‘Plan’ to move fires up brain stem neurons

"We have also known that neurons in the [pedunculopontine nucleus] are activated during limb movement, but our study has shown they were also activated when patients were simply thinking about walking," says Pankaj Sah. "This is a complete surprise, because general thinking has been that movement planning takes place in the cortex, but this study indicates it might be happening in the brain stem as well." (Credit: Pliketi Plok/Flickr, font by Vernon Adams)

Neurons deep in the brain not only fire when people walk, but also when people think about walking, new research on Parkinson’s disease reveals.

Professor Pankaj Sah of the University of Queensland Brain Institute says the researchers examined the brains of 10 patients with Parkinson’s disease while the patients were awake during deep brain stimulation surgery, and found more than one part of the brain is responsible for planning movement.

“This study aimed to improve understanding of how different parts of the brain are involved in planning movement and controlling gait,” says Sah.

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The team was particularly interested in a part of the brain stem known as the pedunculopontine nucleus (PPN), which lies in the deepest part of the brain.

The PPN has previously been targeted as a treatment point for people with advanced Parkinson’s disease who are unable to walk.

“To date, we have known that walking is generally controlled by the outer part of the brain known as the cortex,” Sah says.

“When you decide to walk, the cortex sends signals to your brain stem which in turn signals the spinal cord to initiate movement.

“We have also known that neurons in the PPN are activated during limb movement, but our study has shown they were also activated when patients were simply thinking about walking.

“This is a complete surprise, because general thinking has been that movement planning takes place in the cortex, but this study indicates it might be happening in the brain stem as well.”

Parkinson’s disease, the second most common neurodegenerative disorder after Alzheimer’s disease, affects more than six million people globally.

Sah says improved understanding of how the brain plans movement could lead to more targeted treatments for people with Parkinson’s.

“The cells involved in these networks seem to be one type of cell, so when thinking about drug treatments for Parkinson’s, maybe we should be targeting these cells,” says Sah.

All the patients treated with deep brain stimulation also recorded positive outcomes with improvements with gait.

Grants from the Australian National Health and Medical Research Council and the Australian Research Council supported the work, which appears in Nature Neuroscience.

Source: University of Queensland