What disconnection tells about motor imagery: evidence from paraplegic patients.

Wise Young · 03-28-2005, 09:49 PM

So, have you ever wondered what happens in your brain when you have spinal cord injury and you try to move? These investigators imaged brain activity with fMRI in paraplegic patients who tried to move their legs. Interestingly, they found activity in the motor cortex when people tried to execute movements and this activity is as strong and even stronger than in non-injured subjects. Furthermore, the activation in the cortex correlated with the vividness of movement imagery.

[QUOTE]
Alkadhi H, Brugger P, Boendermaker SH, Crelier G, Curt A, Hepp-Reymond MC and Kollias SS (2005). What disconnection tells about motor imagery: evidence from paraplegic patients. Cereb Cortex 15: 131-40. Brain activation during motor imagery has been the subject of a large number of studies in healthy subjects, leading to divergent interpretations with respect to the role of descending pathways and kinesthetic feedback on the mental rehearsal of movements. We investigated patients with complete spinal cord injury (SCI) to find out how the complete disruption of motor efferents and sensory afferents influences brain activation during motor imagery of the disconnected feet. Eight SCI patients underwent behavioral assessment and functional magnetic resonance imaging. When compared to a healthy population, stronger activity was detected in primary and all non-primary motor cortical areas and subcortical regions. In paraplegic patients the primary motor cortex was consistently activated, even to the same degree as during movement execution in the controls. Motor imagery in SCI patients activated in parallel both the motor execution and motor imagery networks of healthy subjects. In paraplegics the extent of activation in the primary motor cortex and in mesial non-primary motor areas was significantly correlated with the vividness of movement imagery, as assessed by an interview. The present findings provide new insights on the neuroanatomy of motor imagery and the possible role of kinesthetic feedback in the suppression of cortical motor output required during covert movements. Institute of Neuroradiology, University Hospital Zurich, CH-8091 Zurich, Switzerland.

Link Here

[This message was edited by mk99 on 03-30-05 at 09:08 AM.]

manouli · 03-29-2005, 05:37 AM

Dr. Young, I am C7-C8 complete and any time i try to move my feet, i feel like someone is squeeze my legs hard and won't let them go. When I am thinking and try to move my big toe i am getting spasm on my toe and feel like butterflies are moving on my legs. Hey my friends, what feelings do you get? Maybe we all feel the same. manouli.

Wise Young · 03-29-2005, 06:18 PM

Manuouli,

I think that two things are happening when you try to move your legs. The first is what this article describes... you are turning on those portions of your brain that would normally send messages to your spinal cord to move those muscles. Probably, some of the messages are getting through because you are seeing spasm in your toe and feel butterflies moving on your legs. Second, after injury, there is a lot of rewiring in your brain and spinal cord above the injury site, as well as separate rewiring of circuits below the injury site. This is because a lot of neurons have lost their connections. Other connections replace them. Some of those connections are aberrant, in other words, abnormal and would not normally occur. This may account for the "squeeze" feeling in your legs. Your brain is interpreting these local signals.

The brain is actually much more plastic than we had ever imagined it could be. Various studies have now shown that the visual cortex can be taken over for somatosensory functions when you blindfold a person for a week. People's ability to read braille with their fingertips improve dramatically when they have been blindfolded for a week. When the people use their fingers to read, the visual cortex lights up with activity, suggesting that the somatosensory systems have recruited the unused visual cortex to help with interpreting what the fingers are "seeing". When you take the blind-fold off, the activity levels in the visual cortex fall off over a day or two.

Spinal cord injury essentially denervates over a third or more of brain cells that normally receive inputs from the body. Many of the neurons that were previously devoted to controlling motor systems now have little to do. I have always thought that if I were spinal-injured, I would learn a new language or two, try to play music, and try to make more use of my unused cortex. I would probably figure, why not... until the cure comes?

Wise.

manouli · 03-30-2005, 03:20 PM

Thank you Dr. Young for making it easy for me to understand why I have these responses.manouli.

03-28-2005, 09:49 PM	#1
Wise Young Administrator Join Date: Jul 2001 Location: New Brunswick, NJ, USA Posts: 37,988	What disconnection tells about motor imagery: evidence from paraplegic patients. So, have you ever wondered what happens in your brain when you have spinal cord injury and you try to move? These investigators imaged brain activity with fMRI in paraplegic patients who tried to move their legs. Interestingly, they found activity in the motor cortex when people tried to execute movements and this activity is as strong and even stronger than in non-injured subjects. Furthermore, the activation in the cortex correlated with the vividness of movement imagery. [QUOTE] Alkadhi H, Brugger P, Boendermaker SH, Crelier G, Curt A, Hepp-Reymond MC and Kollias SS (2005). What disconnection tells about motor imagery: evidence from paraplegic patients. Cereb Cortex 15: 131-40. Brain activation during motor imagery has been the subject of a large number of studies in healthy subjects, leading to divergent interpretations with respect to the role of descending pathways and kinesthetic feedback on the mental rehearsal of movements. We investigated patients with complete spinal cord injury (SCI) to find out how the complete disruption of motor efferents and sensory afferents influences brain activation during motor imagery of the disconnected feet. Eight SCI patients underwent behavioral assessment and functional magnetic resonance imaging. When compared to a healthy population, stronger activity was detected in primary and all non-primary motor cortical areas and subcortical regions. In paraplegic patients the primary motor cortex was consistently activated, even to the same degree as during movement execution in the controls. Motor imagery in SCI patients activated in parallel both the motor execution and motor imagery networks of healthy subjects. In paraplegics the extent of activation in the primary motor cortex and in mesial non-primary motor areas was significantly correlated with the vividness of movement imagery, as assessed by an interview. The present findings provide new insights on the neuroanatomy of motor imagery and the possible role of kinesthetic feedback in the suppression of cortical motor output required during covert movements. Institute of Neuroradiology, University Hospital Zurich, CH-8091 Zurich, Switzerland. Link Here [This message was edited by mk99 on 03-30-05 at 09:08 AM.]

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03-29-2005, 05:37 AM	#2
manouli Senior Member Join Date: Nov 2004 Location: florida Posts: 9,356	Dr. Young, I am C7-C8 complete and any time i try to move my feet, i feel like someone is squeeze my legs hard and won't let them go. When I am thinking and try to move my big toe i am getting spasm on my toe and feel like butterflies are moving on my legs. Hey my friends, what feelings do you get? Maybe we all feel the same. manouli.

03-29-2005, 06:18 PM	#3
Wise Young Administrator Join Date: Jul 2001 Location: New Brunswick, NJ, USA Posts: 37,988	Manuouli, I think that two things are happening when you try to move your legs. The first is what this article describes... you are turning on those portions of your brain that would normally send messages to your spinal cord to move those muscles. Probably, some of the messages are getting through because you are seeing spasm in your toe and feel butterflies moving on your legs. Second, after injury, there is a lot of rewiring in your brain and spinal cord above the injury site, as well as separate rewiring of circuits below the injury site. This is because a lot of neurons have lost their connections. Other connections replace them. Some of those connections are aberrant, in other words, abnormal and would not normally occur. This may account for the "squeeze" feeling in your legs. Your brain is interpreting these local signals. The brain is actually much more plastic than we had ever imagined it could be. Various studies have now shown that the visual cortex can be taken over for somatosensory functions when you blindfold a person for a week. People's ability to read braille with their fingertips improve dramatically when they have been blindfolded for a week. When the people use their fingers to read, the visual cortex lights up with activity, suggesting that the somatosensory systems have recruited the unused visual cortex to help with interpreting what the fingers are "seeing". When you take the blind-fold off, the activity levels in the visual cortex fall off over a day or two. Spinal cord injury essentially denervates over a third or more of brain cells that normally receive inputs from the body. Many of the neurons that were previously devoted to controlling motor systems now have little to do. I have always thought that if I were spinal-injured, I would learn a new language or two, try to play music, and try to make more use of my unused cortex. I would probably figure, why not... until the cure comes? Wise.

03-30-2005, 03:20 PM	#4
manouli Senior Member Join Date: Nov 2004 Location: florida Posts: 9,356	Thank you Dr. Young for making it easy for me to understand why I have these responses.manouli.