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Switches in the spinal cord

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Spinal cord injury disrupts connections between the brain and the spinal cord. However, some of the spinal cord circuits remain intact, but are not working properly anymore,   This leads for example to paralysis. In some cases, those circuits can be re-awakened, for example by using pharmacological agents or electrical stimulation.

ON and OFF switches in the spine
Contrary to what many believe the spinal cord is more than a bunch of cables relaying information from the brain to the body and vice-versa. In fact, it contains very complex circuits that are formed by a special type of neurons called interneurons. It is estimated that there are more than 100 billion interneurons in the human body, which makes them the most abundant type of neurons. Interneurons are like switches that are either turned ON or OFF, allowing or not the information to go through.

Spinal cord shutdown
The main result of this study is that spinal cord injury turns all switches OFF, meaning that no message is coming through. Interestingly, studies in animals show that the same injury results in a different degree of paralysis, depending on age, since in younger injured animals the same switches remain ON, allowing them to recover many lost functions. This means that there is a real possibility to revert the switches back ON. In conclusion the team identified an effective target on which rehabilitation and future treatments, e. g. pharmacological, should focus on in order to promote functional recovery.

This study was published in the journal Nature Neuroscience and was supported by Wings for Life.

Source: Bertels H, Vicente-Ortiz G, El Kanbi K, Takeoka A. Neurotransmitter phenotype switching by spinal excitatory interneurons regulates locomotor recovery after spinal cord injury. Nat Neurosci. 2022;25(5):617-629. doi:10.1038/s41593-022-01067-9

You can find out more on the spinal cord and the influence of its damage on the human body in our basic-information. Wings for Life Glossary gives an understanding of scientific terms.