Do chimpanzees have a theory of mind? 30 years later

Call and Tomasello offer a review in the May issue of Trends in Neuroscience on the controversial question of how much our nearest relatives understand about the minds of others:

On the 30th anniversary of Premack and Woodruff's seminal paper asking whether chimpanzees have a theory of mind, we review recent evidence that suggests in many respects they do, whereas in other respects they might not. Specifically, there is solid evidence from several different experimental paradigms that chimpanzees understand the goals and intentions of others, as well as the perception and knowledge of others. Nevertheless, despite several seemingly valid attempts, there is currently no evidence that chimpanzees understand false beliefs. Our conclusion for the moment is, thus, that chimpanzees understand others in terms of a perception–goal psychology, as opposed to a full-fledged, human-like belief–desire psychology.

Here is one description of an experimen showing that Chimpanzees infer a human's intentions:

Buttelmann et al. [Dev. Sci. 10 (2007 pp. F31–F38]...tested six human-raised chimpanzees in the so-called rational-imitation paradigm. The chimpanzees were shown how to operate an apparatus to produce an interesting result (e.g. lights or sounds), and then they were given a turn. The most natural behavior for them in all cases was to operate it with their hands. But this obvious behavior was never demonstrated for them; they always saw a human manipulate the apparatus in a novel way with some other body part. The idea was that in some cases the physical constraints of the situation dictated that the human (referred to as ‘E’ in the figure) had to use that unusual body part; for example, he had to turn on a light with his head because his hands were occupied holding a blanket or he had to operate a light with his foot because his hands were occupied with a heavy bucket (see Figure I). When the chimpanzees saw this forced use of the unusual body part, they mostly discounted it and used their hands as they normally would (because the constraints were not present for them). However, when they saw the human use the unusual body part when there was no physical constraint dictating this, they quite often copied the unusual behavioral means themselves. If we interpret this experiment the way it is interpreted for human infants, the conclusion is that the chimpanzees understood not only what the experimenter was trying to do (his goal) but also why he was doing it in the way he was doing it – the rationality behind the choice of the plan of action toward the goal. According to Tomasello et al. [Behav. Brain Sci. 28 (2005), pp. 675–691], an understanding of the action plan chosen toward a goal constitutes an understanding of the intention.

Regulating the brain circuits of compassion

Here is yet more compelling evidence that you are what you spend your time imagining. In a recent study in PLoS ONE, Lutz, Davidson and colleagues extend their previous work on correlations between brain states and meditation to show that one particular kind of Buddhist meditation, which emphasizes empathetic and loving thoughts towards others and self, changes the brain's reactivity to emotional sounds. In experienced practitioners of the 'loving-kindness-compassion' meditation technique, such images caused larger reactions in the insular and anterior cingulate cortices than were observed in novices. Here is their abstract and one figure from the paper.

Recent brain imaging studies using functional magnetic resonance imaging (fMRI) have implicated insula and anterior cingulate cortices in the empathic response to another's pain. However, virtually nothing is known about the impact of the voluntary generation of compassion on this network. To investigate these questions we assessed brain activity using fMRI while novice and expert meditation practitioners generated a loving-kindness-compassion meditation state. To probe affective reactivity, we presented emotional and neutral sounds during the meditation and comparison periods. Our main hypothesis was that the concern for others cultivated during this form of meditation enhances affective processing, in particular in response to sounds of distress, and that this response to emotional sounds is modulated by the degree of meditation training. The presentation of the emotional sounds was associated with increased pupil diameter and activation of limbic regions (insula and cingulate cortices) during meditation (versus rest). During meditation, activation in insula was greater during presentation of negative sounds than positive or neutral sounds in expert than it was in novice meditators. The strength of activation in insula was also associated with self-reported intensity of the meditation for both groups. These results support the role of the limbic circuitry in emotion sharing. The comparison between meditation vs. rest states between experts and novices also showed increased activation in amygdala, right temporo-parietal junction (TPJ), and right posterior superior temporal sulcus (pSTS) in response to all sounds, suggesting, greater detection of the emotional sounds, and enhanced mentation in response to emotional human vocalizations for experts than novices during meditation. Together these data indicate that the mental expertise to cultivate positive emotion alters the activation of circuitries previously linked to empathy and theory of mind in response to emotional stimuli.


(AI) and (Ins.) stand for anterior insula and insula, respectively (z = 12 and z = 19, 15 experts and 15 novices, color codes: orange, p less than 5.10ˆ-2, yellow, p less than 2.10ˆ-2). B, C. Impulse response from rest to compassion in response to emotional sounds in AI (B) and Ins. (C). D–E. Responses in AI (D) and Ins. (E) during poor and good blocks of compassion, as verbally reported, for 12 experts (red) and 10 novices (blue).

Neuroimaging shows use of self thoughts to infer others' mental states

Jenkins et al. offer a fascinating study of how we infer the mental states of others (mentalize), making use of a phenomenon (repetition suppression) that I had not been aware of before. Here I've done a cut/paste/edit from the abstract and article to try to outline the basic idea, and also show the central figure:

One useful strategy for inferring others' mental states (i.e., mentalizing) may be to use one's own thoughts, feelings, and desires as a proxy for those of other people (This approach to social cognition is alternately described as "simulationist," "projectionist," or "self-referential".) A dorsal aspect of the medial prefrontal cortex has been associated with mentalizing about people perceived to be dissimilar from oneself, whereas a more ventral aspect of medial prefrontal cortex (vMPFC) has been linked to mentalizing about those perceived to be similar. Critically, this vMPFC region also has been observed repeatedly during tasks that require participants to introspect about their own mental experiences, suggesting a connection between tasks that require self-referential thought and those that require inferences about the mental states of similar others.

Because such techniques integrate neural activity across hundreds of thousands of neurons, activation of the same brain voxel by different tasks might occur because each activates distinct, but neighboring or interdigitated, neuronal populations. In this way, two tasks could possibly coactivate the same brain voxel despite engaging different sets of neurons that subserve disparate cognitive processes.

This technical limit can now be circumvented by recently developed paradigms that support stronger conclusions regarding the coactivation of the same neurons by different stimuli or different tasks. These techniques rely on an effect known as "repetition suppression," the observation that neural activity in stimulus-sensitive brain regions is typically reduced when a stimulus is repeated

Suppression across two stimuli indicates that the same (or at least a largely overlapping) population of neurons is engaged by both stimuli. For example, a demonstration of repetition suppression for the number "3" when it follows "4" but not when it follows "40" might suggest that a relatively high proportion of the neurons that code for the number "3" also participate in representations of similar numerosities (such as "4"), but not in representations of more distant numerosities.

If (i) repeatedly considering one's own mental states produces repetition suppression in self-sensitive regions such as vMPFC, and (ii) one engages in self-referential processing when considering the minds of similar others, then (iii) repetition suppression also should be observed when perceivers first mentalize about a similar other and then introspect about self.

Consistent with this hypothesis this perceivers spontaneously engage in self-referential processing when mentalizing about particular individuals, vMPFC response was suppressed when self-reflections followed either an initial reflection about self or a judgment of a similar, but not a dissimilar, other. These results suggest that thinking about the mind of another person may rely importantly on reference to one's own mental characteristics.

Here is the basic figure:

Figure legend (click on figure to enlarge it). A region of vMPFC (–6, 45, 3; 47 voxels in extent) was defined from an explicit self-reference task in which judgments of one's own personality characteristics were compared with judgments of another person (i.e., self > other). On a separate task, participants completed a series of paired judgments, in which they introspected about their own preferences and opinions immediately after one of three types of judgments: (i) an initial report about self (self-after-self), (ii) a judgment of a person with the same sociopolitical attitudes as oneself (self-after-similar), or (iii) a judgment of a person with opposing attitudes (self-after-dissimilar). On an equal number of trials, participants considered the identical question for prime and self or a different question across the two phases. The bar graph depicts the BOLD response associated with these self-reports after subtracting out the response associated with the initial judgment (see Methods); values therefore represent the additional BOLD response specifically associated with subsequent judgments of self. For comparison purposes, the figure includes the response in this region to self-reports made in isolation (gray bar). Significant repetition suppression was observed for self-reports that followed either an initial self-report (blue bars) or a judgment of a similar other (red bars), but not judgments of a dissimilar other (green bars). Error bars represent the 95% confidence interval for within-subject designs.

Like many of the cognitive heuristics that typically serve us well, but periodically lead to undesirable or maladaptive behavior, the use of self-reference in mentalizing may be a double-edged sword: a useful strategy for providing rich and accurate insights into the minds of similar individuals, but rife with the potential to exclude those minds assumed at first glance to be different from our own.

Moral Neuropolitics

Gary Olson, who is Chair of the Dept. of Political Science of Maravian College in Bethlehm, PA., sent me a latest draft of his article "From Mirror Neuron to Moral Neuropolitics." It does a nice job with the literature on mirror neurons and its implications, as well as political and cultural factors that enhance and inhibit moral behaviors. Gary is willing to pass on the draft article to blog readers for further comment (web version here; PDF download here).

My main comment was that the article might - in addition to covering cultural and political factors that work against moral behaviors between groups of distant people - add more data from evolutionary and developmental biology studies that also offer some evidence for factors working against morality and compassion. There is evidence for xenophobia and aggression between groups of animals (intra-group morality and cooperation, but also inter-group aggression and warfare), well documented in Chimps (cf. Feb. 19 Killer Instincts post), and other social animals (cf. March 8 post on Hyenas). Also, experiments show that that groups of children spontaneously invent not only language, but also in-groups and out-groups (cf. July 31 post) that can become competitive.

Songbirds also have mirror neurons.

Mirror neurons in humans and other primates fire both when a given action is either performed or observed (see the 'mirror neuron' category in the left column of this blog.) Now Prather et al. have found similar neurons in the swamp sparrow, which like humans depends on auditory experience to learn its vocal repertoire. These forebrain neurons are specialized for auditory-vocal monitoring and have virtually the same response to a given note sequence, whether performed or heard. They also innervate striatal structures important for song learning, raising the possibility that singing-related activity in these cells is compared to auditory feedback to guide vocal learning. Here is a graphic from a New and Views article on this work by Tchernichovski1 & Wallman in the same issue of Nature.

(click to enlarge) Figure legend: The neurons identified by Prather and colleagues could be involved in three sensorimotor processes. a, The delayed corollary discharge of song patterns can be simultaneously compared with auditory feedback of the bird's own song, allowing tuning. b, The auditory responses (in the mirroring neurons) to songs of a neighbour might be compared with the memory of the corollary discharge produced during singing. This might allow the bird to identify an imitation by that neighbour. c, Corollary discharges while singing might be compared with a memory of the mirroring neurons' response to the parent's song. The error may then feed back to the song generator and guide vocal learning during song development, in addition to guidance from auditory input during singing (lowest arrow).

The Impressionable Brain

I want to pass on this essay by Marcel Kinsbourne, which is an interesting exegesis of the implication of mirror neuron systems in our brain, especially with respect to possibly making moot the issue of brain versus environmental effects:

When the phenomenon of "mirror neurons" that fire both when a specific action is perceived and when it is intended was first reported, I was impressed by the research but skeptical about its significance...I have come to realize that mirror neurons are not only less than meets the eye but also more. Instead of being a specific specialization, they play their role as part of a fundamental design characteristic of the brain; that is, when percepts are activated, relevant intentions, memories and feelings automatically fall into place.

That an individual is likely to act in the same ways that others act is seen in the documented benefit for sports training of watching experts perform. "Emotional contagion" occurs when someone witnesses the emotional expressions of another person and therefore experiences that mood state oneself. People's viewpoints can subtly and unconsciously converge when their patterns of neural activation match, in the total absence of argument or attempts at persuasion. When people entrain with each other in gatherings, crowds, assemblies and mobs, diverse individual views reduce into a unified group viewpoint.

People's views are surreptitiously shaped by their experiences, and rationality comes limping after, downgraded to rationalization. Once opinions are established, they engender corresponding anticipations. People actively seek those experiences that corroborate their own self-serving expectations. This may be why as we grow older, we become ever more like ourselves. Insights become consolidated and biases reinforced when one only pays attention to confirming evidence. Diverse mutually contradictory "firm convictions" are the result.

If I am correct in my changed views as to what mirror neurons stand for and how representation routinely merges perception, action, memory and affect into dynamic reciprocal interaction, these views would have a bearing on currently disputed issues. Whether an effect is due to the brain or the environment would be moot if environmental causes indeed become brain causes, as the impressionable brain resonates with changing circumstances. What we experience contributes mightily to what we are and what we become.

What people experience indeed changes their brain, for better and for worse. In turn, the changed brain changes what is experienced. Regardless of its apparent stability over time, the brain is in constant flux, and constantly remodels. Heraclitus was right: "You shall not go down twice to the same river". The river will not be the same, but for that matter, neither will you. We are never the same person twice. The past is etched into the neural network, biasing what the brain is and does in the present. William Faulkner recognized this: "The past is never dead. In fact, it's not even past".

The hidden structure of over-imitation

Human children, unlike chimpanzees, will copy unnecessary or arbitrary parts of an action sequence they observe in adults, Lyons et al. term this process overimitation and suggest in an open access article with the title of this post that it reveals a hidden structure behind how children learn to attribute causality. Here is their abstract, and a graphic showing one of the three puzzle boxes used in the experiements:

Young children are surprisingly judicious imitators, but there are also times when their reproduction of others' actions appears strikingly illogical. For example, children who observe an adult inefficiently operating a novel object frequently engage in what we term overimitation, persistently reproducing the adult's unnecessary actions. Although children readily overimitate irrelevant actions that even chimpanzees ignore, this curious effect has previously attracted little interest; it has been assumed that children overimitate not for theoretically significant reasons, but rather as a purely social exercise. In this paper, however, we challenge this view, presenting evidence that overimitation reflects a more fundamental cognitive process. We show that children who observe an adult intentionally manipulating a novel object have a strong tendency to encode all of the adult's actions as causally meaningful, implicitly revising their causal understanding of the object accordingly. This automatic causal encoding process allows children to rapidly calibrate their causal beliefs about even the most opaque physical systems, but it also carries a cost. When some of the adult's purposeful actions are unnecessary—even transparently so—children are highly prone to mis-encoding them as causally significant. The resulting distortions in children's causal beliefs are the true cause of overimitation, a fact that makes the effect remarkably resistant to extinction. Despite countervailing task demands, time pressure, and even direct warnings, children are frequently unable to avoid reproducing the adult's irrelevant actions because they have already incorporated them into their representation of the target object's causal structure.

Impairment of action chains in autism.

When we observe the start of an action sequence that can end in two possible ways (in the figure shown a piece of food is placed in the mouth or in a container on the shoulder) appropriate sympathetic muscle EMG signals are detected at the start of the sequence. Thus, if the sequence will end in food to the mouth, activity is observed in the mouth-opening mylohyoid (MH) muscle at the onset. Rizzolatti and collaborators find that typically developing children show an activation of their MH muscle already when they observe the experimenter's initial motor act, food reaching. This activation reflects their understanding of the final goal of the observed action. In children with autism this action-understanding motor activation is lacking. Further, when typically developing children actually perform the observed action, MH muscle activation is observed at the very beginning of the sequence, while in children with autism, the activation is not observed until immediately before the muscle is actually used.

Figure - Schematic representation of the tasks. (Upper) The individual reaches for a piece of food located on a touch-sensitive plate, grasps it, brings it to the mouth, and finally eats it. (Lower) The individual reaches for a piece of a paper located on the same plate, grasps it, and puts into a container placed on the shoulder.

They suggest that high-functioning autistic children may understand the intentions of others cognitively but lack the mechanism for understanding them experientially because they lack the chains of action-constrained neurons that code specific motor acts (e.g., grasping) according to the final goal of the action in which the motor act is embedded.

Plasticity and learning in the human mirror neuron system

I pass on a review by Welberg of an interesting study by Catmur et al. [Catmur, C., Walsh, V. & Heyes, C. Sensorimotor learning configures the human mirror system. Curr. Biol. 17, 1527–1531 (2007)]:

Neurons in the frontoparietal mirror system fire when one performs an action and when one observes someone else performing that same action. This system is thought to have a role in social cognition and, perhaps, in language acquisition. How the mirror neurons map sensory input onto its motor representation is unknown, but Catmur et al. demonstrate that these representations are not innate and can be altered by training.

The authors used transcranial magnetic stimulation (TMS) to stimulate the motor cortex of volunteers who were watching a video of a hand. When the volunteers watched the hand's index finger move, the TMS-induced motor-evoked potential (MEP) was greater in the abductor muscle of their own index finger than when they watched the little finger move; conversely, the MEP of their little finger's abductor muscle was greatest when they watched the little finger move. In other words, a muscle showed MEP enhancement when its owner watched a movement that is normally performed by that muscle; this 'mirror effect' is thought to reflect activity of the mirror neuron system.

Half of the volunteers then underwent incongruent training trials, in which they were asked to extend their little finger if the video showed a hand extending the index finger, and vice versa. People in congruent trials simply had to repeat the movement they saw in the video. The incongruent trials were assumed to train the mirror system to associate an observed finger movement with movement of a different finger of the volunteer's own hand.

Measuring TMS-induced MEPs after training, the authors found that volunteers who had undergone the incongruent training now showed greater MEPs in the muscle of one finger when watching the 'wrong' finger move in the video, indicating that a reversal of muscle-specific MEP enhancement during action observation had taken place.

This study shows that the 'mirror properties' of the mirror system are not innate. Rather, they can be trained, through sensorimotor experience, to transform observation into action. These findings imply that insufficient social interaction and consequent inadequate sensory experience might affect the development of the mirror neuron system, for example, in children with autism.

When watching a tactile stroke is the same as receiving one.

An interesting report from Banissy and Ward (PDF here)... People who have 'mirror-touch' synesthesia, when watching another person being touched, have the same experience as being touched themselves...an extreme form of empathy! They developed a protocol to provide evidence for the authenticity of this form of synesthesia, in which participants have difficulty in discriminating between actual and synesthetic touch. Their abstract:

Watching another person being touched activates a similar neural circuit to actual touch and, for some people with 'mirror-touch' synesthesia, can produce a felt tactile sensation on their own body. In this study, we provide evidence for the existence of this type of synesthesia and show that it correlates with heightened empathic ability. This is consistent with the notion that we empathize with others through a process of simulation.

Where the brain understands animate agents..

Wheatley et al offer an interesting study in a recent issue of Psychological Science (vol 18, pg 469, 2007, PDF here). Here is the abstract and two figures:

How people understand the actions of animate agents has been vigorously debated. This debate has centered on two hypotheses focused on anatomically distinct neural substrates: The mirror-system hypothesis proposes that the understanding of others is achieved via action simulation, and the social-network hypothesis proposes that such understanding is achieved via the integration of critical biological properties (e.g., faces, affect). In this study, we assessed the areas of the brain that were engaged when people interpreted and imagined moving shapes as animate or inanimate. Although observing and imagining the moving shapes engaged the mirror system, only activation of the social network was modulated by animacy.

Lateral and medial views of the social network (top, highlighted in yellow) and mirror system (bottom, highlighted in blue). The social network includes areas associated with biological motion (superior temporal sulcus, labeled "1"), biological form (lateral fusiform gyrus, labeled "6"), mentalizing (medial prefrontal cortex and posterior cingulate, labeled "3" and "4," respectively), and affective processing (insula and amygdala, labeled "2" and "5," respectively). The mirror system consists of the inferior parietal cortex (labeled "7") and the ventral-premotor/inferior-frontal cortex (labeled "8").


Experimental results. The brain slices in (a) depict areas of the social network that were more active when moving shapes were inferred (red) or imagined (orange) as animate than when they were inferred or imagined as inanimate. Yellow areas were more active for both animate inference and imagery ("conjunction"). The graph in (b) displays the average hemodynamic responses within the conjunction areas as a function of animacy (animate, inanimate) and condition (motion, imagery). (Results are not shown for the posterior insula, although this was also a conjunction area.) The illustration in (c) shows areas of the mirror system that were more active when subjects watched and made inferences about the moving shapes (purple) and when they imagined (dark blue) the moving shapes relative to when they viewed the backgrounds alone; light-blue areas were more active during both the motion and imagery conditions ("conjunction") than in the background condition. The graph in (d) shows the average hemodynamic responses of the conjunction mirror areas as a function of animacy and condition. For purposes of illustration, all group data are presented on the N27 (AFNI software) brain. Error bars represent standard errors. STS = superior temporal sulcus; PFC = prefrontal cortex.

Esthetic experience and mirror neurons - motion, emotion and empathy

David Freedberg (Art History, Columbia Univ.) and Vittorio Gallese (Neuroscience, Parma) offer an interesting perspective on possible relationships between mirror neuron systems and artistic experience. Here is their abstract (and PDF of article is here.), followed by some of their illustrations.

The implications of the discovery of mirroring mechanisms and embodied simulation for empathetic responses to images in general, and to works of visual art in particular, have not yet been assessed. Here, we address this issue and we challenge the primacy of cognition in responses to art. We propose that a crucial element of esthetic response consists of the activation of embodied mechanisms encompassing the simulation of actions, emotions and corporeal sensation, and that these mechanisms are universal. This basic level of reaction to images is essential to understanding the effectiveness both of everyday images and of works of art. Historical, cultural and other contextual factors do not preclude the importance of considering the neural processes that arise in the empathetic understanding of visual artworks.

Figure 1. Embodied simulation in esthetic experience: actions. The sense of exertion, which Michelangelo intended his figures to show as they struggle to escape from the block of stone, is effectively conveyed to the spectator. Michelangelo, Slave called Atlas, Florence, Academia (ca. 1520–1523), marble © Scala/Art Resource, NY.

Figure 2. Embodied simulation in esthetic experience: empathy for pain. The viewing of images of punctured or damaged body parts activates part of the same network of brain centers that are normally activated by our own sensation of pain, accounting for the feeling of physical sensation and corresponding shock upon observation of pressure or damage to the skin and limbs of others. Goya, Que hay que hacer mas? (What more is there to do?), plate 33 from Los Desastres de la Guerra (Disasters of War), etching, Biblioteque Nationale, Paris, France © Bridgeman-Giraudon/Art Resource, NY.

Figure 3. Embodied simulation in esthetic experience: implied gestures of the artist. The gestures that are only implicit in the marks on these works of art are corporeally felt by their spectators. (a) Jackson Pollock, Number 14: Gray (1948), enamel over gesso on paper, Yale University Gallery, The Katharine Ordway Collection © 2004 The Pollock-Krasner Foundation/Artists Rights Society (ARS), New York. (b) Lucio Fontana, Concetto Spaziale ‘Atteza’ (‘Waiting’) (1960), canvas, Tate Gallery, London © Tate Gallery, London/Art Resource, NY/ Fondazione Lucio Fontana, Milano.

Figure 4. The mirror neuron system in monkeys and humans. (a) Activation of the area F5 mirror neuron during motor-act observation. (b) Activation of the area F5 mirror neuron during action execution. For both conditions, six consecutive rasters (spike recordings) during six consecutive trials are shown. The arrows indicate the onset of observed and executed grasping. (a) and (b) modified, with permission, from Ref. [60]. (c) Somatotopy of premotor and parietal cortices as revealed by fMRI during action observation. Activation foci are projected on the lateral surface of a standard brain (MNI). Red, activation during the observation of mouth grasping; green, activation during the observation of hand grasping; blue, activation during the observation of foot kicking. Overlap of colors indicates activation foci present during observation of actions made by different effectors.

More on the mirror "hearing-doing" system

Here is a more extended commentary on a paper I mentioned in my Jan. 30 post "The pianist in the mirror.." D'Ausilio (PDF here) discusses this work of Lahav et al. showing an auditory mirror area in the left inferior frontal gyrus for complex and newly acquired actions. In addition to rote auditory-motor mapping for learning and online execution control, this mirror mechanism might subserve other evolutionary critical functions like action recognition, and interindividual emotional resonance. This auditory mirror-like property seems indeed to be valid for a wide range of functions that in turn elicit very different behaviors.

Neural correlates of social cognition

Vittorio Gallese writes an interesting summary in Proc. Roy. Soc. B titled "Before and below ‘theory of mind’: embodied simulation and the neural correlates of social cognition." (PDF here). His abstract:

The automatic translation of folk psychology into newly formed brain modules specifically dedicated to mind-reading and other social cognitive abilities should be carefully scrutinized. Searching for the brain location of intentions, beliefs and desires—as such—might not be the best epistemic strategy to disclose what social cognition really is. The results of neurocognitive research suggest that in the brain of primates, mirror neurons, and more generally the premotor system, play a major role in several aspects of social cognition, from action and intention understanding to language processing. This evidence is presented and discussed within the theoretical frame of an embodied simulation account of social cognition. Embodied simulation and the mirror neuron system underpinning it provide the means to share communicative intentions, meaning and reference, thus granting the parity requirements of social communication.

Integrating different theory of mind models.

Keysers and Gazzola propose a speculative model (Trends in Cognitive Sciences
Volume 11, Issue 5, May 2007, Pages 194-196. PDF here) that attempts to integrate the perspective of two polarized camps:

The simulation camp focuses on so-called shared circuits (SCs) that are involved in one's own actions, sensations and emotions and in perceiving those of others. The theory of mind (ToM) camp emphasizes the role of midline structures in mentalizing about the states of others.

Social cognitions range from the intuitive examples studied by simulationists to the reflective ones used by ToM investigators. Witnessing someone drink a glass of milk with a face contracting in an expression of disgust is an example at the intuitive extreme of this continuum. In such cases, premotor and parietal areas for actions, the insula for emotions and and SII for sensations form SCs that translate the bodily states of others into the neural language of our own states. These SCs seem to implement a pre-reflective, intuitive and empathic level of representation: neural activity in these areas does not require specific instructions that encourage conscious reflections.

Thinking about what gift would please a foreign colleague is an example at the more reflective extreme. In such cases, we must browse consciously through what we know about his country and culture to deduce what he might like. Such explicit knowledge about the inner life of others is the product of reflecting upon the states of others and is linked with activity in midline structures and the temporoparietal junction. False beliefs are prototypical examples of such reflective representations.

They suggest a working hypothesis:

While dealing with states of the self, areas of the SCs represent pre-reflective bodily states. If asked to introspect and report these states, subjects additionally activate (v)mPFC structures. When dealing with states of other individuals, activity in SCs might represent the empathic transformation of the bodily states of others into pre-reflective neural representations of similar states of the self. These simulated pre-reflective representations correlate with empathy and might provide an intuitive understanding of what goes on in others. If asked to reflect on the states of others, the pathways that are normally used to reflect on the bodily representations of the self are now used on simulated bodily states of others, leading to simulated reflective representations. Thus, SCs and midline structures form an integrated system that applies to cases where we perceive the other as similar enough for simulation to be useful. In this view, both SCs and vmPFC reflect simulation, albeit at different levels (pre-reflective versus reflective), rather than radically different processes (SC versus ToM).

Illustration of the model (click to enlarge). The self is shown in red, the other is shown in green and candidate brain areas that are thought to implement representation are shown in blue. During our own experiences, pre-reflective representations can lead, through introspection, to reflective representations (red). While witnessing the states of others, mirroring leads to activations that simulate pre-reflective representations of our own bodily states. A process of social introspection, utilizing the mechanisms of introspection, activates representations that simulate reflective representations of our own bodily states. A more cognitive route leads to more abstract knowledge about the other that escapes from the constraints of our own experiences.

The Myth of Mirror Neurons?

In an article in a special issue of Slate devoted to the brain (well worth checking over...I'll give some links to articles in the Slate issue in subsequent posts), Gopnik argues that excitement over the discovery of mirror neurons in our brains (the subject of a number of blog posts and my lecture posted earlier...) is generating a new scientific myth. Like a traditional myth, it captures intuitions about the human condition through vivid metaphors. Some clips:

It didn't take long for scientists and science writers to speculate that mirror neurons might serve as the physiological basis for a wide range of social behaviors, from altruism to art appreciation. Headlines like "Cells That Read Minds" or "How Brain's 'Mirrors' Aid Our Social Understanding" tapped into our intuitions about connectedness. Maybe this cell, with its mellifluous name, gives us our special capacity to understand one another—to care, to learn, and to communicate. Could mirror neurons be responsible for human language, culture, empathy, and morality?.

The evidence for individual mirror neurons comes entirely from studies of macaque monkeys. That's because you can't find these cells without inserting electrodes directly (though painlessly) into individual neurons in the brains of living animals. These studies haven't been done with chimpanzees, let alone humans.

The trouble is that macaque monkeys don't have language, they don't have culture, and they don't understand other animals' minds. In fact, careful experiments show that they don't even systematically imitate the actions of other monkeys—and they certainly don't imitate in the prolific way that the youngest human children do. Even chimpanzees, who are much more cognitively sophisticated than macaques, show only very limited abilities in these areas. The fact that macaques have mirror neurons means that these cells can't by themselves explain our social behavior.

Motor cortex for the hand and numerical counting

The April 2007 issue of the Journal of Cognitive Neuroscience has interesting articles on this topic by Andres et al. and Sato et al. Their abstracts:

Andres et al.

The finding that number processing activates a cortical network partly overlapping that recruited for hand movements has renewed interest in the relationship between number and finger representations. Further evidence about a possible link between fingers and numbers comes from developmental studies showing that finger movements play a crucial role in learning counting. However, increased activity in hand motor circuits during counting may unveil unspecific processes, such as shifting attention, reciting number names, or matching items with a number name. To address this issue, we used transcranial magnetic stimulation to measure changes in corticospinal (CS) excitability during a counting task performed silently and using either numbers or letters of the alphabet to enumerate items. We found an increased CS excitability of hand muscles during the counting task, irrespective of the use of numbers or letters, whereas it was unchanged in arm and foot muscles. Control tasks allowed us to rule out a possible influence of attention allocation or covert speech on CS excitability increase of hand muscles during counting. The present results support a specific involvement of hand motor circuits in counting because no CS changes were found in arm and foot muscles during the same task. However, the contribution of hand motor areas is not exclusively related to number processing because an increase in CS excitability was also found when letters were used to enumerate items. This finding suggests that hand motor circuits are involved whenever items have to be put in correspondence with the elements of any ordered series.

Sato et al.

Developmental and cross-cultural studies show that finger counting represents one of the basic number learning strategies. However, despite the ubiquity of such an embodied strategy, the issue of whether there is a neural link between numbers and fingers in adult, literate individuals remains debated. Here, we used transcranial magnetic stimulation to study changes of excitability of hand muscles of individuals performing a visual parity judgment task, a task not requiring counting, on Arabic numerals from 1 to 9. Although no modulation was observed for the left hand muscles, an increase in amplitude of motor-evoked potentials was found for the right hand muscles. This increase was specific for smaller numbers (1 to 4) as compared to larger numbers (6 to 9). These findings indicate a close relationship between hand/finger and numerical representations.

Self and social cognition in the brain

Uddin et al. speculate in Trends in Cognitive Science (Volume 11, Issue 4 , April 2007, Pages 153-157) about the respective roles of cortical midline structures (CMS) and frontoparietal mirror neurons (MNS) in evaluation of self and others. Below I relay one of their summary paragraphs, and the PDF which contains images of relevant brain regions can be obtained HERE.

It has recently been proposed that internally oriented processes that focus on one's own or others’ mental states rely on cortical midline structures, whereas externally focused processes based on one's own or others’ visible features and actions rely on lateral frontoparietal networks. We suggest here a similar distinction, which might further reconcile disparate findings with regard to the various proposed functions of cortical midline structures, while incorporating what is known about the role of the human mirror-neuron system in social cognition. Whereas there is mounting evidence that the right frontoparietal system is involved in representing the physical, embodied self (in addition to its role in understanding the actions of others), the cortical midline structures that comprise the default-mode network seem to be more involved in maintaining a self-representation in evaluative terms, which requires self-referential processing and understanding of others’ mental states. We speculate that the CMS might support evaluative simulation in the same way that the MNS supports motor simulation. This distinction serves as a practical division of labor between two networks that are specialized for two related processes that are crucial to navigating the social world. The mirror-neuron system provides the essential physical other-to-self mapping that is necessary for comprehending physical actions of intentional agents, whereas cortical midline structures maintain and support processes that are related to understanding complex psychological aspects of others, such as attitudes, perhaps by simulation of one's own attitudes.

Mirror Neurons - gee whiz popular video

A engaging and easy to watch popularized version of material I've written about earlier (see 1/20/07; 12/19/06; and my lecture 10/27/06)).

Neuroscience will change society

Interesting reflections by Marco Iacoboni, one of the discoverers of mirror neurons, which have been mentioned a number of times in this blog:

"...a concept that emerges from recent neuroscience research is that humans are "wired for empathy". We have cells in our brains that make us understand each other in a simple, unmediated, automatic manner. But, if our neurobiology makes us wired for empathy, why is our world so full of atrocities?

The explanation for this apparent paradox is probably as follows. The neurobiological mechanisms that make us wired for empathy work at a pre-reflective, automatic, implicit level. Our societies are built on deliberate, reflective, explicit discourse. The two different levels of implicit and explicit mental processes rarely intersect; indeed there is evidence that they can often dissociate. This is probably why the massive belief systems—from religious to political ones—that operate at the deliberate, reflective level are able to divide us in such a powerful way even though our neurobiology should bring us together.

The good news is that the awareness of neurobiological mechanisms that make us wired for empathy is entering the public discourse.... This awareness won't go away and will seep through the reflective level of our mental processes. Indeed, people seem to have an intuitive understanding of how neural mechanisms for empathy work. It seems that people 'recognize' how their brain works, when they are told about it. People can finally articulate what they already 'knew' at a pre-reflective level. My optimism is that this explicit level of understanding of our empathic nature will at some point dissolve the massive belief systems that dominate our societies and that threaten to destroy us."