Neuropsychology of Action

 
 

What we are doing ...

 

Evaluation of object functionality and mechanical reasoning in humans

Humans among other species excel in the complexity and flexibility of tool usage and manipulation of objects. We investigate the cognitive evaluation of the possible use and manipulation offered by an object through its structure, texture, and material and the neuronal systems that are involved in this evaluation. How do we recognise the usefulness of a tool? What are memory and learned knowledge contributing to this cognitive process? What is the contribution of visual analysis and deductive reasoning? A small group of neurological patients demonstrates specific problems in understanding and using unknown and unfamiliar tools whereas they can easily use well-known standard tools. Therefore, examinations of such patients can help us to disentangle the abovementioned different contributions to tool evaluation and tool use.


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 in 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.