Tuesday, September 8, 2015
In the video by Dr. Derakhshan from his very interesting site Mimicking Man there is a demonstration of a patient with spasticity to the left arm with ipsilateral left hemisphere lesions. If we are wired simply as the right hemisphere controls only the left side of the body then and the left hemisphere controls only the right then there should not spasticity on the same side. His theory of the one directionality of the corpus callosum could explain the spasticity in the left if the dominant left hemisphere (my assumption)has a executive command for both and the lesion is in the specific area where it relates to control solely of the left arm. There appears to be some transient improvement in the movement of the left arm after he manipulates the right.
In the work with my left tongue there is and has been a feel that my usual mode of movement is more under control of what I assume to be my left hemisphere. It is commonly accepted the tongue as a whole should be half left and half right corresponding contralaterally. I have been working on trying to accentuate the ability of my left tongue throat musculature to be more independent which I have been messing around with the last 5 years or so.
The new movements that I am feel are mainly in the sub-lingual region when I try to access my left tongue/throat/face.. The 'left tongue movement is extremely tiny and often I am unclear if I am really moving it. However the sublingual region extending to below the hyoid even though small visibly feels much larger. The left lower face including left lips now are cooperating in a different way when I attempt to talk from the left side. The movements feel somewhat spastic and as if I am pushing through resistance. If I expand the area that I pay attention to, the spine and skull have a different sense of movement and orientation. There is some sense that I have to reorient what the right side musculature does to allow the left to be put in slight position of advantage. In kinesiology we are taught the lengthened position of the muscles are more advantageous than the ones at end range. With many of my right sided movements I feel my left has more of a stabilizing role where the right is given a position where it has relatively more freedom even before the movement is originated.
My gut feel is that my structures close to my midline are somehow more or less directed by the left hemisphere in my older more normal way of moving and still by far the usual if I am not paying attention. In a study referred by the Doctor it suggests what I found in my own movement. (Evidence for bilateral innervation of certain homologous motoneurone pools in man L. J. Carr, Linda M. Harrison * and J. A. Stephens)
Some significant quotes the first of which relates to the muscles of the more distal arms"This lack of a common drive to these co-contracting muscles is presumably commensurate with the independent control of the two arms by the central nervous system." and the following opposite behavior by the muscles closer to the midline "Cross-correlation analysis suggests that the left and right diaphragm, rectus abdominis and masseter muscles each share a common drive. As argued above, this drive probably comprises activity in last-order branched fibres and presynaptic synchronization. Focal magnetic stimulation of the motor cortex produced bilateral responses in these homologous muscle pairs. For the rectus abdominis and masseter muscle pairs, the latencies and sizes of these ipsilateral and contralateral responses were not significantly different. Taken together with the results of the cross-correlation analysis for these two muscle pairs, the results suggest that corticospinal fibres may provide the common drive to the left and right motoneurone pools. This common drive may arise from activity in corticospinal fibres that branch and supply the left and right motoneurone pools and from activity in corticospinal tract cells whose activity is synchronized at the cortical level." Much in the study is far above what I currently understand.
I have referred to the pelvic clock exercise by Moshe Feldenkrais before where over time and slow movements I learned the left lower quadrant of my stomach muscles never relaxed during the exercise until I learned how. If one lays on one's back and pretend one is laying on a clock with the center of the face under the middle of the sacrum one rolls the sacrum up to 12:00 and down to 6:00. The outside left in the middle is 3:00 and 9:00 is the outside right. To make the movement the more easier and pleasurable I had to come to the realization that I never relaxed the muscles of left lower quadrant musculature as the right upper contracted. In a sense fighting myself in doing the circle of the left lower quadrant. I could do the movement but with a sense of irritation and being rushed. Bringing that sense to the throat region, I could not separate in my mind what the left tongue/sub-lingual/face musculature does compared to the right. When I sense the the throat, tongue musculature I get a feel it is the most known but least accessible to differentiate in terms of movement. What is suggested by the Dr. Derakshan is that the control of the non dominant hemisphere from the dominant is always excitatory never inhibitive(relaxative).
However something as distal as my left hand should independent according to my model and from my understanding of the above study that he references in his article. There may be an executive timing motor planning issue directed from the left hemisphere that I can not rule out or feel, but the spasticity in the hand in the Dr's video suggest far more than that to me.
How can I can account for the difference? There is a theory about Kernohan's notch which the Doctor is well aware of and discounts. So there is a disconnect between what he is saying and I am feeling but there is also a large overlap as well. I can not account for the discrepancy in timing of attempted simultaneously movements. His idea the role of the non-dominant eye expanding the field of the dominant but not consciously seeing also corresponds to what I sense, but I do not think it is fixed in stone His study is scientifically based although not well accepted as far as I know. Mine is neither.