This project is supported by the German Research Foundation (HE 3592/7-1) Two methods for one network: Toward an understanding of the left lateralized pathways for tool use Salazar-López E. 1 , Brandi M.L. 1,2 , Schwaiger B. J. 2 , Goldenberg G. 3 , Wohlschläger A. 2 , Hermsdörfer J. 1 1 Department of Sport and Health Sciences, Technische Universität München 2 Klinikum Rechts der Isar, Neuroradiologie, Technische Universität München 3 Klinikum München-Bogenhausen, Klinik für Neuropsychologie, München elvira.salazar@tum.de Results A left-lateralized network is similarly involved in tool use in elderly healthy subjects and in LBD patients. In the fMRI study, the elderly subjects recruit a wider and less focused network during action planning but a smaller, weaker activation pattern during actual motion execution. The use of bars recruits a network similar to the one significant for tool use; however, in lesion studies the difference is manifested only in the dorso-dorsal pathway. References • Brandi, M. L., Wohlschlager, A., Sorg, C., & Hermsdorfer, J. (2014). The neural correlates of planning and executing actual tool use. J Neurosci, 34(39), 13183-13194. doi: 10.1523/jneurosci.0597-14.2014 • MGoldenberg G, Spatt J (2009) The neural basis of tool use. Brain 132:1645-1655 • Johnson-Frey, S. H. (2004). The neural bases of complex tool use in humans. Trends in Cognitive Science, 8(2), 71-78. Introduction The project investigates the neural networks involved in the daily use of tools. This fundamental human activity may be impaired in patients who have suffered strokes, particularly in the middle cerebral artery, resulting in apraxia. Previous experiments with healthy adults and brain damaged patients reveal that a left lateralized network is responsible for the manipulation and employment of tools. The tool carousel paradigm define the tool use network in healthy elderly subjects and left-sided chronic stroke patients (LBD) using well-controlled and comparable conditions of naturalistic tool use, while employing two fundamentally different methods of brain imaging. Results are expected to reveal a correspondence between areas activated by task performance and damaged areas in case of deficits. fMRI in healthy subjects N=17 healthy elderly adults Event related fMRI protocol for the task use/transport with the left hand. Data analyzed with SPM8 with the factor object (tools/bars) during planning and execution phase. Results are presented with FWE cluster correction (p < .001). Lesion analysis in brain damaged patients N= 31 LBD patients Execution of tool use with the left hand scored with a error scale. Brain lesions mapped using MRIcron and spatially processed and normalized with SPM8 using a symptom cost function masking to match MNI space. VLSM performed for continuous data with NPM, using non- parametric analyses with BM test corrected for FDR at threshold of p < 0.05. Methods -Similar version of “tool carousel”, an apparatus constructed for the presentation of (12) single tools and objects. -Task: actual tool use with tool and recipient present. Rotable tool carousel set. A Patient view, B Experimenter view, C Top view A Experimental set up for fMRI scans. B Examples of bars and tools used B A Map of the areas reflecting significant results for the contrast tool-baseline in the execution phase in healthy controls (cyan) and significant results for the VLSM of tool use in the group of LBD patients (red), as well as overlap (grey). Map of the areas reflecting for the plot of significant results for the contrast tool-baseline in the planning phase in healthy controls (cyan) and significant results for the VLSM of tool use in the group of LBD patients (red), as well as overlap (grey). Map of the areas reflecting significant results for the contrast tool-bar in the planning phase in healthy controls (cyan) and significant results for the VLSM of the difference tool minus bar in the group of LBD patients with disturbed tool use score (red), as well as overlap (grey). Conclusions • The correspondence of the areas revealed by fMRI in healthy subjects and left-side areas damaged in the patient group demonstrates the role of dorsal and ventral pathways in complex actions like tool use, with a particular emphasis on the frontal and parietal components. • The difference of the findings with the two neuroimaging methods allows to identify areas involved in the task (e.g. visual areas manifested in the fMRI study in planning phase for the baseline contrast), which are not relevant for tool use deficits in patients according to lesion analysis. • Areas presented in fMRI contrast but not relevant for tool use impairment according to lesion analysis in patients might be more sensitive to plasticity mechanisms, and therefore, less determinant for apraxic impairments. • The lesion analysis suggest similar areas responsible for processing bars and tools; however, the parietal and frontal areas not relevant for the use of the bar highlight their key role for tool use. • The carousel makes it possible to test actual tool use in a variety of populations, here in patients and healthy participants. Common but also specific networks found in the two studies contribute to present robust findings. Map of the areas reflecting significant results for the contrast tool-bar in the execution phase in healthy controls (cyan) and significant results for the VLSM of the difference tool minus bar in the group of LBD patients with disturbed tool use score (red), as well as overlap (grey). fMRI - planning: tools vs baseline VLSM in LBD: tool use score fMRI - execution: tools vs baseline VLSM in LBD: tool use score fMRI - planning: tools vs bars VLSM in LBD: tool – bar score fMRI – execution: tools vs bars VLSM in LBD: tool – bar score