Deric Bownds

Mirroring Minds: Are Mirror Neuron Systems the DNA of Psychology or a Red Herring?
(note: the following is minimally edited lectures notes for a talk I gave to the chaos and complexity seminar group in the in the Physics Dept. Univ. Wisc. Madison, on 10/24/06)
I have been puttering with a talk/web lecture that would logically follow the "I Illusion" and "The Beast Within."
The "I Illusion" talk was mainly on sensing and acting, how our brains massage these processes mainly outside our awareness, so that we are in fact 'late to consciousness' with our subjective experience being an after the fact report of what has already happened. You can measure this happening with machines, you can have some introspective access to it.
"The Beast Within," described regulatory and emotional layers of our experience that we share with other mammals, and that operate alongside, and sometimes more rapidly than, our more distinctive human cognitions. You can measure this with machines, you can have some introspective access to it.
My thought about this talk/web lecture, "Mirroring Minds" was to focus on our social brain, on brain processes that link us to other humans and the larger social contexts that are a basis of our survival. What is the neuronal basis of "intersubjectivity?"
I thought the core of this might be describing recently discovered mirror neuron systems and their implications. There is a lot of speculation based on a few simple experiments that don't take a lot of time time to cover.
I'm am not getting a satisfying bottom line on 'social brain' of the sort that came together in the earlier talks. Robin Chapman, an organizer of the weekly Chaos and Complexity seminar at the University of Wisconin said "Hey, not to worry just lead an open discussion."
Many lines of evidence have suggested we should look for a neuronal basis of intersubjectivity. We know that mammals have highly developed evolved neuronal and hormonal substrates of affiliative behavior, and a new field of "affiliative neuroscience" has been defined in just the past ten years. Oxytocin and vasopression regulate infant parent interaction in prairie voles and in humans. Oxytocin delivered with a nasal inhaler makes humans more trusting.
Human infants discriminate happy, sad, and surprised faces within a few hours after birth and make primitive imitations of the expressions they see, they are equating their own unseen behaviors with gestures they see others perform.
This is imitation, not reflexes or ethological releasing mechanisms which are highly specific to limited stimuli. It is flexible, takes time, the range of behaviors displayed by infants would require one to postulate distinct releasing mechanisms for each kind of behavior: tongue protrusion, mouth openings, lip protrusion, head movement, finger movement, as well as smile, frown, etc.
So, we come equipped with innate seeing, moving, and sensing systems that include a self/other model. We're born into a world of other humans with a computational model that transforms visual information into motor commands - a phenomenal connection between self and others exists from birth... 'experientially' (whatever that means for a neonate), and not just objectively, we are born into a world of others.
This makes adaptive sense, the function of bonding to caretaker. Touch and stroking by a caretaker is required to support and stimulate growth. In its absence wasting and death can occur both in us and in other mammals. Studies using mice have documented how stroking and licking promote brain growth and development. Its absence can lead to permanent activation of stress hormone pathways and stunted growth of parts of the brain.
Human bodies and brains generate selves, or rather, the evolving idea of the self generates us ­ the culture's contemporary model of the self generates us as we mirror the actions, emotions, intentions of caretakers and peers - self that is generated by mimicry or mirroring initially and then gains a more self referential internal loop as development continues. - the selves we experience today, with its particular sense of introspective agency and individuality, would have been completely alien to most people living a thousand years ago.
The main recent driving force in hominid evolution has been competition between different human groups, the shifting natures of inter- and intra-group cooperation and competition. We follow countless intricate social rules, as in traffic, or kinesic communication. Both within our own groups and with respect to other groups. We need to be mind reading all the time, be empathetic to the feelings of others.
We really haven't know much about the neuronal basis of empathy, of knowing what someone else is feeling or doing, or of attributing beliefs and motivations to others. .... can we measure something, like, physical, mechanisms?
This is why there is been so much excitement in recent years over the discovery of a kind of neuron, and neuronal systems: mirror neurons. The prominent neuroscientist Ramachandran, for example, has invoked them as doing for Psychology what DNA did for Biology. There is a bit of a backlash against the concept being totally oversold.
I want to give you a brief description of them, as they've been found to mirror both actions and emotions,
People now have come up with models that make motor systems central to explaining volition, agency, language, and consciousness. The idea is that the logic of the motor/ sensory system might be at the core of many operation we have usually considered to be more dis-embodied pure cognition.
Mirror neuron systems were first discovered by Rizzolatti, Gallese et al. in studies of premotor cortex of macaques (the red and yellow areas in the figure) , microelectrode recordings of how movements are planned, organized, executed.
They respond both to the movements that a monkey makes and when the monkey observes another monkey making the same movements. Hence the name. There is evidence, mostly brain imaging data more indirect than in monkeys, that humans have a mirror neuron system too. In us, it's thought to be located around the right superior temporal sulcus (red and yellow areas in figure B).
There are two main ideas on how action understanding occurs. The first is a 'visual model', saying that action understanding is based on a visual analysis of the different elements that form an action, and that no motor involvement is required.
The second is a 'direct-matching hypothesis', saying we understand actions when we map the visual representation of the observed action onto our motor representation of the same action. An action is understood when its observation causes the motor system of the observer to 'resonate'.
Evidence for the second is what is accumulating. The Italians had electrodes implanted in the pre-motor cortex of a macaque monkey to measure nerve cell activity during the planning and execution of a movement: picking up a peanut. During a lull in the experiments, one of the experimenters picked up a peanut, just as the monkey would.
The monkey was doing nothing but watching, but the pre-motor cortical cells that had been active when the monkey was picking up the peanut, now became active when the same activity was observed in someone else.
Typically, mirror neurons do not respond to the sight of a hand mimicking an action in the absence of the target. Similarly, they do not respond to the observation of an object alone, even when it is of interest to the monkey.
from Rizzolatti et al., Nature Reviews Neuroscience 2, 661-670 (2001)
A Strong activation is present in F5 during observation of the experimenter's grasping movements, and while the same action is performed by the monkey. B Note the absence of a neural response when the observed action is performed with a tool. Rasters and histograms show activity before and after the point at which the experimenter touched the food
It turns out that there is another regions in the parietal (usually thought of as mainly sensory) lobe that contains cells that also discharge during action observations and execution.
Umiltà et al. studied the responses of F5 mirror neurons in two conditions. In the first one, the monkey could see the whole action made by the experimenter (full-vision condition). In the second, the monkey could see only the beginning of the same action; the crucial part - the hand/object interaction - was hidden from view (hidden condition), although the monkey was shown that an object or some food had previously been located behind the screen. So, the meaning of the experimenter's action could be inferred from the monkey's knowledge of the situation and the view of the hand disappearing behind the screen.
The results showed that more than half of the recorded mirror neurons also discharged in the hidden condition. This indicates that, despite the fact that the monkey did not see the action, it knew its meaning; its neurons signalled 'the experimenter is grasping' or 'the experimenter is holding' . This argues against the need for a visual description of action for action understanding, and therefore oppose the visual hypothesis.
Evidence for mirror systems in humans has been obtained from MEG (magnetoencephalogray), TMS (trans cranial magentic stimulation), and MRI (magnetic resonance imaging).
Recall the homunculus.... note where mouth, hands, feet are represented in the brain, moving from lateral to dorsal.
Brain activation in frontal and parietal areas during the observation of mouth, hand and foot actions. Showing both sides of brain. Motor areas, again, are active during observation of the actions they can generate.
a, b | Activation foci during the observation of non-object-related (chewing; a) and object-related (biting an apple; b) mouth actions. In both cases, activations were present in Brodmann areas (BA) 6 and 44 in both hemispheres, and in BA 45 in the right hemisphere.
During the observation of object-related mouth action, two additional activation foci were found in the parietal lobe.
. c,d | Activation foci during the observation of hand actions that were non-object related (mimicking grasping an object; c) and object related (actually grasping an object; d). This activation was dorsal to that found during the observation of mouth actions.
Two additional object related activation foci were present in the parietal lobe.
e,f | Activation foci during the observation of foot actions that were non-object related (mimicking kicking an object; e) and object related (actually kicking an object; f). During the observation of object-related actions, there was an additional activation of the posterior parietal lobe (including area PE) that partially overlapped with activations seen during the observation of mouth and hand actions.
Frontal and parietal activation foci are presented in colour. Other activations (mostly occipital) are shown in grey.
NOW, I could give you more examples of mirroring in motor systems, but I want to move to give just a few examples of how brain areas involved in emotion also show mirroring behavior.
Remember watching James Bond, Sean Connery in Dr. NO
...if you get the creeps watching the spider crawl up James Bond's arm, it may because the scene fires up the same neurons that would be active were the spider making its way up your arm.
So, we have papers on seeing and feeling touch, also seeing and feeling disgust.
The figure below from Keysers et al Neuron, 42:335-346, 2004) shows the overlap between Areas Activated by Touch and Areas Activated by the Vision-of-Touch(A) Two coronal sections illustrate the extent of the overlap between visual and somatosensory activations. Areas activated only by the touch of the right or left leg are shown in red , areas activated only by the vision-of-touch are shown in blue; areas activated by both the touch and the vision-of-touch conditions are shown in white.
Note that the overlap is lateralized to the left hemisphere.
SII appears to be part of a circuitry that is shared between the first and third person experience.
In the context of the existing results on actions and emotions, one might speculate that the brain is parsimonious: it uses the same mechanism of shared circuitry for actions, emotions, and sensations
Wicker et al (Neuron, 40:655-664 (2003) performed an fMRI study in which participants inhaled odorants producing a strong feeling of disgust. The same participants observed video clips showing the emotional facial expression of disgust. Observing such faces and feeling disgust activated the same sites in the anterior insula and to a lesser extent in the anterior cingulate cortex.
The following illustration shows the overlap (white) between the brain activation during the observation (blue) and the feeling (red) of disgust. The olfactory and visual analysis were performed separately as random-effect analysis. The results are superimposed on parasagittal slices of a standard MNI brain.
Then, there is work on empathy for pain (Singer et al., Science 303: 1157-1162 (2004))
They assessed brain activity while volunteers experienced a painful stimulus (electrical shock delivered to right hand) and compared it to that elicited when they observed a signal indicating that their loved one-present in the same room-was receiving a similar pain stimulus.
Areas in green represent significant activation (P < 0.001) for the contrast pain­no pain in the "self" condition and areas in red for the contrast pain­no pain in the "other" condition. The results are superimposed on a mean structural scan of the 16 subjects. Activations are shown on sagittal (A and B) and axial (C and D) slices.
Bilateral anterior insula (AI), rostral anterior cingulate cortex (ACC), brainstem, and cerebellum were activated when subjects received pain and also by a signal that a loved one experienced pain. AI and ACC activation correlated with individual empathy scores.
Thus, a neural response in AI and rostral ACC, activated in common for "self" and "other" conditions, suggests that the neural substrate for empathic experience does not involve the entire "pain matrix." They conclude that only that part of the pain network associated with its affective qualities, but not its sensory qualities, mediates empathy.
OK, so.... where are we.... we've seen some examples of mirroring, so what? simple mimicking is kind of boring, what about the intentions behind the movements of others we are mirroring.?
The following graphic, taken from Rizzolatti et al.'s article in the Nov. 2006 Scientific American, shows that firing of neurons in the inferior parietal lobe of the macaque monkey can discriminate intention, noting the difference between placing a food object in the mouth or in a bowl.
Marco Iacoboni et al. (PloS Biology, 3:1-7 (2005)) used functional magnetic resonance imaging in humans to investigate "Grasping the Intentions of Others with One's Own Mirror Neuron System"
Twenty-three subjects watched three kinds of stimuli: grasping hand actions without a context, context only (scenes containing objects), and grasping hand actions performed in two different contexts.
The images are organized in three columns and two rows. Each column corresponds to one of the experimental conditions. From left to right: Context, Action, and Intention.
In the Context condition there were two types of clips, a "before tea" context (upper row) and an "after tea" context (lower row). In the Action condition two types of grips were displayed an equal number of times, a whole-hand prehension (upper row) and a precision grip (lower row).
In the Intention condition there were two types of contexts surrounding a grasping action. The "before tea" context suggested the intention of drinking (upper row), and the "after tea" context suggested the intention of cleaning (lower row).
Whole-hand prehension (displayed in the upper row of the Intention column) and precision grip (displayed in the lower row of the Intention column) were presented an equal number of times in the "drinking" Intention clip and the "cleaning" Intention clip.
the Intention condition contained information that allowed the understanding of intention, whereas the Action and Context conditions did not (i.e., the Action condition was ambiguous, and the Context condition did not contain any action).
As expected, given the complexity of the stimuli, large increases in neural activity were observed in occipital, posterior temporal, parietal, and frontal areas (especially robust in the premotor cortex) for
observation of the Action and Intention conditions. Notably, the observation of the Intention and of the Action clips compared to rest yielded significant signal increase in the parieto-frontal cortical circuit for grasping. This circuit is known to be active during the observation, imitation, and execution of finger movements (''mirror neuron system'')
Actions embedded in contexts, compared with the other two conditions, yielded a significant signal increase in the posterior part of the inferior frontal gyrus and the adjacent sector of the ventral premotor cortex where hand actions are represented.
To see the differences you performs subtractions shown in this next slide:
The subtractions high light differences in posterior part of the inferior frontal gyrus and the adjacent sector of the ventral premotor cortex where hand actions are represented.
Upper row.....The Intention condition yielded significant signal
increases-compared to the Action condition-in visual
areas and in the right inferior frontal cortex, in the dorsal
part of the pars opercularis of the inferior frontal gyrus
Lower row ... in the Intention condition minus the Context
condition signal increase was also found in the same right inferior frontal cortex previously seen activated in the comparison of the Intention condition versus Action condition.
Thus, the differential activation in inferior frontal cortex observed in the Intention condition versus Action condition, cannot be simply due to the presence of objects in the Intention clips, given that the Context clips also contain objects.
Thus, premotor mirror neuron areas-areas active during the execution and the observation of an action-previously thought to be involved only in action recognition are actually also involved in understanding the intentions of others.
To ascribe an intention is to infer a forthcoming new goal, and this is an operation that the motor system does automatically.
The conventional view on intention understanding is that the description of an action and the interpretation of the reason why that action is executed rely on largely different mechanisms.
This works shows that the intentions behind the actions of others can be recognized by the motor system using a mirror mechanism.
They suggest that coding the intention associated with the actions of others is based on the activation of a neuronal chain formed by mirror neurons coding the observed motor act and by "logically related" mirror neurons coding the motor acts that are most likely to follow the observed one, in a given context. To ascribe an intention is to infer a forthcoming new goal, and this is an operation that the motor system does automatically.
I want to mention a clever experiment: distinction of self and other in mirroring motor neurons.
The fact that the brain might represent others' actions like one's own raise the issue of how we distinguish self from other. What keeps us from constantly miming the actions of others? (This happens in echolalia, the involuntary repetition of words being heard that occurs in many persons with autism. ecopraxia, the involuntary mimicking of movements)
Schütz-Bosbach et al (Current Biology 16:1830-1834 (2006)) have done a very clever experiment to examine this by manipulating the sense of body ownership (using the "rubber-hand illusion") to compare effects of observing actions that either were or were not illusorily attributed to the subject's own body.
Let me give you their description of the experiment: When subjects watch a rubber hand being stroked while they feel synchronous stroking of their own unseen hand, they feel that the rubber hand becomes part of their body. Identical asynchronous stroking has no effect.
Thus, the sense of owning the rubber hand requires congruence of visual and tactile stimulation.
The neural counterparts of this sense of ownership have been identified in premotor and sensorimotor cortices.
The rubber-hand illusion therefore allows balanced comparison between the self and the other because a single stimulus is either linked to the self or not depending on the pattern of previous stimulation.
They used a real human hand instead of the conventional rubber hand because several studies show stronger mirroring effects for viewing a live action than for viewing artificial equivalents.
They show that observing another's actions facilitated the motor system, like in the examples we've seen...... whereas observing identical actions, which were illusorily attributed to the subject's own body, showed the opposite pattern.
Thus, motor facilitation strongly depends on the agent to whom the observed action is attributed.
This result contradicts the idea of close equivalence between one's own actions and actions of others and suggests that social differentiation, not equivalence, is characteristic of the human action system....
Their quote: "This suggests that the neural mechanisms underlying action observation are intrinsically social. These mechanisms map the actions of others to corresponding actions on one's own body but do not simply represent the other agent as a derivative of, or even an equal to, the self." In contrast, there appear to be an agent-specific representation in the primary motor cortex."
WHOA.... look how much is going on in what we previously thought to be simple old motor cortex that just plans and executes actions, its doing intentionality, self vs. others, etc.
There aren't distinct modular or phrenological type intentionality, self vs. other brain areas, these functions get carried out hear the relevant sites of sensing and acting, just as memories are distributed over the cortex among areas relevant to their context, just as vision isn't just he visual cortex but happens in the 80+ percent of cortical neurons whose firing can be influenced by visual input.
We clearly have in mirror systems a potential neural mechanism for empathy, understanding others by mirroring their brain activity.
That idea is bolstered by evidence of abnormalities in the mirror systems of people with autism and other disorders that impair the ability to empathize with and understand the behavior of others. There seems to be mirror neuron dysfunction in children with autism spectrum disorders, or ASD
Mirella Dapretto et al. (Nature Neuroscience, 9:28-31 (2006) looked at mirror neuron abnormalities in autism by studying high-functioning children with autism and matched controls. Both underwent fMRI while imitating and observing emotional expressions. Although both groups performed the tasks equally well, children with autism showed no mirror neuron activity in the inferior frontal gyrus (pars opercularis). Notably, activity in this area was inversely related to symptom severity in the social domain, suggesting that a dysfunctional 'mirror neuron system' may underlie the social deficits observed in autism.
LEGEND: Reliable activity during IMITATION of emotional expressions. (a,b) Activity in bilateral pars opercularis (stronger in the right) of the inferior frontal gyrus is seen in the typically developing group (a) but not in the ASD group (b). A between-group comparison (c) revealed that this difference was significant (t > 1.83, P < 0.05, corrected for multiple comparisons at the cluster level). RH, right hemisphere; LH, left hemisphere.
Mirror neuron system activity during OBSERVATION of emotional expressions. The right pars opercularis showed significantly greater activity in typically developing children than in children with ASD (t > 1.83, P < 0.05, small volume corrected).
This Dapretto et al paper references a strikingly complementary study, Hadjikhani et al. (Neuroimage 22:1141-1150 (2004)) who have recently reported that adults with ASD displayed significantly reduced cortical thickness in the main mirror neuron areas, namely the bilateral pars opercularis of the inferior frontal gyrus (also in the inferior parietal lobule and superior temporal sulcus). These areas are the same that failed to activate when children with ASD imitated facial expressions . Again in agreement with functional data, cortical thinning in these areas was correlated with severity of communication and social symptoms.
Now, so far we have been dealing with context and behavior correlates with brain activity..... I want to mention some interpretions and speculations about where this is taking us.
Gallese has written a number of review papers making summary points...
He wants to describe The mirror neuron matching systems and the other non-motor mirroring neural clusters as embodied simulation. 'as if' we would be doing a similar action or experiencing a similar emotion or sensation.
Social cognition, then, is not only explicitly reasoning about the contents of someone else's mind. Embodied simulation, is a feeling, experiential insight of other minds. The share-ability of the content of the intentional relations of others, is what "being empathic" is about ­ there is a shared neural state realized in two different bodies that obey to the same anatomical functional rules.
This of course doesn't account for all of our social cognitive skills. The same actions performed by others in different contexts can lead the observer to different interpretations, that was the drinking tea versus cleaning example we just saw. So, social stimuli are also understood on the basis of the explicit cognitive elaboration of their contextual aspects and of previous information.
Embodied simulation and cognitive elaboration are not mutually exclusive. The idea is that embodied simulation scaffolds the propositional, more cognitively sophisticated mind reading abilities. When embodied simulation is not present or malfunctioning, as perhaps in autism, cognitive elaboration can provides a more pale, detached account of the social experiences of others.
It will be an ongoing project to determine how much of social cognition, language included, can be explained by embodied simulation and its neural underpinnings.
One area of speculation is that the mirror neuron process is an important part of the evolution, development and execution of our language abilities
Classic language areas--Broca's and Wernicke's (yellow)--overlap (orange) with areas critical for imitation (red)
So, there is the idea that mirror neurons could facilitate the imitation of skilled movements like the hand and mouth movements used for communication. Learning by imitation is a key feature of language acquisition in infants and is widely considered a prerequisite for language evolution.
It turns out that listening to speech cues up activity in regions of the frontal cortex that are active during speech production.
This fits well with the old "motor theory of speech perception," ...when children imitate their first words, they seem to be guided by the "gestural" features of the sound--that is, by the actions of the mouth rather than by a sound's acoustic features. Apparently there is a well-known trick to demonstrate this is known as the McGurk effect: If you watch someone pronounce the syllable "ga" while listening to a recording of someone saying "ba," you will likely hear "da," a sound anatomically between the other two.
The idea is that we perceive speech by referring the sounds we hear to our own production mechanism. .. because of an intuitive sense of how our body parts correspond with those of others. Like a small child knows how to raise its hand in response to a parental wave. There's obviously a direct representation of your body in its body.
There are further speculations on implication of mirror systems for basic Ontology and also higher cognitition. Gallese collaborates with Metzinger on a paper titled: Motor Ontology:The representational reality of goals, actions and selves (see Metzinger's website for download, Metzinger, for my money, has written, in his book "Being No One" the most coherent account to date integrating philosophical and neuroscientific of what a human self actually is.
Here is condensation and abstracting of their article, which contains a bit of philosophy-speak:
In generating a coherent internal world-model, the brain decomposes target space in a certain way. In doing so, it defines an "ontology": To have an ontology is to interpret a world. It decomposes target space in a way that exhibits certain invariances, which in turn are functionally significant. The motor system constructs goals, actions, and intending selves as basic constituents of the world it interprets. Empirical evidence now clearly shows how the brain actually codes movements and action goals in terms of multimodal representations of organism-object-relations. Under a representationalist analysis, this process can be interpreted as an internal representation of the intentionality-relation itself.
What makes humans special is the fact that their functional ontology is much richer in socially individuated goal representations and that their model of reality is not only richer and much more flexible, but that they can actively expand their own functional ontology by mentally ascribing distal goals to conspecifics.
The idea, in summary, is that a complex form of representational content, once it is in place, can later function as the building block for social cognition and a for more complex, consciously experienced representation of the first-person perspective as well. The motor system would then play a decisive role in understanding how the functional ontology of the human brain could be gradually extended into the subjective and social domains.
And, Gallese pairs off with Lakoff to head into conceptual knowledge in a paper titled: The Brain's Concepts: The Role of the Sensory_Motor System in Conceptual Knowledge. (Download from )
They propose that the sensory-motor system has the right kind of structure to characterize both sensory-motor and more abstract concepts. ....that brain structures in the sensory-motor regions are exploited to characterize the so-called "abstract" concepts that constitute the meanings of grammatical constructions and general inference patterns.
Time to wrap up: As I've said, I've got no bottom line beyond repeating how we have to add some layers to Mr. Descartes model.....
With what we are calling embodied cognition that mirrors our social developmental context we have Sumus ergo Cogitamus .... the social wiring of our brains grows and develops from mirroring processes of the sort we have been talking about. While some mirroring systems are in place at birth, most of what we are seeing in the experiments listed above is mirroring that results from extended observation and learning during development.
The activity of a mirroring system within monkeys or ourselves need not be accompanied by awareness of its presence. These mirroring neuron systems are presumably the basis of the mirroring of non-goal directed behaviors in schools of fish, flocks of birds, or human yawning or laughing spreading through a group without participants knowing it what it is `about'.
Capacity to control this mirror system, decouple it from the actual executive motor structure is a precondition for achieving voluntary control. I've mentioned the human psychiatric disorders such as echopraxia in which subjects involuntarily mimic others.
So, we need to distinguish, in terms of both objective description and our own subjective introspection, pre-reflective embodied simulation (monkeys have it) with cognition enhanced contextual mirroring. To note and distinguish what is automatic (facial and body language mimicking) from reflective, cognitive and relatively more dis-embodied.
Descartes got it right on this distinctively human fraction of our repetoire. "I think therefore I am" is correct to the extent the thoughts are a cognitive invention beyond the reflexive mirroring
We are dealing with a gradient, we have homeostatic, emotional and cognitive layers. The mirroring system at the emotional (and motion) level is the platform on which more cognitive enhancements are constructed.
The old homily "You are what you spend your time doing" might also be put as "You are what you spend your time mirroring or imagining." This possibly being how George Bush manages to live in such a perfect bubble.
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