What is mood? A computational perspective

“However, modern accounts of brain function reject the classical notion of the brain as a passive organ in favour of theories of embodiment and self-organisation (Friston, 2010; Seth, 2013; Corlett & Fletcher, 2014).”

“However, they also showed that methylation rates rapidly declined in rodents who were maternally groomed and nurtured while rates remained elevated in neglected pups (Weaver et al. 2004).”

“This hierarchical minimisation of prediction errors allows allostatic control over homoeostatic reflexes (Sterling & Eyer, 1988; McEwen, 1998; Ramsay & Woods, 2014).”

“Mood disorders are heterogeneous and complex and depend upon the interplay of several neuromodulator systems and genetic and epigenetic factors (Hirschfeld, 2000; Holsboer, 2000; Nestler & Carlezon, 2006; Nutt et al. 2007; Dowlati et al. 2010; Möhler, 2012).”

“Similarly, it has been argued that pharmacotherapy may work via its effects on neurogenesis and synaptic plasticity (Santarelli et al. 2003; Anacker et al. 2011; Castrén & Hen, 2013) and that stressors may leave an indelible scar on key neurobiological systems that disrupts their structure and/or…”

“In this regard, active inference may explain the established finding that childhood trauma poses a risk for various psychopathologies (Bernet & Stein, 1999; Heim & Nemeroff, 2001; Heim et al. 2008).”

“In current predictive coding formulations of the Bayesian brain, expectation and prediction error units are thought to occupy deep and superficial pyramidal layers of cortex, respectively (Friston & Kiebel, 2009; Bastos et al. 2012; Shipp et al. 2013); such that predictions generated, from expectations, at one level o…”

“We also propose that these pathologic beliefs are ascribed excessive precision, weight, or influence in many psychiatric disorders (Clark et al., 2018).”

“Clark and colleagues similarly emphasize precision, associating major depression with being certain about encountering uncertain environments, thereby precluding effective allostatic regulation [83].”

“In other contexts, it has been suggested that action model precision updates (what we have labeled AC ) could be used to inform selective attention (e.g., Clark et al., 2018; Palacios, Razi, Parr, Kirchhoff, & Friston, 2019).”

“38 The central idea here is that neural systems not only maintain estimates in the con fi dence or precision of their prior beliefs about outcomes, but also estimates of con fi dence in their beliefs about that precision (i.e., the degree to which the unknowns are known).”

“There are many interesting instances of this formulation; ranging from failures of sensory attenuation in autonomic and interoceptive inference, through depression and emotional processing [82, 140, 149, 174], to functional medical symptoms and dissociative phenomena [137, 164].”

“Based on previous work (Clark et al., 2018; Joffily & Coricelli, 2013), we would expect pleasant and unpleasant valence to correspond to unexpected increases (pleasant) and decreases (unpleasant) in expected free energy at a lower hierarchical level of processing, reflecting unexpected changes in precision over polici…”

“(71) review the evidence for depression as a computational pathology in the proprioceptive and interoceptive (behavioral and autonomic) domain.”

“On the other hand, sensory attenuation or reducing the precision of afferent information occurs when one is highly confident about the sensory consequences of one ’ s own action (Clark et al., 2018).”

“One possibility is that uncertainty estimates reflect the “psychological backstory” of each participant: past experiences with uncertain environments (or risk factors) may lead to altered beliefs about uncertainty (Clark et al., 2018; Huys and Dayan, 2009).”

“As such, interoceptive prediction errors are used to infer emotional states (Allen, 2020), and emotional states reflect the interoceptive precision given to prior beliefs about the consequences of action, whereas mood states represent a hyperprior over emotional states (Clark et al., 2018).”

“In PP formulations, emotions are intimately tied to inferences about motor and physiological states (Barrett, 2017; Clark et al., 2018; Wilkinson et al., 2019).”

“Converging the predictive model with the topographic account, we suppose that the abnormally high synchronization of default-mode network regions with themselves and other regions of the brain exerts an abnormally strong top-down prediction on lower-order sensory and motor regions [112 – 114].”

“1; Clark et al., 2018).”

“Within the conceptual framework of active inference, disorders of affect are understood as aberrant precision control, mediated by high-level representations of being in one emotional state or another (Clark et al., 2018; Friston, 2017; Parr et al., 2018b, 2018a).”

“…creates confident behavior and motivates action, whereas decreasing precision subverts action through uncertainty (Friston et al., 2012; Clark, 2013a; Hohwy, 2013; Seth and Friston, 2016; Badcock et al., 2017; Parr and Friston, 2017; Peters et al., 2017; Clark et al., 2018; Palmer et al., 2019).”

“High-level priors constraining more domain-general affective states such as mood (Clark et al. 2018) would also be relaxed under the REBUS model.”

“…might be of particular interest for mechanistic insights in depression, as it represents such an internal model with potentially (pathologically) variations in its statistical structure (Barrett et al., 2016; Chekroud, 2015; J. E. Clark et al., 2018; Kube et al., 2020; Smith et al., 2020).”

“Recent work has extended these ideas to cognitive phenomena related to interoception (Seth, 2013), including the shaping of emotions (Seth and Friston, 2016; Clark et al., 2018) and the development of depression (Barrett et al.”

“How proprioceptive and interoceptive signals are interpreted with respect to the external environment and in the context of emotional state remains an open question (Clark et al., 2018).”

“Broadly, these works interpret anxiety disorders as encoded uncertainty: agents encode and act upon beliefs that the world is unpredictable and uncertain, meaning that action policies cannot sufficiently minimize expected surprise or uncertainty (see Mathys et al., 2014; Clark et al., 2018; Smith et al., 2019a, 2021b;…”

“Lucero et al. (2022) extended these insights by showing that the link between mood disorders and childhood trauma is mediated by fears of social evaluation, supporting Clark et al. (2018) ’ s hypothesis that mood disorders stem from the misinterpretation of bodily signals.”

“This insensitivity to external cues, driven by skewed predictions and impaired network communication, likely contributes to the cognitive and emotional symptoms commonly observed in depression (24, 30).”

“…if emotions reflect short-term changes in precision, these emotions are modulated by mood, which track and average over the longer-term error-dynamics (Clark et al., 2018 ) – reflecting a kind of ‘overall faring’ of the predictive agent’s pursuit of error minimisation (Kiverstein et al., 2020 ).”

“However, the possibility of overweighted iPEs in depression has also been noted (Clark et al., 2018), which contradiction will be addressed in the next section.”

“The idea behind such a formulation is that emotional states reflect changes in the uncertainty about the somatic consequences of action (Wager et al., 2015; Seth and Friston, 2016; Clark et al., 2018).”

“…et al., 2015a; Minkova et al., 2017) and adolescents (Monk et al., 2008; Perlman et al., 2012; Keshavan et al., 2014) and dysfunctional valencedependent coupling might underlie the attention and processing bias in mood disorders (Disner et al., 2011; Groenewold et al., 2013; Clark et al., 2018).”

“This suggestion accords with a recent perspective that mood itself can be treated as a prior that shapes the perception of reward (Clark et al., 2018).”

“These phenomena show the importance of the interrelation between interoception and exteroception for the valence (positive or negative value) of sensory signals (Bottemanne et al., 2022a; Hsueh et al., 2023; Clark et al., 2018), and highlight the role of interoception in emotional functioning.”

“Computational perspectives on mood and emotion suggest that emotional states reflect the certainty (or precision) regarding the interoceptive consequences of action, such that negative emotion “contextualize events that induce expectations of unpredictability” ([45], p.”

“Given that similar types of ‘hyperpriors’ have already been proposed as a critical element of mood disorders [80], further research into sensorimotor skills could examine the persistence of participants’ volatility beliefs (e.g., volatility of volatility) and/or the mechanisms that underpin…”

“This failure of attention and attenuation has been used to explain several conditions, including autism, schizophrenia, Parkinson’s disease and depression [71, 72, 73, 74, 75].”

“Recent research has elucidated the phenomena related to interoception, de fi ned as the sense of the body ’ s physiological condition [93], including the shaping of emotions [33, 94 – 96] and the development of depressive adaptive responses to social adversity [77, 78, 97 – 99].”

“Thus, when predictions and reality resemble one another, certainty is generated; when they do not resemble one another, uncertainty is generated [7].”

“Depression and anxiety change over time and studies examining such conditions at a single time point will not represent their course and progression [11].”

“They might be associated with more positively-valenced affect [21, 22], but given that they are also indicative of greater uncertainty, they have also been associated with more negatively-valenced affect [23, 41, 42].”

“…Quadt et al., 2018; R. Smith et al., 2020), including depression (Arnaldo et al., 2022; Badcock et al., 2017; Barrett et al., 2016; Seth & Friston, 2016; Stephan et al., 2016) and anxiety-related disorders (J. E. Clark et al., 2018; Gerrans & Murray, 2020; Linson et al., 2020; Peters et al., 2017).”

“, 2015), and mood and eating disorders (Frank et al., 2016; Clark et al., 2018).”

“Recent perspectives suggest that disturbances in interoceptive and exteroceptive predictive processing may be related to depressive symptomatology (Barrett et al., 2016; Clark et al., 2018; Fabry, 2020; Kube et al., 2019, 2020; Paulus et al., 2019).”

“This idea has been aptly expressed by Clark et al. (2018, p. 2,278), “Major depression occurs when the brain is certain that it will encounter an uncertain environment, i.e., the world that is inherently volatile, capricious, unpredictable and uncontrollable.”

“…reflect a hyperprior , which encodes the expected long-term average of short-term (emotional) fluctuations in precision by determining the set-point of neuromodulatory mechanisms (e.g., dopaminergic and serotenergic systems) that govern the sensitivity of our responses to prediction errors [187].”

“Such formulations assume that emotional states reflect changes in the uncertainty represented by free energy over time (Clark et al., 2018; Seth & Friston, 2016; Wager et al., 2015).”

“…by predictive processing advocates is that depressed individuals are burdened with top-down models that dysregulate bodily functioning, generating painful emotions and leading sufferers to attend more to negative than positive information (Barrett et al. 2016; Clark et al. 2018; Smith et al. 2021).”

“Ce principe a été utilisé pour comprendre de nombreux phéomènes perceptuels, cognitifs, et affectifs, comme la perception isuelle binoculaire [68], la focalisation attentionnelle [69], la étacognition [70], les phénomènes hallucinatoires [71], la déterination de la valence émotionnelle [72] ou encore les variations de…”

“Recent advances in depression theory formulation have adopted a predictive processing perspective, taking into account that people’s expectations are strongly intertwined with the perception of novel information (Barrett et al., 2016; Clark et al., 2018; Kube et al., 2020).”

“Others have emphasised the importance of estimating uncertainty in predictive coding models, and that an inability to reduce uncertainty seems to be particularly related to anxiety and depressive symptoms, whereas reducing uncertainty is related to positive emotions (Clark et al., 2018).”

“In other work, mood has been conceptualized as a hyperprior that weights the salience of sensory input (Clark et al., 2018).”

“…als hoch eingeschätzt werden darf, hinterfragen aktuelle Metaanalysen die tatsächliche Effektivität von Psychotherapie bei Depression (Cuijpers et al. 2019) bzw. weisen mindestens darauf hin, dass viele Patientinnen und Patienten auf die verfügbaren Ansätze nicht ausreichend…”

“7 A more straightforward way of framing this is that mood determines the strength of beliefs about the likely consequences of action.”

“From a neurophysiological perspective, this strategy may be understood as the modulation of hyper priors in the predictive model and the refinement of prior expectations to align with sensorimotor information, resulting in a fine-tuning of the overall processing (Clark, 2013; Clark et al., 2018).”