Isacescu Department of Psychology University of Waterloo 200 University Avenue West Waterloo, Ontario, CANADA, N2L 3G1 Corresponding author: J. Danckert Email: [email protected] Abstract We recently showed that posterior components of the default mode network (DMN) are prominently active when people are bored. In addition, the anterior insular is anti-correlated with the DMN during a boredom mood induction, suggestive of a failure to activate executive network regions necessary for engaging with the information at hand. Importantly, while the DMN was also active during rest, there was no evidence of anticorrelated insula activity. Here we replicate these findings in another sample of healthy individuals. In this sample, we did find some anticorrelated activity in the insular both at rest and when bored. In line with our original study, the region of insula that was anticorrelated with the DMN was substantially larger in the boredom mood induction. Limitations of the work are outlined within the context of the neural networks associated with state boredom and distinct modes of self-regulation. Key Words: boredom, fMRI, insula cortex Introduction Boredom is not a trivial cognitive-affective state. Negatively valenced and conceived of as a state of disengagement from one’s environment, boredom is associated with a raft of negative cognitive, affective, and behavioural consequences [1]. Those high in boredom proneness have an increased propensity to take risks, engage in substance abuse and problem gambling, and tend to have poor outcomes in achievement settings [2-5]. From the point of view of cognitive mechanisms, boredom has consistently been associated with failures of attention both in terms of everyday activities (e.g., pouring orange juice on your cereal)[6, 7] and in terms of experimental evaluations of sustained attention [8, 9]. In terms of affect regulation, boredom proneness has been associated with a broad range of negatively valenced affective states and syndromes, most notably, depression [10, 11]. In addition, research has shown strong associations between boredom and difficulties dealing with and expressing anger [12], and exhibiting aggressive tendencies [13, 14]. The cognitive and affective dysregulation that is characteristic of boredom begs the question of a common underlying mechanism. The capacity for effective self-regulation in the pursuit of goals 1 represents one possible mechanism underlying the cognitive and affective correlates of boredom proneness. That is, boredom represents a kind of failed motivational state. The bored individual wants to be engaged with their environment in some meaningful and satisfying way [15], but all attempts to do so fail [1]. That failure, which in turn leads to the cognitive and affective consequences of boredom, may result from impoverished self-regulatory skills [13, 16, 17]. Indeed, recent research from our lab demonstrates a strong negative relationship between boredom proneness and individual levels of self-control [17]. In other words, the more adept one is at controlling one’s own thoughts, emotions, and actions, the more effective they will be in goal pursuit and the less likely they are to be boredom prone. Interestingly, age has been shown to be a consistent negative predictor of boredom proneness levels [18]. That is, as we get older we are less prone to boredom. Key for our purposes is the age range over which this has been demonstrated – in our case age operated as a negative predictor of boredom even when the age range was restricted to 17 to 22 year olds [18]. This age range reflects the developmental period in which late stage maturation of frontal cortex occurs [19]. These results suggest a prominent role for frontal cortical regions in behavioural regulation that may be operating suboptimally in those highly prone to experiencing boredom. As already suggested, boredom is consistently associated with failures of attentional control and more recently with off-task thinking (i.e., spontaneous mind-wandering) [18]. Functional neuroimaging research exploring off-task processing and spontaneous mind-wandering, have shown neural activation within a network of brain regions known collectively as the default mode network (DMN) [20-26]. A highly-interconnected set of brain regions, the DMN supports internally-focused thinking (i.e., thinking to oneself, imagining past events, thinking of the future) and is activated when there is no external task or stimulus for an individual to engage with [22, 25]. Structurally, the main hubs of the DMN include the posterior cingulate cortex and precuneus, ventromedial prefrontal cortex and medial, lateral, and inferior parietal cortices [22]. Research exploring the neural underpinnings of boredom is in its infancy. While imaging studies have assessed boredom levels in passing, few have made it the primary focus. For instance, Ulrich and colleagues [27] assessed the neural networks of an experimentally induced state of “flow” – a state one might consider to be the opposite of boredom, in which the individual is deeply engaged in an activity to the point that all else fades away [28, 29]. In their experiment, participants performed mental arithmetic tasks at varying levels of difficulty: the task with the lowest degree of difficulty was considered “boring” and was used as a control relative to an adaptive “flow” condition in which difficulty levels were adjusted to match participants’ performance [27]. Relative to the boring condition, the state of flow was associated with a decrease in DMN activation, specifically in medial prefrontal cortex and the amygdala. In addition, posterior portions of the DMN were more active during the boring condition [27]. We examined the state of boredom more directly via a video mood induction [30, see 31 for the video mood induction]. This boring mood induction was contrasted with a resting state, an induction of interest/engagement, and a sustained attention task [30]. Results showed that posterior components of the DMN were active during the boredom mood induction and resting state scans. Interestingly, anticorrelated activity was observed in the anterior insula during the boredom mood induction and was not evident during the resting state [30]. In a more recent study, people were asked to do a very simple task (decide if the frame around a picture was blurry or not) that was presumably also very boring, prior to making decisions about how much they would be willing to pay to download music [32]. These purchasing decisions were also made after having done a more challenging visual search task or a task that simply asked them which images they liked more. When bored, people were willing to pay more for music – as though desperate for any stimulation to escape the boredom. Activity in the caudate nucleus – a 2 subcortical structure known to be important for representing reward value [33] – was associated with decisions to avoid the boring task. Activity in the insula cortex was associated with just how willing people were to pay to avoid boredom – the higher your willingness to pay to avoid boredom the more activity was seen in the insula [32]. So on the one hand, failures to engage are reflected in the downregulation of the insula [30], while an increased desire to engage (by paying more to avoid boredom) is associated with upregulation of the insular [32]. Here we present a replication of our initial work that we deemed important for a number of reasons. First, the original sample consisted of individuals very low in boredom proneness. Here, our sample had more typical responses on this trait measure. Second, the initial sample was rather small given current standards in imaging (n=10). The current sample was slightly larger, but we saw potential strength in replicating our initial results in a new sample. Finally, replication in psychology has increasingly been viewed as a vital part of the scientific endeavor with a spotlight on failures to replicate [34]. This is particularly concerning for imaging studies in which replication attempts are typically lower than in experimental psychology. Results Trait self-report measures Boredom Proneness Participants’ mean score on the SBPS was 22.33 (SD=7.34, range=10-33), which is on par with the SBPS scores obtained in larger pools of participants in our prior work [18]. Mind-Wandering Participants’ mean score on the deliberate mind-wandering scale was 21.00 (SD=1.95, range=7-17), while spontaneous mind-wandering scores were somewhat lower (M= 15.08, SD = 4.81, range 8-26). These scores are comparable to the larger sample size tested in our prior work [18]. State self-report measures Boredom Probes Participants reported feeling most bored in the boredom (M = 6.85, SD = 1.82; Figure 1) and resting state conditions (M = 7.54, SD = 1.71), which did not differ significantly from each other (t = -1.74, p = .108). Both conditions were significantly more boring than the interest condition (M = 5.15, SD = 2.34; t = 2.48, p = .029 and t = 3.48, p = .005, respectively). Mind-Wandering Probes A similar pattern emerged with respect to the mind-wandering probes: participants mind- wandered the most during the boredom (M = 6.23, SD = 2.35; Figure 2) and resting state (M = 6.92, SD = 1.66) scans. Again, these two conditions did not differ significantly from each other (t = -.987, p = .343). Participants mind-wandered significantly less in the Interest condition relative to both the boredom and resting state conditions (t = 3.811, p = .002; t = 4.251, p = .001 respectively). 3 Figure 1. Self-reported levels of state boredom (white bars) and mind-wandering (black bars) ratings for each scanning condition. Error bars represent SE +/-1. fMRI Results largely replicated our earlier work. For the boredom mood induction posterior regions of the DMN showed correlated activity prominently in the posterior cingulate cortex (PCC; Figure 2 and Table 1).

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