Brain machine interface (BMI) systems hold the potential to return lost functions to patients with motor disorders. Currently most efforts in BMI have concentrated on decoding neural activity from forearm areas of cortex to operate a robotic arm or perform other manipulation tasks. Efforts have neglected the locomotion functions of hindlimb / trunk cortex. However, the role of cortex in hindlimb locomotion of intact rats, which are often model systems for BMI testing, is usually considered to be small. Thus, the quality of representations of locomotion available in this area was uncertain. We designed a new rodent BMI system, and tested decoding of the kinematics of trunk and hindlimbs during locomotion using linear regression. Recordings were made from the motor cortex of the hindlimb / trunk area in rats using arrays of 6 tetrodes (24 channels total). We found that multiple movement related variables could be decoded simultaneously during locomotion, ranging from the proximal robot / pelvis attachment point, and the distal toe position, through hindlimb joint angles and limb endpoint in a polar coordinate system. Remarkably, the best reconstructed motion parameters were the more proximal kinematics, which might relate to global task variables. The pelvis motion was significantly better reconstructed than any other motion features.

Unlike adult spinalized rats, approximately 20% of rats spinalized as postnatal day 1 or 2 (P1/P2) neonates achieve autonomous hindlimb weight support. Cortical representations of mid/low trunk occur only in such rats with high weight support. However, the importance of hindlimb/trunk motor cortex in function of spinalized rats remains unclear. We tested the importance of trunk sensorimotor cortex in their locomotion using lesions guided by cortical microstimulation in P1/P2 weight-supporting neonatal spinalized rats and controls. In four intact control rats, lesions of hindlimb/trunk cortex caused no treadmill deficits. All spinalized rats lesioned in trunk cortex (n = 16: 4 transplant, 6 transect, 6 transect + fibrin glue) lost an average of about 40% of their weight support. Intact trunk cortex was essential to their level of function. Lesion of trunk cortex substantially increased roll of the hindquarters, which correlated to diminished weight support, but other kinematic stepping parameters showed little change. Embryonic day 14 (E14) transplants support development of the trunk motor representations in their normal location. We tested the role of novel relay circuits arising from the grafts in such cortical representations in E14 transplants using the rats that received (noncellular) fibrin glue grafting at P1/P2 (8 allografts and 32 xenografts). Fibrin-repaired rats with autonomous weight support also had trunk cortical representations similar to those of E14 transplant rats. Thus acellular repair and intrinsic plasticity were sufficient to support the observed features. Our data show that effective cortical mechanisms for trunk control are essential for autonomous weight support in P1/P2 spinalized rats and these can be achieved by intrinsic plasticity.

Background Rodents are important model systems used to explore Spinal Cord Injury (SCI) and rehabilitation, and Brain Machine Interfaces. We present a new method to provide mechanical interaction for BMI and rehabilitation in rat models of SCI. New Method We present the design and implantation procedures for a pelvic orthosis that allows direct force application to the skeleton in brain machine interface and robot rehabilitation applications in rodents. We detail the materials, construction, machining, surgery and validation of the device. Results We describe the statistical validation of the implant procedures by comparing stepping parameters of 8 rats prior to and after implantation and surgical recovery. An ANOVA showed no effects of the implantation on stepping. Paired tests in the individual rats also showed no effect in 7/8 rats and minor effects in the last rat, within the group's variance. Comparison with Existing Methods Our method allows interaction with rats at the pelvis without any perturbation of normal stepping in the intact rat. The method bypasses slings, and cuffs, avoiding cuff or slings squeezing the abdomen, or other altered sensory feedback. Our implant osseointegrates, and thus allows an efficient high bandwidth mechanical coupling to a robot. The implants support quadrupedal training and are readily integrated into either treadmill or overground contexts. Conclusions Our novel device and procedures support a range of novel experimental designs and motor tests for rehabilitative and augmentation devices in intact and SCI model rats, with the advantage of allowing direct force application at the pelvic bones.

Study Design. Prospective. Objectives. The goal of this study was to evaluate the effect of posterior spinal fusion surgery terminating at different lowest instrumented vertebrae (LIV) on trunk mobility in individuals with adolescent idiopathic scoliosis (AIS).NOT THE PUBLISHED VERSION; this is the author's final, peer-reviewed manuscript. The published version may be accessed by following the link in the citation at the bottom of the page.Spine Deformity, Vol 2, No. 4 (July 2014): pg. 291-300. DOI. This article is © Elsevier and permission has been granted for this version to appear in e-Publications@Marquette. Elsevier does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Elsevier. 3Summary of Background Data. Posterior spinal fusion with instrumentation is the standard surgical technique employed in AIS for correcting spine deformities with Cobb angles exceeding 50°. Surgical correction of curve deformity reduces trunk mobility and range of motion. However, conflicting findings from previous studies investigating the impact of different LIV levels on the reduction in trunk mobility after surgery have been reported. Methods. The study was designed as a prospective study with 47 patients (7 males and 40 females) with AIS who underwent posterior spinal fusion. Patients were classified into 5 groups based on their surgical LIV level (ie, T12, L1, L2, L3, and L4). Trunk flexion-extension (sagittal plane), lateral bending (coronal plane), and axial rotation (transverse plane) kinematics were assessed during preoperative, 1 year postoperative, and 2 years postoperative evaluation visits. Results. There were postoperative reductions of 41%, 51%, and 59% in trunk range of motion in the sagittal, coronal, and transverse planes, respectively (p < .0001). A trend toward greater postoperative reductions in peak forward flexion at more distal LIVs was observed (p = .04). Conclusions. Fusion reduces trunk mobility in the sagittal, coronal, and transverse planes. More distal LIV fusions limit peak forward flexion to a greater extent which is considered clinically significant. After fusion, the reductions seen in axial rotation, lateral bending, and backward extension do not differ significantly at more distal LIVs.