Mirror effects in neurons learned?

Blogging on Peer-Reviewed ResearchLike many observers of the neurosciences from other fields, I have watched the debate about the function, origin, and nature of ‘mirror neurons’ with no small amount of interest. Since their discovery in the early 1990s by Giancomo Rizzolatti and his research group at the University of Parma, the ‘mirror system(s?)’ in primates and humans have been extensively explored and discussed.

For anyone living under a neurosciences rock, ‘mirror neurons’ are typically premotor or parietal neurons that are active both when a subject perceives and executes an action. In a host of research projects which I’ll probably try to discuss later (I wrote a lengthy piece on them that was recently rejected by a major anthro publication, and I’m considering posting the original in the anthropology open source archive and then doing a MAJOR revision to seek publication elsewhere). Anyway, mirror neurons have been linked to action understanding, empathy, imitation (a personal interest), language, and ‘mind reading’ (not a sixth sense, but the abiltity to understand other’s intentions and perceptions).

A new paper by Caroline Catmur, Vincent Walsh, and Cecilia Heyes (one of the really innovative scholars working on mirror neuron research) in Current Biology has some fascinating implications for neuroanthropology(abstract or pdf download). In particular, the article suggests, in the words used in the abstract:

…it is unclear how mirror neurons acquire their mirror properties—how they derive the information necessary to match observed with executed actions. We address this by showing that it is possible to manipulate the selectivity of the human mirror system, and thereby make it operate as a countermirror system, by giving participants training to perform one action while observing another. Before this training, participants showed event-related muscle-specific responses to transcranial magnetic stimulation over motor cortex during observation of little- and index-finger movements. After training, this normal mirror effect was reversed. These results indicate that the mirror properties of the mirror system are neither wholly innate nor fixed once acquired; instead they develop through sensorimotor learning. Our findings indicate that the human mirror system is, to some extent, both a product and a process of social interaction [please note I’ve removed citation numbers that appear in the abstract].

In this particular case, the word ‘learned’ might suggest a greater degree of structuring or intent than something more neutral like, ‘mirror properties in neurons arise through sensorimotor development,’ but who am I to complain when so important a research team as that headed by Cecilia Heyes is providing us with well-designed, powerful demonstration of the emergent qualities of the brain, even something so foundational (and timely) as mirror properties in the premotor system. (Heyes is coming to Macquarie to speak in January, and I’m certainly looking forward to it.)

So what does this mean to anthropologists? Likely, not a lot. Unfortunately, the majority of the field, although it pays lip service to ‘practice,’ is really far more idealist, even in its treatment of things like skill acquisition, bodily enculturation, habits, and movement. That is, anthropologists tend to assume that there is some ideational, semiotic, or symbolic content ‘behind’ all movement, skill, or motor learning. The evidence from the brain sciences does not support the assumption that all implicit learning has ideational foundations or backing, but most models of culture really do not allow for motor learning to exist on its own as a relevant category of culture. I know, some will try to call me out on this and argue that late Pierre Bourdieu’s notion of the habitus is really a motor learning theory, but the fact that he has to assume that there is either a sociological structure (class) or cultural structure (a kind of crypto-structuralist cognitive set of categories) behind all action suggests that it is, ultimately, either a sociological- or cognitive-determinist model, not one that allows motor realms any autonomy.

In contrast, the discussion of mirror properties in the premotor system (and other places, as well) suggests that human enculturation might proceed through non-conscious, motor imitation shaped by (and shaping) the properties of the neurons responsible for motor apprehension and execution. The fact that Catmur and colleagues were able to ‘re-code’ mirror neurons to get them to match non-identical action supports Heyes’ and others’ contentions (against some who see mirror neuron properties as innate) that even these basic equivalences are established, at least partially, through experience. The fact that organisms dependably wind up with mirror neurons only demonstrates the degree to which certain properties of the developmental environment are stable (of course, this might not be the case when some basic part of the development relationship breaks down, as may be the case with autism, for example). The fact that a great deal of the ‘information’ necessary for development likely does not reside ‘in’ the genome has long been argued, for example, by Susan Oyama so persuasively in her book, The Ontogeny of Information: Developmental Systems and Evolution (Duke, 2000, 2nd revised edition).

The developmental origins of mirror neurons also runs counter to those who argue that the brain must have certain basic information ‘pre-programmed’ or ‘pre-wired’ so that it can perceive and accomplish certain tasks. This assumption, often under the rubric of ‘massive modularity,’ has been a hallmark of the way that brain sciences are being widely interpreted, even by those anthropologists who pay the neurosciences any attention. The ability to retrain such basic functions of neurons undermines the argument that these representational relations have to be foreordained for the brain to put them together.

7 thoughts on “Mirror effects in neurons learned?

  1. Pingback: Video Games and Cultural Perception « Neuroanthropology

  2. Greg,
    Great post, and fascinating research. I agree with your take on most cultural theory. The ideational approach will likely end up being shown to have small but consistent effects, I am thinking of the work of Bill Dressler on cultural consensus. Here’s a couple citations:
    2005 Dressler, William W. What’s cultural about biocultural research? Ethos 33: 20-45
    2007 Dressler, William W., Mauro C. Balieiro, Rosane P. Ribeiro, and José Ernesto Dos Santos. Cultural consonance and psychological distress: Examining the associations in multiple cultural domains. Culture, Medicine and Psychiatry 31: in press.

    But I think Bill overplays his hand too, seeing his approach as “the” way to both measure and explain culture–so he recreates the ideational problem.

    What’s more exciting to me in relation to your work is research that builds from perception and motor interactions to ideas and knowledge. I am thinking particularly of the work of Larry Barsalou in psychology at Emory. Here’s his website, you can download most of his papers there:

    This forthcoming review piece by Barsalou seems particularly relevant:

  3. Here’s a link I found from John Hawks’ blog on mirror neurons and video games! Sounds like we’re not so far off from each other, Greg.

    The original article is here in GameSpot, one of the more widely read gaming sites:

    So, have you heard of these super mirror neurons? Are these like second order or third order cognition? A literal embodiment of Pearce’s trilogy of signs?

  4. Greg, I came across these two citations, they might prove of interest given their focus on mirror neurons, motor gestures, and cultural variability.

    Molnar-Szakacs I, Wu AD, Robles FJ, Iacoboni M (2007) Do You See What I Mean? Corticospinal Excitability During Observation of Culture-Specific Gestures. PLoS ONE 2(7): e626. doi:10.1371/journal.pone.0000626
    http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0000626 [link doesn’t always work for me]
    People all over the world use their hands to communicate expressively. Autonomous gestures, also known as emblems, are highly social in nature, and convey conventionalized meaning without accompanying speech. To study the neural bases of cross-cultural social communication, we used single pulse transcranial magnetic stimulation (TMS) to measure corticospinal excitability (CSE) during observation of culture-specific emblems. Foreign Nicaraguan and familiar American emblems as well as meaningless control gestures were performed by both a Euro-American and a Nicaraguan actor. Euro-American participants demonstrated higher CSE during observation of the American compared to the Nicaraguan actor. This motor resonance phenomenon may reflect ethnic and cultural ingroup familiarity effects. However, participants also demonstrated a nearly significant (p = 0.053) actor by emblem interaction whereby both Nicaraguan and American emblems performed by the American actor elicited similar CSE, whereas Nicaraguan emblems performed by the Nicaraguan actor yielded higher CSE than American emblems. The latter result cannot be interpreted simply as an effect of ethnic ingroup familiarity. Thus, a likely explanation of these findings is that motor resonance is modulated by interacting biological and cultural factors.

    Modulation of Motor Cortex Excitability by Physical Similarity with an Observed Hand Action. Marie-Christine Désy and Hugo Théoret. PLoS ONE. 2007; 2(10): e971.
    The passive observation of hand actions is associated with increased motor cortex excitability, presumably reflecting activity within the human mirror neuron system (MNS). Recent data show that in-group ethnic membership increases motor cortex excitability during observation of culturally relevant hand gestures, suggesting that physical similarity with an observed body part may modulate MNS responses. Here, we ask whether the MNS is preferentially activated by passive observation of hand actions that are similar or dissimilar to self in terms of sex and skin color. Transcranial magnetic stimulation-induced motor evoked potentials were recorded from the first dorsal interosseus muscle while participants viewed videos depicting index finger movements made by female or male participants with black or white skin color. Forty-eight participants equally distributed in terms of sex and skin color participated in the study. Results show an interaction between self-attributes and physical attributes of the observed hand in the right motor cortex of female participants, where corticospinal excitability is increased during observation of hand actions in a different skin color than that of the observer. Our data show that specific physical properties of an observed action modulate motor cortex excitability and we hypothesize that in-group/out-group membership and self-related processes underlie these effects.

  5. Pingback: Beyond Bourdieu’s ‘body’ — giving too much credit? « Neuroanthropology

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