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 Jack DiGiovanna
A1 Nadia Dominici
A1 Lucia Friedli
A1 Jacopo Rigosa
A1 Simone Duis
A1 Julie Kreider
A1 Janine Beauparlant
A1 Rubia van den Brand
A1 Marco Schieppati
A1 Silvestro Micera
A1 Grégoire Courtine
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.