lecture x. brain pathways: movement · bio 3411 ! lecture x. brain pathways: movement! october 1,...
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Bio 3411 !Lecture X. Brain Pathways: Movement!
October 1, 2012!
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Lecture X. Brain Pathways: Movement!
Bio 3411 !Monday!
October 1, 2012!!
October 1, 2012! 1!Lecture X. Brain Pathways: Movement!
October 1, 2012! Lecture X. Brain Pathways: Movement!
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Neuroscience 5th ed!Page(s) !Feature!353-398!Upper motor control of !
! !Brain Stem and Spinal Cord!!Neuroscience 4th ed!Page(s) !Feature!423-451!Upper motor control of !
! !Brain Stem and Spinal Cord!!!The Brain Atlas 3rd ed!Page(s) !Feature!198-199 !Vestibular Pathways!200-201 !Direct Corticospinal tract!202-203 !Rubrospinal and Tectospinal tracts!204-205 !Reticulospinal Pathways!
Readings (background only)!
Bio 3411 !Lecture X. Brain Pathways: Movement!
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October 1, 2012! Lecture X. Brain Pathways: Movement!
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†Gleeson, J. G., Keeler, L. C., Parisi, M. A., Marsh, S. E., Chance, P. F., Glass, I. A., Graham Jr, J. M., Maria, B. L., Barkovich, A. J., & Dobyns, W. B. (2004). Molar tooth sign of the midbrain-hindbrain junction: occurrence in multiple distinct syndromes. Am J Med Genet A, 125A(2), 125-134; discussion 117.!
†Sicotte, N. L., Salamon, G., Shattuck, D. W., Hageman, N., Rub, U., Salamon, N., Drain, A. E., Demer, J. L., Engle, E. C., Alger, J. R., Baloh, R. W., Deller, T., & Jen, J. C. (2006). Diffusion tensor MRI shows abnormal brainstem crossing fibers associated with ROBO3 mutations. Neurology, 67(3), 519-521.!
†Tovar-Moll, F., Moll, J., Bramati, I. E., de Souza, A. S., Andreiuolo, P. A., & de Oliveira-Souza, R. (2007). The human pyramidal syndrome Redux. Neuroreport, 18(14), 1417-1421.!
†Vulliemoz, S., Raineteau, O., & Jabaudon, D. (2005). Reaching beyond the midline: why are human brains cross wired? Lancet Neurol, 4(2), 87-99.!
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†(pdfs on course websites: [http://www.nslc.wustl.edu/courses/Bio3411/bio3411.html]
References!
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What the last Lecture was About!!Sensory Transduction!
!Receptive Fields!
!Adaptation!
!Feature Detection!
!Maps!
!Sensory Integration !!
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Bio 3411 !Lecture X. Brain Pathways: Movement!
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October 1, 2012! Lecture X. Brain Pathways: Movement!
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Overview!Corticospinal Tract: Activation & Somatotopy!Activity of Motor Cortex Neurons Directs Movement:
Force & Direction!
Four Other Motor Pathways to Spinal Cord!Role(s) of Descending Pathways in Movement Control!Effects of Corticospinal Tract Lesion!Why is left right, and right left?!!
Corticospinal (Pyramidal) Pathway. !!This is the direct connection from the cerebral cortex for control of fine movements in the face and distal extremities, e.g., buttoning a jacket or playing at trumpet.!
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Bio 3411 !Lecture X. Brain Pathways: Movement!
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THE BRAIN ATLAS 3rd, pp. 36, 43!
Corticospial Tract (Pyramid) at Medulla!
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THE BRAIN ATLAS, 3rd ed., p. 147!
Pyramidal Tracts!
Cross Section Through Human Medulla!
Bio 3411 !Lecture X. Brain Pathways: Movement!
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THE BRAIN ATLAS 3rd ed, pp. 20, 201!
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Normal Pyramid
Electrical !stimulation of !different points !in motor cortex !with small !currents !(thresholds)!causes!different !movements!
Cartoons of movements evoked by direct cortical stimulation. The shading indicates the joint(s) moved.!!
Currents required to just provoke the above movements (threshold).!
Bio 3411 !Lecture X. Brain Pathways: Movement!
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The left hemisphere of the monkey brain - Motor (Ms) and Somatosensory (Sm) Maps!
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A neuron in the motor cortex of of an awake behaving monkey fires when the wrist is extended (red arrow in diagram above). It fires more when more force is required (flexors loaded) and not at all if no contraction is needed to extend the rest (extensors loaded). !
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A neuron in the motor cortex of of an awake behaving monkey fires in relation to the direction of the movement (see “tuning” curve - left).!
Each small vertical line marks an action potential of the neuron.!
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Sources of Descending Pathways for Movement Control!
4.!
3.!
2.!
1.!
4. Medulla (Reticular Formation and Vestibular Nuclei)!!
3. Pons (Reticular Formation)!
2. Midbrain (Red Nucleus & Superior Colliculus)!
1. Forebrain (Cortex) !
Bio 3411 !Lecture X. Brain Pathways: Movement!
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THE BRAIN ATLAS, 3rd ed, p. 203!
Rubrospinal Pathway. !!This pathway (from the red nucleus) mediates voluntary control of movements, excepting the fine movements of the fingers, toes and mouth.!
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THE BRAIN ATLAS, 3rd ed, p. 203!
Tectospinal Pathway. !!This pathway (from the superior colliculus) mediates head and body orientation in response to localized visual, auditory and tactile stimuli, often from the same source.!
Bio 3411 !Lecture X. Brain Pathways: Movement!
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THE BRAIN ATLAS, 3rd ed, pp. 199, 205!
Vestibulospinal Pathways. !!These pathways (from the vestibular nuclei) mediates head and body orientation in response to changes in head linear and angular velocity and with respect to gravity .!
Reticulospinal Pathways. !!These pathways carry information from the brain stem reticular formation to the spinal cord to stabilize movement on uneven surfaces.!
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Descending systems from the brain influence cells in the spinal cord to create movements. The cerebellum and the basal ganglia indirectly influence movements as indicated schematically here.!
Purves 5th ed, p. 354
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NEUROSCIENCE (1st ed), p. 319, Fig 16.8
Other cortical areas influence the initiation of movements to achieve particular goals through specific sequences, as in playing a scale on the piano. These areas are also activated when a person is instructed to think about performing the sequence without actually moving.!
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THE BRAIN ATLAS 3rd ed, pp. 36, 43!
Corticospial Tract (Pyramid) at Medulla!
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After the pyramid was cut
(lesioned) the
opposite hand (the
right hand) was used
to try to get food
from a well but all
fingers were used.
The monkey
could not get food from the smallest
well. !
The hand opposite the normal pyramid (the left hand) was used to get food from the small well by opposing the thumb and fore finger. The monkey got the food from the smallest well. !
Bio 3411 !Lecture X. Brain Pathways: Movement!
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Cut Pyramid Normal Pyramid
Electrical !stimulation of !
different points !in motor cortex !
with small !currents !
(thresholds)!causes!
different !movements!
After the pyramid
was cut the
movements were
coarser and the
currents required
to produce them
were larger.!
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(Tovar-Moll et al., 2007)!
Pyramid (CST)!
Normal!
Pathological!
Bio 3411 !Lecture X. Brain Pathways: Movement!
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Normal!
Pathological!
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(Tovar-Moll et al., 2007)!
Pyramid (CST)!
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The corticospinal (pyramidal) tract controls fine
movements particularly of the lips, fingers and toes.
When it is cut, other descending pathways such as the
rubrospinal pathway can be used for grasping
movements. These lack the precision of those activated
by the corticospinal pathway and the monkey cannot
pickup its food.!
Bio 3411 !Lecture X. Brain Pathways: Movement!
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Relative Size of Different Brain Parts In Phylogeny -!The forebrain becomes relatively larger as new pathways (functions) are added.!
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S. Ramón y Cajal, (1911) Histology of the Nervous System, Volume II. (English translation by N. & L. Swanson, Oxford: New York pp 309-310, 1995).
Ramón y Cajal suggested that brain pathways are crossed to preserve the appropriate relationships after optical inversion by the lens as indicated schematically by the arrows in the uncrossed (left) and the crossed (right) visual pathways. !
Why are brain pathways “crossed”?!
Bio 3411 !Lecture X. Brain Pathways: Movement!
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(Vulliemoz, Raineteau, & Jabaudon, 2005) !
HGPS!(horizontal gaze paralysis !and progressive scoliosis) !
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What this Lecture was about!Corticospinal Tract: Activation & Somatotopy!Activity of Motor Cortex Neurons Directs Movement:
Force & Direction!
Four Other Motor Pathways to Spinal Cord!Role(s) of Descending Pathways in Movement Control!Effects of Corticospinal Tract Lesion!Why is left right, and right left?!!
Bio 3411 !Lecture X. Brain Pathways: Movement!
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END!
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