[not in handout, see intranet]
Avenanti, A., Bueti, D., Galati, G., & Aglioti, S. M. (2005). Transcranial magnetic stimulation highlights the sensorimotor side of empathy for pain. Nature Neuroscience, 8(7), 955-960.
The authors suggest that freezing or response inhibition is a typical reaction to pain.
They measured the evoked potentials from two muscles in the hand after stimulating the relevant areas of motor cortex (via magnetic stimulation) while subjects observed 3 videos: a hand with a needle penetrating one of the muscles; a Q-tip being pressed on the same muscle; or the same needle penetrating a tomato.
The evoked motor potentials were inhibited when subjects were observing penetration of that particular muscle by a needle in another hand, but not in the control conditions.
The inhibition correlated with the subjects' subjective rating of the pain being experienced by the observed hand, and the interpretation is therefore in terms of empathy.