Modulation of premotor mirror neuron activity during observation of unpredictable grasping movements

Using transcranial magnetic stimulation, we explored the properties of premotor mirror neurons during the passive observation of a reaching-grasping movement in human subjects. Two different experiments were run using video-clips as visual stimuli. Video-clips showed a normally performed (control stimulus) or an anomalous reaching-grasping movement executed by delaying the time of the appearance of the maximal finger aperture (experiment 1), or substituting it with an unpredictable closure (experiment 2). Motor evoked potentials were recorded at different time-points during the observation of the video-clips. Profiles of cortical excitability were drawn and compared with the kinematic profiles of the corresponding movement. Passive observation of the natural movement evoked a profile of cortical excitability that is in concordance with the timing of the kinematic profile of the shown finger movements. Observation of the uncommon movements did not exert any modulation (experiment 1) or evoked an activity that matched, at the beginning, the modulation obtained with observation of the natural movement (experiment 2). Results show that the resonant motor plan is loaded as whole at the beginning of observation and once started tends to proceed to its completion regardless of changes to the visual cues. The results exclude the possibility of a temporal fragmentation of the resonant plan, because activation of different populations of mirror neurons for each phase of the ongoing action. They further support the notion of the role of the mirror system as neural substrate for the observing-execution matching system and extend the current knowledge regarding mechanisms that trigger the internal representation of an action

Release of premotor activity after repetitive transcranial magnetic stimulation of prefrontal cortex

In the present study we aimed to explore by means of repetitive transcranial magnetic stimulation (rTMS) the reciprocal influences between prefrontal cortex (PFC) and premotor cortex (PMC). Subjects were asked to observe on a computer monitor different pictures representing manipulations of different kind of tools. They had to produce a movement (go condition) or to keep the resting position (no-go condition) at the appearance of different cue signals represented by different colors shown alternatively on the hands manipulating the tools or on the picture background. Motor evoked potentials (MEPs) were collected at the offset of the visual stimuli before and after a 10 minute, 1 Hz rTMS train applied to the dorsolateral PFC (Experiment 1), to the PMC (Experiment 2) or to the primary motor cortex (Experiment 3). Following rTMS to the PFC, MEPs increased in the go condition when the cue for the go command was presented on the hand. In contrast, following rTMS to the PMC, in the same condition, MEPs were decreased. rTMS to the primary motor cortex did not produce any modulation. Results are discussed according to the presence of a visual-motor matching system in the PMC and to the role of the PFC in the attention-related processes. We hypothesize that the perceptual analysis for action selection within the PFC was modulated by rTMS and its temporary functional inactivation in turn influenced the premotor areas for motor programming

Self-Knowledge in Personality Disorders: An Emotion-Focused Perspective.

Emotional knowledge about one's own and others' emotional experience are central features of mental health and may be characteristic of therapeutic processes leading to good outcome. Clients with personality disorders (PDs) often lack in their ability to access and accept emotional experiences, or to reflect on emotion and use it in adaptive ways. The present theoretical and clinical review discusses self-knowledge, and lack thereof, in personality disorders, from an emotion-focused perspective. A first section differentiates between two fundamental types of meaning construction processing. The second section describes, from an integrative therapy perspective, how self-knowledge may be facilitated in psychotherapy by the client-therapist interaction. A subsequent section discusses lack of awareness of one's own emotions in the construction of meaning associated with PDs. The final section describes initial studies that demonstrate change occurring in constructing emotional self-knowledge as a correlate of treatment. The concepts of the review are illustrated throughout with three clinical cases of PD

Modulation of cortical motor outputs by the symbolic meaning of visual stimuli.

Abstract The observation of an action modulates motor cortical outputs in specific ways, in part through mediation of the mirror neuron system. Sometimes we infer a meaning to an observed action based on integration of the actual percept with memories. Here, we conducted a series of experiments in healthy adults to investigate whether such inferred meanings can also modulate motor cortical outputs in specific ways. We show that brief observation of a neutral stimulus mimicking a hand does not significantly modulate motor cortical excitability (Study 1) although, after prolonged exposure, it can lead to a relatively nonspecific modulation (Study 2). However, when such a neutral stimulus is preceded by exposure to a hand stimulus, the latter appears to serve as a prime, perhaps enabling meaning to the neutral stimulus, which then modulates motor cortical excitability in accordance with mirror neuron-driving properties (Studies 2 and 3). Overall results suggest that a symbolic value ascribed to an otherwise neutral stimulus can modulate motor cortical outputs, revealing the influence of top-down inputs on the mirror neuron system. These findings indicate a novel aspect of the human mirror neuron system: an otherwise neutral stimulus can acquire specific mirror neuron-driving properties in the absence of a direct association between motor practice and perception. This significant malleability in the way that the mirror neuron system can code otherwise meaningless (i.e. arbitrarily associated) stimuli may contribute to coding communicative signals such as language. This may represent a mirror neuron system feature that is unique to humans

Review: Non‐invasive brain stimulation in behavioral addictions: insights from direct comparisons with substance use disorders

Background and Objectives Treatment models developed for substance use disorders (SUDs) are often applied to behavioral addictions (BAs), even though the correspondence between these forms of addiction is unclear. This is also the case for noninvasive brain stimulation (NIBS) techniques being investigated as potential treatment interventions for SUDs and BAs. Objectives: to contribute to the development of more effective NIBS protocols for BAs. Methods Two literature searches using PubMed and Google Scholar were conducted identifying a total of 35 studies. The first search identified 25 studies examining the cognitive and neurophysiological overlap between BAs and SUDs. The second search yielded 10 studies examining the effects of NIBS in BAs. Results Impulsivity and cravings show behavioral and neurophysiologic overlaps between BAs and SUDs, however, other outcomes like working‐memory abilities or striatal connectivity, differ between BAs and SUDs. The most‐employed NIBS target in BAs was dorsolateral prefrontal cortex (DLPFC), which was associated with a decrease in cravings, and less frequently with a reduction of addiction severity. Conclusions and Scientific Significance Direct comparisons between BAs and SUDs revealed discrepancies between behavioral and neurophysiological outcomes, but overall, common and distinctive characteristics underlying each disorder. The lack of complete overlap between BAs and SUDs suggests that investigating the cognitive and neurophysiological features of BAs to create individual NIBS protocols that target risk‐factors associated specifically with BAs, might be more effective than transferring protocols from SUDs to BAs. Individualizing NIBS protocols to target specific risk‐factors associated with each BA might help to improve treatment interventions for BAs. (Am J Addict 2019;00:1–23

Experimental Designs and the 'Emotion Stimulus Critique': Hidden Problems and Potential Solutions in the Study of Emotion.

Emotional experience is increasingly being measured using experimental tasks, but the stimuli used are often only proxies for the emotion being studied. Stimuli are intended to evoke a distinct emotional experience, but certain designs fail to adequately control for the actual experience in question. In this methodological paper, we review designs used in clinical psychology aimed at measuring emotion and develop the argument of the 'emotion stimulus critique'. Designs of neuroimaging studies on emotion in this context are given preference. We argue that studies often concentrate on standardization of the stimulus material (i.e. words, images, and movies) for eliciting an emotional experience, whereas standardization of the actual participant's experience is seldom performed. Our proposal discusses the use of standardized stimuli in experimental designs and contrasts this with the necessity of controlling for a participant's unique emotional response. We highlight the importance of each participant's 'inner metric', i.e. the individual's experiential anchor, which needs to be taken into account when examining the emotional correlates of psychiatric disorders or psychotherapeutic change. Implications of the emotion stimulus critique for research are discussed within the context of psychology, particularly clinical psychology and psychotherapy

Studying the Neurobiology of Social Interaction with Transcranial Direct Current Stimulation—The Example of Punishing Unfairness

Studying social behavior often requires the simultaneous interaction of many subjects. As yet, however, no painless, noninvasive brain stimulation tool existed that allowed the simultaneous affection of brain processes in many interacting subjects. Here we show that transcranial direct current stimulation (tDCS) can overcome these limits. We apply right prefrontal cathodal tDCS and show that subjects' propensity to punish unfair behavior is reduced significantl