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Motor Systems. Spinal reflex arcs. Reflex arc Monosynaptic (spindle) Interneurone Golgi tendon organ (clasp-knife) Ia interneurone Renshaw autoinhibition Antagonist inhibition Polysynaptic (flexor). a. Ia. homonomous. a. Ib. homonomous. antagonoist. Caudate Putamen
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Spinal reflex arcs • Reflex arc • Monosynaptic (spindle) • Interneurone • Golgi tendon organ (clasp-knife) • Ia interneurone • Renshaw autoinhibition • Antagonist inhibition • Polysynaptic (flexor) a Ia homonomous a Ib homonomous antagonoist
Caudate Putamen Globus pallidus Substantia nigra Initiation of action Gating SNPR-Eye movement Decision making Basal ganglia
Motor hierarchy Posture, stepping, standing • Spinal nucleus • Reticular formation • Vestibular nucleus limb extension • Red nucleus limb flexion • Cerebellum
Cerebellar pathways Vestibular n. Vestibuloc. Emboliform n. Vestibular n. Tonsil, Archic., Sensory flocculonodular Clarke's col. Spinoc. Fastigial n. Reticulospinal Pons Paleoc., Motor Cx Red n. N. interpositus Vermis Neoc. Inf. olive Dentate n. VL/VA thal Sensory Lateral hemisphere deep n. CBM
Cerebellum • Paleocerebellum (vermis) • Spinocerebellum, anterior lobe • Spinal c. (Clarke's column) > Fastigial n., red n. • Archicerebellum (tonsil) • Vestibulocerebellum, flocculonodular lobe • Vestibular n. > Emboliform n., Vestibular n. • Neocerebellum • lateral hemisphere • pons, inf. olive > Dentate n., VA/VL, Cx
Motor hierarchy Volition Association Context Cx Premotor Supplementary 1º Motor MA Cx CX Cerebellum Striatum Emotion VA VL thalamus thalamus
Primary motor Spasticity Cortical reflexes LLR, expectation Association Balint, patient DF (Goodale & Milner 92) Combining Decomposition Cx structure, inputs Sequencing Dysdiadochokinesia Rhythm, reciting? Tuning Ataxia, VOR Compare and contrast the roles of cerebral cortex and cerebellum in the control of voluntary movement
SMA vs. PMA • Both • somatotopic map • motor planning • SMA • PMA