Larger than the Milky Way: Exploring Hidden Functions of the Nervous System

Faculty of Science
Better healthcare
Research and innovation
Students by the Rideau canal with STEM complex in the background
Comprising over 100 billion neurons and an enigmatic number of connections between them, the human nervous system is the most complex system in the body.

In fact, there are more connections in a single human brain than stars in the Milky Way! Exploring the nervous system is crucial to advance our understanding of bodily functions, human behaviour and cognition, as well as the progression of diseases and injuries.

Alex Laliberté, a Postdoctoral Fellow supervised by Professor Tuan Bui, studies the nervous system by breaking it down into more digestible populations of neurons. He is primarily studying DI3 interneurons – a spinal cord neuron population – to uncover their role in controlling movement. Alex established genetic systems that allow him to selectively express designer receptors exclusively activated by designer drugs (DREADDs). DREADDS were used to remotely turn the DI3 interneurons on and off in mice during different behavioural tasks. For instance, a drug was administered to mice to turn off their DI3 interneurons while they were running on a treadmill to observe how this would affect their running behaviour. Alex’s results showed that silencing DI3 interneurons in healthy mice had a fairly subtle effect on their movement. However, mice with spinal cord injuries lost their ability to support their body weight and to recover motor function. Mice with spinal cord injuries are capable of performing steps on a treadmill. The stepping function occurs despite the injury to the spinal cord through the activation of limb reflexes. The results from Alex’s experiments demonstrated that DI3 interneurons play an essential role in amplifying stretch reflexes and sensory information, functions that are essential to walking in mice following a spinal cord injury due to the body’s inability to send signals from the brain to the spinal cord.    

Alex Laliberté

Alex is also studying spasticity, an increased stiffness of muscles caused by brain or spinal cord injury that prevents normal movement. He is developing a new animal model of spasticity to replace existing ones that are not translatable to humans. Alex utilized optogenetics – a biological technique to control neuronal activity using light – to easily and consistently trigger spasms in mice with spinal cord injuries. This new model will allow him to collect spasm data faster and more reliably, as well as potentially test antispastic treatments.

Alex presented his remarkable findings at the 2022 International Motor Neuron Society meeting in Banff. He also received a 2-year, $200K USD fellowship from the Craig H. Neilsen Foundation to advance his research on spinal cord injury.

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