Mapping motor representations with positron emission tomography

Coupling movement with imagery as a new perspective for motor imagery practice

Background

Recent data support the beneficial role of gesturing during mental practice. The present study examined whether coupling motor imagery (MI) with some movement sequences (dynamic imagery condition) impacted motor performance to a greater extent than performing MI while remaining motionless.

Methods

A group of active high jumpers imagined their jump both with and without associated arm movement. Three outcome variables were measured: the number of successful attempts, the temporal congruence between MI and actual jump performance, and the technical quality of the jump.

Results

Data revealed that dynamic imagery enhanced both MI quality and temporal congruence between MI and motor performance, and further improved the technical efficacy of the jump. Athletes also reported more vivid representation while coupling MI with actual movement.

Conclusions

These data support the hypothesis that performing dynamic imagery might contribute to enhance MI quality and efficacy, and sketch potentially fruitful new directions for MI practice.

Near-infrared spectroscopy-mediated neurofeedback enhances efficacy of motor imagery-based training in poststroke victims: a pilot study

BACKGROUND AND PURPOSE

Despite the findings that motor imagery and execution are supposed to share common neural networks, previous studies using imagery-based rehabilitation have revealed inconsistent results. In the present study, we investigated whether feedback of cortical activities (neurofeedback) using near-infrared spectroscopy could enhance the efficacy of imagery-based rehabilitation in stroke patients.

METHODS

Twenty hemiplegic patients with subcortical stroke received 6 sessions of mental practice with motor imagery of the distal upper limb in addition to standard rehabilitation. Subjects were randomly allocated to REAL and SHAM groups. In the REAL group, cortical hemoglobin signals detected by near-infrared spectroscopy were fed back during imagery. In the SHAM group, irrelevant randomized signals were fed back. Upper limb function was assessed using the finger and arm subscales of the Fugl-Meyer assessment and the Action Research Arm Test.

RESULTS

The hand/finger subscale of the Fugl-Meyer assessment showed greater functional gain in the REAL group, with a significant interaction between time and group (F(2,36)=15.5; P<0.001). A significant effect of neurofeedback was revealed even in severely impaired subjects. Imagery-related cortical activation in the premotor area was significantly greater in the REAL group than in the SHAM group (T(58)=2.4; P<0.05).

CONCLUSIONS

Our results suggest that near-infrared spectroscopy-mediated neurofeedback may enhance the efficacy of mental practice with motor imagery and augment motor recovery in poststroke patients with severe hemiparesis.

Observing expertise-related actions leads to perfect time flow estimations

The estimation of the time of exposure of a picture portraying an action increases as a function of the amount of movement implied in the action represented. This effect suggests that the perceiver creates an internal embodiment of the action observed as if internally simulating the entire movement sequence. Little is known however about the timing accuracy of these internal action simulations, specifically whether they are affected by the level of familiarity and experience that the observer has of the action. In this study we asked professional pianists to reproduce different durations of exposure (shorter or longer than one second) of visual displays both specific (a hand in piano-playing action) and non-specific to their domain of expertise (a hand in finger-thumb opposition and scrambled-pixels) and compared their performance with non-pianists. Pianists outperformed non-pianists independently of the time of exposure of the stimuli; remarkably the group difference was particularly magnified by the pianists' enhanced accuracy and stability only when observing the hand in the act of playing the piano. These results for the first time provide evidence that through musical training, pianists create a selective and self-determined dynamic internal representation of an observed movement that allows them to estimate precisely its temporal duration.

Multimodal functional imaging of motor imagery using a novel paradigm

Neuroimaging studies have shown that the neural mechanisms of motor imagery (MI) overlap substantially with the mechanisms of motor execution (ME). Surprisingly, however, the role of several regions of the motor circuitry in MI remains controversial, a variability that may be due to differences in neuroimaging techniques, MI training, instruction types, or tasks used to evoke MI. The objectives of this study were twofold: (i) to design a novel task that reliably invokes MI, provides a reliable behavioral measure of MI performance, and is transferable across imaging modalities; and (ii) to measure the common and differential activations for MI and ME with functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG). We present a task in which it is difficult to give accurate responses without the use of either motor execution or motor imagery. The behavioral results demonstrate that participants performed similarly on the task when they imagined vs. executed movements and this performance did not change over time. The fMRI results show a spatial overlap of MI and ME in a number of motor and premotor areas, sensory cortices, cerebellum, inferior frontal gyrus, and ventrolateral thalamus. MI uniquely engaged bilateral occipital areas, left parahippocampus, and other temporal and frontal areas, whereas ME yielded unique activity in motor and sensory areas, cerebellum, precuneus, and putamen. The MEG results show a robust event-related beta band desynchronization in the proximity of primary motor and premotor cortices during both ME and MI. Together, these results further elucidate the neural circuitry of MI and show that our task robustly and reliably invokes motor imagery, and thus may prove useful for interrogating the functional status of the motor circuitry in patients with motor disorders.

How does brain activation differ in children with unilateral cerebral palsy compared to typically developing children, during active and passive movements, and tactile stimulation? An fMRI study

The aim of the functional magnetic resonance imaging (fMRI) study was to investigate brain activation associated with active and passive movements, and tactile stimulation in 17 children with right-sided unilateral cerebral palsy (CP), compared to 19 typically developing children (TD). The active movements consisted of repetitive opening and closing of the hand. For passive movements, an MRI-compatible robot moved the finger up and down. Tactile stimulation was provided by manually stroking the dorsal surface of the hand with a sponge cotton cloth. In both groups, contralateral primary sensorimotor cortex activation (SM1) was seen for all tasks, as well as additional contralateral primary somatosensory cortex (S1) activation for passive movements. Ipsilateral cerebellar activity was observed in TD children during all tasks, but only during active movements in CP children. Of interest was additional ipsilateral SM1 recruitment in CP during active movements as well as ipsilateral S1 activation during passive movements and tactile stimulation. Another interesting new finding was the contralateral cerebellum activation in both groups during different tasks, also in cerebellar areas not primarily linked to the sensorimotor network. Active movements elicited significantly more brain activation in CP compared to TD children. In both groups, active movements displayed significantly more brain activation compared to passive movements and tactile stimulation.

Action observation versus motor imagery in learning a complex motor task: a short review of literature and a kinematics study

Both motor imagery and action observation have been shown to play a role in learning or re-learning complex motor tasks. According to a well accepted view they share a common neurophysiological basis in the mirror neuron system. Neurons within this system discharge when individuals perform a specific action and when they look at another individual performing the same or a motorically related action. In the present paper, after a short review of literature on the role of action observation and motor imagery in motor learning, we report the results of a kinematics study where we directly compared motor imagery and action observation in learning a novel complex motor task. This involved movement of the right hand and foot in the same angular direction (in-phase movement), while at the same time moving the left hand and foot in an opposite angular direction (anti-phase movement), all at a frequency of 1Hz. Motor learning was assessed through kinematics recording of wrists and ankles. The results showed that action observation is better than motor imagery as a strategy for learning a novel complex motor task, at least in the fast early phase of motor learning. We forward that these results may have important implications in educational activities, sport training and neurorehabilitation.

Mental imagery of speech: linking motor and perceptual systems through internal simulation and estimation

The neural basis of mental imagery has been investigated by localizing the underlying neural networks, mostly in motor and perceptual systems, separately. However, how modality-specific representations are top-down induced and how the action and perception systems interact in the context of mental imagery is not well understood. Imagined speech production ("articulation imagery"), which induces the kinesthetic feeling of articulator movement and its auditory consequences, provides a new angle because of the concurrent involvement of motor and perceptual systems. On the basis of previous findings in mental imagery of speech, we argue for the following regarding the induction mechanisms of mental imagery and the interaction between motor and perceptual systems: (1) Two distinct top-down mechanisms, memory retrieval and motor simulation, exist to induce estimation in perceptual systems. (2) Motor simulation is sufficient to internally induce the representation of perceptual changes that would be caused by actual movement (perceptual associations); however, this simulation process only has modulatory effects on the perception of external stimuli, which critically depends on context and task demands. Considering the proposed simulation-estimation processes as common mechanisms for interaction between motor and perceptual systems, we outline how mental imagery (of speech) relates to perception and production, and how these hypothesized mechanisms might underpin certain neural disorders.

N300 and social affordances: a study with a real person and a dummy as stimuli

Pictures of objects have been shown to automatically activate affordances, that is, actions that could be performed with the object. Similarly, pictures of faces are likely to activate social affordances, that is, interactions that would be possible with the person whose face is being presented. Most interestingly, if it is the face of a real person that is shown, one particular type of social interactions can even be carried out while event-related potentials (ERPs) are recorded. Indeed, subtle eye movements can be made to achieve an eye contact with the person with minimal artefacts on the EEG. The present study thus used the face of a real person to explore the electrophysiological correlates of affordances in a situation where some of them (i.e., eye contacts) are actually performed. The ERPs this person elicited were compared to those evoked by another 3D stimulus: a real dummy, and thus by a stimulus that should also automatically activate eye contact affordances but with which such affordances could then be inhibited since they cannot be carried out with an object. The photos of the person and of the dummy were used as matching stimuli that should not activate social affordances as strongly as the two 3D stimuli and for which social affordances cannot be carried out. The fronto-central N300s to the real dummy were found of greater amplitudes than those to the photos and to the real person. We propose that these greater N300s index the greater inhibition needed after the stronger activations of affordances induced by this 3D stimulus than by the photos. Such an inhibition would not have occurred in the case of the real person because eye contacts were carried out.

Top down effect of strategy on the perception of human biological motion: a pet investigation

This experiment was designed to investigate the neural network engaged by the perception of human movements using positron emission tomography. Perception of meaningful and of meaningless hand actions without any purpose was contrasted with the perception of the same kind of stimuli with the goal to imitate them later. A condition that consisted of the perception of stationary hands served as a baseline level. Perception of meaningful actions and meaningless actions without any aim was associated with activation of a common set of cortical regions. In both hemispheres, the occipito-temporal junction (Ba 37/19) and the superior occipital gyrus (Ba 19) were involved. In the left hemisphere, the middle temporal gyrus (Ba 21) and the inferior parietal lobe (Ba 40) were found to be activated. These regions are interpreted as related to the analysis of hand movements. The precentral gyrus, within the area of hand representation (Ba 4), was activated in the left hemisphere. In addition to this common network, meaningful and meaningless movements engaged specific networks, respectively: meaningful actions were associated with activations mainly located in the left hemisphere in the inferior frontal gyrus (Ba 44/45) and the fusiform gyrus (Ba 38/20), whereas meaningless actions involved the dorsal pathway (inferior parietal lobe, Ba 40 and superior parietal lobule, Ba 7) bilaterally and the right cerebellum. In contrast, meaningful and meaningless actions shared almost the same network when the aim of the perception was to im itate. Activations were located in the right cerebellum and bilaterally in the dorsal pathway reaching the prem otor cortex. Additional bilateral activations were located in the SMA and in the orbitofrontal cortex during observation of meaningful actions.

Real and imagined body movement primes metaphor comprehension

We demonstrate in two experiments that real and imagined body movements appropriate to metaphorical phrases facilitate people's immediate comprehension of these phrases. Participants first learned to make different body movements given specific cues. In two reading time studies, people were faster to understand a metaphorical phrase, such as push the argument, when they had previously just made an appropriate body action (e.g., a push movement) (Experiment 1), or imagined making a specific body movement (Experiment 2), than when they first made a mismatching body action (e.g., a chewing movement) or no movement. These findings support the idea that appropriate body action, or even imagined action, enhances people's embodied, metaphorical construal of abstract concepts that are referred to in metaphorical phrases.

Neural correlates of conceptual knowledge for actions

The neural correlates of conceptual knowledge for actions are not well understood. To begin to address this knowledge gap, we tested the hypothesis that the retrieval of conceptual knowledge for actions depends on neural systems located in higher-order association cortices of left premotor/prefrontal, parietal, and posterior middle temporal regions. The investigation used the lesion method and involved 90 subjects with damage to various regions of the left or right hemisphere. The experimental tasks measured retrieval of knowledge for actions, in a nonverbal format: Subjects evaluated attributes of pictured actions, and compared and matched pictures of actions. In support of our hypothesis, we found that the regions of highest lesion overlap in subjects with impaired retrieval of conceptual knowledge for actions were in the left premotor/prefrontal sector, the left parietal region, and in the white matter underneath the left posterior middle temporal region. These sites are partially distinct from those identified previously as being important for the retrieval of words for actions. We propose that a key function of the sites is to operate as two-way intermediaries between perception and concept retrieval, to promote the retrieval of the multidimensional aspects of knowledge that are necessary and sufficient for the mental representation of a concept of a given action.

Far from action-blind: Representation of others' actions in individuals with Autism

It has been suggested that theory of mind may rely on several precursors including gaze processing, joint attention, the ability to distinguish between actions of oneself and others, and the ability to represent goal-directed actions. Some of these processes have been shown to be impaired in individuals with autism, who experience difficulties in theory of mind. However, little is known about action representation in autism. Using two variants of a spatial compatibility reaction time (RT) task, we addressed the question of whether high-functioning individuals with autism have difficulties in controlling their own actions and in representing those of others. Participants with autism showed automatic response activation and had no difficulties with response inhibition. When two action alternatives were distributed among pairs of participants, participants with autism represented a co-actor's task, showing the same pattern of results as the matched control group. We discuss the possibility that in high-functioning individuals with autism, the system matching observed actions onto representations of one's own actions is intact, whereas difficulties in higher-level processing of social information persist.

The influence of individual motor imagery ability on cerebral recruitment during gait imagery

Motor imagery (MI) is often used in combination with neuroimaging techniques to study the cognitive control of gait. However, imagery ability (IA) varies widely across individuals, potentially influencing the pattern of cerebral recruitment during MI. The aim of the current study was to investigate this effect of IA on the neural correlates of gait control using functional magnetic resonance imaging (fMRI). Twenty healthy young subjects were subdivided into a good and bad imagers group, on the basis of their performance on two mental chronometry tests. For the whole group, MI activated a bilateral network of areas highly consistent with previous studies, encompassing primary motor cortex (BA 4), supplementary motor area, and other frontal and parietal areas, anterior insula, and cerebellum. Compared to bad imagers, good imagers showed higher activation in the right BA 4, left prefrontal cortex (BA 10), right thalamus, and bilateral cerebellum. Good imagers thus appear better able to recruit motor areas during MI, but also activate a prefrontal executive area (BA 10), which integrates information from the body and the environment and participates in higher-order gait control. These differences were found even though the two groups did not differ in other imagery abilities according to a standard questionnaire for vividness of motor and visual imagery. Future studies on MI should take into account these effects, and control for IA when comparing different populations, using appropriate measures. A better understanding of the neural mechanisms that underlie MI ability is crucial to accurately evaluate locomotor skills in clinical measures and neurorehabilitation techniques.

Selective influence of circadian modulation and task characteristics on motor imagery time

In this study, we examined the effect of circadian modulation on motor imagery (MI) time while also considering the effects of task complexity and duration. The ability to imagine in real time was influenced by circadian modulation in a simple walking condition, with longer MI times in the morning and evening sessions. By contrast, there was no effect of circadian rhythm in the complex, short or long walking conditions. We concluded that motor imagery time is modulated during the course of the day, but the effect of task difficulty is stronger than circadian modulation in altering the temporal congruence between physical practice and MI performance. Practical applications in motor learning and rehabilitation are discussed.

Tractography-based parcellation of the human left inferior parietal lobule

The inferior parietal lobule (IPL) is a functionally and anatomically heterogeneous region. Much of the information about the anatomical connectivity and parcellation of this region was obtained from histological studies on non-human primates. However, whether these findings from non-human primates can be applied to the human inferior parietal lobule, especially the left inferior parietal lobule, which shows evidence of considerable evolution from primates to humans, remains unclear. In this study, diffusion MRI was employed to investigate the anatomical connectivities of the human left inferior parietal lobule. Using a new algorithm, spectral clustering with edge-weighted centroidal voronoi tessellations, to search for regional variations in the probabilistic connectivity profiles of all left inferior parietal lobule voxels with all the rest of the brain identified six subregions with distinctive connectivity properties in the left inferior parietal lobule. Consistent with cytoarchitectonic findings, four subregions were found in the left supramarginal gyrus and two subregions in the left angular gyrus. The specific connectivity patterns of each subregion of the left inferior parietal lobule were supported by both the anatomical and functional connectivity properties for each subregion, as calculated by a meta-analysis-based target method and by voxel-based whole brain anatomical and functional connectivity analyses. The proposed parcellation scheme for the human left inferior parietal lobule and the maximum probability map for each subregion may facilitate more detailed future studies of this brain area.

The dual loop model: its relation to language and other modalities

The current neurobiological consensus of a general dual loop system scaffolding human and primate brains gives evidence that the dorsal and ventral connections subserve similar functions, independent of the modality and species. However, most current commentators agree that although bees dance and chimpanzees grunt, these systems of communication differ qualitatively from human language. So why is language unique to humans? We discuss anatomical differences between humans and other animals, the meaning of lesion studies in patients, the role of inner speech, and compare functional imaging studies in language with other modalities in respect to the dual loop model. These aspects might be helpful for understanding what kind of biological system the language faculty is, and how it relates to other systems in our own species and others.

Imagined tool-use in near and far space modulates the extra-striate body area

Active tool-use can result in the incorporation of the tool into the body schema, e.g., the representation of the arm is enlarged according to tool length. This modification even influences the processing of space: using a long tool leads to a remapping of far space as near space. We here further investigate the interaction of the neural representations of the human body, tool use, and spatial domain. Functional magnetic resonance imaging (fMRI) was performed in twelve right-handed healthy individuals while they imagined moving a cylinder towards a target position in far or near space by mentally using either pliers or a joystick. The fMRI data revealed that already the imagined use of preferred tools in near and far space (i.e., pliers in far space, joystick in near space) modulated the neural activity in the extra-striate body area (EBA) located in the occipito-temporal cortex. Moreover, psycho-physical interaction analysis showed that during imagined tool-use the functional connectivity of left EBA to a network representing the near-personal space around the hand was strengthened. This increased functional connectivity is likely to reflect the neural processes underlying the incorporation of the tool into the body schema. Thus, the current data suggest that simulating tool-use modulates the representation of the human body in extra-striate cortex.

Perceptual and motor-based responses to hand actions on objects: evidence from ERPs

We carried out a study examining the electrophysiological responses when participants made object decisions to objects and non-objects subject to congruent and incongruent hand-grip actions. Despite the grip responses being irrelevant to the task, event-related potentials were sensitive to the handgrip. There were effects of grip congruency on both P1 and N1 components, over both posterior and motor cortices, with the effects emerging most strongly for familiar objects. In addition, enhanced lateralized readiness potentials were observed for incongruent grips. The results suggest that there are increased perceptual and motor-based responses to objects and object-like stimuli that are grasped correctly, even when the grip is irrelevant to the task. This is consistent with the automatic coding of potential appropriate actions based on visual information from objects in the environment.

Cortical activation during executed, imagined, observed, and passive wrist movements in healthy volunteers and stroke patients

Motor imagery, passive movement, and movement observation have been suggested to activate the sensorimotor system without overt movement. The present study investigated these three covert movement modes together with overt movement in a within-subject design to allow for a fine-grained comparison of their abilities in activating the sensorimotor system, i.e. premotor, primary motor, and somatosensory cortices. For this, 21 healthy volunteers underwent functional magnetic resonance imaging (fMRI). In addition we explored the abilities of the different covert movement modes in activating the sensorimotor system in a pilot study of 5 stroke patients suffering from chronic severe hemiparesis. Results demonstrated that while all covert movement modes activated sensorimotor areas, there were profound differences between modes and between healthy volunteers and patients. In healthy volunteers, the pattern of neural activation in overt execution was best resembled by passive movement, followed by motor imagery, and lastly by movement observation. In patients, attempted overt execution was best resembled by motor imagery, followed by passive movement, and lastly by movement observation. Our results indicate that for severely hemiparetic stroke patients motor imagery may be the preferred way to activate the sensorimotor system without overt behavior. In addition, the clear differences between the covert movement modes point to the need for within-subject comparisons.

Disentangling motor execution from motor imagery with the phantom limb

Amputees can move their phantom limb at will. These 'movements without movements' have generally been considered as motor imagery rather than motor execution, but amputees can in fact perform both executed and imagined movements with their phantom and they report distinct perceptions during each task. Behavioural evidence for this dual ability comes from the fact that executed movements are associated with stump muscle contractions whereas imagined movements are not, and that phantom executed movements are slower than intact hand executed movements whereas the speed of imagined movements is identical for both hands. Since neither execution nor imagination produces any visible movement, we hypothesized that the perceptual difference between these two motor tasks relies on the activation of distinct cerebral networks. Using functional magnetic resonance imaging and changes in functional connectivity (dynamic causal modelling), we examined the activity associated with imagined and executed movements of the intact and phantom hands of 14 upper-limb amputees. Distinct but partially overlapping cerebral networks were active during both executed and imagined phantom limb movements (both performed at the same speed). A region of interest analysis revealed a 'switch' between execution and imagination; during execution there was more activity in the primary somatosensory cortex, the primary motor cortex and the anterior lobe of the cerebellum, while during imagination there was more activity in the parietal and occipital lobes, and the posterior lobe of the cerebellum. In overlapping areas, task-related differences were detected in the location of activation peaks. The dynamic causal modelling analysis further confirmed the presence of a clear neurophysiological distinction between imagination and execution, as motor imagery and motor execution had opposite effects on the supplementary motor area-primary motor cortex network. This is the first imaging evidence that the neurophysiological network activated during phantom limb movements is similar to that of executed movements of intact limbs and differs from the phantom limb imagination network. The dual ability of amputees to execute and imagine movements of their phantom limb and the fact that these two tasks activate distinct cortical networks are important factors to consider when designing rehabilitation programmes for the treatment of phantom limb pain.

Daytime naps improve motor imagery learning

Sleep is known to contribute to motor memory consolidation. Recent studies have provided evidence that a night of sleep plays a similar functional role following motor imagery (MI), while the simple passage of time does not result in performance gains. Here, we examined the benefits of a daytime nap on motor memory consolidation after MI practice. Participants were trained by MI on an explicitly known sequence of finger movements at 11:00. Half of the participants were then subjected (at 14:00) to either a short nap (10 min of stage 2 sleep) or a long nap (60-90 min, including slow wave sleep and rapid eye movement sleep). We also collected data from both quiet and active rest control groups. All participants remained in the lab until being retested at 16:00. The data revealed that a daytime nap after imagery practice improved motor performance and, therefore, facilitated motor memory consolidation, as compared with spending a similar time interval in the wake state. Interestingly, the results revealed that both short and long naps resulted in similar delayed performance gains. The data might also suggest that the presence of slow wave and rapid eye movement sleep does not provide additional benefits for the sleep-dependent motor skill consolidation following MI practice.

Self-determined, but not non-self-determined, motivation predicts activations in the anterior insular cortex: an fMRI study of personal agency

Neuroscientific studies on agency focus rather exclusively on the notion of who initiates and regulates actions, not on the notion of why the person does. The present study focused on the latter to investigate two different reasons underlying personal agency. Using event-related functional magnetic resonance imaging, we scanned 16 healthy human subjects while they imagined the enactment of volitional, agentic behavior on the same task but either for a self-determined and intrinsically motivated reason or for a non-self-determined and extrinsically motivated reason. Results showed that the anterior insular cortex (AIC), known to be related to the sense of agency, was more activated during self-determined behavior while the angular gyrus, known to be related to the sense of loss of agency, was more activated during non-self-determined behavior. Furthermore, AIC activities during self-determined behavior correlated highly with participants' self-reported intrinsic satisfactions. We conclude that self-determined behavior is more agentic than is non-self-determined behavior and that personal agency arises only during self-determined, intrinsically motivated action.

Neurofeedback using real-time near-infrared spectroscopy enhances motor imagery related cortical activation

Accumulating evidence indicates that motor imagery and motor execution share common neural networks. Accordingly, mental practices in the form of motor imagery have been implemented in rehabilitation regimes of stroke patients with favorable results. Because direct monitoring of motor imagery is difficult, feedback of cortical activities related to motor imagery (neurofeedback) could help to enhance efficacy of mental practice with motor imagery. To determine the feasibility and efficacy of a real-time neurofeedback system mediated by near-infrared spectroscopy (NIRS), two separate experiments were performed. Experiment 1 was used in five subjects to evaluate whether real-time cortical oxygenated hemoglobin signal feedback during a motor execution task correlated with reference hemoglobin signals computed off-line. Results demonstrated that the NIRS-mediated neurofeedback system reliably detected oxygenated hemoglobin signal changes in real-time. In Experiment 2, 21 subjects performed motor imagery of finger movements with feedback from relevant cortical signals and irrelevant sham signals. Real neurofeedback induced significantly greater activation of the contralateral premotor cortex and greater self-assessment scores for kinesthetic motor imagery compared with sham feedback. These findings suggested the feasibility and potential effectiveness of a NIRS-mediated real-time neurofeedback system on performance of kinesthetic motor imagery. However, these results warrant further clinical trials to determine whether this system could enhance the effects of mental practice in stroke patients.

Using touch or imagined touch to compensate for loss of proprioception: a case study

Proprioception is the sense of the position of one's own body. Here, we present a case study of an individual with proprioceptive loss in one limb consequent to stroke. The patient indicated that merely touching his impaired arm with his unimpaired arm temporarily restored his proprioception. We examined this claim and the effects of imagined touch by the unimpaired arm. Assessments were made using three-dimensional tracking of reaching trajectories towards targets in conditions of light and darkness. Both actual and imagined touching significantly reduced movement error and jerk, specifically for targets located in regions that both hands would be able to reach.

Sexual addiction: insights from psychoanalysis and functional neuroimaging

Sexual motivation is a fundamental behavior in human. For a long time, this behavior has been somehow ignored from psychological and neuroscientific research. In this article - reflecting the collaboration of a clinical psychologist and a neuroscientist - we show that in the current period, sexual affiliation is one of the most promising affiliation context to articulate a debate, a dialog and convergence points between psychoanalysis and neuroscience. Recent data on healthy sexual behavior and its compulsive variant are discussed under the prism of neuroscience and psychoanalysis.

The role of volleyball expertise in motor simulation

We explored the impact of motor experience on the interaction between implicit motor simulation and language-processing. In an action familiarity judgment task, expert volleyball players, fans and novices were presented with semantically correct sentences describing possible and not possible motor actions, all as negative or positive contexts, e.g., "Don't shank!" or "Assist!". As processing negated action-phrases is known to reduce simulation states, exposure to negative or positive contexts was used here to test how simulation varies according to motor feasibility (possible, impossible) and experience (experts and fans). A significant group×stimulus×context interaction showed that athletes and fans, took longer to process negative than positive contexts for possible actions, compared to action-impossible sentences. In addition, experts were significantly faster and more accurate than fans and, in turn, they were both more accurate than novices. Thus, implicit motor simulation impacts on action-verb processing depending on (i) the domain-relevant expertise, (ii) the feasibility of the actions, and (iii) on whether scenes are presented in a negated context. These results suggest that the implicit triggering of motor representations is modulated by the context and it is tuned to people's motor repertoire, even when actions are described linguistically.

An exploratory fNIRS study with immersive virtual reality: a new method for technical implementation

For over two decades Virtual Reality (VR) has been used as a useful tool in several fields, from medical and psychological treatments, to industrial and military applications. Only in recent years researchers have begun to study the neural correlates that subtend VR experiences. Even if the functional Magnetic Resonance Imaging (fMRI) is the most common and used technique, it suffers several limitations and problems. Here we present a methodology that involves the use of a new and growing brain imaging technique, functional Near-infrared Spectroscopy (fNIRS), while participants experience immersive VR. In order to allow a proper fNIRS probe application, a custom-made VR helmet was created. To test the adapted helmet, a virtual version of the line bisection task was used. Participants could bisect the lines in a virtual peripersonal or extrapersonal space, through the manipulation of a Nintendo Wiimote ® controller in order for the participants to move a virtual laser pointer. Although no neural correlates of the dissociation between peripersonal and extrapersonal space were found, a significant hemodynamic activity with respect to the baseline was present in the right parietal and occipital areas. Both advantages and disadvantages of the presented methodology are discussed.

Experimental research on dreaming: state of the art and neuropsychoanalytic perspectives

Dreaming is still a mystery of human cognition, although it has been studied experimentally for more than a century. Experimental psychology first investigated dream content and frequency. The neuroscientific approach to dreaming arose at the end of the 1950s and soon proposed a physiological substrate of dreaming: rapid eye movement sleep. Fifty years later, this hypothesis was challenged because it could not explain all of the characteristics of dream reports. Therefore, the neurophysiological correlates of dreaming are still unclear, and many questions remain unresolved. Do the representations that constitute the dream emerge randomly from the brain, or do they surface according to certain parameters? Is the organization of the dream's representations chaotic or is it determined by rules? Does dreaming have a meaning? What is/are the function(s) of dreaming? Psychoanalysis provides hypotheses to address these questions. Until now, these hypotheses have received minimal attention in cognitive neuroscience, but the recent development of neuropsychoanalysis brings new hopes of interaction between the two fields. Considering the psychoanalytical perspective in cognitive neuroscience would provide new directions and leads for dream research and would help to achieve a comprehensive understanding of dreaming. Notably, several subjective issues at the core of the psychoanalytic approach, such as the concept of personal meaning, the concept of unconscious episodic memory and the subject's history, are not addressed or considered in cognitive neuroscience. This paper argues that the focus on singularity and personal meaning in psychoanalysis is needed to successfully address these issues in cognitive neuroscience and to progress in the understanding of dreaming and the psyche.

Bidirectional semantic interference between action and speech

Research on embodied cognition assumes that language processing involves modal simulations that recruit the same neural systems that are usually used for action execution. If this is true, one should find evidence for bidirectional crosstalk between action and language. Using a direct matching paradigm, this study tested if action-languages interactions are bidirectional (Experiments 1 and 2), and whether the effect of crosstalk between action perception and language production is due to facilitation or interference (Experiment 3). Replicating previous findings, we found evidence for crosstalk when manual actions had to be performed simultaneously to action-word perception (Experiment 1) and also when language had to be produced during simultaneous perception of hand actions (Experiment 2). These findings suggest a clear bidirectional relationship between action and language. The latter crosstalk effect was due to interference between action and language (Experiment 3). By extending previous research of embodied cognition, the present findings provide novel evidence suggesting that bidirectional functional relations between action and language are based on similar conceptual-semantic representations.

Impaired egocentric memory and reduced somatosensory cortex size in temporal lobe epilepsy with hippocampal sclerosis

Recent research indicates that longstanding temporal lobe epilepsy (TLE) is associated with extratemporal, i.e. parietal cortex damage. We investigated egocentric and allocentric memory by use of first-person large-scale virtual reality environments in patients with TLE. We expected that TLE patients with parietal cortex damage were impaired in the egocentric memory task. Twenty-two TLE patients with hippocampal sclerosis (HS) and 22 TLE patients without HS were compared with 42 healthy matched controls on two virtual reality tasks affording to learn a virtual park (allocentric memory) and a virtual maze (egocentric memory). Participants further received a neuropsychological investigation and MRI volumetry at the time of the assessment. When compared with controls, TLE patients with HS had significantly reduced size of the ipsilateral and contralateral somatosensory cortex (postcentral gyrus). When compared with controls or TLE patients without HS, TLE patients with HS were severely impaired learning the virtual maze. Considering all participants, smaller volumes of the left-sided postcentral gyrus were related to worse performance on the virtual maze. It is concluded that the paradigm of egocentric navigation and learning in first-person large-scale virtual environments may be a suitable tool to indicate significant extratemporal damage in individuals with TLE.

The motivated brain: insights from neuroimaging studies of human male sexual affiliation context

The advent of functional neuroimaging techniques has allowed to address the question of the role of the brain in a new light, being now able to record brain activity under different kinds of perceptual, cognitive or motor paradigms. Two exponentially emerging fields, i.e. social and affective neurosciences, converge on topics such as brain processing of emotional information issued by the congeners. As any social interaction obbeys a motivational dimension of interattraction, it is therefore important to study the role of the brain in specific functional contexts. In this paper we show how the emergence of a new field crystallized around the study of brain circuits involved in sexual affiliation has helped providing important results to understand the brain’s role in social motivated interactions. Specifically, these studies show for this involvement a central physiological component and its cortical representation that seems to be essential for social interactions with motivational component.

Parieto-frontal network in humans studied by cortico-cortical evoked potential

Parieto-frontal network is essential for sensorimotor integration in various complex behaviors, and its disruption is associated with pathophysiology of apraxia and visuo-spatial disorders. Despite advances in knowledge regarding specialized cortical areas for various sensorimotor transformations, little is known about the underlying cortico-cortical connectivity in humans. We investigated inter-areal connections of the lateral parieto-frontal network in vivo by means of cortico-cortical evoked potentials (CCEPs). Six patients with epilepsy and one with brain tumor were studied. With the use of subdural electrodes implanted for presurgical evaluation, network configuration was investigated by tracking the connections from the parietal stimulus site to the frontal site where the maximum CCEP was recorded. It was characterized by (i) a near-to-near and distant-to-distant, mirror symmetric configuration across the central sulcus, (ii) preserved dorso-ventral organization (the inferior parietal lobule to the ventral premotor area and the superior parietal lobule to the dorsal premotor area), and (iii) projections to more than one frontal cortical sites in 56% of explored connections. These findings were also confirmed by the standardized parieto-frontal CCEP connectivity map constructed in reference to the Jülich cytoarchitectonic atlas in the MNI standard space. The present CCEP study provided an anatomical blueprint underlying the lateral parieto-frontal network and demonstrated a connectivity pattern similar to non-human primates in the newly developed inferior parietal lobule in humans.

Cortico-Cortical Connectivity between Right Parietal and Bilateral Primary Motor Cortices during Imagined and Observed Actions: A Combined TMS/tDCS Study

Previous transcranial magnetic stimulation (TMS) studies showed functional connections between the parietal cortex (PC) and the primary motor cortex (M1) during tasks of different reaching-to-grasp movements. Here, we tested whether the same network is involved in cognitive processes such as imagined or observed actions. Single pulse TMS of the right and left M1 during rest and during a motor imagery and an action observation task (i.e., an index-thumb pinch grip in both cases) was used to measure corticospinal excitability changes before and after conditioning of the right PC by 10 min of cathodal, anodal, or sham transcranial direct current stimulation (tDCS). Corticospinal excitability was indexed by the size of motor-evoked potentials (MEPs) from the contralateral first dorsal interosseous (FDI; target) and abductor digiti minimi muscle (control) muscles. Results showed selective ipsilateral effects on the M1 excitability, exclusively for motor imagery processes: anodal tDCS enhanced the MEPs' size from the FDI muscle, whereas cathodal tDCS decreased it. Only cathodal tDCS impacted corticospinal facilitation induced by action observation. Sham stimulation was always uneffective. These results suggest that motor imagery, differently from action observation, is sustained by a strictly ipsilateral parieto-motor cortex circuits. Results might have implication for neuromodulatory rehabilitative purposes.

Word intelligibility and age predict visual cortex activity during word listening

The distractibility that older adults experience when listening to speech in challenging conditions has been attributed in part to reduced inhibition of irrelevant information within and across sensory systems. Whereas neuroimaging studies have shown that younger adults readily suppress visual cortex activation when listening to auditory stimuli, it is unclear the extent to which declining inhibition in older adults results in reduced suppression or compensatory engagement of other sensory cortices. The current functional magnetic resonance imaging study examined the effects of age and stimulus intelligibility in a word listening task. Across all participants, auditory cortex was engaged when listening to words. However, increasing age and declining word intelligibility had independent and spatially similar effects: both were associated with increasing engagement of visual cortex. Visual cortex activation was not explained by age-related differences in vascular reactivity but rather auditory and visual cortices were functionally connected across word listening conditions. The nature of this correlation changed with age: younger adults deactivated visual cortex when activating auditory cortex, middle-aged adults showed no relation, and older adults synchronously activated both cortices. These results suggest that age and stimulus integrity are additive modulators of crossmodal suppression and activation.

Neural coding of cooperative vs. affective human interactions: 150 ms to code the action's purpose

The timing and neural processing of the understanding of social interactions was investigated by presenting scenes in which 2 people performed cooperative or affective actions. While the role of the human mirror neuron system (MNS) in understanding actions and intentions is widely accepted, little is known about the time course within which these aspects of visual information are automatically extracted. Event-Related Potentials were recorded in 35 university students perceiving 260 pictures of cooperative (e.g., 2 people dragging a box) or affective (e.g., 2 people smiling and holding hands) interactions. The action's goal was automatically discriminated at about 150–170 ms, as reflected by occipito/temporal N170 response. The swLORETA inverse solution revealed the strongest sources in the right posterior cingulate cortex (CC) for affective actions and in the right pSTS for cooperative actions. It was found a right hemispheric asymmetry that involved the fusiform gyrus (BA37), the posterior CC, and the medial frontal gyrus (BA10/11) for the processing of affective interactions, particularly in the 155–175 ms time window. In a later time window (200–250 ms) the processing of cooperative interactions activated the left post-central gyrus (BA3), the left parahippocampal gyrus, the left superior frontal gyrus (BA10), as well as the right premotor cortex (BA6). Women showed a greater response discriminative of the action's goal compared to men at P300 and anterior negativity level (220–500 ms). These findings might be related to a greater responsiveness of the female vs. male MNS. In addition, the discriminative effect was bilateral in women and was smaller and left-sided in men. Evidence was provided that perceptually similar social interactions are discriminated on the basis of the agents' intentions quite early in neural processing, differentially activating regions devoted to face/body/action coding, the limbic system and the MNS.

Imagining being the agent of actions that carry different moral consequences: an fMRI study

To investigate the contribution of agency to neural processing involved in aggression and morality, participants viewed in the MRI scanner a series of short visual scenarios in which an individual was either intentionally harming another person or easing the other's pain. They were required to mentally simulate being the perpetrator or the recipient of those actions. Functional connectivity analyses demonstrate that positive agency (easing the pain of another) was associated with increased activity in ventral striatum, while negative agency (harming the other) resulted in a strong signal decrease in the ventromedial prefrontal cortex and activation in the amygdala. Overall, our data show that explicit perspective taking strategy has profound impact on the neural recruitment associated with distinct behaviors as well as their moral consequences. Results from this study can inform new strategies both for therapeutic interventions for patients with socioemotional disorders and the education of medical practitioners.