Like 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.