Uncorrected Author Proof NeuroRehabilitation xx (20xx) x–xx DOI:10.3233/NRE-161430 IOS Press 1 Afferent electrical stimulation during cycling improves spinal processing of sensorimotor function after incomplete spinal cord injury 1 2 3 4 Stefano Piazza a,∗ , DiegoSerrano-Mu˜ noz b , Julio G ´ omez-Soriano b,c , DiegoTorricelli a , Antonio Segura-Fragosa d , Jos´ e Luis Pons a,e and JulianTaylor b,f ,g 5 6 a Neural Rehabilitation Group, Cajal Institute, CSIC, Madrid, Spain 7 b Sensorimotor Function Group, Hospital Nacional de Parapl´ ejicos, Toledo, Spain 8 c Toledo Physiotherapy Research Group (GIFTO), Nursing and Physiotherapy School, Castilla La Mancha University, Toledo, Spain 9 10 d Health Sciences Institute, Avenida de Madrid s/n, Talavera de la Reina, Toledo, Spain 11 e Tecnol´ ogico de Monterrey, Mexico 12 f Stoke Mandeville Spinal Research, National Spinal Injuries Centre, Aylesbury HP218AL, UK 13 g Harris Manchester College, University of Oxford, Oxford OX1 3TD, UK 14 Abstract. 15 OBJECTIVE: Appropriate afferent feedback delivery during the execution of motor tasks is important for rehabilitation after incomplete spinal cord injury (iSCI). However, during leg-cycling therapy, the plantar afferent feedback is minimal. We hypothesize that the augmentation of sensory input by combining cycling with a locomotor-like stimulation of plantar cutaneous innervations (ES-cycling), might help to restore proper spinal processing of sensorimotor function. 16 17 18 19 METHODS: 13 non-injured subjects and 10 subjects with iSCI performed 10 minutes of cycling and, on another session, of ES-cycling. To assess spinal processing of sensorimotor function, soleus H-reflex response was tested following a conditioning plantar electrical stimulation applied at 25–100ms inter-stimulus intervals (ISI’s), measured before and after the execution of the tasks. 20 21 22 23 RESULTS: Before tasks execution, the conditioned H-reflex response was modulated in non-injured subjects, and absent in subjects with iSCI; after cycling, modulation profiles were unchanged. However, after ES-cycling a significant increase in H-reflex excitability was observed in the non-injured group at 100 ms ISI (p < 0.05), and in the iSCI group between 50–75 ms ISI (p < 0.001). 24 25 26 27 CONCLUSION: The loss of reflex modulation in subjects with iSCI suggests reduced spinal processing of sensorimotor function. Reflex modulation recovery after ES-cycling may indicate the partial reactivation of these mechanisms. 28 29 Keywords: Spinal cord injury, sensorimotor processing, soleus H-reflex, leg-cycling, afferent feedback 30 1. Introduction 31 During voluntary motor activities, afferent feed- 32 back interacts with descending input inducing 33 ∗ Address for correspondence: Stefano Piazza, Cajal Institute, Av Doctor Arce, 37, 28002 Madrid, Spain. Tel.: +34 915854750; Fax: +34 915854754; E-mail: stefano.piazza@csic.es. activity-dependent plasticity in the central nervous 34 system, at both brain and spinal cord level (Wolpaw, 35 2007). In particular, plantar cutaneous afferents from 36 the foot sole play an important role in reflex regulation 37 during the execution of phasic movements such as 38 locomotion (Panek, Bui, Wright, & Brownstone, 39 2014; Rossignol, Dubuc, & Gossard, 2006; Van 40 1053-8135/16/$35.00 © 2016 – IOS Press and the authors. All rights reserved