Depth Electrode Recordings in the Brain
Marco Iacoboni, MD PhD, is a neurologist and neuroscientist originally from Italy. Today he is at the David Geffen School of Medicine at UCLA, where he serves on the faculty of the Department of Psychiatry and Biobehavioral Sciences and is Director of the Transcranial Magnetic Stimulation laboratory of the Ahmanson-Lovelace Brain Mapping Center. Iacoboni s lab is arguably the leading lab in human mirror neuron research and he has a close relationship with Giacomo Rizzolatti in whose lab mirror neurons were originally discovered in monkeys.
In the monkey premotor cortex, Rizzolatti and colleagues discovered cells that fire not only when the monkey performs goal oriented actions, but also when it observes the same action performed by somebody else. These cells are called mirror neurons, and are thought to be the evolutionary precursors of neural mechanisms supporting several aspects of social behavior, from imitation to empathy. The many evolutionary steps between small apes and humans suggest that mirror neurons may have also evolved from the monkey brain to the human brain. Investigations of the human brain, however, typically do not allow to study individual cells. Using a rare clinical opportunity, we have recently recorded single and multi-unit spiking activity from human neurons. Our data provide several novel findings: first, direct evidence for the existence of mirror neurons in the human brain; second, the anatomical distribution of these neurons extends from previously reported inferior frontal and inferior parietal cortex to the medial frontal and medial temporal cortices; third, excitatory and inhibitory responses in mirror neurons are equally represented; fourth, a third of human mirror neurons show opposing pattern of excitation and inhibition during action observation and action execution, a neural feature that may help preserving the sense of being the owner of an action during mirroring, and exert control on unwanted imitation. Taken together, these findings suggest that mirror neurons form a multimodal system for flexible integration of the perceptual and motor aspects of actions of the self and others.