ABSTRACT
In the processing of emotions, the brain prepares and reacts in distinctive manners depending upon the negative or positive nuance of the emotion elicitors. Previous investigations showed that negative elicitors generally evoke more intense neural activities than positive and neutral ones, as reflected in the augmented amplitude of all sub-components of the event-related potentials (ERP) late posterior positivity (LPP) complex, while less is known about the emotion of disgust. The present study aimed to examine whether the LPP complex during the processing of disgust stimuli showed greater amplitude than other emotion elicitors with negative or positive valences, thus confirming it as a neural marker of disgust-related negativity bias at earlier or later stages. Thus, in the present study, we leveraged the ERP technique during the execution of an affective self-administered visual stimuli task to disentangle the neural contributions associated with images of positive, negative, disgust, or neutral emotions. Crucially, we showed that handling with disgust elicitors prompted the greatest neural activity and the highest delay during self-administration. Overall, we demonstrated progressive neural activities associated with the unpleasantness of the emotion elicitors and peculiar processing for disgust compared with all other emotions.
ABSTRACT
The study of bimanual movements has allowed to describe an interesting phenomenon known as the bimanual coupling effect: a lack of independence between the two hands that induces an interference process, which has been reported in both the spatial and temporal domain. Here, we studied for the first time the electro-cortical activity of the temporal bimanual coupling effect, specifically focused on the motor preparation of the two hands movements. Participants performed congruent movements, with both hands heading towards easy or difficult targets, and incongruent movements, with the two hands heading to separate targets (i.e. left to the easy target and right to the difficult target). Motor Related Cortical Potentials (MRCPs) showed no effect of conditions or difficulty on the early phase of the activity (posterior and anterior BP). Additionally, the two hands were prepared together, as if a single movement was about to start. As such, behavioral results showed strong synchronization between the hands, which always tended to start and end their movement together. Importantly, the effect of movement difficulty was present at the movement onset and just after it when the movement unfolded. Coherently with behavioral results, difficult movements generated a strong Post-motor potential (N4), more prominent when the right hand was heading towards the difficult target. Our findings show that bimanual movements are actually planned and programmed as a single motor program, but movement difficulty emerges in the execution of the action.
Subject(s)
Evoked Potentials/physiology , Functional Laterality/physiology , Hand , Movement/physiology , Psychomotor Performance/physiology , Female , Healthy Volunteers , Humans , Male , Young AdultABSTRACT
The parietal lobes contribute to body-space representation. The present work aims at characterizing the functional role of the inferior parietal lobe in body-space representation and at studying the different roles of the angular gyrus in the right and left hemisphere. We conducted three separate transcranial direct current stimulation (tDCS) experiments using "tactile distance task" as an implicit measure of body representation. Whereas anodal tDCS on the right angular gyrus influences vocal reaction times (vRT) for stimuli delivered on the ipsilateral body parts without changes of accuracy, right tDCS improved both vRT and accuracy for tactile stimuli on the contralateral limbs. Sham or left parietal anodal tDCS had no effect. These evidences support the view that right parietal areas have a crucial role in the metric component of the body representation.
