The Research Group "Neuropsychology of Action" is dedicated to investigations of human action control. We study clinical impairments of action control and their neural substrates in patients with brain damage due to stroke or neurodegenerative diseases. Through the observation of typical characteristics of their diseases and their participation in our experimental behavioural studies, these patients help us to understand not only the particular consequences of disorders of the sensory and motor systems but also to draw conclusions on the normal functioning of the intact systems in healthy humans. Our work with the patients motivates functional neuroimaging studies that explore the neuronal foundations of human motor behaviour. We are particulularly interested in the cortical systems of reach-to-grasp movements, cortical systems of tool use and tool evaluation, and sensorimotor functions and networks of the human tectum.
Evaluation of object functionality and mechanical reasoning in humans
Human action control is characterized by its impressive complexity and flexible adjustment in tool use and object manipulation. We aim to investigate the cognitive control mechanisms involved in the evaluation of action affordances associated with an object and their neuronal correlates. How do we recognize an usable tool for a particular technical problem? How do memory and acquired knowledge about tools on the one hand and visual analysis and deductive reasoning on the other hand contribute to our respective decision? A small group of brain-damaged patients are especially impaired in using novel, unfamiliar tools while they are less impaired in using familiar tools. The examination of such patients and further behavioral and neuroimaging studies based on observations in these patients can help us to understand the way different cognitive sources are combined to come up with a motor behavior that no other living species can match.
The human superior colliculi – a small big player in the human brain?
The superior colliculi are located at the upper brainstem of humans. In contradiction of established textbook knowledge, research in nonhuman primates through the last decade demonstrated that the superior colliculi play some role in the execution of arm movements. In our ongoing studies we found clear evidence for its role in the control of arm movements also in healthy humans. However, the precise functional contribution of the colliculi to the processes of planning and execution and the processing of a movement’s sensory feedback is still unknown. To explore this unknown territory we currently develop experimental designs that allow for event-related analyses and transfer our paradigms to the ultra-high field 9,4T scanner at the MPI for High-field Magnetic Resonance. Using tensor imaging and resting state fMRI we investigate the connectivity of the superior colliculi within the sensorimotor network. First studies in nonhuman primates have already demonstrated a connection between the functions of superior colliculi and the appearance of motor disorders like cervical dystonia. A precise functional mapping of the colliculi in living humans will not only be important for the understanding of neurological motor disorders but might also reveal that this concise structure could be good candidate regions in the framework of neuroprosthetics and brain stimulation in the future.
The impact of object knowledge on visual motor control
We grasp a screwdriver in a specific way if we are about to use it and in a very different way if we just want to put it aside. Despite of such quite obvious dependencies of visual motor control on object recognition, many researchers believe that the actual control of human grasping depends almost entirely on the direct visual information about object sizes irrespective of any stored knowledge in our memory. In contrast, we demonstrated that well established associations, build through a long-term learning process, are powerful enough to change visual motor control. Interestingly, we also observed some patients with impairments in the control of grasping who apparently exploited such associations for an individual improvement: they are better in grasping very familiar in comparison to neutral geometrical objects. Our work suggests that the role of object familiarity on the control of movements was underestimated in the past.
The role of dorsal and ventral visual systems on motor control
The two-visual-stream model of visual perception and visual action control had a considerable influence on the cognitive neuroscience of perception and action control over that last 25 years. As influential as it is, it also became heavily critisized by many researchers. Appreciating the enormous impetus of this model we scrutinise some of its basic assumptions and postulations. Thus, we investigate the influence of delays on hand- and arm-movement accuracy in healthy humans and patients with brain damage, particularly patients with optic ataxia or visual agnosia. We look into the cortical systems of online movement corrections and map the functional responses of the human parieto-occipital cortex during visually-guided reaching.
Coming soon
Hertie Center of Neurology
Hertie Institute for Clinical Brain Research
Otfried-Müller-Str. 27
72076 Tübingen
Phone: +49 (0)7071 29-81943
Fax: +49 (0)7071 29-5957
