Science reports that people born without hands show ‘mirror neuron’ activity when they view hand actions, but in the area of the brain that controls the feet.
The ‘mirror neuron‘ system is a brain network that activates both when an action is being carried out, and when it is being observed, and has been hypothesised to be involved in perceiving and comprehending others’ actions.
The mirror neuron system is widely hyped but there’s no doubt it is an important brain function.
The researchers in this study were interested what sort of ‘mirror neuron’ activity would be apparent in people who had never had hands, while they watched hand actions.
The study, led by Dr Valeria Gazzola, recruited two people with arm aplasia, a developmental condition where the arms and hands are missing at birth, and sixteen comparison participants with normally developed hands.
The participants were brain scanned while being shown video of hands manipulating various objects (e.g. grabbing a glass or scooping soup out of a bowl) as well as still images of the hands resting behind the same objects.
Scans were also taken while participants completed actions with their lips, feet, and for the control group, with their hands – to see how this matched up with the ‘mirror neuron’ activity when watching the video.
When watching the hand actions, activity in the brain of two handless participants looked more like they were moving their feet.
As both participants use their feet to manipulate objects on a day-to-day basis, the researchers suggest that they are ‘mirroring’ the same goal, but using the brain systems that match how they would actually get the job done in everyday life.
One difficulty is that the activity from the two aplasic participants is quite variable, meaning the study really needs to be replicated to be sure of the effect.
However, if it bears out, it is a fascinating finding. It suggests that the mirror neuron system is much less action-based than we thought, and is, perhaps, equally as wrapped up with perceiving outcomes as movements.
Link to write-up from Science.
Link to abstract of scientific study.
One thought on “Hand actions fire mirror neurons in handless people”
I¬¥m also inlcined to believe that the human “mirror neuron system” is more tuned to goals rather than any duplication or emulation of a given movement. As Gallese and Goldman (1998) suggested, the primary evolutionary function of mirror neurons is to understand the “meaning” of actions.
But the dualistic property of intention and movement-the same intention to do something can recruit many distincts patterns of movement, or the inverse, different patterns of movement can involve the very same intention- seems difficult to reconcile any universal neuropragmatics codified by the human mirror system or in their co-cursors (or forerunners) in other non-human animals, i think. This finding is more approapiate to highlight the amazing ability of the brain to modified it¬¥s structure whatever function is involved, rather than anything else.