This comes from
Cell Press's
Current Biology, a rare open access article available through the
Science Direct portal. This quick guide to mirror neurons accompanied a few temporarily open access articles from previous journals that examined mirror neurons, their functions, and the validity of the claims made for them. This is from 2009, so the info is mostly correct, but not fully so.
Christian Keysers; Social Brain Lab, Department of Neuroscience, University Medical Center, Groningen, Groningen and Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam
http://dx.doi.org/10.1016/j.cub.2009.08.026, How to Cite or Link Using DOI
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What are mirror neurons?
Mirror neurons are multimodal association neurons that increase their
activity during the execution of certain actions and while hearing or
seeing corresponding actions being performed by others. Neurons
responding to the sound or sight of some actions, but only to the
execution of different actions, are not mirror neurons.
Where are mirror neurons found? Three research groups have reported the existence of mirror neurons in three regions of the macaque cortex (Figure 1).
Pending systematic explorations, we do not know whether mirror neurons
exist elsewhere in the macaque brain. Recently, mirror neurons have also
been reported in the song-bird.
Figure 1. Mirror neurons.Left:
regions in which mirror neurons have been recorded in the macaque; and
right, voxels showing activity both during observation and execution in
the human brain (from Gazzola and Keysers (2009)). Both brains have been
partially inflated to reveal the sulci. Many brain regions have not yet
been explored for mirror neurons in the monkey, hence the ‘?’s. IPS,
intraparietal sulcus; PF/PFG, areas of the inferior parietal lobule.
Do humans have mirror neurons?
This issue has been highly contentious, with no individual piece of
evidence generally accepted as definitive, but quite a lot of indirect
evidence for human mirror neurons has been reported. First, if a subject
moves, the power of the mu-rhythm in the electro-encephalogram (EEG)
recorded from his or her brain decreases. Similarly, the EEG rhythm
desynchronizes when the subject observes somebody else move. Second,
behavioral experiments indicate that the execution of an action is
facilitated by viewing someone else execute a similar action, but
hindered by viewing an incompatible action. Moreover, transcranial
magnetic stimulation (TMS) studies evidence that watching performance of
an action facilitates the motor cortical representation of the muscles
involved in doing the same action. This shows that some neurons involved
in performing an action are indeed selectively activated by seeing a
similar action — in other words, mirror neurons do exist somewhere in
the human brain.
Read the whole article.
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