RESEARCH REPORT POSTER DISPLAY

LOWER LIMB SENSORIMOTOR NETWORK: AN FMRI STUDY. Kapreli E^1,2, Athanasopoulos S¹, Strimpakos N², Papathanasiou M³, Gliatis I⁴, Van Hecke P⁵, Gouliamos A³, Peters R⁵, Sunaert S⁵; ¹Department of Sports Medicine and Biology of Exercise, Sports Physiotherapy Laboratory, National & Kapodistrian University of Athens, Greece. ²Department of Physiotherapy, T.E.I of Lamia, Greece. ³2nd Department of Radiology, Medical School, National & Kapodistrian University of Athens, Greece. ⁴Department of Orthopedics and Traumatology, University Hospital of Patras, Rio-Patras, Greece. ⁵Department of Radiology, University Hospitals of K.U. Leuven, Belgium

PURPOSE: The purpose of the current study was 1) to describe the pattern of whole brain activity during motion of isolated joints of the lower limb, 2) to examine the somatotopic organization of lower limb joint representations in the primary sensorimotor cortex and the anterior lobe of the cerebellum, and 3) to quantify the degree of overlap between these lower limb joint activations. RELEVANCE: The better understanding of central nervous system function during lower limb motion could enhance rehabilitation, formatting new aspects and purposes. PARTICIPANTS: Eighteen, right-leg dominant volunteers (n = 18, males, aged 27±5 years) participated in this study after giving written informed consent in accordance with Helsinki Declaration. The study protocol was approved by the Scientific Committee of Attikon University Hospital of Athens, Greece. METHODS: The fMRI measurements were carried out on a 1.5 T MR scanner (Gyroscan ACS-NT; Phillips) using a quadrate head coil. All subjects performed repetitive knee, ankle, and toes flexion/extension movements. In order to relate lower limb joints activation to the well described patterns of finger movement, serial finger-to-thumb opposition was assessed also. All movements were auditory paced at 72 beats/min (1.2 Hz). ANALYSIS: Statistical analysis was performed using SPM99 package implemented in Matlab. Statistical parametric mapping was used to analyze functional and anatomical data. The SPM activation maps of the different isolated joint movements were mapped on Caret 5.1 Atlas flat map. A statistical evaluation of somatotopy in contralateral SM1 and ipsilateral cerebellum (anterior lobe) during right-sided and left-sided movements was performed using one-way analysis of variance (ANOVA) and conditional on a significant main effect, Tukey’s least square difference tests were calculated for post-hoc identification of significantly different locations of individual joints representations. The significant threshold adopted throughout was p < 0.05. RESULTS: Isolated lower limbs movement activated a distributed sensorimotor network, including primary and nonprimary sensorimotor areas. Although a large overlap was evident in primary sensorimotor cortex (SM1) and cerebellum representations of the three lower limb joints, a somatotopic arrangement was recognizable with reference to center of mass coordinates of each individual joint in the above areas. CONCLUSIONS: A somatotopic arrangement was recognizable with reference to center- of-mass coordinates of each individual joint in SM1 and cerebellum, although ankle and toes presented a close neighboring position. The activated areas differed for the different joints of upper and lower limbs, not only considering the somatotopy but also the activation pattern of specific areas, implying the functional variation of the corresponding joints. IMPLICATIONS: Detection of active brain regions during movement of the lower limb joints is feasible with fMRI, encouraging future studies especially on neurological patients. However, a carefully optimized methodology protocol is required. KEYWORDS: primary sensorimotor cortex; cerebellum; somatotopy; brain activation; fMRI; lower limb. FUNDING ACKNOWLEDGEMENTS: The current study was supported by Marie Curie Training Fellowship (QLK2-CT-2000-60057). CONTACT: ekapreli@teilam.gr

ETHICS COMMITTEE: The study protocol was approved by the Scientific Committee of Attikon University Hospital of Athens, Greece.