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PY460: Biological Bases of Behavior Chapter 8: Movement Module 8.1: The Control of Movement Module 8.2: Brain Mechanisms in Movement Module 8.3:Disorders.

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Presentation on theme: "PY460: Biological Bases of Behavior Chapter 8: Movement Module 8.1: The Control of Movement Module 8.2: Brain Mechanisms in Movement Module 8.3:Disorders."— Presentation transcript:

1 PY460: Biological Bases of Behavior Chapter 8: Movement Module 8.1: The Control of Movement Module 8.2: Brain Mechanisms in Movement Module 8.3:Disorders of Movement

2 Slide 2: The Control of Movement Introduction: Clip #10: Sensory Motor Integration *movement-- an extremely complex process  complex “motor control” often w/o thought X Muscles-- “The Final Path”- multiple fibers X Smooth Muscle *movement of internal organs  stomach, arterial lining X Cardiac muscles (myocardium)-  interconnected bands of muscle X Skeletal Muscles- striated *long cylindrical fibers- “striped appearance”

3 Slide 3: Muscle Movement: Axons and Acetylcholine X Axon to fiber ratio- greater the ratio the more precise the movements [class; “typing with & w/o mittens]  e.g., eye= 1:3 arm (bicep)1:100 X Neuromuscular junction- where the “motor neuron” meets a muscle fiber *NTR of movement- acetylcholine *effect:“contraction”, no Ach = relaxation X Myasthenia Gravis- An “autoimmune disease”- body attacks acetylcholine receptors  2-3 per 100,000 over 75 years of age  Symptoms-progressive weakening and rapid fatigue of striated muscles as receptors are gradually destroyed.  Treatment-Immune suppressants & drugs inhibiting Acetylcholinesterase

4 Slide 4: Muscles Types and Functions X Antagonistic Muscles- opposing sets of muscles  Flexors- flexes or raises muscles  Extensors- extends or straightens X Fish Muscles- (movements & duration)  red (slow & long), pink (slow & not as long), white (fast & short) X Chicken Muscles (“white and dark meat”)  breast- fast acceleration, short duration  leg- long duration, not as fast (walking). X Human Muscles  Fast Twitch (anaerobic) –sprints/fast acceleration  Slow Twitch (aerobic) –duration/slow acceleration, speed

5 Slide 5: Proprioceptors-Feedback on Position & Movement X Proprioceptor: a receptor on the muscle sensitive to changes in muscle position and movement (“stretch”) of muscle. Respond with muscle contraction X Stretch Reflex- mediated at the spinal cord level X Muscle Spindle- stretch receptor attached parallel to muscle fibers sensitive to elongation of fibers *knee-jerk response X Golgi Tendon Organ- responds to increases in muscle tension.  Prevents excessive vigorous contraction (which would occur without it) X Life with reduced proprioception (babies, case in text)

6 Slide 6: Voluntary/Involutary Movements & Feedback X Types of Movements *Ballistic- large reflexive (all or none type) movements *Few ballistic movements-- most subject to feedback modifications Limits on Voluntary and Involuntary movement *few strictly involuntary, few strictly voluntary *limits of each (try swallowing 10 times) X Parkinson patients walking characteristics X INFANT REFLEXES: grasp reflex, Babinski reflex, rooting reflex, allied reflex *presence in adults signal damage to Cerebral Cortex

7 Slide 7: Coordinated Movement X Central Pattern Generator- proposed mechanism in spinal cord or brain that generates rhythmic patterns of “coordinated motor activity” that is extreme regular within species *stimulation of this mechanism affect action, but not frequency (apparently) –dog shaking off water, scratching reflex X Sequence of movements (e.g., walking) called a “Motor Program”  can be learned and built in. Think of a few!  Can be part of evolutionary inheritance –Yawning

8 Slide 8: The Spinal Cord-- Motor Program Keeper X How is it that a chicken can run without its head? X In humans *chewing, swallowing, breathing are controlled below the brain at the level of spinal cord/medulla. X Some motor programs (scratch reflex) are independent of brain feedback altogether *isolating of “scratch reflex” neurons from brain axons does not affect intrinsic firing rate and subsequent behavior. *Rhythm of firing even unaffected by muscular paralysis (the neurons are autorhythmic)

9 Slide 9: Brain and Movement (Begin Module 2) X Areas to be discussed *Cortical Areas in Movement  Primary Motor Cortex- messages (axons) to the medulla and spinal cord (just anterior to the precentral gyrus of the cerebral cortex) –control of “complex movement plans” –not reflexive (sneezing, cough, gag, cry etc.)  Areas near Primary Motor Cortex *Medulla and Spinal Cord- receive messages from PMC, control muscle movements (reflexive, bilateral, peripheral) –not much in chap 8, but see table 8.1 *Basal Ganglia & Cerebellum moderate movements but do not directly cause. (“selection, order, smoothing & future precision”)

10 Slide 10: The Cerebral Cortex X Primary Motor Cortex X Fritsch & Hitzig- ESB of PMC= coordinated movement *No direct connections to muscles, rather controls “complex movement plans” involving several muscles, not individual muscles.  i.e., activates central pattern generators  see fig 8.9- “motor homunculus” *See Figure distribution of cells activated during hand movements

11 Slide 11: Working with the Primary Motor Cortex- Adjacent Areas X Posterior Parietal Cortex- control actions related to visual or somatosensory stimuli. *“cannot walk toward something they see” X Prefrontal Cortex- active in planning a potential movement- responds to sensory stimuli (future movement planning) X Premotor Cortex- active in preparation for movement, not during movement though. X Supplementary Motor Cortex- active during planning stage for rapid series of movements that require starting one movement before finishing another *e.g., Typing X Preparation for Movement- * coordinated waves of activity among these structure sending complex signals to PMC then down to the medulla and spinal cord.

12 Slide 12: Brain to Spinal Cord: 2 Tracks of Action X Dorsolateral Tract- axons projecting from PMC and Red Nucleus of Midbrain *axons cross over to opposite side of body controlling peripheral unlearned fine movements.  hands, fingers, toes *sometimes called the pyramidal tract X Ventromedial Tract- axons from PMC and SMC *axons branch to both sides- damage affects coordinate “side to side movements” like walking, standing, sitting, “twisting”, that is “bilateral movements”.  Neck, shoulders, trunk X 2 tracks act together to produce complete set of function muscle movements

13 Slide 13: The Cerebellum- “Follow My Finger” X Cerebellum- important in learned motor responses *programs allowing rapid sequential movement *damage-- trouble with rapid motor sequences requiring accuracy and timing  tapping to a rhythm  speaking  “adapting to prisms that distort vision” X “Saccades”- ballistic eye movements from one fixation point to another *damage or drunkenness (cerebellum 1st place affected by drink)- many small movements to fixate X Finger-to-Nose- inaccurate first movement, finger wavers during “hold ”

14 Slide 14: Cellular Organization of Cerebellum & Duration of Movement X Perpendicular Organization of Cerebellar Cortex *precisely organized cellular structure  Parallel Fibers  Purkinge Cells (transmit to interior) –fire separately –inhibitory X Duration of movement *affected by number of Purkinge cells affected by parallel fiber excitation

15 Slide 15: Basal Ganglia: Organizing Planned Movements X Basal Ganglia has many roles- damage often results in much more than movement problems (e.g., memory, problem solving). *but some insight on its contributions to movement  seems to help in organizing new and habitual movements and inhibit unwanted movements (caudate nucleus) –e.g., signing your name  study of clumsy children

16 Slide 16: Parkinson’s Disease [video] X Symptoms- gradually increasing muscles tremors, slowed movement, inaccurate aim, difficult initiating physical, mental activity *Muhammad Ali X Prevalence: 1 per 100 over age 50 X Physiology- cell degradation in the substantia nigra & amygdala *decreased dopamine at D1 and D2 receptors resulting in net inhibitory response, thus “downstream” decreased excitation by cerebral cortex and thalamus X Natural degradation with age, some start with less cells, or lose at faster rate than others. *[Early and Late-Onset Parkinson’s (p.243)]

17 Slide 17: Etiology and Treatment of Parkinson’s X Suggested Causes  Inheritance *Interrupted blood flow to areas of the brain *Previous encephalitis or viral infection *Prolonged exposure to drugs/toxins  unlikely however that cause of most cases are due to drug abuse or exposure to toxin (Paraquat) (MPP+ MPTP). –Likely these factors contribute to process of degradation already active X Treatment: L-Dopa- cross BBB converted to dopamine. *Stereotyped movements, Delusions, Hallucinations *A “window” where helpful, soon disease too severe *Nicotine-- Smoking?? X Other Therapies [p.245]

18 Slide 18: Huntingdon’s Disease X A severe neurological disorder marked by gradually worsening tremors/twitches to severe writhing affecting daily movements like talking, walking, eating etc. *Prevalence: 1 per 10,000 X Widespread brain damage, particular area releasing GABA an inhibitory neurotransmitter *especially in basal ganglia (caudate nucleus etc.) X Genetic Conditions/Considerations *A dominant mutant gene.. Thus parent has 50% chance of passing disorder on. *Can test for the gene to determine not only who will get, but approximately when. *In vitro testing, other ethical issues

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20 Slide 20: Spinal Cord Disorders X Paralysis- X Paraplegia- X Quadriplegia- X Poliomyelitis- X Lou Gehrig’s Disease- X Others *Flaccid Paralysis *Spastic Paralysis *Tabes Dorsalis


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