Motor system corticospinal
Transcript of Motor system corticospinal
VOLUNTARY MOTOR CONTROL
ORGANIZATION OF MOTOR NERVOUS SYSTEM
CONTROL OF VOLUNTARY MOVEMENT
ORGANIZATION OF MOTOR SYSTEM
SEARCH FOR SEAT OF MINDAncient
THE RENAISSANCE OF NEUROSCIENCE
BIRTH OF NEUROANATOMY
1664 - Thomas WillisAndreas Vesalius
Leonardo Da Vinci
BIRTH OF NEUROPHYSIOLOGY
1791 - Luigi Galvani
1809 - Luigi Rolando
LOCALIZING BRAIN FUNCTIONRecent
PHRENOLOGY FRANZ JOSEPH GALL 1806
The theory of Gall and Spurzheim is ... an instance of a theory which, while essentially wrong, was just enough right to further scientific thought…Edwin Boring
1824 - MARIE-JEAN-PIERRE FLOURENS
CHARLES DARWIN 1808-1882
1825 - JEAN-BAPTISTE BOUILLAUD Presents cases of loss of
speech after frontal lesions from clinicopathological correlation.
We cannot test speech in animal
Frontal lobe has other higher function which differentiate from animal.
By symptom we can localize the cerebral lesion.
Cerebellum controlled equilibrium and station
Frontal lobe and higher mental functions
HUGHLING JACKSON 1858
Three level of organization Spinal/brain stem Frontal Prefrontal
Sensory integration and role of Basal ganglia was missed
PIERRE GRATIOLET <>ERNEST AUBURTIN
brain acted as a whole and that localized functional centers did not exist
Brain Size and Volume
Paul Broca 1861
1870, HITZIG AND FRITSCH Electrically stimulated various
parts of a dog's motor cortex. They observed that
depending on what part of the cortex they stimulated, a different part of the body contracted.
Then they found that if they destroyed this same small area of the cortex, the corresponding part of the body became paralyzed.
This is how it was discovered that every part of the body has a particular region of the primary motor cortex that controls its movement.
1870 - DAVID FERRIER
DISCOVERY OF NEURON
Ramony Cajal and Camillo Golgi 1906 Noble
1906 - SIR CHARLES SCOTT SHERRINGTON
1906- The Integrative Action of the Nervous system that describes the synapse and motor cortex
Spinal reflex 1932 Nobel Prize
LEYTON SSF & SHERRINGTON CS (1917).OBSERVATIONS ON THE EXCITABLE CORTEX OF THE CHIMPANZEE, ORANG-UTAN AND GORILLA. Q J EXP PHYSIOL 11, 135–222.
Figure 1. Motor maps of the gorilla cortexA, scale drawing of the left hemisphere of one of Leyton & Sherrington’s experiments
on a gorilla (gorilla 1). The numbers and letters encode a wide range of different primary movements evoked by faradic stimulation. Eye movements (372–388) were generally evoked from an area further rostral from the motor cortex. Owing to lack of space, many motor effects were not plotted. B, simplified ‘map’ showing ‘responses grouped diagrammatically’,
BRODMANN’S AREA: 1909
FUNCTIONAL ORGANIZATION OF THE PRIMARY MOTOR CORTEX
MORE INTRICATE MOTOR MAPS Intracortical micro-stimulation
of layer V confirms the spatial motor map of Penfield
Stimulation of small regions of the map activated single muscles, suggesting that vertical columns of cells in the motor cortex were responsible for controlling the actions of particular muscles.
Microstimulation with simultaneous EMG recording shows that organized movements represented in motor map
Individual pyramidal cells terminates on group of muscles in anterior horn cells in mosaic fashion
LATERAL AND MEDIAL SYSTEM
The initiation of skilled voluntary movement in primates
Loss of precise movement, retained power movement by lateral corticospinal destruction
Anterior corticospinal system destruction produce axial muscle deficits that cause difficulty with balance, walking, and climbing.
CORTICAL CONTROL OF MOVEMENT
1947 Chang, Ruth could stimulate individual muscle by monkey motor cortex stimulation
1954 Bernhard and Bohm : single shock stimulation produces monosynaptic response in forelimb
Landgren, Phillips and Porter (1962). stimulated the surface of the motor cortex while recording intracellularly from motoneurons and demonstrated the existante of a cluster of neurons which projected monosynaptically to motor neurons
1953, Malis, Pribram and Kruger showed that the motor cortex received afferent inputs from the periphery in the absence of the sensory cortex
CELLULAR ORGANIZATION OF M1
THE ORGANIZATION OF CORTICAL EFFERENT SYSTEM
AFFERENT CORTICAL ZONES
EXPERIMENTAL APPARATUS DEVELOPED TO RECORD THE ACTIVITY OF SINGLE NEURONS IN AWAKE PRIMATES TRAINED TO PERFORM SPECIFIC MOVEMENTS : ED EVARTS 1960
DIRECT CORTICOSPINAL CONTROL OF MOTOR NEURONS IS NECESSARY FOR FINE CONTROL OF THE DIGITS
MOTOR CORTICAL CELL FIRING WITH FORCE GENERATED
CORTICOMOTONEURONAL (CM) CELL IS ACTIVE DEPENDS ON THE MOTOR TASK
ACTIVITY IN INDIVIDUAL NEURONS OF THE PRIMARY MOTOR CORTEX IS RELATED TO MUSCLE FORCE AND DIRECTION OF MOVEMENT
SPIKE TRIGGERED AVERAGING 1970
DIFFERENT AREAS OF CORTEX ARE ACTIVATED DURING SIMPLE, COMPLEX, AND IMAGINED SEQUENCES OF FINGER MOVEMENTS (XENON PET)
CELL ACTIVITY IN THE MOTOR CORTEX DEPENDS ON WHETHER A SEQUENCE OF MOVEMENTS IS GUIDED BY VISUAL CUES OR BY PRIOR TRAINING
A SET-RELATED NEURON IN THE DORSAL PREMOTOR AREA BECOMES ACTIVE WHILE THE MONKEY PREPARES TO MAKE A MOVEMENT TO THE LEFT
DIRECTION TUNING IN MOTOR CORTEX; CONTROL OF KINEMATIC VARIABLES
MOTOR CORTEX CONTROL MUSCLE OR MOVEMENT?
REPRESENTATION OF SPEED IN A MOTOR CORTEX CELL
THE CASE FOR KINETIC CONTROL
THE VISUOMOTOR TRANSFORMATIONS REQUIRED FOR REACHING AND GRASPING INVOLVE TWO DIFFERENT PATHWAYS
Individual neurons in the ventral premotor area fire during specific hand actions only
A. ACTIVITY IN THE NEURON AS THE MONKEY OBSERVES ANOTHER MONKEY MAKE A PRECISION GROUP.B. ACTIVITY IN THE SAME NEURON AS THE MONKEY OBSERVES THE HUMAN EXPERIMENTER MAKE THE PRECISION GRIP.C. ACTIVITY IN THE SAME NEURON AS THE MONKEY ITSELF PERFORMS A PRECISION GRIP. (FROM RIZZOLOTTI ET AL 1996.)
CORTICAL MOTOR AREAS
MOTOR CORTICAL CENTER
THE SOMATOTOPIC ORGANIZATION OF THE MOTOR CORTEX IS PLASTIC
AS A MOVEMENT BECOMES MORE PRACTICED, IT IS REPRESENTED MORE EXTENSIVELY IN PRIMARY MOTOR CORTEX
SUMMARY Primary Motor Cortex:
Codes force and direction of movement Spinal motor neuron are directly under control for
precise movement. Dorsal Premotor Cortex
Movement related neuron encodes sensorimotor transformation for visual and sensory cue
Fire before movement Ventral Premotor Cortex
Encodes learned motor act fire before movement
All cortical neurons are adaptable and plastic
MOTOR CORTEX AFFERENT
1. Adjacent cortex1. the somatosensory areas of the
2. theadjacent areas of the frontal cortex anterior to the motor cortex, and
3. the visual and auditory cortices.
2. Opposite cerebral hemisphere.
3. Somatosensory fibers directly from the ventrobasal complex of the thalamus.
4. Tracts from the ventrolateral and ventroanterior nuclei of the thalamus, which in turn receive signals from the cerebellum and basal ganglia
5. Fibers from the intralaminar nuclei of the thalamus (RAS).
CONVERGENCE OF MOTOR CONTROL ON THE ANTERIOR MOTOR NEURON