Opposing effects of appetitive and aversive cues on go/no-go behavior and motor excitability

Emotional cues reduce Pavlovian interference in feedback-based go and nogo learning

It is easier to execute a response in the promise of a reward and withhold a response in the promise of a punishment than vice versa, due to a conflict between cue-related Pavlovian and outcome-related instrumental action tendencies in the reverse conditions. This robust learning asymmetry in go and nogo learning is referred to as the Pavlovian bias. Interestingly, it is similar to motivational tendencies reported for affective facial expressions, i.e., facilitation of approach to a smile and withdrawal from a frown. The present study investigated whether and how learning from emotional faces instead of abstract stimuli modulates the Pavlovian bias in reinforcement learning. To this end, 137 healthy adult participants performed an orthogonalized Go/Nogo task that fully decoupled action (go/nogo) and outcome valence (win points/avoid losing points). Three groups of participants were tested with either emotional facial cues whose affective valence was either congruent (CON) or incongruent (INC) to the required instrumental response, or with neutral facial cues (NEU). Relative to NEU, the Pavlovian bias was reduced in both CON and INC, though still present under all learning conditions. Importantly, only for CON, the reduction of the Pavlovian bias effect was adaptive by improving learning performance in one of the conflict conditions. In contrast, the reduction of the Pavlovian bias in INC was completely driven by decreased learning performance in non-conflict conditions. These results suggest a potential role of arousal/salience in Pavlovian-instrumental regulation and cue-action congruency in the adaptability of goal-directed behavior. Implications for clinical application are discussed.

The intracortical excitability changes underlying the enhancing effects of rewards and punishments on motor performance

Monetary rewards and punishments enhance motor performance and are associated with corticospinal excitability (CSE) increases within the motor cortex (M1) during movement preparation. However, such CSE changes have unclear origins. Based on converging evidence, one possibility is that they stem from increased glutamatergic (GLUTergic) facilitation and/or decreased type A gamma-aminobutyric acid (GABAA)-mediated inhibition within M1. To investigate this, paired-pulse transcranial magnetic stimulation was used over the left M1 to evaluate intracortical facilitation (ICF) and short intracortical inhibition (SICI), indirect assays of GLUTergic activity and GABAA-mediated inhibition, in an index finger muscle during the preparation of sequences initiated by either the right index or little finger. Behaviourally, rewards and punishments enhanced both reaction and movement time. During movement preparation, regardless of rewards or punishments, ICF increased when the index finger initiated sequences, whereas SICI decreased when both the index and little fingers initiated sequences. This finding suggests that GLUTergic activity increases in a finger-specific manner whilst GABAA-mediated inhibition decreases in a finger-unspecific manner during preparation. In parallel, both rewards and punishments non-specifically increased ICF, but only rewards non-specifically decreased SICI as compared to neutral. This suggests that to enhance performance rewards both increase GLUTergic activity and decrease GABAA-mediated inhibition, whereas punishments selectively increase GLUTergic activity. A control experiment revealed that such changes were not observed post-movement as participants processed reward and punishment feedback, indicating they were selective to movement preparation. Collectively, these results map the intracortical excitability changes in M1 by which incentives enhance motor performance.

How does Go/No-Go training lead to food devaluation? Separating the effects of motor inhibition and response valence

Palatable, unhealthy food stimuli can be devalued via Go/No-Go (GNG) training that consistently pairs such stimuli with motor inhibition. However, it remains unclear whether this devaluation is caused via learned associations with motor inhibition or via inferential learning based on the valence of emitted motor responses. The present research disentangles the effects of motor assignment and response valence in GNG training through task instructions. In two studies, chocolate stimuli were consistently paired with motor inhibition ("no-go") or with motor excitation ("go"). Task instructions indicated that no-go responses were negatively valenced ("do not take") and that go responses were positively valenced ("take"), or identified no-go responses as positively valenced ("keep") and go as negatively valenced ("throw away"). The results show an effect of response valence on chocolate evaluations, but no effect of motor assignment: Chocolate stimuli were consistently devalued following pairings with a negatively valenced response, regardless of whether this response entailed motor inhibition or excitation. These findings align best with an inferential account of GNG training, suggesting that devaluation effects critically depend on inferential processes regarding motor response valence. GNG training procedures may, therefore, be optimised by disambiguating the valence of go and no-go motor responses prior to training.

Nurses' Psychological Trauma and Cognitive Control in the COVID-19 Pandemic

Introduction

During the COVID-19 pandemic, nurses have faced various nurse-specific traumas in their workplaces, but there is limited understanding of the resulting outcomes and factors that contribute to them.

Objective

To address this gap, the study employed the middle-range theory of nurses' psychological trauma (NPT) to examine these relationships among frontline nurses working in critical care areas.

Methods

In a quantitative cross-sectional study, the study compared nurses identified as probable cases of posttraumatic stress disorder (PTSD) with those identified as not probable cases. The study investigated the nurse-specific traumas they experienced, their individual personality traits, and the buffers they possessed. The study also sought to identify specific types of nurse-specific traumas that could be associated with negative outcomes, such as alcohol and drug use.

Results

It was found that PTSD-probable nurses reported higher levels of trauma from disasters and system/medically induced trauma compared to not-probable nurses. They also experienced more nonwork-related humankind traumas and displayed lower resilience. Furthermore, PTSD-probable nurses identified with trait urgency and trait avoidance motivation. Additionally, trauma from disasters was associated with alcohol use.

Conclusion

The study highlights the elevated levels of trauma, lower resilience, and specific psychological traits associated with PTSD-probable nurses, emphasizing the need for targeted interventions and support to mitigate the negative outcomes experienced by frontline nurses.

State-dependent effects of neural stimulation on brain function and cognition

Invasive and non-invasive brain stimulation methods are widely used in neuroscience to establish causal relationships between distinct brain regions and the sensory, cognitive and motor functions they subserve. When combined with concurrent brain imaging, such stimulation methods can reveal patterns of neuronal activity responsible for regulating simple and complex behaviours at the level of local circuits and across widespread networks. Understanding how fluctuations in physiological states and task demands might influence the effects of brain stimulation on neural activity and behaviour is at the heart of how we use these tools to understand cognition. Here we review the concept of such 'state-dependent' changes in brain activity in response to neural stimulation, and consider examples from research on altered states of consciousness (for example, sleep and anaesthesia) and from task-based manipulations of selective attention and working memory. We relate relevant findings from non-invasive methods used in humans to those obtained from direct electrical and optogenetic stimulation of neuronal ensembles in animal models. Given the widespread use of brain stimulation as a research tool in the laboratory and as a means of augmenting or restoring brain function, consideration of the influence of changing physiological and cognitive states is crucial for increasing the reliability of these interventions.

Action Selection and Motor Decision Making: Insights from Transcranial Magnetic Stimulation

In everyday life, goal-oriented motor behaviour relies on the estimation of the rewards/costs associated with alternative actions and on the appropriate selection of movements. Motor decision making is defined as the process by which a motor plan is chosen among a set of competing actions based on the expected value. In the present literature review we discuss evidence from transcranial magnetic stimulation (TMS) studies of motor control. We focus primarily on studies of action selection for instructed movements and motor decision making. In the first section, we delve into the usefulness of various TMS paradigms to characterise the contribution of motor areas and distributed brain networks to cued action selection. Then, we address the influence of motivational information (e.g., reward and biomechanical cost) in guiding action choices based on TMS findings. Finally, we conclude that TMS represents a powerful tool for elucidating the neurophysiological mechanisms underlying action choices in humans.

The Effect of Odour Valence and Odour Detection Threshold on the Withholding and Cancellation of Reach-to-Press Responses

Introduction

Withholding uninitiated actions and cancelling ongoing ones are two main components of response inhibition, a key element of the executive control. Inhibitory performance is sensitive to emotional contexts elicited by subliminal and supraliminal visual material. However, whether stimuli from other sensory modalities, such as odours, would equally modulate response inhibition remains unclear. Here, we aimed to assess the effect of task-irrelevant odours as a function of their valence and threshold on both action withholding and action cancellation of reach-to-press movements.

Method

Thirty-two healthy participants performed a Go/No-Go task that included the presentation of pleasant (orange) and unpleasant (trimethyloxazole) odour primes at supra- and sub-threshold levels; clean air was included as a control condition. The reach-to-press responses were composed of an initial release phase and a subsequent reaching phase.

Results

Only the supra-threshold pleasant (vs. control) odour impaired action withholding. Moreover, the pleasant (vs. control) odour—presented at both sub- and supra-threshold levels—elicited more accurate Go responses, whereas the sub- and supra-threshold pleasant and unpleasant (vs. control) odours triggered faster responses in the release phase. Additionally, only the supra-threshold pleasant (vs. unpleasant) odour impaired action cancellation in the reaching phase. Furthermore, reaching responses were slower following the supra-threshold unpleasant (vs. control) odour.

Conclusions

Our findings extend the sparse literature on the impact of odour stimuli on goal-directed behaviour, highlighting the role of both odour valence and threshold in the modulation of response inhibition.

Implications

Determining the mechanisms by which odour stimuli modulate response inhibition lays the foundations for research on odour-triggered disinhibition.

Olfactory influences on reach-to-press movements in a stop-signal task

Response inhibition is sensitive to unexpected changes in the environment triggered by emotional stimuli. Whereas the impact of visual material on inhibition has been widely documented, the attention on the influence of olfactory stimuli has been neglected. Here, we examined the effect of pleasant (orange), unpleasant (trimethyloxazole), and control (clean air) odour primes in a stop-signal task. Twenty-five participants had to elicit or inhibit reach-to-press actions which allowed to examine the olfactory influences on both the planning (release phase) and the on-line control (reaching phase) of responses. Additionally, we manipulated the distance between the initial hand position and the target to be pressed (10 vs. 20 vs. 30 cm). The pleasant (vs. control) odour impaired inhibition, as reflected in slower stop-signal reaction times and higher release errors, indicating greater mobilisation of inhibitory resources by pleasant stimuli. Further, faster release responses were triggered by pleasant and unpleasant primes, supporting the idea of perceptual prioritisation of emotional (vs. non-emotional) stimuli. The olfactory manipulation did not affect the reaching phase of the responses. Instead, the distance manipulation modulated the reaching but not the release phase. These results extend the sparse literature on the influences of odour stimuli on response inhibition.

Reward does not modulate corticospinal excitability in anticipation of a Stroop trial

Action preparation is associated with a transient decrease of corticospinal excitability just before target onset. We have previously shown that the prospect of reward modulates preparatory corticospinal excitability in a Simon task. While the conflict in the Simon task strongly implicates the motor system, it is unknown whether reward prospect modulates preparatory corticospinal excitability in tasks that implicate the motor system less directly. To that effect, we examined reward-modulated preparatory corticospinal excitability in the Stroop task. We administered a rewarded cue-target delay paradigm using Stroop stimuli that afforded a left or right index finger response. Single-pulse transcranial magnetic stimulation was administered over the left primary motor cortex and electromyography was obtained from the right first dorsal interosseous muscle. In line with previous findings, there was a preparatory decrease in corticospinal excitability during the delay period. In contrast to our previous study using the Simon task, preparatory corticospinal excitability was not modulated by reward. Our results indicate that reward-modulated changes in the motor system depend on specific task-demands, possibly related to varying degrees of motor conflict.

Influence of post-stroke fatigue on reaction times and corticospinal excitability during movement preparation

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Higher the fatigue, lesser the inhibition in movement preparation in stroke survivors.

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Higher the fatigue, lesser the pre-movement facilitation and slower the reaction times.

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Poor excitability modulation supports sensory attenuation model of fatigue.

Objectives

Reduced corticospinal excitability at rest is associated with post-stroke fatigue (PSF). However, it is not known if corticospinal excitability prior to a movement is also altered in fatigue which may then influence subsequent behaviour. We hypothesized that the levels of PSF can be explained by differences in modulation of corticospinal excitability during movement preparation.

Methods

73 stroke survivors performed an auditory reaction time task. Corticospinal excitability was measured using transcranial magnetic stimulation. Fatigue was quantified using the fatigue severity scale. The effect of time and fatigue on corticospinal excitability and reaction time was analysed using a mixed effects model.

Results

Those with greater levels of PSF showed reduced suppression of corticospinal excitability during movement preparation and increased facilitation immediately prior to movement onset (β = −0.0066, t = −2.22, p = 0.0263). Greater the fatigue, slower the reaction times the closer the stimulation time to movement onset (β = 0.0024, t = 2.47, p = 0.0159).

Conclusions

Lack of pre-movement modulation of corticospinal excitability in high fatigue may indicate poor sensory processing supporting the sensory attenuation model of fatigue.

Significance

We take a systems-based approach and investigate the motor system and its role in pathological fatigue allowing us to move towards gaining a mechanistic understanding of chronic pathological fatigue.

Proactive engagement of cognitive control modulates implicit approach-avoidance bias

Implicit social-affective biases-reflected in a propensity to approach positive and avoid negative stimuli-have been documented in humans with paradigms, such as the Approach-Avoidance Task (AAT). However, the degree to which preemptively engaging cognitive control can help to down-regulate those behavioral tendencies remains poorly understood. While undergoing functional magnetic resonance imaging (fMRI), 24 healthy participants completed a cued version of the AAT, in which they responded to pictures of happy or angry faces by pulling a joystick toward themselves (approach) or pushing the joystick away (avoidance) based on the color of the stimulus frame. On some trials, they were cued to reverse the frame color/joystick action instructions. Before stimulus onset, a reverse cue was associated with deactivation of a visuo-spatial and motor planning network and subsequent slowing down in response to stimuli. During the stimulus phase, a reverse cue was associated with a) activation of cognitive control areas, including the right inferior frontal gyrus (IFG) and right inferior parietal lobule (IPL); and b) reduced right precentral gyrus activation when having to push (avoid) a happy face. Overall, these results suggest that proactively engaging cognitive control can help fine-tune behavioral and neural adjustment to emotionally incongruent behavioral conditions.

Inhibitory control in trauma-exposed youth: A systematic review

The aim of this systematic review was to provide insight in inhibitory control (prepotent response inhibition and interference control) in trauma-exposed youth from a developmental perspective and exploring the effects of prolonged stress. A systematic search was conducted, resulting in 1722 abstracts. Of those, 33 studies met inclusion criteria. Twelve studies measured prepotent response inhibition (Go/no-go and Stop-signal task), 20 studies measured interference control (Flanker and Stroop task), and one measured both. Some studies indeed found evidence for prolonged trauma exposure impeding both subcomponents of inhibitory control, although others did not. At a later age, inhibitory control problems on task performance seem to disappear. However, distinct patterns of brain activity may suggest that those individuals employ compensation strategies. Together, the findings may suggest that non-specific inhibitory control problems occur after prolonged trauma exposure, with older youth possibly employing compensation strategies on the tasks. Future studies may provide a clearer picture of the compensation strategies and the circumstances in which they become visible.

The role of affect, emotion management, and attentional bias in young adult drinking: An experience sampling study

RATIONALE

Coping with negative affect is central to several prominent etiological models of alcohol use. These models posit that alcohol use becomes negatively reinforced due to its ability to alleviate negative affect. However, there have been mixed findings when testing this association at the event-level.

OBJECTIVES

The current experience sampling study sought to clarify this by testing if (1) within-person changes in the perceived difficulty of managing emotional distress is a significant predictor of alcohol consumption, over and above levels negative and positive affect and (2) whether acute changes in affective experiences give rise to increased attentional bias toward alcohol-related cues in the environment and if attentional bias mediates the association between difficulty managing emotions and alcohol consumption. Participants were 92 college students aged 18-25, who drink alcohol at least moderately.

METHODS

Participants completed 28 days of experiencing sampling measures on their mood, difficulty managing emotions, alcohol-related attentional biases, and drinking.

RESULTS

Findings showed that neither negative affect nor difficult managing emotions had significant effects on alcohol use. However, positive affect exhibited the expected associations with both attentional biases and drinking. State positive affect predicted acute increases in attentional biases and drinking, whereas trait positive affect was inversely associated with trait attentional biases and alcohol use. Alcohol-related attentional biases exhibited significant within-person variance; however, its relationship with drinking was only significant when the constructs were assessed concurrently at night and did not mediate the relationship between affect and alcohol use.

CONCLUSIONS

Results highlight the importance of positive affect in this population.

Task-irrelevant odours affect both response inhibition and response readiness in fast-paced Go/No-Go task: the case of valence

Whether emotional stimuli influence both response readiness and inhibition is highly controversial. Visual emotional stimuli appear to interfere with both under certain conditions (e.g., task relevance). Whether the effect is generalisable to salient yet task-irrelevant stimuli, such as odours, remains elusive. We tested the effect of orthonasally-presented pleasant (orange) and unpleasant odours (trimethyloxazole and hexenol) and clean air as a control on response inhibition. In emotional Go/No-Go paradigms, we manipulated the intertrial interval and ratios of Go/No-Go trials to account for motor (Experiment 1, N = 31) and cognitive (Experiment 2, N = 29) response inhibition processes. In Experiment 1, participants had greater difficulty in withholding and produced more accurate and faster Go responses under the pleasant vs. the control condition. Faster Go responses were also evident in the unpleasant vs. the control condition. In Experiment 2, neither pleasant nor unpleasant odours modulated action withholding, but both elicited more accurate and faster Go responses as compared to the control condition. Pleasant odours significantly impair action withholding (as compared to the control condition), indicating that more inhibitory resources are required to elicit successful inhibition in the presence of positive emotional information. This modulation was revealed for the motor aspect of response inhibition (fast-paced design with lower Go/No-Go trial ratio) rather than for attentional interference processes. Response readiness is critically impacted by the emotional nature of the odour (but not by its valence). Our findings highlight that the valence of task-irrelevant odour stimuli is a factor significantly influencing response inhibition.

Biasing Actions by Incentive Valence in an Approach/Avoidance Task

The present study investigates interactions between incentive valence and action, which mirror well-known valence-action biases in the emotional domain. In three joystick experiments, incentive valence (win/loss) and action type (approach/avoid) were signaled by distinct orthogonal stimulus features. By combining several design aspects, i.e., the use of bi-directional joystick movements, the inclusion of no-incentive baseline trials, and cue-locked versus target-locked valence and action signals, we tried to bridge between paradigms used in the emotional and motivational domain, and to understand previous, partly inconsistent results. In the first task variant (Experiment 1), we observed performance benefits for compatible mappings (win-approach; loss-avoid) relative to incompatible ones (loss-approach; win-avoid) when valence and action signals were target-locked, consistent with a fairly automatic response activation that can benefit or impair task performance. In contrast, cue-locked valence signals led to response facilitation (relative to a no-incentive baseline) more or less independent of actual valence (win/loss) and action type (approach/avoid), which is reminiscent of general facilitation effects of incentive cues across diverse cognitive tasks. Slight design variations did not change this main result pattern, indicating that it was neither driven by the close proximity between target and performance feedback (Experiment 2), nor by mere temporal coincidence of valence and action signals (Experiment 3), but rather by differences between preparatory (cued) and immediate (non-cued) effects of incentive valence. The present study provides novel insights regarding the nature of valence-action biases in the motivational domain and helps to integrate previous, partly inconsistent findings across domains.

Motor Memory: Revealing Conditioned Action Tendencies Using Transcranial Magnetic Stimulation

Action tendencies can be elicited by motivationally salient stimuli (e.g., appetitive rewards) or objects that support utilization behaviors. These action tendencies can benefit behavioral performance through speeded RTs in response tasks and improve detection accuracy in attentional capture tasks. However, action tendencies can be counterproductive when goals change (e.g., refraining from junk foods or abstaining from alcohol). Maintaining control over cue-elicited action tendencies is therefore critical for successful behavior modification. To better understand this relationship, we used transcranial magnetic stimulation to investigate the neural signatures of action tendencies in the presence of previously trained response cues. Participants were presented with a continuous letter stream and instructed to respond quickly to two target letters using two different response keys. Following this training phase, the target letters were embedded in a new task (test phase), and we applied transcranial magnetic stimulation to the motor cortex and measured motor evoked potentials as an index of corticospinal excitability (CSE). We found that CSE could be potentiated by a former response cue trained within a single experimental session, even when participants were instructed to withhold responses during the test phase. Critically, attention to the previously trained response cue was required to elicit the primed modulation in CSE, and successful control of this activity was accompanied by CSE suppression. These findings suggest that well-trained response cues can come to prime a conditioned action tendency and provide a model for understanding how the implementation of cognitive control can override action automaticity.

Reward anticipation changes corticospinal excitability during task preparation depending on response requirements and time pressure

The preparation of an action is accompanied by transient corticospinal (CS) excitability changes. Motivation can modulate these changes. Specifically, when a cue indicates that a reward can be obtained, CS excitability initially increases, followed by a pronounced decrease. This dynamic could reflect processes related to reward expectancy, processes related to action preparation, or a combination of both. Here we set up two experiments to dissociate these accounts. A rewarded choice reaction time task was used in which individuals were cued at the beginning of each trial whether or not a response would be required at target onset and whether or not a reward could be obtained. We used single-pulse transcranial magnetic stimulation (spTMS) over the left primary motor cortex (M1) early (shortly after cue onset) or late (shortly before target onset) preceding target onset to examine CS excitability during motivated action preparation. Electromyography (EMG) was obtained from the right first dorsal interosseous (FDI) muscle. In the first experiment, we used a lenient response deadline, whereas a strict response time-out procedure was employed in the second experiment. Reward modulated CS excitability differentially only in the second experiment: CS excitability was highest during reward anticipation for the early stimulation epoch and was reduced for the late stimulation epoch when individuals were required to prepare a response, while CS excitability remained unchanged during non-reward anticipation. Our findings suggest that the reward effect on CS excitability is dependent on the actual implementation of effort to attain reward (i.e., the preparation of an actual action), as well as on temporal requirements (i.e., time pressure) invoked by the task.

Motor cortex inhibition and modulation in children with ADHD

OBJECTIVE

Compared to typically developing (TD) peers, children with attention-deficit/hyperactivity disorder (ADHD) consistently demonstrate impaired transcranial magnetic stimulation (TMS)-evoked short interval cortical inhibition (SICI) of motor evoked potentials (MEPs) in resting motor cortex (M1). To determine whether perturbed M1 physiology also reflects clinically relevant behavioral dysfunction, we evaluated M1 physiology during a cognitive control task taxing motor response selection/inhibition.

METHODS

In this case-control study, behavioral ratings, motor skill (assessed using standardized examination), and left M1 physiology were evaluated in 131 right-handed, 8- to 12-year-old children (66 ADHD: mean 10.5 years, 43 male; 65 TD: mean 10.6 years, 42 male). The primary outcomes were MEP amplitudes and SICI, evaluated during rest and during a modified "racecar" Slater-Hammel stop signal reaction task, with TMS pulses administered 150 ms prior to the target go action and after the dynamic stop cue.

RESULTS

Go responses were significantly slower (p = 0.01) and more variable (p = 0.002) in ADHD. Children with ADHD showed less M1 SICI at rest (p = 0.02) and during go (p = 0.03) and stop trials (p = 0.02). Rest M1 excitability increased during response inhibition task engagement (p < 0.0001). This Task-Related Up-Modulation (TRUM) was less robust across and within groups, with diminished task upmodulation associated with significantly more severe ADHD behavioral ratings and slower stop signal reaction times.

CONCLUSION

Children with ADHD show anomalous motor cortex physiology, with deficient SICI across behavioral states and less TRUM from rest to action selection. Associations of these physiologic measures with ADHD symptoms and cognitive control measures support further investigation into biological mechanisms.

Motor Cortex Excitability Reflects the Subjective Value of Reward and Mediates Its Effects on Incentive-Motivated Performance

Performance-based incentives tend to increase an individual's motivation, resulting in enhancements in behavioral output. While much work has focused on understanding how the brain's reward circuitry influences incentive-motivated performance, fewer studies have investigated how such reward representations act on the motor system. Here we measured motor cortical excitability with transcranial magnetic stimulation while female and male human participants performed a motoric incentive motivation task for prospective monetary gains and losses. We found that individuals' performance increased for increasing prospective gains and losses. While motor cortical excitability appeared insensitive to prospective loss, temporal features of motor cortical excitability for prospective gains were modulated by an independent measure of an individual's subjective preferences for incentive (i.e., loss aversion). Those individuals that were more loss averse had a greater motor cortical sensitivity to prospective gain, closer to movement onset. Critically, behavioral sensitivity to incentive and motor cortical sensitivity to prospective gains were both predicted by loss aversion. Furthermore, causal modeling indicated that motor cortical sensitivity to incentive mediated the relationship between subjective preferences for incentive and behavioral sensitivity to incentive. Together, our findings suggest that motor cortical activity integrates information about the subjective value of reward to invigorate incentive-motivated performance.SIGNIFICANCE STATEMENT Increasing incentives tend to increase motivation and effort. Using a motoric incentive motivation task and transcranial magnetic stimulation, we studied the motor cortical mechanisms responsible for incentive-motivated motor performance. We provide experimental evidence that motor cortical sensitivity to incentive mediates the relationship between subjective preferences for incentive and incentive-motivated performance. These results indicate that, rather than simply being a reflection of motor output, motor cortical physiology integrates information about reward value to motivate performance.

Motivational sensitivity of outcome-response priming: Experimental research and theoretical models

Outcome-response (O-R) priming is at the core of various associative theories of human intentional action. This is a simple and parsimonious mechanism by which activation of outcome representations (e.g. thinking about the light coming on) leads to activation of the associated motor patterns required to achieve it (e.g. pushing the light switch). In the current manuscript, we review the evidence for such O-R associative links demonstrated by converging (yet until now, separate) strands of research. While there is a wealth of evidence that both the perceptual and motivational properties of an outcome can be encoded in the O-R association and mediate O-R priming, we critically examine the integration of these mechanisms and the conditions under which motivational factors constrain the sensory O-R priming effect. We discuss the clinical relevance of this O-R priming mechanism, whether it can satisfactorily account for human goal-directed behaviour, and the implications for theories of human action control.

The Cue-Approach Task as a General Mechanism for Long-Term Non-Reinforced Behavioral Change

Recent findings show that preferences for food items can be modified without external reinforcements using the cue-approach task. In the task, the mere association of food item images with a neutral auditory cue and a speeded button press, resulted in enhanced preferences for the associated stimuli. In a series of 10 independent samples with a total of 255 participants, we show for the first time that using this non-reinforced method we can enhance preferences for faces, fractals and affective images, as well as snack foods, using auditory, visual and even aversive cues. This change was highly durable in follow-up sessions performed one to six months after training. Preferences were successfully enhanced for all conditions, except for negative valence items. These findings promote our understanding of non-reinforced change, suggest a boundary condition for the effect and lay the foundation for development of novel applications.

The neural basis of improved cognitive performance by threat of shock

Anxiety can have both detrimental and facilitatory cognitive effects. This study investigates the neural substrates of a replicated facilitatory effect of anxiety on sustained attention and response inhibition. This effect consisted of improved performance on the Sustained Attention to Response Task (a Go-NoGo task consisting of 91% Go and 9% NoGo trials) in threat (unpredictable electrical shock) vs safe (no shock) conditions. This study uses the same experimental design with fMRI and relies on an event-related analysis of BOLD signal changes. Findings reveal that threat-related cognitive facilitation (improved NoGo accuracy) is associated with greater activation of a right-lateralized frontoparietal group of regions previously implicated in sustained attention and response inhibition. Moreover, these same regions show decreased activation in the Go trials preceding NoGo errors. During NoGo trials, striatal activity is also greater in the threat vs safe condition, consistent with the notion of enhanced inhibitory processing under threat. These findings identify potential mechanisms by which threat of unpredictable shock can facilitate distinct cognitive functions. A greater understanding of the complex interaction of the anxious state and cognitive processes may have critical clinical implications.

Anxiety-mediated facilitation of behavioral inhibition: Threat processing and defensive reactivity during a go/no-go task

Anxiety can be broken down into multiple facets including behavioral components, such as defensive reactivity, and cognitive components, such as distracting anxious thoughts. In a previous study, we showed that anticipation of unpredictable shocks facilitated response inhibition to infrequent no-go trials during a go/no-go task. The present study extends this work to examine the distinct contribution of defensive reactivity, measures with fear-potentiated startle, and anxious thought, assessed with thought probes, on go and no-go performance. Consistent with our prior findings, shock anticipation facilitated response inhibition (i.e., reduced errors of commission) on the no-go trials. Regression analyses showed that (a) no-go accuracy was positively associated with fear-potentiated startle and negatively associated with threat-related/task-unrelated thoughts and (b) go accuracy correlated negatively with fear-potentiated startle. Thus, while the present findings confirm the influence of anxiety on response inhibition, they also show that such influence reflects the balance between the positive effect of defensive reactivity and the negative effect of distracting anxious thoughts. (PsycINFO Database Record

Easy to learn, hard to suppress: The impact of learned stimulus-outcome associations on subsequent action control

The inhibition of impulsive response tendencies that conflict with goal-directed action is a key component of executive control. An emerging literature reveals that the proficiency of inhibitory control is modulated by expected or unexpected opportunities to earn reward or avoid punishment. However, less is known about how inhibitory control is impacted by the processing of task-irrelevant stimulus information that has been associated previously with particular outcomes (reward or punishment) or response tendencies (action or inaction). We hypothesized that stimulus features associated with particular action-valence tendencies, even though task irrelevant, would modulate inhibitory control processes. Participants first learned associations between stimulus features (color), actions, and outcomes using an action-valence learning task that orthogonalizes action (action, inaction) and valence (reward, punishment). Next, these stimulus features were embedded in a Simon task as a task-irrelevant stimulus attribute. We analyzed the effects of action-valence associations on the Simon task by means of distributional analysis to reveal the temporal dynamics. Learning patterns replicated previously reported biases; inherent, Pavlovian-like mappings (action-reward, inaction-punishment avoidance) were easier to learn than mappings conflicting with these biases (action-punishment avoidance, inaction-reward). More importantly, results from two experiments demonstrated that the easier to learn, Pavlovian-like action-valence associations interfered with the proficiency of inhibiting impulsive actions in the Simon task. Processing conflicting associations led to more proficient inhibitory control of impulsive actions, similar to Simon trials without any association. Fast impulsive errors were reduced for trials associated with punishment in comparison to reward trials or trials without any valence association. These findings provide insight into the temporal dynamics of task irrelevant information associated with action and valence modulating cognitive control. We discuss putative mechanisms that might explain these interactions.

Withholding a Reward-driven Action: Studies of the Rise and Fall of Motor Activation and the Effect of Cognitive Depletion

Controlling an inappropriate response tendency in the face of a reward-predicting stimulus likely depends on the strength of the reward-driven activation, the strength of a putative top-down control process, and their relative timing. We developed a rewarded go/no-go paradigm to investigate such dynamics. Participants made rapid responses (on go trials) to high versus low reward-predicting stimuli and sometimes had to withhold responding (on no-go trials) in the face of the same stimuli. Behaviorally, for high versus low reward stimuli, responses were faster on go trials, and there were more errors of commission on no-go trials. We used single-pulse TMS to map out the corticospinal excitability dynamics, especially on no-go trials where control is needed. For successful no-go trials, there was an early rise in motor activation that was then sharply reduced beneath baseline. This activation-reduction pattern was more pronounced for high- versus low-reward trials and in individuals with greater motivational drive for reward. A follow-on experiment showed that, when participants were fatigued by an effortful task, they made more errors on no-go trials for high versus low reward stimuli. Together, these studies show that, when a response is inappropriate, reward-predicting stimuli induce early motor activation, followed by a top-down effortful control process (which we interpret as response suppression) that depends on the strength of the preceding activation. Our findings provide novel information about the activation-suppression dynamics during control over reward-driven actions, and they illustrate how fatigue or depletion leads to control failures in the face of reward.

Transcranial Magnetic Stimulation

Preparing actions requires the operation of several cognitive control processes that influence the state of the motor system to ensure that the appropriate behavior is ultimately selected and executed. For example, some form of competition resolution ensures that the right action is chosen among alternatives, often in the presence of conflict; at the same time, impulse control ought to be deployed to prevent premature responses. Here we review how state-changes in the human motor system during action preparation can be studied through motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation over the contralateral primary motor cortex (M1). We discuss how the physiological fingerprints afforded by MEPs have helped to decompose some of the dynamic and effector-specific influences on the motor system during action preparation. We focus on competition resolution, conflict and impulse control, as well as on the influence of higher cognitive decision–related variables. The selected examples demonstrate the usefulness of MEPs as physiological readouts for decomposing the influence of distinct, but often overlapping, control processes on the human motor system during action preparation.

Training response inhibition to food is associated with weight loss and reduced energy intake

The majority of adults in the UK and US are overweight or obese due to multiple factors including excess energy intake. Training people to inhibit simple motor responses (key presses) to high-energy density food pictures reduces intake in laboratory studies. We examined whether online response inhibition training reduced real-world food consumption and weight in a community sample of adults who were predominantly overweight or obese (N = 83). Participants were allocated in a randomised, double-blind design to receive four 10-min sessions of either active or control go/no-go training in which either high-energy density snack foods (active) or non-food stimuli (control) were associated with no-go signals. Participants' weight, energy intake (calculated from 24-h food diaries), daily snacking frequency and subjective food evaluations were measured for one week pre- and post-intervention. Participants also provided self-reported weight and monthly snacking frequency at pre-intervention screening, and one month and six months after completing the study. Participants in the active relative to control condition showed significant weight loss, reductions in daily energy intake and a reduction in rated liking of high-energy density (no-go) foods from the pre-to post-intervention week. There were no changes in self-reported daily snacking frequency. At longer-term follow-up, the active group showed significant reductions in self-reported weight at six months, whilst both groups reported significantly less snacking at one- and six-months. Excellent rates of adherence (97%) and positive feedback about the training suggest that this intervention is acceptable and has the potential to improve public health by reducing energy intake and overweight.

Suppressing a motivationally-triggered action tendency engages a response control mechanism that prevents future provocation

Reward-predicting stimuli can induce maladaptive behavior by provoking action tendencies that conflict with long-term goals. Earlier, we showed that when human participants were permitted to respond for a reward in the presence of a task-irrelevant, reward-predicting stimulus (i.e. goCS+ trials), the CS+ provoked an action tendency to respond compared to when a non-rewarding CS- stimulus was present (i.e. goCS- trials). However, when participants were not permitted to respond, response suppression was recruited to mitigate the action tendency that was triggered by the motivating CS+ stimulus (i.e. on nogoCS+ trials) (Freeman et al., 2014). Here we tested the hypothesis that repeated response suppression over a motivationally-triggered action tendency would reduce subsequent CS+ provocation. We compared groups of participants who had different proportions of nogoCS+ trials, and we measured CS+ provocation on go trials via reaction time. Our results showed that CS+ provocation on go trials was reduced monotonically as the proportion of nogoCS+ trials increased. Further analysis showed that these group differences were best explained by reduced provocation on goCS+ trials that followed nogoCS+ (compared to nogoCS-) trials. Follow-up experiments using a neurophysiological index of motor activity replicated these effects and also suggested that, following nogoCS+ trials, a response suppression mechanism was in place to help prevent subsequent CS+ provocation. Thus, our results show that performing response suppression in the face of a motivating stimulus not only controls responding at that time, but also prevents provocation in the near future.

The many faces of affect: a multilevel model of drinking frequency/quantity and alcohol dependence symptoms among young adults

This research tested a multilevel structural equation model of associations between 3 aspects of affective functioning (state affect, trait affect, and affective lability) and 3 alcohol outcomes (likelihood of drinking, quantity on drinking days, and dependence symptoms) in a sample of 263 college students. Participants provided 49 days of experience sampling data over 1.3 years in a longitudinal burst design. Within-person results: At the daily level, positive affect was directly associated with greater likelihood and quantity of alcohol consumption. Daily negative affect was directly associated with higher consumption on drinking days and with higher dependence symptoms. Between-person direct effects: Affect lability was associated with higher trait negative, but not positive, affect. Trait positive affect was inversely associated with the proportion of drinking days, whereas negative affectivity predicted a greater proportion of drinking days. Affect lability exhibited a direct association with dependence symptoms. Between-person indirect effects: Trait positive affect was associated with fewer dependence symptoms via proportion of drinking days. Trait negative affect was associated with greater dependence symptoms via proportion of drinking days. The results distinguish relations of positive and negative affect to likelihood versus amount of drinking and state versus trait drinking outcomes, and highlight the importance of affect variability for predicting alcohol dependence symptoms.