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Neuroni specchio, azione e relazione. Il cervello che agisce come fondamenta della mente sociale
No full textMirror neurons responding to observation of actions made with tools in monkey ventral premotor cortex
No full textIn the present study, we describe a new type of visuomotor neurons, named tool-responding mirror neurons, which are found in the lateral sector of monkey ventral premotor area F5. Tool-responding mirror neurons discharge when the monkey observes actions performed by an experimenter with a tool (a stick or a pair of pliers). This response is stronger than that obtained when the monkey observes a similar action made with a biological effector (the hand or the mouth). These neurons respond also when the monkey executes actions with both the hand and the mouth. The visual and the motor responses of each neuron are congruent in that they share the same general goal, that is, taking possession of an object and modifying its state. It is hypothesized that after a relatively long visual exposure to tool actions, a visual association between the hand and the tool is created, so that the tool becomes as a kind of prolongation of the hand. We propose that tool-responding mirror neurons enable the observing monkey to extend action-understanding capacity to actions that do not strictly correspond to its motor representations. Our findings support the notion that the motor cortex plays a crucial role in understanding action goals
Neural Coding for Action Execution and Action Observation in the Prefrontal Cortex and Its Role in the Organization of Socially Driven Behavior
Full text linkThe lateral prefrontal cortex (LPF) plays a fundamental role in planning, organizing, and optimizing behavioral performance. Neuroanatomical and neurophysiological studies have suggested that in this cortical sector, information processing becomes more abstract when moving from caudal to rostral and that such processing involves parietal and premotor areas. We review studies that have shown that the LPF, in addition to its involvement in implementing rules and setting behavioral goals, activates during the execution of forelimb movements even in the absence of a learned relationship between an instruction and its associated motor output. Thus, we propose that the prefrontal cortex is involved in exploiting contextual information for planning and guiding behavioral responses, also in natural situations. Among contextual cues, those provided by others' actions are particularly relevant for social interactions. Functional studies of macaques have demonstrated that the LPF is activated by the observation of biological stimuli, in particular those related to goal-directed actions. We review these studies and discuss the idea that the prefrontal cortex codes high-order representations of observed actions rather than simple visual descriptions of them. Based on evidence that the same sector of the LPF contains both neurons coding own action goals and neurons coding others' goals, we propose that this sector is involved in the selection of own actions appropriate for reacting in a particular social context and for the creation of new action sequences in imitative learning
Grasping actions and social interaction: neural bases and anatomical circuitry in the monkey.
No full textThe study of the neural mechanisms underlying grasping actions showed that cognitive functions are deeply embedded in motor organization. In the first part of this review, we describe the anatomical structure of the motor cortex in the monkey and the cortical and sub-cortical connections of the different motor areas. In the second part, we review the neurophysiological literature showing that motor neurons are not only involved in movement execution, but also in the transformation of object physical features into motor programs appropriate to grasp them (through visuo-motor transformations). We also discuss evidence indicating that motor neurons can encode the goal of motor acts and the intention behind action execution. Then, we describe one of the mechanisms – the mirror mechanism – considered to be at the basis of action understanding and intention reading, and describe the anatomo-functional pathways through which information about the social context can reach the areas containing mirror neurons. Finally, we briefly show that a clear similarity exists between monkey and human in the organization of the motor and mirror systems. Based on monkey and human literature, we conclude that the mirror mechanism relies on a more extended network than previously thought, and possibly subserves basic social functions. We propose that this mechanism is also involved in preparing appropriate complementary response to observed actions, allowing two individuals to become attuned and cooperate in joint actions
Projections from Caudal Ventrolateral Prefrontal Areas to Brainstem Preoculomotor Structures and to Basal Ganglia and Cerebellar Oculomotor Loops in the Macaque
No full textThe caudal part of the macaque ventrolateral prefrontal (VLPF) cortex hosts several distinct areas or fields—45B, 45A, 8r, caudal 46vc, and caudal 12r—connected to the frontal eye field (area 8/FEF). To assess whether these areas/fields also display subcortical projections possibly mediating a role in controlling oculomotor behavior, we examined their descending projections, based on anterograde tracer injections in each area/field, and compared them with those of area 8/FEF. All the studied areas/fields displayed projections to brainstem preoculomotor structures, precerebellar centers, and striatal sectors that are also targets of projections originating from
area 8/FEF. Specifically, these projections involved: 1) the intermediate and superficial layers of the superior colliculus; 2) the mesencephalic and pontine reticular formation; 3) the dorsomedial and lateral pontine nuclei and the reticularis tegmenti pontis; and 4) the body of the caudate nucleus. Furthermore, area 45B projected also to the regions around the trochlear nucleus and to the raphe interpositus. The present data provide evidence for a role of the caudal VLPF areas/fields in controlling oculomotor behavior not only through their connections to area 8/FEF, but also in parallel through a direct access to preoculomotor brainstem structures and to the cerebellar and basal ganglia oculomotor loops
Connections of the macaque Granular Frontal Opercular (GrFO) area: a possible neural substrate for the contribution of limbic inputs for controlling hand and face/mouth actions
No full textProjections of the hand field of the macaque ventral premotor area F5 to the brainstem and spinal cord
No full textIn the present study we first assessed that the hand motor field of the macaque ventral premotor area F5, involved in visuomotor control of hand actions, is connected to both the hand field of the primary motor cortex (M1) and the spinal cord. We then injected retroanterograde tracers in this field to completely illustrate its possible descending motor projections. In the brainstem the F5 hand motor field projects to the intermediate and deep layers of the superior colliculus (SC) and to sectors of the mesencephalic, pontine, and bulbar reticular formation, which are the sources of spinal projections. In the spinal cord, labeled terminals were virtually all confined to the C2-T1 segments, mostly contralaterally. At C6-T1 levels the labeling was weaker and mostly clustered laterally in the intermediate zone. At C2-C5 levels, labeled terminals were much denser and diffusely distributed over the mid-dorsal part of the intermediate zone where a propriospinal system that directly controls hand muscle motoneurons and mediates commands for the control of dexterous finger movements is located (Isa et al. [2007] Physiology 22:145-152). Thus, the F5 hand motor field has a weaker direct access and a stronger indirect access to spinal segments where hand muscle motoneurons are located, suggesting a role of this field in the generation and control of hand movements not only at the M1 level, but also at the spinal cord level. These projections may represent the neural substrate for the F5 hand motor field's role in the recovery of manual dexterity after M1 lesions. J. Comp. Neurol. 518:2570-2591, 2010
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