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V Gallese

Publications and source records attributed to V Gallese.

At least 19 recordsLinked to original sources
PubMed2005

Listening to action-related sentences modulates the activity of the motor system: a combined TMS and behavioral study.

Transcranial magnetic stimulation (TMS) and a behavioral paradigm were used to assess whether listening to action-related sentences modulates the activity of the motor system. By means of single-pulse TMS, either the hand or the foot/leg motor area in the left hemisphere was stimulated in distinct experimental sessions, while participants were listening to sentences expressing hand and foot actions. Listening to abstract content sentences served as a control. Motor evoked potentials (MEPs) were recorded from hand and foot muscles. Results showed that MEPs recorded from hand muscles were specifically modulated by listening to hand-action-related sentences, as were MEPs recorded from foot muscles by listening to foot-action-related sentences. This modulation consisted of an amplitude decrease of the recorded MEPs. In the behavioral task, participants had to respond with the hand or the foot while listening to actions expressing hand and foot actions, as compared to abstract sentences. Coherently with the results obtained with TMS, when the response was given with the hand, reaction times were slower during listening to hand-action-related sentences, while when the response was given with the foot, reaction times were slower during listening to foot-action-related sentences. The present data show that processing verbally presented actions activates different sectors of the motor system, depending on the effector used in the listened-to action.

Adult↗
PubMed2003

Audiovisual mirror neurons and action recognition.

Many object-related actions can be recognized both by their sound and by their vision. Here we describe a population of neurons in the ventral premotor cortex of the monkey that discharge both when the animal performs a specific action and when it hears or sees the same action performed by another individual. These 'audiovisual mirror neurons' therefore represent actions independently of whether these actions are performed, heard or seen. The magnitude of auditory and visual responses did not differ significantly in half the neurons. A neurometric analysis revealed that based on the response of these neurons, two actions could be discriminated with 97% accuracy.

Acoustic Stimulation↗
PubMed2001

I know what you are doing. a neurophysiological study.

In the ventral premotor cortex of the macaque monkey, there are neurons that discharge both during the execution of hand actions and during the observation of the same actions made by others (mirror neurons). In the present study, we show that a subset of mirror neurons becomes active during action presentation and also when the final part of the action, crucial in triggering the response in full vision, is hidden and can therefore only be inferred. This implies that the motor representation of an action performed by others can be internally generated in the observer's premotor cortex, even when a visual description of the action is lacking. The present findings support the hypothesis that mirror neuron activation could be at the basis of action recognition.

Animals↗
PubMed2001

Cortical mechanism for the visual guidance of hand grasping movements in the monkey: A reversible inactivation study.

Picking up an object requires two basic motor operations: reaching and grasping. Neurophysiological studies in monkeys have suggested that the visuomotor transformations necessary for these two operations are carried out by separate parietofrontal circuits and that, for grasping, a key role is played by a specific sector of the ventral premotor cortex: area F5. The aim of the present study was to test the validity of this hypothesis by reversibly inactivating area F5 in monkeys trained to grasp objects of different shape, size and orientation. In separate sessions, the hand field of the primary motor cortex (area F1 or area 4) was also reversibly inactivated. The results showed that after inactivation of area F5 buried in the bank of the arcuate sulcus (the F5 sector where visuomotor neurones responding to object presentation are located), the hand shaping preceding grasping was markedly impaired and the hand posture was not appropriate for the object size and shape. The monkeys were eventually able to grasp the objects, but only after a series of corrections made under tactile control. With small inactivations the deficits concerned the contralesional hand, with larger inactivations the ipsilateral hand as well. In addition, there were signs of peripersonal neglect in the hemispace contralateral to the inactivation site. Following inactivation of area F5 lying on the cortical convexity (the F5 sector where visuomotor neurones responding to action observation, 'mirror neurones', are found) only a motor slowing was observed, the hand shaping being preserved. The inactivation of the hand field of area F1 produced a severe paralysis of contralateral finger movements with hypotonia. The results of this study indicate the crucial role of the ventral premotor cortex in visuomotor transformations for grasping movements. More generally, they provide strong support for the notion that distal and proximal movement organization relies upon distinct cortical circuits. Clinical data on distal movement deficits in humans are re-examined in the light of the present findings.

Animals↗
PubMed2001

Action observation activates premotor and parietal areas in a somatotopic manner: an fMRI study.

Functional magnetic resonance imaging (fMRI) was used to localize brain areas that were active during the observation of actions made by another individual. Object- and non-object-related actions made with different effectors (mouth, hand and foot) were presented. Observation of both object- and non-object-related actions determined a somatotopically organized activation of premotor cortex. The somatotopic pattern was similar to that of the classical motor cortex homunculus. During the observation of object-related actions, an activation, also somatotopically organized, was additionally found in the posterior parietal lobe. Thus, when individuals observe an action, an internal replica of that action is automatically generated in their premotor cortex. In the case of object-related actions, a further object-related analysis is performed in the parietal lobe, as if the subjects were indeed using those objects. These results bring the previous concept of an action observation/execution matching system (mirror system) into a broader perspective: this system is not restricted to the ventral premotor cortex, but involves several somatotopically organized motor circuits.

Adult↗
PubMed2000

The ability to follow eye gaze and its emergence during development in macaque monkeys.

The ability of monkeys to follow the gaze of other individuals is a matter of debate in many behavioral studies. Physiological studies have shown that in monkeys, as in humans, there are neural correlates of eye direction detection. There is little evidence at the behavioral level, however, of the presence and development of such abilities in monkeys. The aim of the present study was to assess in juveniles and adult pig-tailed macaques (Macaca nemestrina) the capacity to use eye cues only to follow the gaze of an experimenter. Biological stimuli (head, eye, and trunk movements) were presented by an experimenter to 2 adult monkeys with their heads restrained (Experiment 1) and to 11 monkeys of different ages, free to move in their home cages (Experiment 2). A nonbiological stimulus served as a control. Results showed that macaques can follow the gaze of the experimenter by using head/eye and eye cues alone. Trunk movements and nonbiological stimuli did not significantly elicit similar reactions. Juvenile monkeys were not able to orient their attention on the basis of eye cues alone. In general, gaze following was more frequent in adults than in juveniles. Like in humans, however, such abilities in macaques dramatically improve with age suggesting that the transition to adulthood is a crucial period in the development of gaze-following behavior.

Animals↗
PubMed2000

Visuomotor neurons: ambiguity of the discharge or 'motor' perception?

The cortical motor system has been classically considered as the unitary, output stage of the brain processing of sensory information. According to this idea, the motor cortex - the acting brain - receives the result of the perceptual processing (visual, acoustical, tactile, etc.) elaborated by the 'associative cortex'. During the last two decades this perspective has been challenged by a series of anatomical, hodological, and neurophysiological data. This converging evidence delineates a dramatically changed picture. Far from being unitary, the cortical motor system appears to be constituted by a constellation of distinct areas, each of those endowed with specific functional properties and linked by reciprocal connections with distinct sectors of the parietal cortex. Furthermore, several 'motor' neurons in addition to their motor discharge, are also activated by somatosensory and visual stimulation (somatomotor and visuomotor neurons). In the present paper we will discuss the functional properties of those sensorimotor neurons located in the ventral part of the monkey premotor cortex. On the basis of electrophysiological data, we will propose that the apparent parodox stemming from the coexistence within the same neuron of motor and sensory properties can be solved by postulating that the motor system not only executes actions but also internally represents them in terms of 'motor ideas'. These motor ideas may provide the neurobiological basis for space representation, understanding of actions made by others and, possibly, semantic categorization of objects.

Animals↗
PubMed2000

Reply to Schulkin.

Explore the source record for details and available documents.

Journal Article↗
PubMed2000

Selectivity for the shape, size, and orientation of objects for grasping in neurons of monkey parietal area AIP.

In this study, we mainly investigated the visual selectivity of hand-manipulation-related neurons in the anterior intraparietal area (area AIP) while the animal was grasping or fixating on three-dimensional (3D) objects of different geometric shapes, sizes, and orientations. We studied the activity of 132 task-related neurons during the hand-manipulation tasks in the light and in the dark, as well as during object fixation. Seventy-seven percent (101/132) of the hand-manipulation-related neurons were visually responsive, showing either lesser activity during manipulation in the dark than during that in the light (visual-motor neurons) or no activation in the dark (visual-dominant neurons). Of these visually responsive neurons, more than half (n = 66) responded during the object-fixation task (object-type). Among these, 55 were tested for their shape selectivity during the object-fixation task, and many (n = 25) were highly selective, preferring one particular shape of the six different shapes presented (ring, cube, cylinder, cone, sphere, and square plate). For 28 moderately selective object-type neurons, we performed multidimensional scaling (MDS) to examine how the neurons encode the similarity of objects. The results suggest that some moderately selective neurons responded preferentially to common geometric features shared by similar objects (flat, round, elongated, etc.). Moderately selective nonobject-type visually responsive neurons, which did not respond during object fixation, were found by MDS to be more closely related to the handgrip than to the object shape. We found a similar selectivity for handgrip in motor-dominant neurons that did not show any visual response. With regard to the size of the objects, 16 of 26 object-type neurons tested were selective for both size and shape, whereas 9 object-type neurons were selective for shape but not for size. Seven of 12 nonobject-type and all (8/8) of the motor-dominant neurons examined were selective for size, and almost all of them were also selective for objects. Many hand-manipulation-related neurons that preferred the plate and/or ring were selective for the orientation of the objects (17/20). These results suggest that the visual responses of object-type neurons represent the shape, size, and/or orientation of 3D objects, whereas those of the nonobject-type neurons probably represent the shape of the handgrip, grip size, or hand-orientation. The activity of motor-dominant neurons was also, in part, likely to represent these parameters of hand movement. This suggests that the dorsal visual pathway is concerned with the aspect of form, orientation, and/or size perception that is relevant for the visual control of movements.

Animals↗
PubMed1999

Visual responses in the dorsal premotor area F2 of the macaque monkey.

This study aimed to determine the presence of neurons responding to visual stimuli in area F2 of the dorsal premotor cortex of the macaque monkey. In order to delimit the sector in which visually responsive neurons are located, the somatotopic organization of area F2 was studied with intracortical microstimulation and single neuron recording. The results showed that: (1) in area F2 there is a significant percentage of visually responsive neurons (15.9% of all recorded neurons); (2) area F2 is excitable with a low-threshold current (average 28.1 microA) and has a somatotopic representation of the whole body, except the face; and (3) most visually driven neurons (n=130 out of 169) are concentrated within the rostrolateral sector of the forelimb representation of area F2, thus providing for the first time functional support for the neuroanatomical evidence that the visual input to area F2 is mostly restricted to this sector.

Animals↗
PubMed1999

Corticospinal excitability is specifically modulated by motor imagery: a magnetic stimulation study.

Transcranial magnetic stimulation (TMS) was used to investigate whether the excitability of the corticospinal system is selectively affected by motor imagery. To this purpose, we performed two experiments. In the first one we recorded motor evoked potentials from right hand and arm muscles during mental simulation of flexion/extension movements of both distal and proximal joints. In the second experiment we applied magnetic stimulation to the right and the left motor cortex of subjects while they were imagining opening or closing their right or their left hand. Motor evoked potentials (MEPs) were recorded from a hand muscle contralateral to the stimulated cortex. The results demonstrated that the excitability pattern during motor imagery dynamically mimics that occurring during movement execution. In addition, while magnetic stimulation of the left motor cortex revealed increased corticospinal excitability when subjects imagined ipsilateral as well as contralateral hand movements, the stimulation of the right motor cortex revealed a facilitatory effect induced by imagery of contralateral hand movements only. In conclusion, motor imagery is a high level process, which, however, manifests itself in the activation of those same cortical circuits that are normally involved in movement execution.

Adult↗
PubMed1999

Resonance behaviors and mirror neurons.

This article is subdivided into two parts. In the first part we review the properties of a particular class of premotor neurons, the "mirror" neurons. With this term we define neurons that discharge both when the monkey makes a particular action and when it observes another individual (monkey or human) making a similar action. The second part is an attempt to give a neurophysiological account of the mechanisms underlying behaviors where an individual reproduces, overtly or internally, movements or actions made by another individual. We will refer to these behaviors as "resonance behaviors". We distinguish two types of resonance behavior. The first type is characterized by imitation, immediate or with delay, of movements made by other individuals. Examples of resonance behavior of this type are the "imitative" behaviors observed in birds, young infants and patients with frontal lesions. The second type of resonance behavior is characterized by the occurrence, at the observation of an action, of a neural pattern, which, when internally generated, determines the making of the observed action. In this type of resonance behavior the observed action is, typically, not repeated (overtly). We argue that resonance behavior of the second type is at the basis of the understanding of actions made by others. At the end of the article we review evidence of mirror mechanisms in humans and discuss their anatomical localizations.

Animals↗
PubMed1997

Parietal cortex: from sight to action.

Recent findings have altered radically our thinking about the functional role of the parietal cortex. According to this view, the parietal lobe consists of a multiplicity of areas with specific connections to the frontal lobe. These areas, together with the frontal areas to which they are connected, mediate distinct sensorimotor transformations related to the control of hand, arm, eye or head movements. Space perception is not unitary, but derives from the joint activity of the fronto-parietal circuits that control actions requiring space computation.

Animals↗
PubMed1997

Object representation in the ventral premotor cortex (area F5) of the monkey.

Visual and motor properties of single neurons of monkey ventral premotor cortex (area F5) were studied in a behavioral paradigm consisting of four conditions: object grasping in light, object grasping in dark, object fixation, and fixation of a spot of light. The employed objects were six different three-dimensional (3-D) geometric solids. Two main types of neurons were distinguished: motor neurons (n = 25) and visuomotor neurons (n = 24). Motor neurons discharged in association with grasping movements. Most of them (n = 17) discharged selectively during a particular type of grip. Different objects, if grasped in similar way, determined similar neuronal motor responses. Visuomotor neurons also discharged during active movements, but, in addition, they fired also in response to the presentation of 3-D objects. The majority of visuomotor neurons (n = 16) showed selectivity for one or few objects. The response was present both in object grasping in light and in object fixation conditions. Visuomotor neurons that selectively discharged to the presentation of a given object discharged also selectively during grasping of that object. In conclusion, object shape is coded in F5 even when a response to that object is not required. The possible visual or motor nature of this object coding is discussed.

Animals↗
PubMed1996

Premotor cortex and the recognition of motor actions.

In area F5 of the monkey premotor cortex there are neurons that discharge both when the monkey performs an action and when he observes a similar action made by another monkey or by the experimenter. We report here some of the properties of these 'mirror' neurons and we propose that their activity 'represents' the observed action. We posit, then, that this motor representation is at the basis of the understanding of motor events. Finally, on the basis of some recent data showing that, in man, the observation of motor actions activate the posterior part of inferior frontal gyrus, we suggest that the development of the lateral verbal communication system in man derives from a more ancient communication system based on recognition of hand and face gestures.

Animals↗