02316nas a2200157   4500008004100000245006500041210006500106300001600171490000800187520175900195100002501954700002101979700002302000700002402023856011102047       2025                        eng d00aBidirectional locomotion induces asymmetric limb adaptations0 aBidirectional locomotion induces asymmetric limb adaptations  a1774–17840 v1343 aHumans can acquire and maintain motor skills throughout their lives through motor learning. Motor learning and skill acquisition are essential for rehabilitation after neurological disease or injury. Adaptation, the initial stage of motor learning, involves short-term changes in motor performance in response to a new demand in the person’s environment. Repeated adaptation can improve skill performance and result in long-term skill retention. Locomotor adaptation has been extensively studied with split-belt treadmill paradigms. In this study we explored whether bidirectional walking (BDW) on a split-belt treadmill can induce short-term gait adaptations. Twelve healthy volunteers participated in our single session, starting with 2 min of forward walking (FW), followed by four 5-min blocks of BDW with a 1-min passive rest in between blocks, and ending with another 2-min block of FW. We recorded body kinematics and ground reaction forces throughout the experiment. Participants modified both temporal (interlimb phasing, double stance duration) and spatial (step length) aspects of gait to meet the mechanical demands of backward dual walking (BDW). Adaptation occurred rapidly, with bilateral reductions in step length, adjustments in stance and swing phase timing, alterations in interlimb phasing, and decreased double stance duration in the limb walking backward. Notably, only the backward-walking limb (right) exhibited persistent aftereffects upon return to FW. These results demonstrate that BDW elicits adaptations in both spatial and temporal gait parameters, with transient aftereffects consistent with short-term motor learning. To our knowledge, this is the first report characterizing such spatiotemporal adaptations during BDW.1 aHardesty, Russell, L1 aMojtabavi, Helia1 aGemoets, Darren, E1 aWolpaw, Jonathan, R  uhttps://neurotechcenter.org/publications/2025/bidirectional-locomotion-induces-asymmetric-limb-adaptations01898nas a2200241   4500008004100000245011900041210006900160300000800229490000800237520107300245100002401318700001701342700002101359700002501380700001301405700002201418700002301440700002401463700002201487700002101509700001101530856011501541       2025                        eng d00aSoleus H-reflex size versus stimulation rate in the presence of background muscle activity: a methodological study0 aSoleus Hreflex size versus stimulation rate in the presence of b  a2150 v2433 aHoffmann reflex (HR) operant conditioning (HROC) is an important intervention for neurorehabilitation. Current HROC paradigms elicit HRs at low rates (~ 0.2 Hz), minimizing rate-dependent depression (RDD). We investigated the impact of higher stimulation rates on HR size. Fifteen healthy participants maintained low background soleus electromyographic activity (EMG) while standing. Soleus HR and M-wave recruitment curves were obtained at rates of 0.2, 1, and 2 Hz twice, from which Mmax and Hmax were calculated. Seventy-five HRs were collected for each rate at a target M-wave size (~ 10 to 20% of Mmax). HR depression was minimal at higher stimulation rates. The mean HR amplitude was reliable across the two repetitions and three rates, with high intraclass correlation coefficient (ICC) values. HROC could be performed consistently at rates up to 2 Hz with minimal HR depression. Faster rates enable more conditioning trials per session, reducing session duration and/or number, thereby potentially accelerating conditioning and reducing participant burden.1 aBrangaccio, Jodi, A1 aGupta, Disha1 aMojtabavi, Helia1 aHardesty, Russell, L1 aHill, NJ1 aCarp, Jonathan, S1 aGemoets, Darren, E1 aVaughan, Theresa, M1 aNorton, James, JS1 aPerez, Monica, A1 aothers  uhttps://neurotechcenter.org/publications/2025/soleus-h-reflex-size-versus-stimulation-rate-presence-background00568nas a2200157   4500008004100000022001400041245007100055210006900126260001600195300001200211490000800223100002500231700002100256700002400277856010900301       2025                        eng d  a1522-159800aSpinal reflexes: a potential target for treating hemiparetic gait.0 aSpinal reflexes a potential target for treating hemiparetic gait  c2025 Jul 01  a290-2910 v1341 aHardesty, Russell, L1 aMojtabavi, Helia1 aWolpaw, Jonathan, R  uhttps://neurotechcenter.org/publications/2025/spinal-reflexes-potential-target-treating-hemiparetic-gait02054nas a2200157   4500008004100000022001400041245006600055210006500121260001600186520149000202100002501692700002101717700002301738700002401761856011101785       2024                        eng d  a2692-820500aBidirectional locomotion induces unilateral limb adaptations.0 aBidirectional locomotion induces unilateral limb adaptations  c2024 Aug 233 a<p>Humans can acquire and maintain motor skills throughout their lives through motor learning. Motor learning and skill acquisition are essential for rehabilitation following neurological disease or injury. Adaptation, the initial stage of motor learning, involves short-term changes in motor performance in response to a new demand in the person's environment. Repeated adaptation can improve skill performance and result in long-term skill retention. Locomotor adaptation is extensively studied using split-belt treadmill paradigms. In this study we explored whether bidirectional walking (BDW) on a split-belt treadmill can induce short-term gait adaptations. Twelve healthy volunteers participated in our single session, starting with 2 minutes of normal walking (NW), followed by four 5-minute blocks of BDW with a 1-minute passive rest in between blocks, and ending with another 2-minute of NW. We recorded body kinematics and ground reaction forces throughout the experiment. Participants quickly adapted to BDW with both legs showing decreased step lengths. However, only the backward-walking leg exhibited aftereffects upon returning to NW, indicating short-term adaptation. Notable kinematic changes were observed, particularly in hip extension and pelvis tilt, though these varied among participants. Our findings suggest that BDW induces unilateral adaptations despite bilateral changes in gait, offering new insights into locomotor control and spinal CPG organization.</p>1 aHardesty, Russell, L1 aMotjabavi, Helia1 aGemoets, Darren, E1 aWolpaw, Jonathan, R  uhttps://neurotechcenter.org/publications/2024/bidirectional-locomotion-induces-unilateral-limb-adaptations03176nas a2200277   4500008004100000022001400041245010400055210006900159260001200228300001100240490000800251520226600259653002102525653002902546653001102575653001702586653001302603653002102616653001202637653002102649653003802670100002502708700002202733700002402755856011902779       2023                        eng d  a1522-159800aThe human motor cortex contributes to gravity compensation to maintain posture and during reaching.0 ahuman motor cortex contributes to gravity compensation to mainta  c01/2023  a83-1010 v1293 a<p>The neural control of posture and movement is interdependent. During voluntary movement, the neural motor command is executed by the motor cortex through the corticospinal tract and its collaterals and subcortical targets. Here we address the question of whether the control mechanism for the postural adjustments at nonmoving joints is also involved in overcoming gravity at the moving joints. We used single-pulse transcranial magnetic stimulation to measure the corticospinal excitability in humans during postural and reaching tasks. We hypothesized that the corticospinal excitability is proportional to background muscle activity and the gravity-related joint moments during both static postures and reaching movements. To test this hypothesis, we used visual targets in virtual reality to instruct five postures and three movements with or against gravity. We then measured the amplitude and gain of motor evoked potentials in multiple arm and hand muscles at several phases of the reaching motion and during static postures. The stimulation caused motor evoked potentials in all muscles that were proportional to the muscle activity. During both static postures and reaching movements, the muscle activity and the corticospinal contribution to these muscles changed in proportion with the postural moments needed to support the arm against gravity, supporting the hypothesis. Notably, these changes happened not only in antigravity muscles. Altogether, these results provide evidence that the changes in corticospinal excitability cause muscle cocontraction that modulates limb stiffness. This suggests that the motor cortex is involved in producing postural adjustments that support the arm against gravity during posture maintenance and reaching. Animal studies suggest that the corticospinal tract and its collaterals are crucial for producing postural adjustments that accompany movement in limbs other than the moving limb. Here we provide evidence for a similar control schema for both arm posture maintenance and gravity compensation during movement of the same limb. The observed interplay between the postural and movement control signals within the corticospinal tract may help explain the underlying neural motor deficits after stroke.</p>10aElectromyography10aEvoked Potentials, Motor10aHumans10aMotor Cortex10aMovement10aMuscle, Skeletal10aPosture10aPyramidal Tracts10aTranscranial Magnetic Stimulation1 aHardesty, Russell, L1 aEllaway, Peter, H1 aGritsenko, Valeriya  uhttps://neurotechcenter.org/publications/2023/human-motor-cortex-contributes-gravity-compensation-maintain-posture