Applicant: Dr. med. Hedda Lausberg, Klinik für Neurologie, Charité Berlin
Bonus Grant by Charité Berlin, 199928024
Schedule: 2004-2005

In neuroimaging studies pantomiming the use of tools is often considered as a valid proxy for actual tool use and potential differences in the neural representations of these two essential human capacities have hardly been explored. However, neuropsychological lesion studies evidence that these the abilities to use actual tools and to pantomime their use may dissociate. Therefore, the present study investigates the cerebral activation patterns during pantomiming tool use with an imaginary tool in hand (Panto) as compared to demonstration with tool in hand (Tool Demo) by using functional MRI.

Fifteen right-handed male participants displayed Panto and Tool Demo with either hand in response to the visual / visual-tactile presentation of the tool. The conjunction analysis of the right and left hands executions of Panto relative to Tool Demo yielded significant activation in the left middle and superior temporal lobe. In contrast, Tool Demo relative to Panto revealed large bihemispherically distributed homologous areas of activation.        

In the specific context of our study design, the two contrasted conditions only differ regarding the fact that Panto but not Tool Demo requires to act with an imaginary tool in hand, i.e., to project the mental representation of a tool into the gesture space and integrate it in the execution of the movement concept. Thus far, studies have demonstrated the relevance of this left middle and superior temporal gyri in viewing, naming, and matching tools, in generating tool-related actions words and context assessments, and in observing moving tools. As all these factors do not apply to our study design, the present findings enhance the knowledge about the function of the left middle and superior temporal gyri in tool-related cognitive processes. We suggest that the left superior and middle temporal gyri are specifically involved in linking the mental representation of a tool with the appropriate movement concept.