Effect of the subjective intensity of fatigue and interoception on perceptual regulation and performance during sustained physical activity

Background The subjective experience of fatigue impairs an individual’s ability to sustain physical endurance performance. However, precise understanding of the specific role perceived fatigue plays in the central regulation of performance remains unclear. Here, we examined whether the subjective intensity of a perceived state of fatigue, pre-induced through prior upper body activity, differentially impacted performance and altered perceived effort and affect experienced during a sustained, isometric contraction in lower body. We also explored whether (cardiac) interoception predicted the intensity of experienced perceptual and affective responses and moderated the relationships between constructs during physical activity. Methods Using a repeated-measures study design, thirty male participants completed three experimental conditions, with the intensity of a pre-induced state of fatigue manipulated to evoke moderate (MOD), severe (SEV) and minimal (control; CON) intensity of perceptions prior to performance of the sustained contraction. Results Performance of the sustained contraction was significantly impaired under a perceived state of fatigue, with reductions of 10% and 14% observed in the MOD and SEV conditions, respectively. Performance impairment was accompanied by greater perceived effort and more negative affective valence reported during the contraction. However, effects were limited to comparisons to CON, with no difference evident between the two experimental trials (i.e. MOD vs. SEV). Individuals’ awareness of their accuracy in judging resting heartbeats was shown to predict the subjective intensity of fatigue experienced during the endurance task. However, interoception did not moderate the relationships evident between fatigue and both perceived effort and affective valence. Conclusions A perceived state of fatigue limits endurance performance, influencing both how effortful activity is perceived to be and the affective experience of activity. Though awareness of interoceptive representations of bodily states may be important to the subjective experience of fatigue, interoception does not modulate the relationships between perceived fatigue and other perceptual (i.e. effort) and affective constructs.

Individual differences in music reward sensitivity influence the perception of emotions represented by music

Although music is one of the most important sources of pleasure for many people, there are considerable individual differences in music reward sensitivity. Behavioral and neurobiological characterizations of music reward variability have been topics of increasing scientific interest over the last two decades. However, it is not clear how differences in music reward sensitivity might influence the perception of emotions represented by music and, specifically, how music reward sensitivity could influence subjective music evaluation when the affective valence of music is considered. In the present study, we investigated the relationship between music reward sensitivity and the perception of emotions in music, taking into account the emotional category of stimuli (pleasant, neutral, or unpleasant music clips). Music reward and emotion perception were also explored as a function of gender, musicianship, and music discrimination skills. We used the Barcelona Music Reward Questionnaire and the previously validated Film Music Stimulus Set (FMSS); participants rated FMSS excerpts for affective dimensions (valence, energy, and tension arousal) and discrete emotions (happiness, anger, fear, tenderness, and sadness). Our results showed that music reward was the main factor influencing FMSS evaluation, particularly for excerpts associated with positive affect. Gender had an important influence on evaluations linked to the negative pole of emotions, and music discrimination skills seemed to be associated with cognitive aspects of music analysis, rather than with the emotional architecture of pleasant music excerpts. Our findings highlight the need to consider music reward sensitivity and gender in studies of music and emotion, and open the possibility of using the FMSS in studies exploring the neurobiological and psychosocial bases of music emotion.

Behavior and Fos activation reveal that male and female rats differentially assess affective valence during CTA learning and expression

Females are more affected by psychiatric illnesses including eating disorders, depression, and post-traumatic stress disorder than males. However, the neural mechanisms mediating these sex differences are poorly understood. Animal models can be useful in exploring such neural mechanisms. Conditioned taste aversion (CTA) is a behavioral task that assesses how animals process the competition between associated reinforcing and aversive stimuli in subsequent task performance, a process critical to healthy behavior in many domains. The purpose of the present study was to identify sex differences in this behavior and associated neural responses. We hypothesized that females would value the rewarding stimulus (Boost®) relative to the aversive stimulus (LiCl) more than males in performing CTA. We evaluated behavior (Boost® intake, LiCl-induced behaviors, ultrasonic vocalizations (USVs), CTA performance) and Fos activation in relevant brain regions after the acute stimuli [acute Boost® (AB), acute LiCl (AL)] and the context-only task control (COT), Boost® only task (BOT) and Boost®-LiCl task (BLT). Acutely, females drank more Boost® than males but showed similar aversive behaviors after LiCl. Females and males performed CTA similarly. Both sexes produced 55 kHz USVs anticipating BOT and inhibited these calls in the BLT. However, more females emitted both 22 kHz and 55 kHz USVs in the BLT than males: the latter correlated with less CTA. Estrous cycle stage also influenced 55 kHz USVs. Fos responses were similar in males and females after AB or AL. Females engaged the gustatory cortex and ventral tegmental area (VTA) more than males during the BOT and males engaged the amygdala more than females in both the BOT and BLT. Network analysis of correlated Fos responses across brain regions identified two unique networks characterizing the BOT and BLT, in both of which the VTA played a central role. In situ hybridization with RNAscope identified a population of D1-receptor expressing cells in the CeA that responded to Boost® and D2 receptor-expressing cells that responded to LiCl. The present study suggests that males and females differentially process the affective valence of a stimulus to produce the same goal-directed behavior.

The affect bias in the metaphorical representation of anticipated events

When talking about anticipated events, speakers can conceptualize them either as destinations towards which they are moving or as entities moving towards them, which correspond to the Ego- and the Time-moving metaphors, respectively (cf. ‘We are approaching Christmas’ and ‘Christmas is approaching’). Research in psycholinguistics has shown affective valence, i.e. whether the conceptualized event is perceived as positive or negative, to be one of the factors that modulate metaphor choice; positive anticipation is preferentially associated with Ego-moving expressions, whereas negative anticipation is predominantly associated with Time-moving metaphors. This paper sets out to test if the time-affect association surfaces in naturally-occurring language use when both metaphorical patterns are available. By focusing on the temporal usage of the verb approach, we provide linguistic evidence in favor of such an affective bias in time representations. In addition, the language data point to a semantic preference for a particular type of event (i.e., personal vs social) under each metaphorical pattern. We interpret this finding as preliminary evidence for a possible semantic bias in time representations to be further investigated.

Oxytocin enhances neural approach towards social and non-social stimuli of high personal relevance

Oxytocin (OT) plays a pivotal role in a variety of complex social behaviors by modulating approach-avoidance motivational tendencies, but recently, its social specificity has been challenged. Here, a randomized, double-blind, placebo-controlled study was conducted with forty young adult men, investigating the effect of a single-dose of OT (24 IU) on behavioral and neural approach-avoidance. Frontal alpha asymmetry, indexing neurophysiological approach-avoidance, was obtained from electroencephalographic recordings while participants were presented with a series of pictures, individually rated in terms of personal relevance (i.e., high versus low positive/negative emotional evocativeness) and categorized as social or non-social. Additionally, participants could prolong (approach) or shorten (avoid) the viewing-time of each picture, providing a measure of behavioral approach-avoidance. Intranasal OT enhanced both behavioral and neural approach (increased viewing-time), particularly towards negatively valenced pictures of both social and non-social nature, thus challenging the notion that OT’s effects are specific to social stimuli. Neurally, OT specifically amplified approach-related motivational salience of stimuli that were self-rated to have high personal relevance, but irrespective of their social nature or rated affective valence (positive/negative). Together, these findings provide support to the General Approach-Avoidance Hypothesis of OT, suggesting a role of OT in amplifying the motivational salience of environmental stimuli with high (personal) relevance, but irrespective of their social/non-social nature.Clinical Trial Number: The study design was registered at ClinicalTrials.gov (NCT04443647; 23/06/2020; https://clinicaltrials.gov/ct2/show/NCT04443647).

Neurokinin receptor mechanisms in forebrain medial septum modulate nociception in the formalin model of inflammatory pain

The present study has explored the hypothesis that neurokinin1 receptors (NK1Rs) in medial septum (MS) modulate nociception evoked on hind paw injection of formalin. Indeed, the NK1Rs in MS are localized on cholinergic neurons which have been implicated in nociception. In anaesthetized rat, microinjection of L-733,060, an antagonist at NK1Rs, into MS antagonized the suppression of CA1 population spike (PS) evoked on peripheral injection of formalin or on intraseptal microinjection of substance P (SP), an agonist at NK1Rs. The CA1 PS reflects the synaptic excitability of pyramidal cells in the region. Furthermore, microinjection of L-733,060 into MS, but not LS, attenuated formalin-induced theta activation in both anaesthetized and awake rat, where theta reflects an oscillatory information processing by hippocampal neurons. The effects of L-733,060 on microinjection into MS were nociceptive selective as the antagonist did not block septo-hippocampal response to direct MS stimulation by the cholinergic receptor agonist, carbachol, in anaesthetized animal or on exploration in awake animal. Interestingly, microinjection of L-733,060 into both MS and LS attenuated formalin-induced nociceptive flinches. Collectively, the foregoing novel findings highlight that transmission at NK1R provide an affective valence to septo-hippocampal information processing and that peptidergic transmission in the septum modulates nociceptive behaviours.

Individual differences in resilience to stress are associated with affective flexibility

Cognitive flexibility, the capacity to adjust behavior to changing situational demands, is frequently linked to resilience because of its important contribution to stress regulation. In this context, particularly affective flexibility, defined as the ability to flexibly attend and disengage from affective information, may play a significant role. However, there are so far only very few empirical investigations that directly explore the link between flexibility and resilience to stress. In the present study, the relationship of cognitive and affective flexibility and resilience was examined in 100 healthy participants. Resilience was measured with three self-report questionnaires, two defining resilience as a personality trait and one focusing on resilience as an outcome in the sense of stress coping abilities. Cognitive and affective flexibility were assessed in two experimental task switching paradigms with non-affective and affective materials and tasks, respectively. The cognitive flexibility paradigm additionally included measures of cognitive stability and dispositional cognitive flexibility. In the affective flexibility paradigm, we explicitly considered the affective valence of the stimuli before and during task switching. Response time switch costs in the affective flexibility paradigm were significantly correlated to all three self-report measures of resilience. Regarding the valence of the stimuli, the correlation with resilience was not specific to costs when switching from negative to positive information or vice versa. For cognitive (i.e., non-affective) flexibility, a significant correlation of response time switch costs was found with only one of the three resilience measures. A regression analysis including both affective and cognitive switch costs as predictors of resilience indicated that only affective, but not cognitive switch costs, explained unique variance components. Furthermore, the experimental measures of cognitive stability and dispositional cognitive flexibility did not correlate with resilience scores. These findings suggest that specifically the efficiency of flexibly switching between affective and non-affective information is related to resilience.

Common neural bases for processing speech prosody and music: An integrated model

Do speech and music understanding share common neural mechanisms? Here, brain bioelectrical activity was recorded in healthy participants listening to music obtained by digitally transforming speech into viola music. Sentences originally had a positive or negative affective prosody. The aim was to investigate if the emotional content of music was processed similarly to the affective prosody of speech. EEG was recorded from 128 electrodes in 20 healthy students. Participants had to detect rare neutral piano sounds while ignoring viola melodies. Negative affective valence of stimuli increased the amplitude of frontal P300 and N400 components of ERPs, while positive valence enhanced a late inferior frontal positivity. Similar markers were previously found for the processing of positive versus negative music, vocalizations, and speech. Source reconstruction showed that negative music activated the right superior temporal gyrus and cingulate cortex, while positive music activated the left middle and inferior temporal gyrus and the inferior frontal cortex. An integrated model is proposed of a possible common network for processing the emotional content of music, vocalizations, and speech, which might explain some universal and relatively innate brain reaction to music.