Imitation, Language, and Empathy--论文代写范文精选

当有成千的同行评议的成像研究,一系列的实验调查报告模仿的神经基础,然而,最近发表的内容，这一趋势似乎源于两个原因。首先,有一个最近的趋势在神经影像现象,第二,1990年代早期神经模型提供了良好的功能。下面的paper代写范文进行详述。

Introduction 
The study of the neural basis of imitation is in its first stage. Until a few years ago, the only available information on the neural underpinnings of imitative behavior was restricted to lesion data from neurological patients. Although extremely valuable, the information obtained from neurological observations is limited, mostly because the lesions causing the imitative deficits are naturally occurring ones and do not have the precise anatomical boundaries that allow a detailed study of the brain–behavior relationship. Two main factors have limited the neuroscience of imitation. First, there is little consensus on a definition of imitation (R. Byrne & Russon, 1998; Heyes, 2002). This lack of consensus has reduced the enthusiasm of neuroscientists for investigating the neural basis of imitative behavior. 

Second, even though some neuroimaging techniques have been around for about a quarter of a century, brain mappers initially had the tendency to stay away from complex phenomena, and imitation has been definitely perceived by them as a complex phenomenon. These two factors have led to the paradoxical situation of the late 1990s, when there were tens of peer-reviewed imaging studies on, say, saccades, and not even one on imitation! A series of reports on experiments investigating the neural basis of imitation, however, has been published recently (see, for instance, Decety and Chaminade, vol. 1, ch. 4). This trend seems to result from two main causes. First, there is a recent tendency in the neuroimaging world to study complex phenomena, such as theory of mind (C. Frith & Frith, 1999) or even ‘‘social’’-like interactions (Montague et al., 2002; Rilling et al., 2002). Second, macaque single-cell observations published in the early 1990s have provided good neuronal models of functional properties that are relevant to imitation (di Pellegrino et al., 1992; Gallese et al., 1996). 

This is particularly important because the mainstream imaging techniques generally rely onindirect measures of neuronal activity, such as blood flow. The existence of neurophysiological data that can help constrain the interpretation of the imaging data is generally considered extremely valuable. In this chapter I summarize the most meaningful data obtained so far on the neural underpinnings of imitation. The plan is to relate these findings to a neural and functional model of imitation and its relations with two other functional domains, language and empathy. The approach I use here envisions brain mapping techniques as investigative techniques with explanatory power. 

Typically, brain mapping is perceived as some kind of sophisticated phrenology. Detailed aspects of cognitive functions are mapped onto precise neural structures. Obviously, the map obtained looks a lot more sophisticated than the phrenological maps of the nineteenth century. However, the explanatory power of this approach remains limited with regard to testing models. What I advocate here is an approach that combines imaging data with functional information obtained from single-cell observations. With this approach, it is possible to test information-processing models of imitation and its relations with other domains.

An Action Recognition System in the Macaque Brain 
Two European laboratories, David Perrett’s and Giacomo Rizzolatti’s, have systematically studied the properties of temporal, parietal, and frontal neural systems of the macaque brain that seem relevant to action representation and potentially to imitation. Following the leads that resulted from the studies of Charles Gross on the complex visual properties of inferior temporal neurons, Perrett and his collaborators have studied neurons in the superior temporal sulcus (STS) that respond to moving biological stimuli, such as hands, faces, and bodies (Perrett et al., 1989, 1990a; Perrett & Emery, 1994). These neurons seem to respond to moving bodies and body parts only when the body or body part is engaged in goal-oriented actions. For instance, some of these neurons respond to the sight of a hand reaching and grasping an object. The same neuron will not fire at the sight of the hand reaching toward the object but not grasping it. The modulation of activity in STS neurons is independent of low-level visual features. In fact, a point-light version of the same action, that is, a hand reaching and grasping an object, is enough to activate a neuronal response in these STS cells ( Jellema et al., 2002). In other words, what these STS neurons code is the sight of a meaningful interaction between an object and an intentional agent.

The properties of STS neurons are limited exclusively, at least so far, to the visual domain, in that no neuronal responses in STS seem associated with motor behavior. In contrast, Giacomo Rizzolatti and his collaborators have described frontal and parietal neurons with motor properties (in that they are active when a monkey performs a movement) that also have visual responses similar to the ones observed in STS by Perrett (di Pellegrino et al., 1992; Gallese et al., 1996). These neurons have been described for the first time in a region of the inferior frontal cortex called area F5, according to an anatomical nomenclature that is becoming increasingly used (Matelli et al., 1985). In area F5 there exist two types of neurons with identical motor properties and quite different visual properties. 

The two types of neurons are called canonical and mirror. Both types fire when a monkey executes goal-directed actions, such as grasping, holding, tearing, and manipulating. Some of these neurons fire for a precision grip, as when a monkey grasps small objects like a raisin, and some other neurons fire for a whole-hand grasp, as when a monkey grasps larger objects, such as an apple. When it comes to their visual properties, canonical neurons that fire when a monkey grasps a small object with a precision grip also respond to the sight of small objects that can be grasped with a precision grip, but not to the sight of larger objects graspable with, say, a whole-hand grip. Note that these visual responses also occur when a monkey does not reach and grasp the object; the simple sight of the object is sufficient to activate canonical neurons. In other words, canonical neurons seem to be coding the affordance of an object, the pragmatic aspect of how to grab it, rather than its semantic content. 

In contrast, mirror neurons do not fire at the sight of an object, but will fire at the sight of a whole action. So, say that there is a neuron in F5 that fires when a monkey grasps an object. That same neuron, if it is a mirror neuron, will fire at the sight of another individual grasping an object, but will not fire at the sight of the object alone and will not fire at the sight of a pantomime of a grasp in the absence of the object. In other words, these neurons seem to be matching the execution and the observation of an action. The functional properties of these neurons suggest that they may implement a simple, noninferential mechanism of action recognition based on neural identity. This mechanism may be a building block for imitative behavior. A posterior parietal area of the macaque, area PF, situated in the rostral sector of the inferior parietal lobule, contains mirror neurons with functional properties that are substantially identical to the ones described in F5 (Rizzolatti et al., 2001). Area PF and area F5 are anatomically connectedwith robust projections (Rizzolatti et al., 1998). This pattern of corticocortical connectivity leads us to believe that F5 and PF belong to an integrated circuit for action recognition. Furthermore, STS, the region where Perrett has discovered the neurons with the complex visual properties described earlier, is connected with the posterior parietal cortex (Seltzer & Pandya, 1994). Thus these three cortical regions of the macaque brain, STS in the superior temporal cortex, area F5 in the inferior frontal cortex, and area PF in the posterior parietal cortex, seem to have functional properties and connectivity patterns that may instantiate a whole circuit for coding actions. The question that I address in the next section is whether there is a similar circuit for recognition of actions and possibly imitation in the human brain.(paper代写)

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