New Scientist - Mirror Neurons Reflect Personal Space

Mirror neurons are all the rage in neuroscience research, and here's another new study that reveals how these neurons help us decide how we create our personal space.

Mirror neurons reflect personal space

16 April 2009 by Helen Thomson

If somebody is in your personal space, you can thank a bunch of "mirror neurons" in your frontal lobes for helping you to decide how you should respond.

That's the conclusion of a study by German researchers that suggests mirror neurons, which fire both when you perform an action and when you watch someone else perform it, have greater responsibilities than were previously realised.

Antonino Casile from the Hertie Institute for Clinical Brain Research at the University of Tübingen in Germany and colleagues probed the personal space of two rhesus monkeys, while monitoring their mirror neurons that respond to seeing a human grasping an object some distance away.

Monkey do

The team compared how the neurons fired when a person grabbed a metallic object within a monkey's reach and again from a greater distance. They found that rather than simply responding to the action, the mirror neurons also responded to whether or not the action was close enough for the monkey to intervene.

Specific subsets of neurons responded to grasping actions inside and outside of a monkey's reach. Of the mirror neurons that fired when a monkey grabbed an object for itself around a quarter fired only in response to seeing a person grasp an object within the monkey's reaching distance while a different quarter responded to actions outside that space.

To show that those differing responses were to do with what the monkey could reach rather than how close an object was, the experimenters placed a panel in front of the primate's chair, preventing the monkey from reaching objects close to its body.

In this situation, the neurons that previously reacted to reachable objects no longer responded to the human's actions at all, suggesting that mirror neurons change their properties according to the possibility that one can act.

Decision time

"The mirror neurons extract features of actions that are important for generating behaviours. They're not only important to understanding what someone is doing, but they also generate a question of 'what can I do to respond? Shall I interact, shall I leave?'" says Casile.

Mirror neurons are located in the premotor cortex, a region that spans the top of the brain in the middle of the head, roughly where someone might wear an Alice band. In both humans and monkeys, the region engages in programming actions, which have always suggested that mirror neurons could be involved in taking action, says Christian Keysers, of the University of Groningen in the Netherlands. "So the finding that they are differentially affected by whether the observed action can be acted on immediately or has to be postponed till the monkey gets close enough makes perfect sense."

Journal reference: Science (DOI: 10.1126/science.1166818)

Tags: New Scientist, Mirror Neurons, Reflect Personal Space, Helen Thomson, Psychology, brain, consciousness, neuroscience