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Refinement of Corticospinal Neuron Activity During Skilled Motor Acquisition

Weekly Seminar | Not Open to the Public
Who Should Attend: 


Dr. Nadjat Serradj's Photo
Research Scientist
Circuit Repair Laboratory
Burke Neurological Institute


The corticospinal tract is the principal mediator of skilled motor control. Cortical motor representations, or maps, depend on the underlying output of corticospinal and other corticofugal neurons. These maps are plastic and reorganize in response to skilled, but not unskilled, motor training. Modern optogenetic tools allow us to evaluate these networks by imaging endogenous activity of defined neurons over longitudinal studies. We used multiphoton imaging in concert with a head-fixed isometric pull task to record the effects of both skilled and unskilled training on the corticospinal circuit. Both tasks utilize the same muscle movements, and therefore are likely to engage the same motor circuits; however, only the skilled behavioral task was found to be dependent on the corticospinal system. We tracked forepaw corticospinal neuron activity over the course of motor task learning and found critical differences in the response to skilled and unskilled learning paradigms. The development of expertise occurred rapidly on an unskilled task and showed no significant correlation between corticospinal activity and movement kinetics; whereas development of skilled expertise required a refinement of movement kinetics and corresponding task-associated corticospinal neuron activity. Additionally, we found that disrupting corticospinal circuits results in a decorrelation of corticospinal neuron activity.

Dr. Nadjat Serradj's Figure

Figure. Model for plasticity within the motor cortex and spinal cord after SCI. 
Repeated optogenetic mapping of evoked motor maps (top insets) shows the 
early adaptation of maps after C5 dorsal column injury with increased forelimb 
flexor representation (red) and concurrent reduction of motor responses caudal 
to C5. Rehabilitation coincident with corticospinal regeneration promotes map 
reorganization: expansion of proximal extensor maps into de-efferented hindlimb 
regions. Serradj et al. Neurosci Lett (2017).


Najet Serradj, Sydney F Agger, Edmund R Hollis
Corticospinal circuit plasticity in motor rehabilitation from spinal cord injury
Neurosci Lett. 2017 Jun 23;652:94-104. doi: 10.1016/j.neulet.2016.12.003. Epub 2016 Dec 6.
Zirong Gu, Najet Serradj, Masaki Ueno, Mishi Liang, Jie Li, Mark L Baccei, John H Martin, Yutaka Yoshida
Skilled Movements Require Non-apoptotic Bax/Bak Pathway-Mediated Corticospinal Circuit Reorganization
Neuron. 2017 May 3;94(3):626-641.e4. doi: 10.1016/j.neuron.2017.04.019.
Najet Serradj, Sónia Paixão, Tomasz Sobocki, Mitchell Feinberg, Rüdiger Klein, Klas Kullander, John H Martin
EphA4-mediated ipsilateral corticospinal tract misprojections are necessary for bilateral voluntary movements but not bilateral stereotypic locomotion
J Neurosci. 2014 Apr 9;34(15):5211-21. doi: 10.1523/JNEUROSCI.4848-13.2014.


Tuesday, July 28, 2020 - 12:30pm


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