Functional synchronization in repetitive bimanual prehension movements.

To examine the mechanisms of functional bimanual synchronization in goal-directed movements, we studied the movement kinematics of motorically unimpaired subjects while they performed repetitive prehension movements (either unimanually or bimanually) to small food items. Compared to unimanual conditions, bimanual movement execution yielded a significantly prolonged mouth contact phase. We hypothesized that this threefold prolongation led to a proper functional synchronization of the movement onsets of both hands at the beginning of each new movement cycle.

Hand aperture patterns in prehension.

Although variations in the standard prehensile pattern can be found in the literature, these alternative patterns have never been studied systematically. This was the goal of the current paper. Ten participants picked up objects with a pincer grip.

The agent is right: when motor embodied cognition is space-dependent.

The role of embodied mechanisms in processing sentences endowed with a first person perspective is now widely accepted. However, whether embodied sentence processing within a third person perspective would also have motor behavioral significance remains unknown. Here, we developed a novel version of the Action-sentence Compatibility Effect (ACE) in which participants were asked to perform a movement compatible or not with the direction embedded in a sentence having a first person (Experiment 1: You gave a pizza to Louis) or third person perspective (Experiment 2: Lea gave a pizza to Louis).

Impaired visual hand recognition in preoperative patients during brachial plexus anesthesia: importance of peripheral neural input for mental representation of the hand.

Background: Perceptual illusions described in healthy subjects undergoing regional anesthesia (RA) are probably related to short-term plastic brain changes. We addressed whether performance on an implicit mental rotation task reflects these RA-induced changes in body schema brain representations. Studying these changes in healthy volunteers may shed light on normal function and the central mechanisms of pain.

Grip force is part of the semantic representation of manual action verbs.

Motor actions and action verbs activate similar cortical brain regions. A functional interference can be taken as evidence that there is a parallel treatment of these two types of information and would argue for the biological grounding of language in action. A novel approach examining the relationship between language and grip force is presented.

Putting oneself in the perspective of the other: a framework for self-other differentiation.

Self-other differentiation requires both that one can understand the actions others perform, and that one can attribute these actions to them. Understanding implies that a complete description of the actions of other agents can be available in the brain of the observer. Attributing implies that the agent can be clearly differentiated from the self.

The sense of agency and its disturbances in schizophrenia: a reappraisal.

How it happens that one can recognise oneself as the source of one's own actions? This process of self-recognition is in fact far from trivial: although it operates covertly and effortlessly, it depends upon a set of mechanisms involving the processing of specific neural signals, from sensory as well as from central origin. In this paper, experimental situations where these signals can be dissociated from each other and where self-recognition becomes ambiguous will be used in healthy subjects and in schizophrenic patients. These situations will reveal that there are two levels of self-recognition, an automatic level for action identification, and a conscious level for the sense of agency, which both rely on the same principle of congruence of the action-related signals.

Subliminal display of action words interferes with motor planning: a combined EEG and kinematic study.

Recent evidence has shown that processing action-related language and motor action share common neural representations to a point that the two processes can interfere when performed concurrently. To support the assumption that language-induced motor activity contributes to action word understanding, the present study aimed at ruling out that this activity results from mental imagery of the movements depicted by the words. For this purpose, we examined cross-talk between action word processing and an arm reaching movement, using words that were presented too fast to be consciously perceived (subliminally).

Language-induced motor perturbations during the execution of a reaching movement.

In a recent study Boulenger et al. (2006) found that processing action verbs assisted reaching movement when the word was processed prior to movement onset and interfered with the movement when the word was processed at movement onset. The present study aimed to further corroborate the existence of such cross-talk between language processes and overt motor behaviour by demonstrating that the reaching movement can be disturbed by action words even when the words are presented delayed with respect to movement onset (50 ms and 200 ms).

Being oneself.

This paper discusses the difference between self-identification and the self/other differentiation. Self-identification relies on the congruence of self-generated movements and their expected consequences, i.e.

Word processing in Parkinson's disease is impaired for action verbs but not for concrete nouns.

Recent studies have demonstrated that processing of action words recruits cortical motor regions that are also involved in the planning and execution of the actions words refer to. The functional role of these regions in word understanding remains, however, to be clarified. The present study investigates this issue by examining the impact of Parkinson's disease (PD) on lexical decision performance for action words, relative to concrete nouns, in a masked priming paradigm.

Altered processing of sensorimotor feedback in schizophrenia.

Schizophrenia is characterized by an altered sense of the reality, associated with hallucinations and delusions. Some theories suggest that schizophrenia is related to a deficiency of the system that generates information about the sensory consequences of the actions realized by the subject. This system monitors the reafferent information resulting from an action and allows its anticipation.

Simulated actions in the first and in the third person perspectives share common representations.

Normal subjects simulated a grasping action with two levels of difficulty of the grasp. In one condition, they simulated the movement from their own, first person perspective (1P). In the other condition, they simulated the same movement made by a person facing them (third person perspective 3P).

Cross-talk between language processes and overt motor behavior in the first 200 msec of processing.

A recently emerging view sees language understanding as closely linked to sensory and motor processes. The present study investigates this issue by examining the influence of processing action verbs and concrete nouns on the execution of a reaching movement. Fine-grained analyses of movement kinematics revealed that relative to nouns, processing action verbs significantly affects overt motor performance.

The origin of voluntary action: history of a physiological concept.

The notion that actions are internally represented prior to be executed, and that specific brain areas are devoted to the elaboration of these representations is a challenge for neurophysiology. Questions bearing on the nature of motor centres, on their independence with respect to external stimuli, and on the possibility to monitor or even to perceive their activity are still a matter of debate. Here, we describe a thirty-year exemplary period extending between 1870 and 1900, where critical experiments and clinical observations have contributed to resolve these issues.

Perception of self-generated action in schizophrenia.

Introduction: Self-generated actions involve central processes of sensorimotor integration that continuously monitor sensory inputs to ensure that motor outputs are congruent with our intentions. This mechanism works automatically in normal conditions but becomes conscious whenever a mismatch happens during the execution of action between expected and current sensorimotor reafferences. It is now admitted in the literature that sensorimotor processes as well as the ability to predict the consequences of our own actions imply the existence of a forward model of action, which is based on efference copies.

Prehension movements in a patient (AC) with posterior parietal cortex damage and posterior callosal section.

Prehension movements of the right hand were recorded in a right-handed man (AC), with an injury to the left posterior parietal cortex (PPC) and with a section of the left half of the splenium. The kinematic analysis of AC's grasping movements in direct and perturbed conditions was compared to that of five control subjects. A novel effect in prehension was revealed--a hemispace effect--in healthy controls only.

The motor theory of social cognition: a critique.

Recent advances in the cognitive neuroscience of action have considerably enlarged our understanding of human motor cognition. In particular, the activity of the mirror system, first discovered in the brain of non-human primates, provides an observer with the understanding of a perceived action by means of the motor simulation of the agent's observed movements. This discovery has raised the prospects of a motor theory of social cognition.

Neural correlates of action attribution in schizophrenia.

Patients with first-rank symptoms (FRS) of schizophrenia do not experience all of their actions and personal states as their own. FRS may be associated with an impaired ability to correctly attribute an action to its origin. In the present study, we examined regional cerebral blood flow (rCBF) with positron emission tomography during an action-attribution task in a group of patients with FRS.

[Problems in recognizing the self: a neuropsychological approach to the positive symptoms of schizophrenia].

This article present a review of recent work on cognitive neuroscience approaches of schizophrenia. Some of the symptoms displayed by schizophrenic patients can be reconsidered within the framework of disorganization of well identified cognitive functions, like self-recognition. Neuroimaging techniques can reveal in these patients disruption of neural networks normally involved in such functions.

Awareness of action in schizophrenia.

An abnormal sense of agency is among the most characteristic yet perplexing positive symptoms of schizophrenia. Schizophrenics may either attribute the consequences of their own actions to the intentions of others (delusions of influence), or may perceive themselves as causing events which they do not in fact control (megalomania). Previous reports have often described inaccurate agency judgements in schizophrenia, but have not identified the disordered neural mechanisms or psychological processes underlying these judgements.