Who’s copying who?

Hannah’s turned into a great eater. And before you think that this blog has degenerated into self-satisfied mommydom where I list off her preferred foods and tell you how cute it is when she can’t quite get something in her mouth (sweet potato, chicken and avocado, and the self-feeding thing IS hilarious) stick with me. She wasn’t always a great eater, in fact she was quite picky until a stampede breakfast of pancakes and yogurt got her going – oh stampede, you provide so much culinary delight! But I also think that a big part of what encouraged her to eat was something my mom teased me about – I open my mouth when I want her to, and I don’t even know I do it. My mom does it too, and I’m starting to think it’s a universal mom thing. So, of course, I checked google scholar.

There isn’t a lot of research specifically on why mothers open their own mouths to get their babies to eat, but let’s be honest, the topic doesn’t scream Nobel Prize. However, what is fascinating is research showing just how important social cues are to infant development. Most baby books emphasize how emotionally immature infants are – they cannot smile, cannot see their parents’ faces clearly, and in fact have no awareness of their own faces or limbs. However, research has shown that infants as young as twelve days are capable of imitating both facial and manual gestures (Meltzoff and Moore, 1977, Science 4312:75). This implies that they have an awareness of others and their own self that was previously thought to have taken months to develop.

Imitation, even in adults, turns out to be more common than we like to think. How many of us have been asked what kind of accent we have by someone with an accent, only to sheepishly realize that we’ve been unconsciously copying it? Compulsive imitation can occur in stroke patients who have a lesion in their frontal lobes (Lhermitte, F. et al. 1986, Annals of Neurology, 19:326), which suggests that their ability to voluntarily control their imitative behaviour is compromised. However, it was experiments in macaques that showed just how important imitation in is a social species.

In the early 1990s, Giacomo Rizolatti and coworkers were surprised to discover that certain neurons within the brains of macaques activated not only when the monkeys performed a simple task like grasping food, but also when they watched someone else (macaque or human) doing the same task. In other words, perception of an activity resulted in activation of the neurons that would perform that task. The authors termed them mirror neurons. In 1996 a similar phenomenon was observed in humans using PET imaging; when someone grasping an object, subjects showed activation in not only the visual cortex, but in motor areas that would be involved in grasping (Rizolatti and Fabbri-Destro, 2010, Experimental Brain Research, 200:223). This observation revolutionized our understanding of cognition; previously it was thought that the observation of an act required higher order processing in order to be understood. This may still happen for complex tasks, but simple tasks elicit an extreme empathy – the observer mentally imitates the object of her vision.

And in fact mirror neurons may have a lot to do with empathy. When interacting with people, we unconsciously mimic our conversational partner. Children diagnosed with autism, a disorder that includes deficits in empathy, do not mimic others when interacting, and fMRI studies have shown that areas of the brain that become active during observation in normally developing children were underactivated, or silent, in children with autism (Rizolatti and Fabbri-Destro, 2010, Experimental Brain Research, 200:223). In fact, being unable to mimic an expression may impair one’s ability to empathize: a study currently under review suggests that when frozen by botox and rendered unable to frown, subjects were impaired in their ability to interpret sentences that described sad situations (Havas et al. 2009).

Do infants mirror the adults around them in the same way? It has been established that infants mimic their parents at an astonishingly early age, but this could simply be reflex. Imitation in infants starts to lessen after about five months, which is when other reflexive behaviours also start to wane. However, infants have been shown to mimic not only when they see an action, but also when they hear a stimulus associated with that action. This suggests that there might be something more complex going on than simple reflexive mimicry (Bertenthal and Longo, 2007, Developmental Science, 10:526).

Despite the tantalizing clues, there remains a great deal of uncertainty in this area. Mirror neurons have not been directly observed in humans in the same manner that they have in monkeys. Though the name is catchy, it’s not clear whether there are specific neurons in the brain that perform mirror tasks, or whether this is a more generalized phenomenon. However, it is clear that there’s a neural basis to empathy that is more specific and more important than we had previously supposed. The findings that we reflexively try on the emotions of those with whom we communicate suggest that empathy is not simply a nicety but an integral part of how social beings interact. In a bond as strong as that between mother and child, the ties of empathy are crucial, and if it means that mother has to look silly, with phantom bites at an invisible spoon, then so be it.