Reaction - Action - Intention: Neuroimaging and pathology

Simon B. Eickhoff
Institute for Clinical Neuroscience and Medical Psychology, Heinrich-Heine 
University Düsseldorf

Moving as a means to interact with the environment is one of the most basic features 
of life. When investigating the neuronal basis of (human) movement, processes that 
are more related to the kinematic-executive aspect of a movement, such as the 
computation of position and trajectories, kinematic fine-tuning by sensory feedback 
may be distinguished from more upstream processes related to action control. The 
latter comprise all those computations that control the choice of a particular 
movement from the available repertoire that will then be passed on to the executive 
parts of the motor system. Consequently, action control may be thought of as the 
translation of cognitive and affective but also mnestic, motivational and social 
representation into a physical effect, i.e., a motion. In congruence with this 
fundamental but also broadly defined role, disturbances of action control and 
psychomotor functions represent an important though often neglected hallmark of 
many (in particular psychiatric) brain disorders such as depression or schizophrenia. 
This talk is intended to provide an overview of both neuropsychological and 
functional neuroimaging findings addressing what may be conceptualized as different 
aspects of action control, ranging from stimulus-driven reactions to volitionally self-
initiated movements. Bringing together findings from behavioral investigations, 
activation studies and connectivity models, I will make the argument that aside from a 
few key regions that contribute to multiple processes, differential neuronal substrates 
may be identified for the different aspects of action control and which moreover show 
rather specific affections by mental disorders. In summary, this talk will make an 
argument for a albeit yet broad categorization of action control processes ranging 
from reaction to intentional action.