2009•Klinische NeurophysiologieRequires access
Functional anatomy of the human action recognition system
M Hören, Magnus‐Sebastian Vry, C.H. Läppchen, Mona Laible, J Hieß, Irina Mader, Cornelius Weiller, Farsin Hamzei
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Abstract
Mirror neurons were first described in the monkey premotor cortex (area F5) and are defined as neurons that are activated both when a goal directed action is performed and when the same action is observed (Rizzolatti et al., 1996, Gallese et al., 1996). However, the exact functional anatomy of mirror neurons in humans is still disputed. A wealth of literature showed that „mirror neuron's“ activity is localized particularly in the pars opercularis (BA44) within the inferior frontal gyrus (IFG) at the border to the premotor cortex (BA6) and within the anterior intraparietal sulcus (AIP). In 2005, the general opinion of the localisation of mirror neurons within IFG was confirmed by a meta analysis (Molnar-Sczakcs et al., 2005). The aim of this study was to identify the functional anatomical organisation of the action recognition system within IFG and to analyze the associated anatomical pathway between parietal and frontal cortex. 40 healthy subjects were investigated with the following paradigm: observation of an object-related grasping (OG) and imitation of the observed action (IM). Probabilistic fibre tracking was performed on diffusion tensor imaging data. Maximum activation peak voxel of OG was exhibited both within the pars triangularis and pars opercularis (dorsal part) of the IFG, as well as in the AIP. Conversely, IM activation was restricted to ventral and dorsal parts of the pars opercularis, and the parietal cortex. Common activation of OG and IM was localised in the dorsal pars opercularis and AIP. Connecting functionally relevant peak activation clusters of the parietal-frontal axis revealed distinct anatomical connectivity. AIP was connected with the pars opercularis via superior longitudinal fascicle III, whereas AIP was connected with pars triangularis via a ventral route through the extreme capsule. Spatially distinct connections for action observation and imitation lead to further insights into the role of mirror neurons in the context of action recognition.