Non-biological Stimuli Research Articles

Combining three-dimensionality and CaP glass-PLA composites: Towards an efficient vascularization in bone tissue healing

Bone regeneration often fails due to implants/grafts lacking vascular supply, causing necrotic tissue and poor integration. Microsurgical techniques are used to overcome this issue, allowing the graft to anastomose. These techniques have limitations, including severe patient morbidity and current research focuses on stimulating angiogenesis in situ using growth factors, presenting limitations, such as a lack of control and increased costs. Non-biological stimuli are necessary to promote angiogenesis for successful bone constructs. Recent studies have reported that bioactive glass dissolution products, such as calcium-releasing nanoparticles, stimulate hMSCs to promote angiogenesis and new vasculature. Moreover, the effect of 3D microporosity has also been reported to be important for vascularisation in vivo. Therefore, we used room-temperature extrusion 3D printing with polylactic acid (PLA) and calcium phosphate (CaP) based glass scaffolds, focusing on geometry and solvent displacement for scaffold recovery. Combining both methods enabled reproducible control of 3D structure, porosity, and surface topography. Scaffolds maintained calcium ion release at physiological levels and supported human mesenchymal stem cell proliferation. Scaffolds stimulated the secretion of vascular endothelial growth factor (VEGF) after 3 days of culture. Subcutaneous implantation in vivo indicated good scaffold integration and blood vessel infiltration as early as one week after. PLA-CaP scaffolds showed increased vessel maturation 4 weeks after implantation without vascular regression. Results show PLA/CaP-based glass scaffolds, made via controlled 3D printing, support angiogenesis and vessel maturation, promising improved vascularization for bone regeneration.

Genome-wide identification and characterization of large yellow croaker (Larimichthys crocea) suppressors of cytokine signaling (SOCS) in immune response to Pseudomonas plecoglossicida infection and acute hypoxia stress

The suppressor of cytokine signaling (SOCS) gene family is a group of genes involved in the negative regulation of cytokine signal transduction. The members of this family play a crucial role in regulating immune and inflammatory processes. However, comprehensive investigations of these genes have not yet been conducted in the economically significant fish large yellow croaker (Larimichthys crocea). In this study, a total of 13 SOCS genes (LcSOCS1a, LcSOCS1b, LcSOCS2, LcSOCS3a, LcSOCS3b, LcSOCS4, LcSOCS5a, LcSOCS5b, LcSOCS6, LcSOCS7a, LcSOCS7b, LcCISHa and LcCISHb) were identified and analyzed in L. crocea. The phylogenetic tree revealed a high conservation of SOCS genes in evolution, and the gene structure and motif analysis indicated a high similarity in the structure of LcSOCSs in the same subfamily. In addition, the expression patterns of LcSOCSs showed that LcSOCS1b was significantly down-regulated in all time under acute hypoxia stress, but it was markedly up-regulated throughout the entire process after P. plecoglossicida infection, revealing its different immune effects to two stresses. Besides, LcSOCS2a, LcSOCS6 and LcSOCS7a only participated in acute hypoxic stress, while LcSOCS5a was more sensitive to P. plecoglossicida infection. In summary, these results indicated that SOCS genes were involved in stress responses to both biological and non-biological stimuli, setting the foundation for deeper study on the functions of SOCS genes.

Environmental enrichment improves social isolation-induced memory impairment: The possible role of ITSN1-Reelin-AMPA receptor signaling pathway.

Environmental enrichment (EE) through combination of social and non-biological stimuli enhances activity-dependent synaptic plasticity and improves behavioural performance. Our earlier studies have suggested that EE resilience the stress induced depression/ anxiety-like behaviour in Indian field mice Mus booduga. This study was designed to test whether EE reverses the social isolation (SI) induced effect and improve memory. Field-caught mice M. booduga were subjected to behaviour test (Direct wild, DW), remaining animals were housed under SI for ten days and then housed for short-term at standard condition (STSC)/ long-term at standard condition (LTSC) or as group in EE cage. Subsequently, we have examined reference, working memory and expression of genes associated with synaptic plasticity. Our analysis have shown that EE reversed SI induced impairment in reference, working memory and other accompanied changes i.e. increased level of Intersectin 1 (ITSN1), Huntingtin (Htt), Synaptotagmin -IV (SYT4), variants of brain-derived neurotrophic factor (Bdnf - III), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor (GluR1) expression, and decreased variants of Bdnf (IV), BDNF, Reelin, Apolipoprotein E receptor 2 (ApoER2), very low-density lipoprotein receptor (VLDLR), Src family tyrosine kinase (SFKs), Disabled protein (Dab)-1, Protein kinase B (PKB/Akt), GluR2, Mitogen-activated protein kinase (MAPK) and Extracellular signal-regulated kinase (ERK1/2) expression. In addition, SI induced reduction in BDNF expressing neurons in dentate gyrus of hippocampus reversed by EE. Further, we found that SI decreases small neuro-active molecules such as Benzenedicarboxylic acid, and increases 2-Pregnene in the hippocampus and feces reversed by EE. Overall, this study demonstrated that EE is effectively reversed the SI induced memory impairment by potentially regulating the molecules associated with the ITSN1-Reelin-AMPA receptor pathway to increase synaptic plasticity.

What makes a visual scene more memorable? A rapid serial visual presentation (RSVP) study with dynamic visual scenes

ABSTRACT The visual system has been characterized as having limited processing capacity. Research suggests that not all visual information is equal and that certain visual scenes are registered better than others. The present study investigated how people process biological stimuli under time constraint using a Rapid Serial Visual Presentation (RSVP) paradigm with dynamic movie scenes. The results of Experiments 1 and 2 indicated that recognition memory as well as identification performance got better with longer duration (400 ms vs. 200 ms). Most importantly, biological stimuli led to better memory and lower reaction times. Lastly, Experiment 3 was conducted to replicate previously observed dynamic advantage and to disentangle the role of motion from content. The results indicated that dynamic scenes were remembered better than static scenes for both the biological and non-biological stimuli. The ecological validity and retrieval benefit of dynamic scenes were discussed in relation to image memorability.

Design and application of stimuli-responsive DNA hydrogels: A review.

Deoxyribonucleic acid (DNA) hydrogels combine the properties of DNAs and hydrogels, and adding functionalized DNAs is key to the wide application of DNA hydrogels. In stimuli-responsive DNA hydrogels, the DNA transcends its application in genetics and bridges the gap between different fields. Specifically, the DNA acts as both an information carrier and a bridge in constructing DNA hydrogels. The programmability and biocompatibility of DNA hydrogel make it change macroscopically in response to a variety of stimuli. In order to meet the needs of different scenarios, DNA hydrogels were also designed into microcapsules, beads, membranes, microneedle patches, and other forms. In this study, the stimuli were classified into single biological and non-biological stimuli and composite stimuli. Stimuli-responsive DNA hydrogels from the past five years were summarized, including but not limited to their design and application, in particular logic gate pathways and signal amplification mechanisms. Stimuli-responsive DNA hydrogels have been applied to fields such as sensing, nanorobots, information carriers, controlled drug release, and disease treatment. Different potential applications and the developmental pro-spects of stimuli-responsive DNA hydrogels were discussed.

Regulating mirroring of emotions: A social-specific mechanism?

There is evidence that humans mirror others’ emotional responses: brain responses to observed and experienced emotion overlap, and reaction time costs of observing others’ pain suggest that others’ emotional states interfere with our own. Such emotional mirroring requires regulation to prevent personal distress. However, currently it is unclear whether this “empathic interference effect” is uniquely social, arising only from the observation of human actors, or also from the observation of non-biological objects in “painful” states. Moreover, the degree to which this interference relates to individual differences in self-reported levels of empathy is yet to be revealed. We introduce a modified pain observation task, measuring empathic interference effects induced by observation of painful states applied to both biological and non-biological stimuli. An initial validation study (N = 50) confirmed that painful states applied to biological stimuli were rated explicitly as more painful than non-painful states applied to biological stimuli, and also than both painful and non-painful states applied to non-biological stimuli. Subsequently, across two independent discovery (N = 83) and replication (N = 80) samples, the task elicited slowing of response times during the observation of painful states when compared to non-painful states, but the magnitude of this effect did not differ between biological and non-biological stimuli. Little evidence was found for reliable relationships between empathic interference and self-reported empathy. Caution should therefore be taken in using the current task to pursue an individual differences approach to empathic interference, but the task shows promise for investigating the specificity of the mechanism involved in regulating emotional mirroring.

Action observation and imitation in Parkinson's disease: The influence of biological and non-biological stimuli

Action observation and imitation have been found to influence movement in people with Parkinson's disease (PD), but simple visual stimuli can also guide their movement. To investigate whether action observation may provide a more effective stimulus than other visual cues, the present study examined the effects of observing human pointing movements and simple visual stimuli on hand kinematics and eye movements in people with mild to moderate PD and age-matched controls.In Experiment 1, participants observed videos of movement sequences between horizontal positions, depicted by a simple cue with or without a moving human hand, then imitated the sequence either without further visual input (consecutive task) or while watching the video again (concurrent task). Modulation of movement duration, in accordance with changes in the observed stimulus, increased when the simple cue was accompanied by the hand and in the concurrent task, whereas modulation of horizontal amplitude was greater with the simple cue alone and in the consecutive task.Experiment 2 compared imitation of kinematically-matched dynamic biological (human hand) and non-biological (shape) stimuli, which moved with a high or low vertical trajectory. Both groups exhibited greater modulation for the hand than the shape, and differences in eye movements suggested closer tracking of the hand.Despite producing slower and smaller movements overall, the PD group showed a similar pattern of imitation to controls across tasks and conditions. The findings demonstrate that observing human action influences aspects of movement such as duration or trajectory more strongly than non-biological stimuli, particularly during concurrent imitation.

Differences in perceived durations between plausible biological and non-biological stimuli.

Visual motion stimuli can sometimes distort our perception of time. This effect is dependent on the apparent speed of the moving stimulus, where faster stimuli are usually perceived lasting longer than slower stimuli. Although it has been shown that neural and cognitive processing of biological motion stimuli differ from non-biological motion stimuli, no study has yet investigated whether perceived durations of biological stimuli differ from non-biological stimuli across different speeds. Here, a prospective temporal reproduction task was used to assess that question. Biological motion stimuli consisted of a human silhouette running in place. Non-biological motion stimuli consisted of a rectangle moving in a pendular way. Amount and plausibility of movement for each stimulus and frame-rate (speed) were evaluated by an independent group of participants. Although the amount of movement perceived was positively correlated to frame rate both for biological and non-biological stimuli, movie clips involving biological motion stimuli were judged to last longer than non-biological motion stimuli only at frame rates for which movement was rated as plausible. These results suggest that plausible representations of biomechanical movement induce additional temporal distortions to those modulated by increases in stimulus speed. Moreover, most studies reporting neural and cognitive differences in the processing of biological and non-biological motion stimuli acquired neurophysiological data using fMRI. Here, we report differences in the processing of biological and non-biological motion stimuli across different speeds using functional near-infrared spectroscopy (fNIRS), a less costly and portable form of neurophysiological data acquisition.

Designing Next-Generation Functional Food and Beverages: Combining Nonthermal Processing Technologies and Postharvest Abiotic Stresses

Currently, consumers are demanding healthier foods that are at the same time fresh, safe, and long-lasting. However, traditional food processing technologies apply thermal treatments, which lead to modifications of sensory properties and losses of health-promoting compounds. Therefore, novel technologies have been increasingly researched and developed to overcome these problems, including postharvest abiotic stresses (PAS) and nonthermal processing technologies (NTPTs). PAS refer to the application of non-biological stimuli (i.e., wounding stress, modified atmospheres, UV light) to which plants respond by synthesizing secondary metabolites as a defense mechanism. Many of these secondary metabolites are nutraceuticals. On the other hand, NTPTs (i.e., high-pressure processing, ultrasound, pulsed electric fields) extend the shelf-life of foods without using high temperatures, allowing the retention of sensory, nutritional, and nutraceutical quality. Furthermore, certain NTPTs can also act as PAS, enhancing the nutraceutical content of foods through physical, chemical, and metabolic changes. This review describes the physiological response of fruits and vegetables to PAS and NTPTs and discusses their strengths and drawbacks when using them as elicitors to induce the accumulation of nutraceuticals. It presents a new concept that consists of the combined application of PAS and NTPTs to design next-generation food and beverages against chronic diseases using colon cancer as an example. Combining PAS and NTPTs is an emerging field; therefore, more research is needed to establish which combinations are most suitable and cost-effective to satisfy consumer demands.

Dioxin exposure and sexual dimorphism of gaze behavior in prepubertal Vietnamese children living in Da Nang, a hot spot for dioxin contamination

Previous studies have reported that dioxin exposure alters sexual dimorphism of play behavior in pre-pubertal children. We aimed to investigate the effects of perinatal dioxin exposure, indicated by dioxins in breast milk, on sexual dimorphism of gaze behavior after adjusting for salivary testosterone (T). Participants were pre-pubertal children in a hot spot for dioxin contamination originating from herbicide spraying in Vietnam.We used eye tracking to assess gaze behavior in 172 children (100 boys and 72 girls) aged 8–9 years. Two sets of 15 pairs of pictures, one oriented towards boys and one oriented towards girls, containing 5 pairs of toy photos (non-biological stimuli) and 10 pairs of human line drawings (biological stimuli) were shown to all children. The total fixation duration for each picture was extracted using Tobii studio software and a feminine index of gaze behavior was defined as the ratio of the summed fixation duration for the girl- vs boy-oriented versions of each stimuli.When viewing non-biological stimuli, feminine index scores significantly increased with TCDD (β = 0.294) in girls only. For biological stimuli, however, feminine index scores significantly increased with TEQ-PCDD/Fs (β = 0.269) in boys and with TCDD in girls (β = 0.286). These associations were significant even after adjusting for salivary T levels, which were inversely associated with some dioxin congeners in girls. In addition, increased feminine index scores for biological stimuli were associated with lower cognitive scores for hand-movement and word-order tests in boys and for face-recognition tests in girls examined at 5 years of age.In conclusion, these results suggest that perinatal dioxin exposure may increase visual interest in girl-oriented objects through impairment of cognitive abilities in pre-pubertal Vietnamese children. PCDD congeners were associated with gaze behavior independently of T levels in boys, while this was only the case for TCDD levels in girls.

Effects of liking on visual attention in faces and paintings

The visual aesthetics of an object increases visual attention towards the object. It is argued that this relation between liking and attention is an evolutionary adaptation in sexual and natural selection. If this is the case, we would expect this relation to be domain specific, and thus, stronger for biological than for non-biological objects. To test this hypothesis, we conducted two eye-tracking studies, in which we compared the relation between liking and gaze patterns in images of biological (faces) and non-biological (paintings) stimuli. In Study 1, we presented randomly combined image pairs for 20 s in a free-viewing paradigm. Participants then selected the image they liked more in a 2-AFC task and rated the liking of each image on a Likert-scale. In Study 2, we employed the same paradigm but this time, images were combined based on pre-rated liking to ensure that images in each pair were clearly different. In both studies, we found a strong relation between liking and visual attention. Against our expectations, these effects were of similar magnitude for faces as for paintings. We conclude that the relation between liking and visual attention is not limited to biological objects but that its effects are domain general. The evolutionary function of the relation between liking and visual attention might stem from evolutionary adaptations, nonetheless, this link seems to be a rather basic phenomenon that applies across domains.

Eyes versus hands: How perceived stimuli influence motor actions.

Many studies showed that biological (e.g., gaze-shifts or hand movements) and non-biological stimuli (e.g., arrows or moving points) redirect attention. Biological stimuli seem to be more suitable than non-biological to perform this task. However, the question remains if biological stimuli do have different influences on redirecting attention and if this property is dependent on how we react to those stimuli. In two separate experiments, participants interact either with a biological or a non-biological stimulus (experiment 1), or with two biological stimuli (gaze-shifts, hand movements)(experiment 2) to which they responded with two different actions (saccade, button press), either in a congruent or incongruent manner. Results from experiment 1 suggest that interacting with the biological stimulus lead to faster responses, compared to the non-biological stimulus, independent of the response type. Results from experiment 2 show longer reaction times when the depicted stimulus was not matching the response type (e.g., reacting with hand movements to a moving object or gaze-shift) compared to a matching condition, while especially the gaze-following condition (reacting with a gaze shift to a perceived gaze shift) led to the fastest responses. These results suggest that redirecting attention is not only dependent on the perceived stimulus but also on the way how those stimuli are responded to.

Mu suppression – A good measure of the human mirror neuron system?

Mu suppression has been proposed as a signature of the activity of the human mirror neuron system (MNS). However the mu frequency band (8–13 Hz) overlaps with the alpha frequency band, which is sensitive to attentional fluctuation, and thus mu suppression could potentially be confounded by changes in attentional engagement. The specific baseline against which mu suppression is assessed may be crucial, yet there is little consistency in how this is defined. We examined mu suppression in 61 typical adults, the largest mu suppression study so far conducted. We compared different methods of baselining, and examined activity at central and occipital electrodes, to both biological (hands) and non-biological (kaleidoscope) moving stimuli, to investigate the involvement of attention and alpha activity in mu suppression. We also examined changes in beta power, another candidate index of MNS engagement. We observed strong mu suppression restricted to central electrodes when participants performed hand movements, demonstrating that mu is indeed responsive to the activity of the motor cortex. However, when we looked for a similar signature of mu suppression to passively observed stimuli, the baselining method proved to be crucial. Selective suppression for biological versus non-biological stimuli was seen at central electrodes only when we used a within-trial baseline based on a static stimulus: this method greatly reduced trial-by-trial variation in the suppression measure compared with baselines based on blank trials presented in separate blocks. Even in this optimal condition, 16–21% of participants showed no mu suppression. Changes in beta power also did not match our predicted pattern for MNS engagement, and did not seem to offer a better measure than mu. Our conclusions are in contrast to those of a recent meta-analysis, which concluded that mu suppression is a valid means to examine mirror neuron activity. We argue that mu suppression can be used to index the human MNS, but the effect is weak and unreliable and easily confounded with alpha suppression.

Believe it or not: Moving non-biological stimuli believed to have human origin can be represented as human movement

Does our brain treat non-biological movements (e.g. moving abstract shapes or robots) in the same way as human movements? The current work tested whether the movement of a non-biological rectangular object, believed to be based on a human action is represented within the observer’s motor system. A novel visuomotor priming task was designed to pit true imitative compatibility, due to human action representation against more general stimulus response compatibility that has confounded previous belief experiments. Stimulus response compatibility effects were found for the object. However, imitative compatibility was found when participants repeated the object task with the belief that the object was based on a human finger movement, and when they performed the task viewing a real human hand. These results provide the first demonstration that non-biological stimuli can be represented as a human movement if they are believed to have human agency and have implications for interactions with technology and robots.

Mirror me: Imitative responses in adults with autism.

Dysfunctions of the human mirror neuron system have been postulated to underlie some deficits in autism spectrum disorders including poor imitative performance and impaired social skills. Using three reaction time experiments addressing mirror neuron system functions under simple and complex conditions, we examined 20 adult autism spectrum disorder participants and 20 healthy controls matched for age, gender and education. Participants performed simple finger-lifting movements in response to (1) biological finger and non-biological dot movement stimuli, (2) acoustic stimuli and (3) combined visual-acoustic stimuli with different contextual (compatible/incompatible) and temporal (simultaneous/asynchronous) relation. Mixed model analyses revealed slower reaction times in autism spectrum disorder. Both groups responded faster to biological compared to non-biological stimuli (Experiment 1) implying intact processing advantage for biological stimuli in autism spectrum disorder. In Experiment 3, both groups had similar 'interference effects' when stimuli were presented simultaneously. However, autism spectrum disorder participants had abnormally slow responses particularly when incompatible stimuli were presented consecutively. Our results suggest imitative control deficits rather than global imitative system impairments.

The neurophysiology of biological motion perception in schizophrenia.

IntroductionThe ability to recognize human biological motion is a fundamental aspect of social cognition that is impaired in people with schizophrenia. However, little is known about the neural substrates of impaired biological motion perception in schizophrenia. In the current study, we assessed event-related potentials (ERPs) to human and nonhuman movement in schizophrenia.MethodsTwenty-four subjects with schizophrenia and 18 healthy controls completed a biological motion task while their electroencephalography (EEG) was simultaneously recorded. Subjects watched clips of point-light animations containing 100%, 85%, or 70% biological motion, and were asked to decide whether the clip resembled human or nonhuman movement. Three ERPs were examined: P1, N1, and the late positive potential (LPP).ResultsBehaviorally, schizophrenia subjects identified significantly fewer stimuli as human movement compared to healthy controls in the 100% and 85% conditions. At the neural level, P1 was reduced in the schizophrenia group but did not differ among conditions in either group. There were no group differences in N1 but both groups had the largest N1 in the 70% condition. There was a condition × group interaction for the LPP: Healthy controls had a larger LPP to 100% versus 85% and 70% biological motion; there was no difference among conditions in schizophrenia subjects.ConclusionsConsistent with previous findings, schizophrenia subjects were impaired in their ability to recognize biological motion. The EEG results showed that biological motion did not influence the earliest stage of visual processing (P1). Although schizophrenia subjects showed the same pattern of N1 results relative to healthy controls, they were impaired at a later stage (LPP), reflecting a dysfunction in the identification of human form in biological versus nonbiological motion stimuli.

Neural systems for preparatory control of imitation.

Humans have an automatic tendency to imitate others. Previous studies on how we control these tendencies have focused on reactive mechanisms, where inhibition of imitation is implemented after seeing an action. This work suggests that reactive control of imitation draws on at least partially specialized mechanisms. Here, we examine preparatory imitation control, where advance information allows control processes to be employed before an action is observed. Drawing on dual route models from the spatial compatibility literature, we compare control processes using biological and non-biological stimuli to determine whether preparatory imitation control recruits specialized neural systems that are similar to those observed in reactive imitation control. Results indicate that preparatory control involves anterior prefrontal, dorsolateral prefrontal, posterior parietal and early visual cortices regardless of whether automatic responses are evoked by biological (imitative) or non-biological stimuli. These results indicate both that preparatory control of imitation uses general mechanisms, and that preparatory control of imitation draws on different neural systems from reactive imitation control. Based on the regions involved, we hypothesize that preparatory control is implemented through top-down attentional biasing of visual processing.

Sequencing Biological and Physical Events Affects Specific Frequency Bands within the Human Premotor Cortex: An Intracerebral EEG Study

Evidence that the human premotor cortex (PMC) is activated by cognitive functions involving the motor domain is classically explained as the reactivation of a motor program decoupled from its executive functions, and exploited for different purposes by means of a motor simulation. In contrast, the evidence that PMC contributes to the sequencing of non-biological events cannot be explained by the simulationist theory. Here we investigated how motor simulation and event sequencing coexist within the PMC and how these mechanisms interact when both functions are executed. We asked patients with depth electrodes implanted in the PMC to passively observe a randomized arrangement of images depicting biological actions and physical events and, in a second block, to sequence them in the correct order. This task allowed us to disambiguate between the simple observation of actions, their sequencing (recruiting different motor simulation processes), as well as the sequencing of non-biological events (recruiting a sequencer mechanism non dependant on motor simulation). We analysed the response of the gamma, alpha and beta frequency bands to evaluate the contribution of each brain rhythm to the observation and sequencing of both biological and non-biological stimuli. We found that motor simulation (biological>physical) and event sequencing (sequencing>observation) differently affect the three investigated frequency bands: motor simulation was reflected on the gamma and, partially, in the beta, but not in the alpha band. In contrast, event sequencing was also reflected on the alpha band.

Controlling automatic imitative tendencies: Interactions between mirror neuron and cognitive control systems

Humans have an automatic tendency to imitate others. Although several regions commonly observed in social tasks have been shown to be involved in imitation control, there is little work exploring how these regions interact with one another. We used fMRI and dynamic causal modeling to identify imitation-specific control mechanisms and examine functional interactions between regions. Participants performed a pre-specified action (lifting their index or middle finger) in response to videos depicting the same two actions (biological cues) or dots moving with similar trajectories (non-biological cues). On congruent trials, the stimulus and response were similar (e.g. index finger response to index finger or left side dot stimulus), while on incongruent trials the stimulus and response were dissimilar (e.g. index finger response to middle finger or right side dot stimulus). Reaction times were slower on incongruent compared to congruent trials for both biological and non-biological stimuli, replicating previous findings that suggest the automatic imitative or spatially compatible (congruent) response must be controlled on incongruent trials. Neural correlates of the congruency effects were different depending on the cue type. The medial prefrontal cortex, anterior cingulate, inferior frontal gyrus pars opercularis (IFGpo) and the left anterior insula were involved specifically in controlling imitation. In addition, the IFGpo was also more active for biological compared to non-biological stimuli, suggesting that the region represents the frontal node of the human mirror neuron system (MNS). Effective connectivity analysis exploring the interactions between these regions, suggests a role for the mPFC and ACC in imitative conflict detection and the anterior insula in conflict resolution processes, which may occur through interactions with the frontal node of the MNS. We suggest an extension of the previous models of imitation control involving interactions between imitation-specific and general cognitive control mechanisms.

Top-down and bottom-up processes during observation: Implications for motor learning

Neurophysiological and behavioural research has linked observational practice (OP) to a mirroring mechanism encompassing the action-observation network (AON). Although, the original findings indicate that biological stimuli alone activate the AON, recent evidence has shown sensitivity to non-biological stimuli. Thus, the AON is suggested to be influenced by interacting bottom-up and top-down processes. In this review, we describe the multi-functional properties of the AON and discuss the implications for OP and subsequent motor learning.