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Theory of mind and mirror neurons; Theory and studies
“To have a theory of mind is to be able to explain and predict human behaviors in terms of mental states: beliefs, desires, goals, thoughts and feelings” (R. Saxe, 2000).
This paper’s goal is to offer a comprehensive view on the theory of mind and it’s mechanisms, by answering the following questions:
What is a theory of mind? What mechanisms are at work in a healthy adult’s mind that allow him to reason about the workings of his own mind and the mind of others?
How is the theory of mind developing; how and when do children become capable of psychological reasoning?
What are the implications of the theory of mind in explaining and anticipating certain behaviors?
What are the physical mechanisms of the brain that come to support the theory of mind?
Short introduction
We humans tend to think that we are the most social of all animals and our social lives are the most fascinating (Frith & Frith, 2010). In spite of the ubiquity of affirmations like this, the scientific and biological basis for them is a novel thing. The use of neuroimaging and computational models has given weight to speculations about the evolution of social behavior and culture in human societies (Frith & Frith, 2010). Yes, there have been social psychologists and neurobiologists for a long time, but the combination of these two sciences is quite recent; this type of research
emerged from comparative studies, thus the term “social brain” that, in turn gave birth to two new theories that try to explain our social behavior from a cognitive and a neural point of view: the theory of mind and the “mirror system”.
The theory of mind or “mentalizing” is what enables us to perceive others as intentional agents and to predict or interpret what the future actions or the rational processes of others, on the basis of their desires and beliefs (Frith & Frith, 2010); while the mirror system enables us to empathize with others’ emotions and understand their goals or intentions through a mechanism of motor resonance (Frith & Frith, 2010).
In this paper, I wish to present a comprehensive description of the theory of mind and the mirror system, from a theoretical and an empirical point of view. I will also expose the conclusions and theories that were postulated after the theory of mind studies in people with brain lesions of neuropsychological or neurodevelopmental disorders, such as autism or Asperger’s syndrome.
Theory of mind: history and perspectives
The term “theory of mind” was first used by D. Premack and G. Woodruff in 1978, in the paper “Does the chimpanzee have a theory of mind?” Their study at that time was speculating about the possibility of the chimpanzee of possessing a theory of mind similar to that of humans. Not only do they present the theory of mind as a given fact, but argue its place as a theory, reaching the following conclusions: “a system of inferences of this kind is properly viewed as a theory because, first, such states are not directly observable and second, because the system can be used to make predictions about the behavior of other organisms”. The definition of theory of mind offered by them is highly resembling to the current one: by saying that an individual has a theory of mind, means that he imputes mental states similar to himself and to others (conspecifics or not). (Premack & Woodruff, 1978).
The means by which they tested the hypothesis was different than the ones approached before in the studies with non-‐humans; instead asking the chimpanzee to perform a series of tasks and recording the way in which it approaches the problem, a new experimental design is created, in which a human experimentator confronting inaccessible food or facing different problems is shown and the chimpanzee is being required to indicate a solution for the experimentator. The desired conclusion to their experiments is that the chimpanzee solves the given problems by imputing states of mind to the human experimentator; the chimpanzee would, thusly, be making sense of what he is seeing by assuming that the human wants the food and is struggling to reach it. They also assume that the chimpanzee believes that the experimentator knows how to reach the food – this being the reason for which, when shown pictures for different means of attaining the food, he chooses correctly in three out of four times. The tests are increasingly difficult, ranging from matching the problem with the solution picture, to choosing the correct picture from four alternatives for each task. The alternative of empathy is also presented -‐where the chimpanzee mentally puts himself in the place of the struggling experimentator and chooses the action he would perform, were he in the place of the experimentator. These two views, the theory of mind or empathy alternative, are , in fact, partly identical, with the empathic view only diverging in the
aspect of not granting the chimpanzee any inferences about somebody else’s knowledge – it is a theory of mind restricted to purpose (Premack & Woodruff, 1978).
It still remains controversial, though, whether non-‐human primates (Tomasello, 2003) engage in mentalizing, as proved in, for example, deliberate deception.
When it comes to the ways in which the theory of mind is most often tested, the task of “false belief”( Wimmer & Perner, 1983) comes to mind. A standard version of this test is the “object transfer” problem, in which a young child is to watch a certain object being moved without someone else’s knowledge. In order to have a correct prediction of explanation of the character’s subsequent actions, the child must also pay attention to the character’s belief, not only to the actual location of the hidden object (Dennet, 1978). During the task the children must make use of their general cognitive abilities: perceptual and linguistic representations of the story, working memory – in order to be able to follow all the stages of the story and motor representations of their own responses. There is a question though, which leaves method, though widely used, still controversial: is there a special separate mechanism, dedicated entirely for reasoning
about beliefs and desires, other than the general ones? This question creates two opposing points of view: one that supports the idea of a special, separate mechanism to be used in imputing the mental states and beliefs of others, and another one, that attributes this skill to the general cognitive skills.
Usually the children’s results on false belief tasks closely resemble the results they have on logically equivalent problems that present non-‐mental false problems. Therefore, the developed capacity might not be a specific one, but a capacity for meta-‐representation. The clearest evidence on this case comes from the studies on autism – children with autism show consistent delays or deficits in passing false belief tests; this result supports the “special mechanism” theory (Cohen et al., 2000). The detailed description of the studies of the theory of mind in autistic children will be presented later on in the paper, in a chapter meant to deal exclusively with the way in which the social brain is affected in patients suffering from autism, Asperger’s syndrome or brain lesions (medial prefrontal cortex). Supporting the general cognitive approach are Stone and Gerrans (2007), who conclude that other than the domain-‐general mechanisms used in the false belief task (meta-‐representation and inhibitory control), there is no need for an additional domain-‐specific mechanism for the attribution of belief, supporting a principle of parsimony (there is no need for adding mechanisms, when a smaller number of entities will, theoretically, be efficient enough). Their perspective triggered different reactions in other researchers, giving way to two papers that make use of the fMRI for the investigation of the “domain specificity”.
The first would belong to Perner et al. (2006), presenting a partly similar point of view: The common ground for the two perspectives is in regard to the features of the specific mechanism
involved in the representation of beliefs (a solid and replicable response to stories that require belief attribution, a significantly lower response to closely matched control stories that require just non-‐mental representations and no difference among non-‐mental stories that do/do not demand meta-‐representation). The difference in the studies is made by Perner who attempts to provide the existence of a region of the brain that meets all the before mentioned demands, after following the studies of Cohen (1994) and Frith (1999) –The study initially identify three regions reliably activated in theory of mind: the temporal pole, the posterior superior temporal suluc and the anterior cingulate cortex. The conclusion of their experiment presented the tempo-‐parietal junction (TPJ), with the right TPJ seemingly specialized in mental perspective (false beliefs), leaving the left TPJ to be associated with a broader range of tasks (that include false beliefs as well as non-‐mental entities –false signs). The RTPJ is activated when subjects read short stories regarding the character’s beliefs, but is not activated when seeing photographs, or when reading stories about maps or signs – which are much alike beliefs, due to their representation of the current reality, which can genuinely be false. Also the RTPJ did not seem to make a distinction between tasks that require a meta-‐representational understanding and tasks that did not involve that. Thusly, the RTPJ might be proof of the existence of a domain-‐specific mechanism involved in the reasoning about beliefs.
The second study was created by Saxe et al. (2006), who claimed that reasoning about others’ beliefs depends on both domain-‐general and domain-‐specific mechanism –creating a theoretical bridge between the two opposing precedent views. Their theoretical trajectory began with the identification of the brain regions implicated in:
1. Belief reasoning
2. Domain-‐general response selection and inhibitory control (Saxe et al. 2006).
They proceeded then with the demonstration that “belief reasoning” “lights up” areas in the brain concerned with domain-‐general mechanisms, response selection and inhibitory control, while causing an equal response in the tests that require subjects to reason about false images. The results of their experiment came to agree with an “emerging consensus” (Saxe et al. 2006), which claims that executive control is responsible in adult performance for at least a part of belief attribution tasks (Theory of Mind), though the construction of representations of other’s beliefs relies on an independent domain-‐specific cognitive and neural substrate. Though the conclusion they reached through the experiment seems to be a sensible one, the participants to the test were characterized as naïve (possibly suffering from brain lesions), which, in my opinion adds a bias, concerning the sector of the population involved, and the lack of a “healthy” control group, in order to detect the normal tendencies in brain activation while being subjected to the same tasks. In spite of the before mentioned problem , the discussion part of their paper, dots the i’s and crosses the t’s by continuing on the issue of the domain-‐specific neural resource involved in producing representations of belief, and by confronting their affirmations with results from other experiments in the same line of research.
They argued that the existence of this domain-‐specific resource might predict that the process of mentalizing is somewhat immune to the exterior interference from other, unrelated mental, cognitive processes; affirmation seconded by the results of the McKinnon and Moscovitch (2007) study, which involved quantifying the results in a mentalizing task, in 2 experimental conditions: with or without the interference of a second, unrelated task. The results showed that in second-‐order beliefs attribution tasks, the presence of a second task highly deteriorated the performance,
while in first-‐order attributions; the second task had no effect at all. Den Ouden, Frith, Frith and Blakemore (2005) had subjects make belief attributions while in the scanner, with or without a secondary task, discovering that mentalizing alone “lit up” the usual regions associated with theory of mind: the tempo-‐parietal junction and the medial prefrontal cortex, while the presence of a second task did not increase the use of the aforementioned parts, as expected, but led to the use of a different set of regions.
Newer neuroimaging studies keep supporting the domain-‐specific theory, though experiments performed on normal control group and on patients suffering from lesions in different areas of the brain. The theory of mind, however, has a number of characteristics which come to reinforce its domain-‐specific character, as a social cognitive ability and not just as a result of general cognitive and reasoning abilities that are applied to the outside social world:
a) it goes through a stereotypical development which begins in early childhood and keeps increasing in complexity
b) it dissociates itself from other areas of mental function (Gregory et al., 2001).
When do children first show evidence of mentalizing?
For more than two decades, researchers have argued that young children do not understand mental states such as beliefs. Part of the evidence for this claim comes from preschoolers' failure at verbal tasks that require the understanding that others may hold false beliefs. (Onishi & Baillargeon 2005).
But as of late, more and more studies come to prove the opposite, such as Onishi’s and Baillargeon study (2005), that claims that 15-‐month-‐old infants are capable to predict an actor’s behavior, based on the false belief task (about an object’s hiding place). Results were positive, making the claim that children are capable of mentalizing, even before acquiring a more complex language, true. The means used were nonverbal and one of the measures was that of the eye movements, the infants posing a surprised look when the actor was looking in the wrong place. This experiment can reveal an implicit form of false-‐belief understanding and the children’s appeal to mental states, to explaining and understanding the behavior of others.
Of course, such studies are still a novelty and the general population of researchers might agree upon a greater age for the identification of mentalizing in children. Although the manifestation of the theory of mind in children can be observed through the explicit mental state language used by the child (eg. “I think my brother is pretending to be a ghost”), there is also an implicit presence in the behavior (through the reaction the child has; eg. instead of crying or being scared, the child removes the sheet in order to reveal the brother underneath).
Dennett (1978) is the one who proposed a stringent test for the presence of theory of mind – the prediction of somebody else’s behavior relying on that person’s false belief. A true belief would be rendered useless, due to the fact that it would be impossible to be completely sure whether the other person would behave according to reality or with his/her own view on reality. This new point
of view required a new experimental paradigm, which was formed no later than 1983, by Perner and Wimmer. The test I am talking about is the well known “Where will X look for the object?” task.
After testing children of various ages the, somewhat, mutual consensus was that children no younger than 4 years are beginning to understand the scenario and are capable of verbally explaining it, along with their reasoning. Already by the age of 5, 90% of the subjects were capable of correctly answering the given task, while at 6 years all children successfully passed the task (Baron-‐Cohen et al. 1985). This type of task was tested throughout cultures, and the results were essentially similar, indicated a clear pattern in the development of mentalizing.
Given the success of the previously developed experimental designs, the tasks devised became more complicated and difficult. Perner & Wimmer (1985) created a test that involved a second-‐order task (the requirement demanding the attribution of a belief about somebody else’s belief). The problems were along the lines of: “Alice believes that Albert believes that she is a good student”. Even in this case, the threshold for efficiency situated itself around ca. five or six years. These children found it easy to understand the task, even when more complex scenarios came into play.
What seems to be amiss conforming to some of these claims though is the sudden cognitive jump that children make at the age of 5, ignoring their development until that age. It seems implausible to believe that no earlier than 5 years of age do children see other people as intentional agents, possessing thoughts and beliefs.
Johnson (2003), on the other hand, claims that as early as one year old, children are capable of responding to objects as intentional agents, based on the interactive behavior they have with another person. And there are studies to support this side of the argument as well. The evaluation of children as young as 2 year old proved itself successful in contra-‐arguing the aforementioned point of view: from the age of 3 children make use of words which refer to mental states “I thought it was a dolphin, now I know it is a whale”. The “language of the mental state” used by 2 year olds is within the lines of “wish, want and pretend”-‐ these words start being used about once every 25 utterances (Bartsch, 2005). Three year olds seem to begin to understand the differences between knowing, guessing and thinking. (Frith & Frith, 2003). Hogrefe et al. (1986) proves that 3 year old children are able to realize that only people who have looked inside a box can genuinely know what is inside it. At the age of four, already, children realize that seeing is knowing and understand why, even though when this capacity is tested in its implicit form, it manifests itself as soon as 18 months of age (Poulin-‐Dubois et al., 2003).
One of the most important roles of the theory of mind in development is the one it has in the evolution of language; it would seem that the attribution of beliefs proceeds facilitate the learning process by placing the intentional value along with the utterance of a word. The child is now capable to discern when his mother is naming an object that proves useful for the child, or an object that has nothing to do with the child’s needs. This type of “belief-‐placing learning” prevents accidental object associations from happening. Mentalization manifests itself through the understanding of pretence as well (the mother that pretends that the spoonful of food is a plane, without confusing the child about the properties of either object). Leslie suggested the term “decoupling” for the mediator of this pretend-‐play, which by and large refers to the need to keep separate the representations of the real evens from the representations of the “fake”, make belief ones.
According to a Vygotskian perspective childhood understanding of mind is, at first inter-‐psychological – which means that is available only in interactions, collaborative dialogues with parents. Through conversations, parents help scaffold their children’s concepts and manage to guide them towards an articulate expression. Only later does this understanding become intra-‐psychological. Although the age at which it is supposed that children are capable of seeing others as intentional agents and inputting mental states onto others keeps decreasing, it does not mean that all humans are capable of mentalizing. Simon Baron-‐Cohen shows, through his studies, that children with disorders from the spectrum of autism (including Asperger’s syndrome) face great difficulty in solving false-‐belief tasks at a normal level. Why is that? The manifestation of the theory of mind in people suffering from different mental disorders
1. Autistic Spectrum Disorders (ASD) Autistic Spectrum Disorders (ASD) is a neuro-‐developmental condition, characterized by
cognitive and behavioral difficulties in communication and social interaction (American Psychiatric Association 1994; World Health Organization 1994). A fundamental part of these difficulties is a delay in the ability to recognize emotions and mental states in others (Baron-‐Cohen 1995). Its characteristics have been made famous in movies such as “Rainman”, “Forest Gump” and “I am Sam”: the presence of stereotyped repetitive behaviors, restricted interests, uneven verbal skills, difficulty in expressing needs, inappropriate response to sound etc. The children diagnosed with ASD seem to be completely self focused (Kanner, 1945); Firth (2003) remodeled this theory changing the concept of “self focus” to the notion of “absent self” – this change was motivated by the observations made upon the details of manifestation of autism: weak central coherence, executive dysfunction and varying degrees of mind blindness (mentalizing failure), which Simon Baron-‐Cohen, (1995) sees as the central feature of autism; in extreme cases, he says, autistic children can completely lack the concept of mind.
These traits have been recently correlated (through neuroimaging studies) to deficient top down modulation of bottom up information processing in the frontal regions of the brain (Baron-‐Cohen et al., 1999). Coming to confirm the concept of “absent-‐self” is the difficulty that individuals with autism and Asperger’s Syndrome encounter when solicited to refer to themselves –their own emotional and mental states; they give fewer descriptions of themselves within social contexts. Such issues often indicate abnormality in self-‐referential cognition. The ability of mentalizing has been tested with the “false belief” task. When asked “Where will X look for the Y-‐object?” the ASD children answered – in the majority-‐ that it was in the place they, not X, saw it hidden. The minority of autistic children that did answer correctly did not reach the conclusion spontaneously, like in the normal cases; their way of coming to the solution is different. Most people cannot justify the means through which they have reached the conclusion, while autists have a justified explanation at the ready, having worked out the solution logically. Complex emotion recognition usually involves attributing a mental state to others and seeing them as intentional agents; children with ASD, though find it hard to recognize emotion from photos of eyes, facial expressions and short voice recording, pictures and linguistic contextual cues (Baron-‐Cohen et al., 2001). Neuroimaging studies have shown weaker activations of typical “theory of mind areas” (TPJ and aFMC) (Castelli et al., 2002); another line of research focused on the condition of the mirror neurons in autistic cases, in trying to relate them with the poor social skills and deficits in imitative
performances –though this issue is still under debate; the issue under argument in this case is not their imitation per se, but the argumentative behavior. Recent studies have shown no deficit in goal-‐directed imitation in autistic and Asperger’s Syndrome children, claim which comes to defy the afore mentioned global failure of the mirror neuron system in autistic cases, but more of a lack of influence of the mirror system by the regions which distinguishes between the self and other agents (Firth, 2003). The social interaction difficulties can be caused by the inability to understand irony, or metaphor as well as difficulties of recognizing emotion in others. While the use of irony in everyday life might be simple, its detection requires complex mental representations – the listener has to be able to understand that the speaker does not mean what he/she said and that the speaker does not have the intention to be taken literally. Studies have shown the associations between theory of mind tasks and the ability to understand irony, in typically developing children and children with autistic spectrum disorders; individuals with ASD who manage to successfully perform second-‐order theory of mind tasks are able to correctly detect irony in a laboratory setting, but still have difficulties in justifying their responses and do not use or understand irony in their everyday life,
outside the experimental settings (Leekam & Prior, 1994). The impairment of detecting irony in ASD individuals might be related to deficits in using prosodic and contextual information in order to make inferences about a speaker’s communicative intent; even more, autistic children present impairments in extracting meaning from tone of voice or prosodic cues, from a very young age .For example, they do not show a preference to listening to their mother’s voice, unlike normal children. Finally, it would seem that adults suffering from an ASD are less capable than healthy adults to make global inferences about a story character’s action as well as to appreciate the intent behind indirect requests (Lee, 2005).
Fig. 3
Brain activity during potentially ironic scenarios relative to rest. Reliable activity was observed in the MPFC in the TD group but not in the ASD group across all conditions. Although both groups engaged the IFG in the left hemisphere, only children with ASD showed reliable prefrontal activity in the right hemisphere. In addition, the ASD group showed reliable activity in the left pre-‐ and post-‐central gyrus. One of the discoveries that I thik, are most influential in the domain-‐specific approach to the theory of mind is that on the Down’s and William’s syndrome patients. These patients, though in most cases, much more challanged, intelectually speaking, face no difficulties in projecting mental states onto others (Baron-‐Cohen, 1995; Baron-‐Cohen et al., 1999a).
2. Frontal and temporal degeneration (Dementia and Alzheimer)
Patients suffering from frontotemporal dementia show visible changes in their social behavior: lack of empathy, disinhibition, altered emotion reactivity, apathy and lack of insight. It is believed that these changes are being determined by the degeneration of the frontal and temporal lobe. These symptoms point towards decaying capacities of mentalizing. The progressive cerebral atrophy offers the chance of studying the theory of mind as it gradually shifts. Damage to the frontal lobes in the early years of the life often results in pervasive difficulties regarding social behavior, moral reasoning, decision-‐making and empathy.
The frontal variant frontotemporal dementia (fvFTD) is the name given to the patients that suffer from degeneration of the frontal lobes, which results in loss of semantic knowledge and leads to a progressive aphasic syndrome. The ages at which the changes start visibly influencing their behavior are between 50 and 60. By this time they have already suffered a clear change of personality, which includes apathy, lack of concern for others, inappropriate behavior –social wise, loss of insight and impaired personal awareness.
Ritualized and stereotypic patterns of behavior, similar to those present in autism, also start to manifest themselves. The theory of mind has a number of characteristics that support the “domain-‐specific mechanism” theory. Neuroimaging studies primarily involve the frontal lobes in ToM, even though the exact area of activation varies in regard to the different experimental paradigm. Of course, other brain regions, such as the amygdala may be involved in the theory of mind; the evidence for the neural basis for the theory of mind is still limited, so far – having as basis the study of brain-‐injured adult subjects, but it does manage to show that certain regions within
the prefrontal cortex might have a critical role. Baron-‐Cohen et al. (1994) was the one to propose that the theory of mind abilites is underpinned by a system which involves many of the regions of the prefrontal cortex and limbic system, including the orbitofrontal complex. The studies on fvFTD patients have as a goal a step up in earlier diagnosis. The secondary goals represented the discovery of the relationship between performance on theory of mind tests, traditional frontal
executive tasks and the degree of degeneration in fvFTD.
The following experiment had 47 subjects (16 dementia patients, 12 Alzheimer’s patients and 16 healthy control volunteers). An assessment of the degree of atrophy in the brain was made through fMRI. The subjects had to solve a battery of tests which included: theory of mind tasks (false belief-‐ first-‐order and second-‐order), faux pas test and a Reading the Mind in the Eyes test.
The results were as it follows: the fvFTD patients showed greater difficulty across the two false belief tasks and with the faux pas tests as well (74% fell below normal). The degree of impairment in the last of the tests (Reading the mind in the eyes) being equivalent to the second-‐order false belief tasks. The group had no difficulties with the non-‐ToM control questions, though. The
Alzheimer’s disease group performed better, overall, than the fvFTD patients, presenting great difficulties in solving the tasks only in the second-‐order false belief and faux pas tasks, with the faux pas test rendering them impaired.
“Patients with fvFTD were relatively mildly impaired, as judged by their ability to undertake a demanding battery of general neuropsychological tests and to cooperate fully with testing. In support of our hypothesis, patients were found to have significant deficits on the ToM tests and, although some were impaired on first-‐ and second-‐order ToM (which normal children are able to perform at the ages of 3–4 and 6–7 years, respectively), a higher proportion of fvFTD patients showed deficits on the faux pas test (which children can pass between the ages of 9 and 11 years) and the Reading the Mind in the Eyes Test (which develops during adolescence). The finding of a high degree of internal consistency between the two false belief and faux pas tasks suggests that these tests may measure a common cognitive process. Patients with Alzheimer’s disease, while severely amnesic, generally showed no deficits on the specific ToM-‐based components of the tasks (Gregory et al., 2001)”. Performance on the Reading the Mind in the Eyes Test did not correlate with any of the other ToM tests, even though the patients’ performance on this task was significantly worse than that of controls. This task evaluates the capacity to infer a judgment about the mental state of a person based just one a photograph of the eyes, and thus may be measuring more visual aspects of mentalizing than the other ToM tasks. In the Alzheimer’s disease patient group, there was, in general, very little evidence of impairment on tests of ToM -‐ the only task on which the Alzheimer’s disease group displayed deficits being the second-‐order false belief test, which placed heavy demands on working and episodic memory, and there is a possibility that the Alzheimer’s disease patients, all of whom were severely amnesic, failed this task for reasons different from those in fvFTD.
An analysis of the performance of fvFTD patients at the theory of mind tasks in relation to the position and degree of severity of their frontal brain atrophy brought to light some interesting discoveries: it confirmed a correlation between the false belief and the faux pas tests and suggested that performance on the Reading the Mind in the Eyes requires, probably, a different cognitive, neural process. Also, it shows a remarkable concordance between the ranking of subjects according to the results they had on the theory of mind tasks and the severity of the frontal lobe atrophy (discovery which comes to support the theory of the frontal substrate for the theory of mind in humans, suggesting that the ventro-‐medial cortex might actually be one of the main areas in the brain underlying the theory of mind) (Gregory et al., 2001).
These discoveries also have a clinical importance, due to their potential use as an adjunct in diagnosis and in the monitoring of treatment responses.
In conclusion, not all of the symptoms that the patients suffering from frontotemporal dementia present are traits of a deterioration of the theory of mind ability, but, more likely they share a common ground with some of the traits in the severely affected theory of mind from the autistic spectrum of disorders (most probable, the impaired social awareness). A novel study, of Bozeat et al. (2002) makes it its priority to show a clear and distinct cluster of symptoms in fvFTD, semantic dementia and Alzheimer’s disease (altered social awareness with loss of empathy and disinhibition, stereotypic behaviors, mood disturbance and dysexecutive features were found to constitute four discrete symptom clusters).
This social brain of ours…
The neural basis of the theory of mind
The social brain theory was originally created as an explanation to the size of the primates’ brains – unusually large in comparison to their body size. The theory stated that the need for such a large brain is related to the complexity of their social life, thusly, primates needing a bigger brain than other mammals in order to be able to cope with all the computations involved. This view ignores a very important, neural consideration: brains are organs that consume a lot of resources for development and maintenance (eg. the human brain weights 2% of the total body weight and consumes 20% of the total energy intake). Knowing this, it is improbable that primates and humans need larger brain than other specimens, to do the same job. And while the computational need might be right in some of the primate species (which perform complex activities as nut-‐cracking or termite-‐extraction), the theory fails to answer why is the larger brain present in common species that perform no special actions. The only case in which this theory is plausible is that of the real social system complexity: primate social tactics that involve deception, coalitions –even though rare and only in certain groups.
The term “social brain” was first used by Leslie Brothers in 1990; in her paper she claimed that there are certain areas in the brain dedicated to social cognition: the amygdala, the orbital frontal cortex and temporal cortex being the main components. According to her, these are the areas that form the social brain. She based this affirmation on the studies she enterprised on monkeys; she noticed that those who had lesions to the amygdala were socially isolated, while those with orbital frontal cortex had an altered social behavior. Brothers’ studies created a basis for the research of the social brain, and after neuroimaging studies on human volunteers two more parts have been added to the “social brain” regions. The first part to be added was the medial prefrontal cortex and the adjacent paracingulate cortex, which are involved in mental processes that require humans to think about mental states (Amodio & Frith, 2006). The second to follow was the “mirror” system that has first been found in the brain of the macaque monkeys, while recording neuron activity during the observation and execution of grasping food or objects. They are located in the F5 area of its brain (lateral ventral premotor cortex – activity related to the control of hand and mouth movements). What makes mirror neurons so special? The fact that not only do they activate while performing an action, but while observing the action as well. Some researchers claim that the use of the mirror neuron system for primates is to facilitate action understanding and imitation (Rizolatt et al., 2000), while for humans it has a more refined purpose, that of understanding the underlying intentions behaving the actions of others ( thoughts and emotions). This system is believed to be a basis for understanding the higher order social processes, among which are: imitation, perspective taking, understanding facial emotions, motor learning and action understanding (Gazzola, 2006); which would mean that in order to be able to adopt somebody else’s point of view, an understanding of the other’s actions is required, without which, an accurate prediction of the other’s behavior is improbable.
While the discovery of the mirror neurons opened doors towards the discovery of our social selves, it seems to have brought more questions than answers: how exactly did this system arise? Are mirror neurons innate (thusly, genetically programmed), or are they acquired and require learning? On one hand, researches show that the imitation of facial and hand gestures in humans and primates takes place since infancy (6-‐7 months) – suggesting that this system might be innate, while on the other, computational models of mirroring activity claim that the sensoriomotor transformations, through Hebbian leaning (simultaneous activation of cells that leads to pronounced increases in the synaptic strength between those cells), are actually developed.
So, basically, what mirror neurons do is to activate when observing a movement, expression, action etc. in the others. What is so amazing about them is that they activate the specific regions in the brain that correspond with the certain observed action, as if the observer would be physically imitating the observed. But how does the observer’s motor system “know” which muscle activations will lead the observed movement (Pineda, 2008)? A partial answer would be in the implicit nature of the mirroring system: a system that” evokes motor representations by movement observation” (Pineda, 2008). This means that, if the specific motor action already exists in the observer’s repertoire then the observation of the action can be sufficient to evoke the representation. Another obvious and uncomfortable question to be asked is “how come we don’t imitate all the time?” Is there an on/off button to this system, because most neuroimaging studies show its activation to be automatic and unconscious (much like the way we infer mental states to others) . Brass and colleagues (2003) come to state that high level areas are involved in their inhibition on imitative response tendencies. Others claim that the phasic changes in oscillatory EEG activity acts as an inhibitory control mechanism. Mirror neurons have yet to be definitively identified in humans, but there is evidence for resonance behavior in humans at the behavioral and the physiological level, as follows. Studies have shown that executing an action while observing an incongruent action leads to longer response time than the observing of a congruent action during execution. Clinical neuropsychological research comes to prove the physical existence of a mirror neuron system in humans, by testing patients with prefrontal lesions; they often have imitative behaviors, which tend to openly and psychically imitate the experimenter, indicating that the behavior they observe turns into their intention (Brass, 2003).
Instead of a conclusion
Going through the research material on the subject of the theory of mind, I found that everytime I threw in an opinion, another reseach would appear, to agree with me, or to better defend the “acused” perspectives. So, not only did I feel of opinion-‐impaired, but the more I searched in order to be able to discern black from white, the more I unraveled, much like pulling a giant fishnet out of the sea. And this witchunt for information somehow managed to turn into a race of squeezing more and more information in less and less space, probably, in order to avoid having a clear definite say on the matter.
Areas like the study of the mirror-‐neurons leave my convinced, from a theoretical point of view, but the enterprised studies vary so much in result it is difficult to tell right from wrong – the fact that I am not a neurscientist does not help either. But there are certain defined sides of the fence in the theory of mind, in which I chose what I feel is right, such as the view that states that the theory of mind employs domain-‐specific neural and cognitive mechanisms and does not only rely on the general cognitive skills; yes, with that I agree.
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