Setup & Apparatus: Task: ! TRANSPORT task: reaching, grasping then transporting an object to the target container; ! USE task: reaching, grasping then pantomiming the use of a tool; ! Tool placement condition: handle-away-from-body and handle-towards-body. Procedure: ! Sequence: shutter close--Experimenter placed a tool-- shutter open--subjects start USE/TRANSPORT tasks. ! During TRANSPORT task, the object placement had to be synchronized with a 800 ms beep (distracter). ! Test sections: TRANSPORT-USE-TRANSPORT-USE, all tool placement conditions were randomized within and between subjects. Results Tool grasping in unilateral-brain-damage patients with/without apraxia Yong Li 1 , Jennifer Randerath 1 , Georg Goldenberg 2 & Joachim Hermsdörfer 1 1. Clinical Neuropsychology Research Group (EKN), Clinic for Neuropsychology, Hospital Munich-Bogenhausen 2. Clinic for Neuropsychology, Hospital Munich-Bogenhausen Email: Yong.Li@extern.lrz-muenchen.de Concepts, Actions, and Objects: Functional and Neural Perspectives (CAOs), April 19-22, 2007 Rovereto, Italy Background " Grip formation for tools varies dependent on the subsequent action (Rosenbaum et al. 1990). " The influence of the cognitive system may not be necessary for efficiently reaching and grasping an object, but at least partial information from the semantic system is needed to grasp an object appropriately in a manner defined by its functional identity (Creem and Proffitt, 2001). " Impaired conceptual knowledge about tool use and object function may contribute to defective tool use in left brain damage and apraxia patients. " Observed deficits of goal-directed movements of the ipsi-lesional hand in patients with unilateral brain damage suggest that online visuo-motor control may be affected. Research Questions: " This study investigates the access of conceptual knowledge and the role of biomechanical costs during tool prehension depending on the subsequent action performed with the tool. Discussion # Against our expectation, grasping for TRANSPORT was influenced by object function in all groups leading to hand-rotation-grip in the handle-away-from-body condition. # LBD patients showed the highest frequency of inappropriate hand grasp formation (non-hand-rotation-grip) during the handle-away-from-body condition in the USE task while this effect was less profound in RBD patients. # LBD patients with apraxia revealed a higher frequency of irregular hand grasp formation during handle-away-from-body condition than LBD without apraxia, i.e., employing less non-hand-rotation-grip in TRANSPORT task but more in USE task. This finding indicates that irregular hand grasp formation is highly correlated to LBD with Apraxia. Conclusion Our data suggest that left brain damage impairs the neural processing of conceptual knowledge of tool use depending on the demands of the subsequent task. In particular patients with apraxia seem unable to anticipate the subsequent action corresponding with their frequent failure to perform the subsequent pantomime. Semantic knowledge of object function seems nevertheless influential since the apraxic patients do not completely switch to a biomechanically easier grasp. Reference 1. Rosenbaum DA, Marchak F, Barnes HJ, Vaughan J, Slotta JD, Jorgensen MJ. Constraints for action selection: overhand versus underhand grips. In: Jeannerod M (ed) Motor Representation and Control. Attention and Performance . Lawrence Erlbaum, Hillsdale, New Jersey, 1999, 321-3422. 2. Creem SH, Proffitt DR. (2001) Grasping objects by their handles: a necessary interaction between cognition and action. J Exp Psychol Hum Percept Perform. 27(1):218-28. Data acquisition & analysis ! Hand grasp formation during the first contact served to characterize the different motor planning depending on the demands of the subsequent actions: $hand-rotation grip : expected in handle-away-from-body condition in USE task; $non-hand-rotation grip : expected in handle-towards-body condition in USE and TRANSPORT tasks as well as handle-away-from- body condition in TRANSPORT task. Methods Subjects: ! Patients: 10 Left-brain-damaged patients (LBD) and 7 Right-brain-damaged patients (RBD) performed the tasks with their non-involved hand. ! Controls: 7 Control Left (non-dominant hand, C_L) & 6 Control Right (dominant hand, C_R). TRANSPORT USE Handle-towards-body Handle-away-from-body Handle-towards-body Handle-away-from-body Non-hand-rotation-grip Hand-rotation-grip TRANSPORT: Handle-Towards-Body Condition 20 40 60 80 100 C_L C_R LBD RBD Group Non-rotation-grip Frequency (%) USE: Handle-Towards-Body Condition 20 40 60 80 100 C_L C_R LBD RBD Group Non-rotation-grip Frequency (%) TRANSPORT: Handle-Away-from-Body Condition 20 40 60 80 100 C_L C_R LBD RBD Group Non-rotation-grip Frequency (%) USE: Handle-Away-from-Body Condition 10 20 30 40 50 60 C_L C_R LBD RBD Group Non-rotation-grip Frequency (%) Handle-Towards-Body Condition 20 40 60 80 100 Non-Apraxia Apraxia Group Non-rotation-grip Frequency (%) TRANSPORT USE Handle-Away-from-Body Condition 20 40 60 80 100 Non-Apraxia Apraxia Group Non-rotation-grip Frequency (%) TRANSPORT USE Grip formation Grip formation of LBD patients : Non-Apraxia vs. Apraxia Shutter Zebris sensor Zebris Marker Target Container Beep PC