RT Journal Article SR Electronic T1 Engagement of the Rat Hindlimb Motor Cortex across Natural Locomotor Behaviors JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 10440 OP 10455 DO 10.1523/JNEUROSCI.4343-15.2016 VO 36 IS 40 A1 DiGiovanna, Jack A1 Dominici, Nadia A1 Friedli, Lucia A1 Rigosa, Jacopo A1 Duis, Simone A1 Kreider, Julie A1 Beauparlant, Janine A1 van den Brand, Rubia A1 Schieppati, Marco A1 Micera, Silvestro A1 Courtine, Grégoire YR 2016 UL http://www.jneurosci.org/content/36/40/10440.abstract AB Contrary to cats and primates, cortical contribution to hindlimb locomotor movements is not critical in rats. However, the importance of the motor cortex to regain locomotion after neurological disorders in rats suggests that cortical engagement in hindlimb motor control may depend on the behavioral context. To investigate this possibility, we recorded whole-body kinematics, muscle synergies, and hindlimb motor cortex modulation in freely moving rats performing a range of natural locomotor procedures. We found that the activation of hindlimb motor cortex preceded gait initiation. During overground locomotion, the motor cortex exhibited consistent neuronal population responses that were synchronized with the spatiotemporal activation of hindlimb motoneurons. Behaviors requiring enhanced muscle activity or skilled paw placement correlated with substantial adjustment in neuronal population responses. In contrast, all rats exhibited a reduction of cortical activity during more automated behavior, such as stepping on a treadmill. Despite the facultative role of the motor cortex in the production of locomotion in rats, these results show that the encoding of hindlimb features in motor cortex dynamics is comparable in rats and cats. However, the extent of motor cortex modulations appears linked to the degree of volitional engagement and complexity of the task, reemphasizing the importance of goal-directed behaviors for motor control studies, rehabilitation, and neuroprosthetics.SIGNIFICANCE STATEMENT We mapped the neuronal population responses in the hindlimb motor cortex to hindlimb kinematics and hindlimb muscle synergies across a spectrum of natural locomotion behaviors. Robust task-specific neuronal population responses revealed that the rat motor cortex displays similar modulation as other mammals during locomotion. However, the reduced motor cortex activity during more automated behaviors suggests a relationship between the degree of engagement and task complexity. This relationship emphasizes the importance of the behavioral procedure to engage the motor cortex during motor control studies, gait rehabilitation, and locomotor neuroprosthetic developments in rats.