Emotion and motor preparation: A transcranial magnetic stimulation study of corticospinal motor tract excitability

In the present study, we examined whether preparing motor responses under different emotional conditions alters motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation delivered to the motor cortex. Analyses revealed three findings: (1) Reaction times were expedited during exposure to unpleasant images, as compared with pleasant and neutral images; (2) force amplitude was greater during exposure to unpleasant images, as compared with pleasant and neutral images; and (3) MEPs were larger while participants viewed unpleasant images, as compared with neutral images. Hence, coupling the preparation of motor responses with the viewing of emotional images led to arousal-driven changes in corticospinal motor tract excitability, whereas movement speed and force production varied as a function of emotional valence. These findings demonstrate that the effects of emotion on the motor system manifest at varying sensitivity levels across behavioral and neurophysiological measures. Moreover, they validate the action readiness component of emotional experience by demonstrating that emotional states influence the execution of future movements but, alone, do not lead to overt movement.     

Emotional state affects the initiation of forward gait

The aim of the current study was to determine the extent to which pleasant and unpleasant emotional states impact the initiation of forward gait. Participants initiated gait and walked for several steps following the presentation of low arousing pleasant, high arousing pleasant, low arousing unpleasant, high arousing unpleasant, and neutral pictures. Reaction time, displacement, and velocity of the center of pressure (COP) trajectory, and length and velocity of the first and second steps were calculated. Exposure to the highly arousing unpleasant pictures reduced reaction times compared to all other affective conditions. Compared to the low arousing unpleasant pictures, exposure to the high and low arousing pleasant pictures increased the displacement of the COP movement during the anticipatory postural adjustment phase of gait initiation. Additionally, exposure to the low arousing pleasant pictures increased the velocity of the COP movement during the anticipatory postural adjustment phase, compared to the high and low arousing unpleasant pictures. Exposure to the high and low arousing pleasant pictures increased the velocity of the first step relative to the low arousing unpleasant pictures. These findings demonstrate that highly arousing unpleasant emotional states accelerate the initial motor response, but pleasant emotional states generally facilitate the initiation of forward gait due to the approach-oriented directional salience of the movement. These findings extend the scope of the motivational direction hypothesis by demonstrating the effects of emotional reactivity on the initiation of gait.     

Films for eliciting emotional states in children

Standardized sets of films have been shown to be effective for eliciting emotional states in adults, but no comparable validated stimuli are available for children. We therefore examined the effects of three pre-selected film clips each of 3-min duration in eliciting a pleasant, neutral and unpleasant emotional state in 297 children aged between 6 and 12 years. After the films were presented on a video projector, affective ratings were obtained with the Self-Assessment-Manikin on the emotional dimensions of valence and arousal. Increasing pleasure ratings were observed from the unpleasant to the neutral to the pleasant film. Associated arousal ratings were stronger for the unpleasant and pleasant films compared to the neutral film. Overall, results showed successful elicitation of targeted emotional states only marginally influenced by age, gender or prior experience with the films. The use of these films is therefore suggested for future studies on emotions in children.     

Emotional reactivity and force control: the influence of behavioral inhibition

Individual difference measures have been shown to alter emotional arousal and emotional arousal alters force production during force control tasks. In the current study we examined whether individual differences in behavioral inhibition influence force control during emotional image viewing. Subjects who scored high and low in behavioral inhibition (BIS) produced force with visual feedback for 5 s. Feedback was then removed and replaced by a mutilation, attack, erotica, or neutral image for 6 s. The magnitude and direction of error in force production during image presentation was compared between groups and across image type. The high BIS group displayed a relative increase in force production during exposure to attack and mutilation images compared to the low BIS group. Bias scores (i.e., comparison of unpleasant image to neutral or pleasant image) further confirmed these findings by demonstrating a relative increase in force for the high BIS group during attack and mutilation images as compared to erotica images, whereas the low BIS group displayed the reverse effect. Together these findings extend the premise of action readiness to demonstrate that dispositional differences in behavioral inhibition interact with emotional state to alter force production.     

Reduced memory for the spatial and temporal context of unpleasant words

Emotional stimuli are consistently better remembered than neutral stimuli. However, the reported effects of emotional stimuli on source memory are less consistent. In four experiments, we examined spatial and temporal source memory and free recall for emotional words previously studied in an fMRI experiment. In the fMRI experiment, the unpleasant but not the pleasant words were shown to activate the amygdala. In the experiments reported here, spatial and temporal source memory were reduced for the unpleasant words compared to pleasant and neutral words. Reduced spatial memory for unpleasant words was observed across studies that varied the specific stimuli, task conditions, and incidental versus intentional encoding instructions. Free recall was enhanced for the pleasant and unpleasant words compared to neutral words. The results demonstrate reduced source memory for unpleasant words even when item recall is enhanced. Our findings are consistent with prior reports of amygdala-mediated amnestic effects evoked by unpleasant stimuli.     

Responding to emotional scenes: effects of response outcome and picture repetition on reaction times and the late positive potential

Processing the motivational relevance of a visual scene and reacting accordingly is crucial for survival. Previous work suggests the emotional content of naturalistic scenes affects response speed, such that unpleasant content slows responses whereas pleasant content accelerates responses. It is unclear whether these effects reflect motor-cognitive processes, such as attentional orienting, or vary with the function/outcome of the motor response itself. Four experiments manipulated participants’ ability to terminate the picture (offset control) and, thereby, the response’s function and motivational value. Attentive orienting was manipulated via picture repetition, which diminishes orienting. A total of N?=?81 participants completed versions of a go/no-go task, discriminating between distorted versus intact pictures drawn from six content categories varying in positive, negative, or neutral valence. While all participants responded faster with repetition, only participants without offset control exhibited slower responses to unpleasant and accelerated responses to pleasant content. Emotional engagement, measured by the late positive potential, was not modulated by attentional orienting (repetition), suggesting that the interaction between repetition and offset control is not due to altered emotional engagement. Together, results suggest that response time changes as a function of emotional content and sensitivity to attention orienting depends on the motivational function of the motor response.     

Role of medial prefrontal cortex in representing one’s own subjective emotional responses: A preliminary study

The medial prefrontal cortex (mPFC) has been implicated in attending to one’s own emotional states, but the role of emotional valence in this context is not understood. We examined valence-specific BOLD activity in a previously validated functional magnetic resonance imaging (fMRI) paradigm. Ten healthy subjects viewed emotional pictures and categorized their experience as pleasant, unpleasant or neutral. All three categories activated a common region within mPFC. Subtraction of neutral from pleasant or unpleasant conditions instead revealed ventromedial PFC (vmPFC), suggesting that this region represents emotional valence. During exteroceptive attention, greater mPFC responses were observed in response to emotional relative to neutral stimuli, consistent with studies implicating mPFC in the top-down modulation of emotion-biased attention. These findings may help to integrate the two proposed roles of mPFC in emotional representation and top-down modulation of subcortical structures.     

Posture affects emotional responses: A Head Down Bed Rest and ERP study

Body posture, mainly represented by horizontal bed rest, has been found to be associated with cortical inhibition, altered perceptual and cognitive processing. In the present research, the influence of Head Down Bed Rest (HDBR) – a condition also termed simulated microgravity – on emotional responses has been studied. Twenty-two male subjects were randomly assigned to either Sitting Control or HDBR group. After 3-h, subjects attended to a passive viewing emotional task in which 75 IAPS slides, divided into 25 pleasant, 25 neutral and 25 unpleasant, were presented in random order for 6 s each, while EEG was recorded from F7, F8 and Pz locations. Results showed in Sitting Controls the expected greater P300 and Late Positive Potential (LPP) to pleasant and unpleasant compared with neutral slides, an effect which indicates greater processing of emotional arousing stimuli. The HDBR group showed smaller non-significant differences among all emotional conditions in both ERP components. Arousal and valence subjective evaluations, typically less sensitive to experimental manipulation, did not differentiate groups. The observed ability of HDBR to inhibit cortical emotional responses raises an important issue on the risk that astronauts underestimate a dangerous/threatening situation or that long-term bedridden inpatients develop depressive symptoms.     

Dissociating motivational direction and affective valence: specific emotions alter central motor processes

We aimed to clarify the relation between affective valence and motivational direction by specifying how central and peripheral components of extension movements are altered according to specific unpleasant affective states. As predicted, premotor reaction time was quicker for extension movements initiated during exposure to attack than for extension movements initiated during exposure to all other valence categories (mutilation, erotic couples, opposite-sex nudes, neutral humans, household objects, blank). Exposure to erotic couples and mutilations yielded greater peak force than exposure to images of attack, neutral humans, and household objects. Finally, motor reaction time and peak electromyographic amplitude were not altered by valence. These findings indicate that unpleasant states do not unilaterally prime withdrawal movements, and that the quick execution of extension movements during exposure to threatening images is due to rapid premotor, rather than motor, reaction time. Collectively, our findings support the call for dissociating motivational direction and affective valence.     

Emotional state and initiating cue alter central and peripheral motor processes

Evidence indicates that voluntary and involuntary movements are altered by affective context as well as the characteristics of an initiating cue. The purpose of this study was to determine the contribution of central and peripheral mechanisms to this phenomenon. During the presentation of pleasant, unpleasant, neutral, and blank images, participants (N = 33) responded to auditory stimuli (startle, 107 dB startle or 80 dB tone) by initiating a bimanual isometric contraction of the wrist and finger extensor muscles. Analyses of electromyography and force measures supported the hypothesis that exposure to unpleasant images accelerates central processing times and increases the gradient of slope of peripheral movement execution. In addition, startle cues as compared with tone cues accelerated and magnified all temporal and amplitude indices. Collectively, these findings have noteworthy implications for (a) those seeking to facilitate the speed and force of voluntary movement (i.e., movement rehabilitation), (b) understanding the higher incidence of motor difficulty in individuals with affective disorders, and (c) those seeking to regulate emotional input so as to optimize the quality of intended movements.     

Event-related potentials of emotional memory: encoding pleasant,unpleasant, and neutral pictures

Emotional events tend to be remembered better than nonemotional events. We investigated this phenomenon by measuring two event-related potential (ERP) effects: the emotion effect (more positive ERPs for pleasant or unpleasant stimuli than for neutral stimuli) and the subsequent memory effect (more positive ERPs for subsequently remembered items than for subsequently forgotten items). ERPs were measured while subjects rated the emotional content of pleasant, unpleasant, and neutral pictures. As was expected, subsequent recall was better for pleasant and unpleasant pictures than for neutral pictures. The emotion effect was sensitive to arousal in parietal electrodes and to both arousal and valence in frontocentral electrodes. The subsequent memory effect at centroparietal electrodes was greater for emotional pictures than for neutral pictures during an early epoch (400-600 msec). This result suggests that emotional information has privileged access to processing resources, possibly leading to better memory formation.     

The persistence of attention to emotion: brain potentials during and after picture presentation

Emotional stimuli have been shown to elicit increased perceptual processing and attentional allocation. The late positive potential (LPP) is a sustained P300-like component of the event-related potential that is enhanced after the presentation of pleasant and unpleasant pictures as compared with neutral pictures. In this study, the LPP was measured using dense array electroencephalograph both before and after pleasant, neutral, and unpleasant images to examine the time course of attentional allocation toward emotional stimuli. Results from 17 participants confirmed that the LPP was larger after emotional than neutral images and that this effect persisted for 800 ms after pleasant picture offset and at least 1,000 ms after unpleasant picture offset. The persistence of increased attention after unpleasant compared to pleasant stimuli is consistent with the existence of a negativity bias. Overall, these results indicate that attentional capture of emotion continues well beyond picture presentation and that this can be measured with the LPP. Implications and directions for future research are discussed.     

Musical pleasure beneficially alters stride and arm swing amplitude during rhythmically-cued walking in people with Parkinson's disease

Entrainment of walking to rhythmic auditory cues (e.g., metronome and/or music) improves gait in people with Parkinson's disease (PD). Studies on healthy individuals indicate that entrainment to pleasant musical rhythm can be more beneficial for gait facilitation than entrainment to isochronous rhythm, potentially as a function of emotional/motivational responses to music and their associated influence on motor function. Here, we sought to investigate how emotional attributes of music and isochronous cues influence stride and arm swing amplitude in people with PD. A within-subjects experimental trial was completed with persons with PD serving as their own controls. Twenty-three individuals with PD walked to the cue of self-chosen pleasant music cue, pitch-distorted unpleasant music, and an emotionally neutral isochronous drumbeat. All music cues were tempo-matched to individual walking pace at baseline. Greater gait velocity, stride length, arm swing peak velocity and arm swing range of motion (RoM) were found when patients walked to pleasant music cues compared to baseline, walking to unpleasant music, and walking to isochronous cues. Cued walking in general marginally increased variability of stride-to-stride time and length compared with uncued walking. Enhanced stride and arm swing amplitude were most strongly associated with increases in perceived enjoyment and pleasant musical emotions such as power, tenderness, and joyful activation. Musical pleasure contributes to improvement of stride and arm swing amplitude in people with PD, independent of perceived familiarity with music, cognitive demands of music listening, and beat salience. Our findings aid in understanding the role of musical pleasure in invigorating gait in PD, and inform novel approaches for restoring or compensating impaired motor circuits.     

Eye movement assessment of selective attentional capture by emotional pictures

The eye-tracking method was used to assess attentional orienting to and engagement on emotional visual scenes. In Experiment 1, unpleasant, neutral, or pleasant target pictures were presented simultaneously with neutral control pictures in peripheral vision under instruction to compare pleasantness of the pictures. The probability of first fixating an emotional picture, and the frequency of subsequent fixations, were greater than those for neutral pictures. In Experiment 2, participants were instructed to avoid looking at the emotional pictures, but these were still more likely to be fixated first and gazed longer during the first-pass viewing than neutral pictures. Low-level visual features cannot explain the results. It is concluded that overt visual attention is captured by both unpleasant and pleasant emotional content.     

Individual differences in emotional intelligence and incidental memory of words1

Participants were required to complete the Japanese version of the Emotional Skills and Competence Questionnaire ( Toyota, Morita, & Tak?i?, 2007 ) to assess their level of emotional intelligence. Then they were asked to rate the pleasantness of an episode that each target reminded them of, followed by unexpected free recall tests. Participants with high emotional intelligence recalled targets with pleasant, neutral, and unpleasant episodes equally. However, for participants with low emotional intelligence, targets with neutral episodes were recalled less than those with pleasant or unpleasant ones. These results were interpreted as showing that the level of emotional intelligence determined the effectiveness of neutral episodes on targets as retrieval cues.     

Gaze Patterns When Looking at Emotional Pictures: Motivationally Biased Attention

Pictures of either emotionally neutral, pleasant (affectionate), or unpleasant (threat and injury) scenes were paired with nonemotional control pictures and presented for 3 s, while eye fixations were monitored. Preferential attention to the emotional picture of eah pair occurred at an early processing stage: The probability of placement of the first fixation and the proportion of viewing time during the first 500 ms were higher for both pleasant and unpleasant pictures than for neutral pictures, whereas later fixation location and time were not differentially affected. This suggests that, when emotional and nonemotional stimuli are presented simultaneously, emotional meaning captures initial overt orienting and engages attention early, as measured by gaze direction and duration. The possibility that this effect could be accounted for by perceptual differences—such as luminance and complexity—between emotional and neutral pictures was ruled out.     

Emotional State,Physical Well-Being,and Performance in the Presence of Feigned Ambient Odor1

Measures of emotional state, physical well-being, performance, and room odor were obtained from subjects given the suggestion of a pleasant, unpleasant, or neutral ambient odor (n= 30 per condition). The hedonic quality of the feigned odor altered self-reports of pleasure, but not dominance or arousal. Subjects given the pleasant suggestion reported a more positive mood. The number of reported physical health symptoms differed as a function of the hedonic quality of the feigned odor. The category corresponding to the fewest number of physical symptoms was predominated by subjects in the pleasant condition, while subjects in the unpleasant condition predominated the category with the greatest number of symptoms. Subjects predicted higher task performance in the unpleasant condition, but no differences were found among conditions in actual performance. Room odor ratings differed in directions consistent with the hedonic quality of the feigned odor. The effects of olfactory suggestion may be relevant to the psychosomatic component of sick building syndrome and to the perception and marketing of fragrance.     

Emotion regulation in action: emotional reactivity in experiential avoidance

The present study examined the relationship between emotional reactivity (self-report and physiological reactivity) to pleasant, unpleasant, and neutral emotion-eliciting stimuli and experiential avoidance (EA). Sixty-two participants were separated into high and low experiential avoiders. Results indicated that high EA participants reported greater emotional experience to both unpleasant and pleasant stimuli compared to low EA participants. In contrast to their heightened reports of emotion, high EA participants displayed attenuated heart rate reactivity to the unpleasant stimuli relative to the low EA participants. These findings are interpreted as reflecting an emotion regulation attempt by high EA participants when confronted with unpleasant emotionally-evocative stimuli.     

Binding neutral information to emotional contexts: Brain dynamics of long-term recognition memory

There is abundant evidence in memory research that emotional stimuli are better remembered than neutral stimuli. However, effects of an emotionally charged context on memory for associated neutral elements is also important, particularly in trauma and stress-related disorders, where strong memories are often activated by neutral cues due to their emotional associations. In the present study, we used event-related potentials (ERPs) to investigate long-term recognition memory (1-week delay) for neutral objects that had been paired with emotionally arousing or neutral scenes during encoding. Context effects were clearly evident in the ERPs: An early frontal ERP old/new difference (300–500 ms) was enhanced for objects encoded in unpleasant compared to pleasant and neutral contexts; and a late central-parietal old/new difference (400–700 ms) was observed for objects paired with both pleasant and unpleasant contexts but not for items paired with neutral backgrounds. Interestingly, objects encoded in emotional contexts (and novel objects) also prompted an enhanced frontal early (180–220 ms) positivity compared to objects paired with neutral scenes indicating early perceptual significance. The present data suggest that emotional—particularly unpleasant—backgrounds strengthen memory for items encountered within these contexts and engage automatic and explicit recognition processes. These results could help in understanding binding mechanisms involved in the activation of trauma-related memories by neutral cues.