Humor and emotion: Quantitative meta analyses of functional neuroimaging studies

Sex differences in resting-state fMRI functional connectivity related to humor styles

Research on how functional connectivity (FC) during resting-state relates to humor styles and sex is limited. This study aimed to address this knowledge gap by analyzing resting-state fMRI data from 56 healthy participants and measuring FC. In addition, participants completed the Humor Styles Questionnaire. We found distinct FC patterns linked to humor styles that differed by sex. Men demonstrated stronger FC between the anterior cingulate cortex (ACC) and the right anterior insula (rAI), right inferior frontal gyrus (rIFG) and right frontal pole (rFP), and between the right rostral prefrontal cortex (rRPFC) and rIFG. These patterns were associated with aggressive and self-enhancing humor. Conversely, women exhibited stronger FC between rRPFC and the posterior cingulate gyrus (PCC), left rostral prefrontal cortex (lRPFC) and right thalamus, correlating with self-defeating and less aggressive humor. These findings suggest a neurobiological basis for sex differences in humor, indicating that men's FC between the salience network (SN), particularly in cognitive monitoring regions, may be linked to aggressive humor. Their FC between the executive control network (ECN) and between the SN and ECN are related to self-enhancing humor and reflect an emphasis on executive function. Conversely, women's FC between the SN and default mode network is correlated with self-defeating humor, suggesting a stronger focus on self-reflection and social relationships.

An Honest Reckoning With the Amygdala and Mental Illness

Anxiety disorders are a leading source of human misery, morbidity, and premature mortality. Existing treatments are far from curative for many, underscoring the need to clarify the underlying neural mechanisms. Although many brain regions contribute, the amygdala has received the most intense scientific attention. Over the past several decades, this scrutiny has yielded a detailed understanding of amygdala function, but it has failed to produce new clinical assays, biomarkers, or cures. Rising to this urgent public health challenge demands an honest reckoning with the functional-neuroanatomical complexity of the amygdala and a shift from theories anchored on "the amygdala" to models centered on specific amygdala nuclei and cell types. This review begins by examining evidence from studies of rodents, monkeys, and humans for the "canonical model," the idea that the amygdala plays a central role in fear- and anxiety-related states, traits, and disorders. Next, the authors selectively highlight work indicating that the canonical model, while true, is overly simplistic and fails to adequately capture the actual state of the evidentiary record, the breadth of amygdala-associated functions and illnesses, or the complexity of the amygdala's functional architecture. The authors describe the implications of these facts for basic and clinical neuroimaging research. The review concludes with some general recommendations for grappling with the complexity of the amygdala and accelerating efforts to understand and more effectively treat amygdala-related psychopathology.

First They Scream, Then They Laugh: The Cognitive Intersections of Humor and Fear

On the surface, fear and humor seem like polar opposite states of mind, yet throughout our lives they continually interact. In this paper, we synthesize neurobiological, psychological, and evolutionary research on fear and humor, arguing that the two are deeply connected. The evolutionary origins of humor reside in play, a medium through which animals benignly explore situations and practice strategies, such as fight or flight, which would normally be accompanied by fear. Cognitively, humor retains the structure of play. Adopting a view of humor as requiring two appraisals, a violation appraisal and a benign appraisal, we describe how fear-inducing stimuli can be rendered benignly humorous through contextual cues, psychological distance, reframing, and cognitive reappraisal. The antagonistic relationship between humor and fear in terms of their neurochemistry and physiological effects in turn makes humor ideal for managing fear in many circumstances. We review five real-world examples of humor and fear intersecting, presenting new data in support of our account along the way. Finally, we discuss the possible therapeutic relevance of the deep connection between humor and fear.

The differential processing of verbal jokes by neural substrates in indigenous and Han Chinese populations: An fMRI study

Limited research has been conducted on humor among the Taiwanese indigenous (IND) population. This study attempted to identify the differential neural correlates of humor comprehension and appreciation between IND and Han Chinese (HAN) populations. Each participant was presented with jokes and non-jokes. IND participants when encountered with jokes displayed a greater activation of the mesolimbic dopaminergic reward system, including the amygdala, midbrain, and nucleus accumbens than HAN participants. This suggests a more pleasurable response and appreciation of humor. The IND group also displayed greater activation in the right temporoparietal junction (rTPJ) than HAN, suggesting that the IND group may experience a greater sense of novelty and be more involved in social understanding, thus exhibiting greater humor appreciation. In terms of humor comprehension, both IND and HAN showed greater activation in the superior temporal gyrus (STG) and dorsal anterior cingulate cortex (dACC). IND exhibited greater activation in the anterior STG (aSTG), while HAN showed greater activation in the posterior STG (pSTG). This suggests that the IND tends to integrate emotional messages, whereas the HAN focuses on comprehending semantic cognitive information. Interestingly, HAN did not show any greater activation than IND in terms of appreciation of humor. These group disparities have substantial implications for advancing our knowledge of the neural mechanisms underlying humor comprehension and appreciation.

Hypo- and hyper-activation in frontotemporal lobe during humor processing in patients with first episode schizophrenia

BACKGROUND

Patients with schizophrenia present difficulties in humor recognition and appreciation, but the neural mechanism of these deficits remains unclear. This study aimed to elucidate neural substrates underlying humor processing in patients with first episode schizophrenia (FES).

METHODS

This study recruited 40 patients with FES (illness duration ≤ 4 years) and 31 healthy controls matching for age, gender and education level. Participants completed a fMRI verbal humor processing paradigm comprising 96 stories, half for funny punch-line condition and the other half for unfunny condition. Participants were required to judge whether the story was funny or not. Signal detection theory (SDT) analysis was used to calculate d' and β values which represented sensitivity and inner criteria for humor signals respectively. The funny-unfunny contrast was analyzed to identify the brain regions related with humor processing. d' and β values were put into the imaging regression analysis.

RESULTS

Patients with FES showed significantly lower hit rate and sensitivity of humor signals (d'). At the neural level, patients with FES hypo-activated in ventral medial prefrontal cortex (vmPFC) and anterior cingulate cortex (ACC) while hyper-activated in middle temporal gyrus (MTG) and superior temporal gyrus (STG) compared to controls. In addition, activity in vmPFC and ACC was positively associated with d' and β values, while activity in STG was positively associated with β values in the clinical group.

CONCLUSIONS

Patients with FES exhibited decreased sensitivity to humor signals. Hypo-activation in frontal regions and hyper-activation in temporal regions were associated with the humor processing deficits.

Establishing the Roles of the Dorsal and Ventral Striatum in Humor Comprehension and Appreciation with fMRI

Humor comprehension (i.e., getting a joke) and humor appreciation (i.e., enjoying a joke) are distinct, cognitively complex processes. Functional magnetic resonance imaging (fMRI) investigations have identified several key cortical regions but have overlooked subcortical structures that have theoretical importance in humor processing. The dorsal striatum (DS) contributes to working memory, ambiguity processing, and cognitive flexibility, cognitive functions that are required to accurately recognize humorous stimuli. The ventral striatum (VS) is critical in reward processing and enjoyment. We hypothesized that the DS and VS play important roles in humor comprehension and appreciation, respectively. We investigated the engagement of these regions in these distinct processes using fMRI. Twenty-six healthy young male and female human adults completed two humor-elicitation tasks during a 3 tesla fMRI scan consisting of a traditional behavior-based joke task and a naturalistic audiovisual sitcom paradigm (i.e., Seinfeld viewing task). Across both humor-elicitation methods, whole-brain analyses revealed cortical activation in the inferior frontal gyrus, the middle frontal gyrus, and the middle temporal gyrus for humor comprehension, and the temporal cortex for humor appreciation. Additionally, with region of interest analyses, we specifically examined whether DS and VS activation correlated with these processes. Across both tasks, we demonstrated that humor comprehension implicates both the DS and the VS, whereas humor appreciation only engages the VS. These results establish the role of the DS in humor comprehension, which has been previously overlooked, and emphasize the role of the VS in humor processing more generally.SIGNIFICANCE STATEMENT Humorous stimuli are processed by the brain in at least two distinct stages. First, humor comprehension involves understanding humorous intent through cognitive and problem-solving mechanisms. Second, humor appreciation involves enjoyment, mirth, and laughter in response to a joke. The roles of smaller subcortical brain regions in humor processing, such as the DS and VS, have been overlooked in previous investigations. However, these regions are involved in functions that support humor comprehension (e.g., working memory ambiguity resolution, and cognitive flexibility) and humor appreciation (e.g., reward processing, pleasure, and enjoyment). In this study, we used neuroimaging to demonstrate that the DS and VS play important roles in humor comprehension and appreciation, respectively, across two different humor-elicitation tasks.

Relation of resting brain signal variability to cognitive and socioemotional measures in an adult lifespan sample

Temporal variability of the fMRI-derived blood-oxygen-level-dependent (BOLD) signal during cognitive tasks shows important associations with individual differences in age and performance. Less is known about relations between spontaneous BOLD variability measured at rest and relatively stable cognitive measures, such as IQ or socioemotional function. Here, we examined associations among resting BOLD variability, cognitive/socioemotional scores from the NIH Toolbox and optimal time of day for alertness (chronotype) in a sample of 157 adults from 20 to 86 years of age. To investigate individual differences in these associations independently of age, we regressed age out from both behavioral and BOLD variability scores. We hypothesized that greater BOLD variability would be related to higher fluid cognition scores, more positive scores on socioemotional scales and a morningness chronotype. Consistent with this idea, we found positive correlations between resting BOLD variability, positive socioemotional scores (e.g. self-efficacy) and morning chronotype, as well as negative correlations between variability and negative emotional scores (e.g. loneliness). Unexpectedly, we found negative correlations between BOLD variability and fluid cognition. These results suggest that greater resting brain signal variability facilitates optimal socioemotional function and characterizes those with morning-type circadian rhythms, but individuals with greater fluid cognition may be more likely to show less temporal variability in spontaneous measures of BOLD activity.

The impact of humor therapy on people suffering from depression or anxiety: An integrative literature review

OBJECTIVES

To identify and synthesize existing research on the effectiveness and feasibility of multiform humor therapy on people suffering from depression or anxiety, with the hope of benefiting future research.

METHODS

An integrative literature review of quantitative, qualitative, and mixed studies was performed. The PubMed, Cochrane Library, Web of Science, Embase, and CINAHL databases were searched up to March 2022. Two independent reviewers conducted each stage of the review process, by assessing eligibility using preferred reporting items for systematic review and meta-analyses (PRISMA) and quality appraisal using the Mixed Methods Appraisal Tool, and data extraction.

RESULTS

In this integrative review, 29 papers were included, containing 2964 participants across a diverse range of studies, including quantitative, qualitative, and mixed methods. The articles were from the United States, Australia, Italy, Turkey, South Korea, Iran, Israel, China, and Germany. The findings indicated that most of the subjects thought humor therapy was effective in improving depression and anxiety while a few participants considered the effect insignificant. However, more high-quality studies will be needed to confirm these conclusions.

DISCUSSION

This review collated and summarized findings from studies examining the impact of humor therapy (medical clowns, laughter therapy/yoga) on people with depression or anxiety, including children undergoing surgery or anesthesia, older people in nursing homes, patients with Parkinson's disease, cancer, mental illness, and undergoing dialysis, retired women, and college students. The results from this review may help inform future research, policy, and practice in humor therapy to improve people's symptoms of depression and anxiety.

IMPACT

This systematic review objectively evaluated the effect of humor therapy on depression and anxiety. As a simple and feasible complementary alternative therapy, humor therapy may provide a favorable alternative for clinicians, nurses, and patients in the future.

The Relationship between Semantic Joke and Idiom Comprehension in Adolescents with Autism Spectrum Disorder

Semantic jokes involve resolving an incongruity emerging from wordplay or from a violation of world knowledge. The research has shown individuals with autism spectrum disorder (ASD) demonstrate a lower performance on humor tasks involving social situations; however, less is known about their semantic joke comprehension. This study examines semantic joke comprehension among adolescents with ASD and its possible relationship to vocabulary size, theory of mind (ToM), and idiom comprehension. Thirty-two adolescents with ASD and 32 typically developed (TD) peers participated. Semantic joke comprehension was assessed via a multiple-choice questionnaire and time-limited computer program. Vocabulary, ToM abilities, and idiom comprehension were also tested. The results reveal that adolescents with ASD are as fast in processing semantic jokes as their age- and vocabulary-matched TD peers, but less accurate. Age and idiom comprehension significantly contributed to semantic joke comprehension among both groups. As semantic joke comprehension is based on incongruity resolution, the greater difficulties in comprehension among the adolescents with ASD may have been due to deficits in simultaneously retaining two alternative interpretations and selecting the relevant one (and not due reduced ToM abilities). Similar to the TD group, semantic joke comprehension among the ASD group appeared to be more developed with age.

Non-literal language processing is jointly supported by the language and theory of mind networks: Evidence from a novel meta-analytic fMRI approach

Going beyond the literal meaning of language is key to communicative success. However, the mechanisms that support non-literal inferences remain debated. Using a novel meta-analytic approach, we evaluate the contribution of linguistic, social-cognitive, and executive mechanisms to non-literal interpretation. We identified 74 fMRI experiments (n = 1,430 participants) from 2001 to 2021 that contrasted non-literal language comprehension with a literal control condition, spanning ten phenomena (e.g., metaphor, irony, indirect speech). Applying the activation likelihood estimation approach to the 825 activation peaks yielded six left-lateralized clusters. We then evaluated the locations of both the individual-study peaks and the clusters against probabilistic functional atlases (cf. anatomical locations, as is typically done) for three candidate brain networks-the language-selective network (Fedorenko, Behr, & Kanwisher, 2011), which supports language processing, the Theory of Mind (ToM) network (Saxe & Kanwisher, 2003), which supports social inferences, and the domain-general Multiple-Demand (MD) network (Duncan, 2010), which supports executive control. These atlases were created by overlaying individual activation maps of participants who performed robust and extensively validated 'localizer' tasks that selectively target each network in question (n = 806 for language; n = 198 for ToM; n = 691 for MD). We found that both the individual-study peaks and the ALE clusters fell primarily within the language network and the ToM network. These results suggest that non-literal processing is supported by both i) mechanisms that process literal linguistic meaning, and ii) mechanisms that support general social inference. They thus undermine a strong divide between literal and non-literal aspects of language and challenge the claim that non-literal processing requires additional executive resources.

Amygdala-frontoparietal effective connectivity in creativity and humor processing

Although both creativity and humor elicit experiences of surprise followed by appreciation, it remains unknown whether shared or distinct patterns of effective connectivity are involved in their processing. The present fMRI study used dynamic causal modeling and parametrical empirical Bayes analysis to examine the effective connectivity between the amygdala and frontoparietal network during two-stage creativity and humor processing. We examined processing during the setup and punch line stages for creativity and humor, including typical forms (alternate uses for creativity and incongruity-resolution humor), atypical forms (aesthetic uses for creativity and nonsense humor), and baseline forms. Our focus was on the mesolimbic pathway during the punch line stage. We found that the amygdala plays a key role in expectation violation and appreciation. Broadly, amygdala-to-IFG connectivity was important for evaluating typical and atypical forms of both creativity and humor, while amygdala-to-precuneus connectivity was involved in evaluating typical forms. Amygdala-to-IFG connectivity was involved in the expectation violation to resolution stage of processing for typical and atypical forms of creativity and humor. Amygdala-to-precuneus connectivity was involved in processing the novelty and usefulness of typical forms of creativity (alternate uses) and understanding others' intentions in typical forms of humor (incongruity-resolution). Interestingly, VTA-to-amygdala connectivity was involved in processing the appreciation of both typical (incongruity-resolution humor) and atypical (nonsense humor) forms of humor while amygdala-to-VTA connectivity was involved in processing the appreciation of atypical (aesthetic uses) forms of creativity. Altogether, these findings suggest that the amygdala and frontoparietal circuitry are critical for creativity and humor processing.

Mapping frontoinsular cortex from diffusion microstructure

We developed a novel method for mapping the location, surface area, thickness, and volume of frontoinsular cortex (FI) using structural and diffusion magnetic resonance imaging. FI lies in the ventral part of anterior insular cortex and is characterized by its distinctive population von Economo neurons (VENs). Functional neuroimaging studies have revealed its involvement in affective processing, and histopathology has implicated VEN loss in behavioral-variant frontotemporal dementia and chronic alcoholism; however, structural neuroimaging of FI has been relatively limited. We delineated FI by jointly modeling cortical surface geometry and its coincident diffusion microstructure parameters. We found that neurite orientation dispersion in cortical gray matter can be used to map FI in specific individuals, and the derived measures reflect a range of behavioral factors in young adults from the Human Connectome Project (N=1052). FI volume was larger in the left hemisphere than the right (31%), and the percentage volume of FI was larger in women than men (15.3%). FI volume was associated with measures of decision-making (delay discounting, substance abuse), emotion (negative intrusive thinking and perception of hostility), and social behavior (theory of mind and working memory for faces). The common denominator is that larger FI size is related to greater self-control and social awareness.

Money or funny: Effective connectivity during service recovery with a DCM-PEB approach

While monetary compensation is considered the most effective service recovery strategy, relief theory claims that humor may also be useful in service recovery situations. This study investigated the effects of humor in service recovery using dynamic causal modeling and parametric empirical Bayes analysis to identify effective connectivity (EC) patterns in the dopaminergic reward system across four conditions representing different service recovery strategies: monetary compensation and humor (MH), monetary compensation and an apology (MA), non-monetary compensation using humor (H), and non-monetary compensation using an apology (CON, the control condition). The findings support the importance of the nucleus accumbens (NAc) in the monetary compensation (MH and MA) conditions and the amygdala in the non-monetary compensation (H and CON) conditions. Monetary compensation (MH and MA) resulted in right substantia nigra (rSN) to NAc EC, suggesting the processing of recovery satisfaction associated with perceived outcome fairness. Conversely, non-monetary compensation strategies (H and CON) resulted in left substantia nigra (lSN) to amygdala EC, suggesting the processing of satisfaction related to perceived interactional fairness. The use of humor for service recovery resulted in VTA-to-lSN-to-amygdala EC during humor appreciation, while the use of apologies (CON and MA) resulted in lSN-to-amygdala and lSN-to-VTA connectivity. Surprisingly, processing satisfaction in the MH condition did not activate the amygdala during humor appreciation. Coping humor could be norm-violating for service recovery, and its effectiveness depends on multiple factors. The results suggest that monetary compensation, humorous responses, and apologies play key roles in neurological responses to service recovery strategies.

Effective connectivity of the amygdala during the consumption of erotic, sexual humor, and monetary rewards with a DCM-PEB approach

While a large body of research exists on the processing of monetary rewards, less is known about sexual reward processing. This study aimed to identify effective connectivity for the consumption of sexual (erotic and sexual humor) and non-sexual (monetary) rewards, using dynamic causal modeling and parametric empirical Bayes with subjective hedonic ratings included. Our results support the importance of the amygdala for sexual humor amusement, the nucleus accumbens (NAc) for monetary rewards, and the lateral orbitofrontal cortex (lOFC) for erotic pleasure. The amygdala, NAc, and lOFC are major dopaminergic targets with known roles in the reward circuitry. Appreciating sexual humor was associated with ventral tegmental area (VTA) to amygdala connectivity. Enjoying monetary gains was associated with VTA-to-NAc and amygdala-to-NAc connectivity. The mesolimbic dopamine system originates in the VTA and sends major projections to the amygdala and NAc. Specifically, sexual humor appreciation was associated with effective connectivity from the ventromedial prefrontal cortex (vmPFC) to the amygdala, suggesting that subjective pleasure triggers activation of the vmPFC which exerts an excitatory influence on the amygdala. Unexpectedly, processing pleasure from monetary gains was linked to VTA-to-vmPFC connectivity, rather than the expected vmPFC-to-NAc connectivity. Importantly, we identified core roles for the amygdala. Sexual humor appreciation was associated with VTA-to-amygdala and vmPFC-to-amygdala effective connectivity, while we found amygdala-to-lOFC connectivity for erotic pleasure and amygdala-to-NAc connectivity for pleasure from monetary gains. Our findings represent an important step in understanding how effective connectivity in the mesocorticolimbic-amygdala circuitry differs for processing the consumption of sexual and monetary rewards.

Toward reanimating the laughter-involved large-scale brain networks to alleviate affective symptoms

INTRODUCTION

The practicality of the idea whether the laughter-involved large-scale brain networks can be stimulated to remediate affective symptoms, namely depression, has remained elusive.

METHODS

In this study, 25 healthy individuals were tested through 21-channel quantitative electroencephalography (qEEG) setup upon resting state and while submitted to standardized funny video clips (corated by two behavioral neuroscientists and a verified expert comedian, into neutral and mildly to highly funny). We evaluated the individuals' facial expressions against the valence and intensity of each stimulus through the Nuldos face analysis software. The study also employed an eye-tracking setup to examine fixations, gaze, and saccadic movements upon each task. In addition, changes in polygraphic parameters were monitored upon resting state and exposure to clips using the 4-channel Nexus polygraphy setup.

RESULTS

The happy facial expression analysis, as a function of rated funny clips, showed a significant difference against neutral videos (p < 0.001). In terms of the polygraphic changes, heart rate variability and the trapezius muscle surface electromyography measures were significantly higher upon exposure to funny vs. neutral videos (p < 0.5). The average pupil size and fixation drifts were significantly higher and lower, respectively, upon exposure to funny videos (p < 0.01). The qEEG data revealed the highest current source density (CSD) for the alpha frequency band localized in the left frontotemporal network (FTN) upon exposure to funny clips. Additionally, left FTN acquired the highest value for theta coherence z-score, while the beta CSD predominantly fell upon the salience network (SN).

CONCLUSIONS

These preliminary data support the notion that left FTN may be targeted as a cortical hub for noninvasive neuromodulation as a single or adjunct therapy in remediating affective disorders in the clinical setting. Further studies are needed to test the hypotheses derived from the present report.

Differential Neural Substrates for Responding to Monetary, Sexual Humor, and Erotic Rewards

Sexual humor involves neural mechanisms related to both humor and sexual arousal. However, evidence on the role of the amygdala in processing sexual humor is lacking. Unlike erotic stimuli that directly involve a biological drive, sexual humor gains its value through learned associations. Processes related to responding to erotic versus monetary rewards have been identified in the lateral orbitofrontal cortex (lOFC) along a postero-anterior axis, but it is less clear whether these processes are also active during the appreciation of sexual humor. Results showed the processing of sexual humor appreciation in the amygdala. Psychophysiological interaction (PPI) analysis further identified functional connectivity in the amygdala-midbrain coupling during sexual humor versus monetary gains appreciation. The present study provides evidence demonstrating roles for the posterior OFC (pOFC) and anterior OFC (aOFC) in distinguishing between sexual (sexual humor and erotic) and non-sexual (monetary) rewards. The experience of sexual pleasure induced by erotic rewards involves phylogenetically and ontogenetically older regions in the pOFC, while the experience of receiving monetary gains involves the aOFC. This study also provides additional insights into sexual humor appreciation in the pOFC, with findings of a postero-anterior dissociation in the processing of sexual humor appreciation. PPI analysis revealed functional connectivity in the pOFC-amygdala coupling in response to both types of sexual rewards versus monetary rewards. Together, our results suggest that the amygdala serves as a reward hub, especially in processing sexual humor versus monetary gains appreciation. Functional connectivity analysis showed amygdala-midbrain and pOFC-amygdala coupling during the appreciation of sexual humor. DATA AVAILABILITY STATEMENT: The data underlying this article is available from the corresponding author upon request.

Narrative imagery: Emotional modulation in the default mode network

The default mode network (DMN) is activated when constructing and imagining narrative events, with functional brain activity in the medial-prefrontal cortex hypothesized to be modulated during emotional processing by adding value (or pleasure) to the episodic representation. However, since enhanced reactivity during emotional, compared to neutral, content is a more frequent finding in both the brain and body in physiological, neural, and behavioral measures, the current study directly assesses the effects of pleasure and emotion during narrative imagery in the DMN by using a within-subject design to first identify the DMN during resting state and then assess activation during pleasant, neutral, or unpleasant imagery. Replicating previous findings, enhanced functional activity in the medial prefrontal cortex was found when imagining pleasant, compared to unpleasant, events. On the other hand, emotion-related activation was found when imagining either pleasant or unpleasant, compared to neutral, events in other nodes of the DMN including the posterior cingulate cortex (PCC), angular gyrus, anterior hippocampus, lateral temporal cortex, temporal pole, dorsomedial prefrontal cortex (dmPFC), and ventrolateral prefrontal cortex (vlPFC). Pervasive emotional modulation in the DMN is consistent with the view that a primary function of event retrieval and construction is to remember, recreate, and imagine motivationally relevant events important for planning adaptive behavior.