Neuroscientists have for decades attempted to understand the configuration of neural circuits. The objective of these attempts is to try and explain the versatility and flexibility of these actions that occur simultaneously and that are efficiently coordinated. The original attempt was through a study on neural circuits in relation to simple recurring behaviors like chewing, or walking, breathing that happens automatically. The circuits that control these activities that trigger the central pattern, and initiate recurrent behaviors, as well as control the responsible muscle, were seen to have a central pattern generator (Samulski et al., 2019). Nevertheless, it remains unclear how these generators cooperate so that they can coordinate in behaviors when numerous muscles take part in a specific behavior or in situations when a specific muscle is responsible for more than one behavior.
Existing studies on invertebrate systems have shown that there exist several neural architectures type namely multifunctional and devoted circuits. On the one hand, devoted circuits cause a specific behavior, which after being activated they block all other circuits responsible for causing other behaviors that use/share the same muscles (Stanek et al., 2014). On the other, multifunctional circuits consist of numerous building blocks attributed to several behavior types; however, not all building blocks are taken part in all behaviors (Berkowitz, 2016). On this basis, for a person to perform multiple simultaneous functions, the multifunctional circuits are at play.
In summary, it is essential to underline that the actions executed by a neuronal circuit are dependent on the features of its neurons as well as their interconnectivity pattern. Accordingly, motoneurons are responsible for transmitting motor instructions from the muscle’s central nervous system. Therefore, to understand the operation mechanism of a motor circuit, it is essential to first establish the premotor neurons attached to the motoneurons. It has been noted that certain premotor neurons present in more than one set of motoneurons (Stanek et al., 2014). Using the same mechanism, multifunctional circuits consist of numerous building blocks attributed to several behavior types that co-occur.
Berkowitz, A. (2016). Governing Behavior. Harvard University Press.
Morquette, P., & Kolta, A. (2014). How do we walk and chew gum at the same time?. Elife, 3. https://doi.org/10.7554/elife.03235
Samulski, B., Prebor, J., Armitano, C., & Morrison, S. (2019). Coupling of motor oscillators – What really happens when you chew gum and walk?. Neuroscience Letters, 698, 90-96. https://doi.org/10.1016/j.neulet.2019.01.016
Stanek, E., Cheng, S., Takatoh, J., Han, B., & Wang, F. (2014). Monosynaptic premotor circuit tracing reveals neural substrates for oro-motor coordination. Elife, 3. https://doi.org/10.7554/elife.02511