The ability to generate appropriate responses, especially in social contexts, requires integrating emotional information with ongoing cognitive processes. In particular, inhibitory control plays a crucial role in social interactions, preventing the execution of impulsive and inappropriate actions. In this study, we focused on the impact of facial emotional expressions on inhibition. Research in this field has provided highly mixed results. In our view, a crucial factor explaining such inconsistencies is the task-relevance of the emotional content of the stimuli. To clarify this issue, we gave two versions of a Go/No-go task to healthy participants. In the emotional version, participants had to withhold a reaching movement at the presentation of emotional facial expressions (fearful or happy) and move when neutral faces were shown. The same pictures were displayed in the other version, but participants had to act according to the actor's gender, ignoring the emotional valence of the faces. We found that happy expressions impaired inhibitory control with respect to fearful expressions, but only when they were relevant to the participants' goal. We interpret these results as suggesting that facial emotions do not influence behavioral responses automatically. They would instead do so only when they are intrinsically germane for ongoing goals. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Facial emotional expressions are a salient source of information for nonverbal social interactions. However, their impact on action planning and execution is highly controversial. In this vein, the effect of the two threatening facial expressions, i.e., angry and fearful faces, is still unclear. Frequently, fear and anger are used interchangeably as negative emotions. However, they convey different social signals. Unlike fear, anger indicates a direct threat toward the observer. To provide new evidence on this issue, we exploited a novel design based on two versions of a Go/No-go task. In the emotional version, healthy participants had to perform the same movement for pictures of fearful, angry, or happy faces and withhold it when neutral expressions were presented. The same pictures were shown in the control version, but participants had to move or suppress the movement, according to the actor’s gender. This experimental design allows us to test task relevance’s impact on emotional stimuli without conflating movement planning with target detection and task switching. We found that the emotional content of faces interferes with actions only when task-relevant, i.e., the effect of emotions is context-dependent. We also showed that angry faces qualitatively had the same effect as fearful faces, i.e., both negative emotions decreased response readiness with respect to happy expressions. However, anger has a much greater impact than fear, as it increases both the rates of mistakes and the time of movement execution. We interpreted these results, suggesting that participants have to exploit more cognitive resources to appraise threatening than positive facial expressions, and angry than fearful faces before acting.

When we make an aiming movement toward a moving visual object, eye–hand coupling is of paramount importance for accurate motor performance. Some studies have suggested that both gaze and manual tracking control systems are driven by a common command signal. However, it has never been demonstrated that a motor plan for the arm is produced even when the object is tracked by the eyes alone. By applying transcranial magnetic stimulation to the motor cortex, we show for the first time that ocular tracking is linked to an overall decrease in the excitability of the motor control system of the relaxed upper limb, as estimated from the amplitude of the motor evoked potentials recorded in contralateral hand and wrist muscles. Furthermore, this reduced excitability is modulated in a manner compatible with a subthreshold neural activation encoding a manual tracking response to the same target pursued by the eyes. In addition, excitability changes are contingent on upper-limb posture, because they are present only with a pronated forearm and not with a supinated hand position. We provide direct evidence that, if the arm is held in a congruent postural configuration, tracking a moving object always entails a coordinated motor plan, which involves both gaze and hand movements. Active inhibitory mechanisms are activated to prevent an overt arm movement, whenever a manual tracking is not requested. Our data provide strong evidence in favor of the existence of a common drive to both eye and hand tracking systems.

The acquisition of a motor skill involves adaptations of spinal and supraspinal pathways to alpha motoneurons. In this study, we estimated the shared synaptic contributions of these pathways to understand the neural mechanisms underlying the short-term acquisition of a new force-matching task. High-density surface electromyography (HDsEMG) was acquired from the first dorsal interosseous (FDI; 7 males and 6 females) and tibialis anterior (TA; 7 males and 4 females) during 15 trials of an isometric force-matching task. For two selected trials (pre- and post-skill acquisition), we decomposed the HDsEMG into motor unit spike trains, tracked motor units between trials, and calculated the mean discharge rate and the coefficient of variation of interspike interval (COV_ISI). We also quantified the post/pre ratio of motor units’ coherence within delta, alpha, and beta bands. Force-matching improvements were accompanied by increased mean discharge rate and decreased COV_ISIfor both muscles. Moreover, the area under the curve within alpha band decreased by ∼22% (TA) and ∼13% (FDI), with no delta or beta bands changes. These reductions correlated significantly with increased coupling between force/neural drive and target oscillations. These results suggest that short-term force-matching skill acquisition is mediated by attenuation of physiological tremor oscillations in the shared synaptic inputs. Supported by simulations, a plausible mechanism for alpha band reductions may involve spinal interneuron phase-cancelling descending oscillations. Therefore, during skill learning, the central nervous system acts as a matched filter, adjusting synaptic weights of shared inputs to suppress neural components unrelated to the specific task.

The ability to generate appropriate responses, especially in social contexts, requires integrating emotional information with ongoing cognitive processes. In particular, inhibitory control plays a crucial role in social interactions, preventing the execution of impulsive and inappropriate actions. In this study, we focused on the impact of facial emotional expressions on inhibition. Research in this field has provided highly mixed results. In our view, a crucial factor explaining such inconsistencies is the task-relevance of the emotional content of the stimuli. To clarify this issue, we gave two versions of a Go/No-go task to healthy participants. In the emotional version, participants had to withhold a reaching movement at the presentation of emotional facial expressions (fearful or happy) and move when neutral faces were shown. The same pictures were displayed in the other version, but participants had to act according to the actor's gender, ignoring the emotional valence of the faces. We found that happy expressions impaired inhibitory control with respect to fearful expressions, but only when they were relevant to the participants' goal. We interpret these results as suggesting that facial emotions do not influence behavioral responses automatically. They would instead do so only when they are intrinsically germane for ongoing goals.

The acquisition of a motor skill involves adaptations of spinal and supraspinal pathways to alpha motoneurons. In this study, we estimated the shared synaptic contributions of these pathways to understand the neural mechanisms underlying the short-term acquisition of a new force-matching task. High-density surface electromyography (HDsEMG) was acquired from the first dorsal interosseous (FDI; 7 males and 6 females) and tibialis anterior (TA; 7 males and 4 females) during 15 trials of an isometric force-matching task. For two selected trials ( pre- and post-skill acquisition), we decomposed the HDsEMG into motor unit spike trains, tracked motor units between trials, and calculated the mean discharge rate and the coefficient of variation of inter-spike interval (CoV _ISI ). We also quantified the post/pre ratio of motor units’ coherence within delta, alpha, and beta bands. Improvements in force-matching were accompanied by a significant increase in the mean discharge rate and a decrease in CoV _ISI for both muscles. Moreover, the area under the curve within alpha band decreased by ∼22% and ∼13% for the TA and FDI muscles, respectively, with no changes in the delta or beta bands. These reductions correlated significantly with increased coupling between force/neural drive and target oscillations. These results suggest that the short-term acquisition of a new force-matching skill is mediated by the attenuation of tremor oscillations in the shared synaptic inputs. In other words, the central nervous system acts as a matched filter to modulate the synaptic weights of shared inputs and suppress neural components unrelated to the specific task. Supported by simulations, a plausible mechanism behind these alpha band reductions may involve spinal interneurons’ phase-cancelling descending oscillations.