26 October 2011 Lecture: Ch. 10 Control of Body Movement Abstracts due Monday Check schedule on website for assistance About spreadsheets & JMP

Chapter 10: Control of somatic motor systems 26 October 2011 Chapter 10: Control of somatic motor systems Riding a bike, playing piano, swinging a bat or golf club…. Video of Trampoline Championship Benjamin Zander: Classical Music and Shining Eyes

1QQ # 21 for 8:30 section Answer one question. Which are characteristics of cardiac myofibers? Ca++ for excitation-contraction coupling originates from intracellular and extracellular sources Cardiac myofibers have a twitch duration longer than smooth myofibers. Produce action potentials that allow the influx of Ca++ for more than 100 ms. Conduct action potentials to neighboring cells via gap junctions of intercalated disks Produce tension in proportion to the amount of cytosolic Ca++. 2. What type of myofiber can enter a latch state and what are the advantages of the latch state?

1QQ # 21 for 9:30 section Answer one question. Which are characteristics of multi-unit smooth myofibers? Each myofiber is individually innervated by autonomic neurons Can be excited or inhibited by somatic motoneurons Often have pacemaker potentials that result in periodic contractions Are found in the walls of small-diameter blood vessels Belong to large motor units. 2. Which properties of smooth muscle cells make them much better suited for their role in the walls of hollow organs than skeletal myofibers?

Each region has a homunculus Fig. 10.10a S 2 Each region has a homunculus 10.10a.jpg

Fig. 10.02 S 3 10.02.jpg Formerly called “basal ganglia”, consist of caudate, putamen, and globus pallidus

Initiates motor command Decision to move Fig. 10.01 S 4 Initiates motor command Coordinates secondary movements Corticospinal and corticobulbar tracts Balance and complex learned movements Pathways? Other inputs: Vestibular & Visual! 10.01.jpg Reflex Examples of motor disorders: Huntington’s Disease and Cerebellar Disorder

Jack Nicholson One Flew Over the Cuckoo’s Nest Frontal lobotomy

Local control Muscle spindle What is their role? The stretch reflex… Spindle Afferent gamma motoneurons Muscle spindle Stretch receptor Intrafusal muscle fiber What is their role? The stretch reflex… Follow the reflex arc Be able to differentiate function of afferent fibers, alpha motor neurons, and gamma motor neurons 10.04.jpg Motor units of alpha motoneurons

Fig. 10.05ab S 7 10.05ab.jpg This doesn’t happen!

Fig. 10.05c S 8 10.05c.jpg Co-activation of alpha and gamma motoneurons insures that the stretch of muscle can be detected regardless of the initial length or state of contraction of that muscle.

Synergistic & Antagonistic Fig. 10.06 S 9 Proprioception pathway via dorsal column-medial lemniscus pathway One component of Stretch reflex is monosynaptic Most common example: patellar reflex = “knee jerk reflex” Synergistic & Antagonistic 10.06.jpg

Stretch Reflex S 10 Monosynpatic excitation of motoneurons of that muscle and synergistic muscles and polysynaptic inhibition of motoneurons to antagonistic muscles. Recall frog reflex lab and existence of spinal reflexes in single-pithed frogs. Also, example Christopher Reeve and patellar reflex. 10.06.jpg

Fig. 10.07 S 11 10.07.jpg

Golgi tendon organs involved in a reflex to oppose excessive muscle tension. Not monosynaptic. Not shown: ascending axons in dorsal column-medial lemniscus tract. S 12 10.08.jpg

S 13 Joint angle detectors and cutaneous mechanoreceptors contribute to sense of body position (proproiception.) Plus vision and vestibular inputs!

S 14 Crossed-extensor reflex: Common sense… check the book!

Something is incorrect on this figure from a textbook. Find it!

Extra-Pyramidal tracts Fig. 10.12 S 16 Pyramidal tract Descending Pathways Corticospinal tract Corticobulbar tract Fine motor control, esp. of extremeties Extra-Pyramidal tracts Reticulospinal tract Vestibulospinal tract Originate in brainstem, more involved with posture and equilibrium 10.12.jpg Not monosynaptic!

Who Cares? S 17 Video of Huntington’s Chorea Video of Cerebellar Dysfunction Locked-in Syndrome