Lecture Notes on December 2 2014 slides 1 61 Bold topic Underline vocabulary Pyramidal System really the only system you need in order to move neurons are lower and upper motor neurons Upper motor neurons brain Lower motor neurons spinal cord to muscle Pyramidal cells line pre central gyrus for motor control Pyramidal cells tend to be in lower levels from development deep layers of cortex are where motor neurons lie layers 5 and 6 these cells make long axons to project into spinal column Upper motor neurons very big project down to spinal column neurons CROSS at the mid line right hemi controls left side of body vice versa injury to right cortex paralysis of left side Neurons are laid out topographically muscles further out distal to spinal column in the body are further out in the vertebral column muscles closer muscles are more centralized Degeneration of UMN if a neuron has no input direction it will fire spontaneously on its on When you lose a UMN the connected LMN becomes rigid spastic due to the fact that they lose their input huge spinal reflexes because brain is no longer telling muscles to calm down you see developmental reflex that are infantile in nature Babinski Reflex toe points upward when object is dragged up the length of the sole of foot normally should point down in adults Disease related to UMN LMN degeneration is ALS Lou Gehrig s Disease Lower motor neuron originates in anterior spinal column salutatory conduction for muscle contraction neuromuscular junction ACh released onto nicotinic receptors for contraction High ratio of motor neurons to muscle finer control less neurons more muscle limited muscle control i e back muscles Motor neuron makes synapse with ACh opens up nicotinic channels depolarizes release of Ca to make muscles contract Muscarinic muscle receptors heart mostly in the brain Nicotinic muscle receptors located in neuromuscular junction as well as brain simple sodium channels depolarizes channels on muscles because they are fast receptors able to depolarize quickly behaves exactly like EPSPs in dendrites Myesthenia gravis when motor system gets attacked by immune system ACh is made in the CoA by CHAT enzyme Degeneration flaccid paralysis no stimulation pre synaptically decreased absent spinal reflexes muscular atrophy fasicullations muscle wobbles groups of muscle fibers contract Peripheral Motor System Knee Jerk Reflex muscles don t like to be passively stressed as soon as you pull on a muscle it wants to pull back even when people are unconscious you can see the activity in the brain Idea is when quadriceps extend knee reacts basic example of all movements that you do allows your spinal column motor system to do things without even thinking about it i e walking Muscle Spindle stretch stress on the muscle detectors i e job is to tell you that something is moving your arm when a person pulls on it sends info back to the brain via sensory neurons Innervated in the spinal column to sense the muscle is being squeezed able to tell motor neurons to react Alpha motor neuron gets whole thing to contract Gamma motor neuron gets a specialized region to contract Muscles attach to bone via tendons attachment spans over joints Tonic clonic seizures if coordination of muscles is off Premotor cortex tells you mental status if you re already frightened your muscle spindles are going to have a higher tension activation so if you need to respond quickly they are ready to go Flexor Reflex tells body to contract muscles to withdraw limb response to painful stimuli contralateral extensor reflex allows body to put force on opposite side of body tells other side to extend b c opposite side just flexed this flexor extensor response is basis for walking contralateral responses going back and forth as you switch legs basically you throw a leg out then fall forward and catch yourself with other leg thus causing a contralateral response With Parkinson s loss of dopaminergic innervation in basal ganglia they want to swing the leg but can t initiate it can walk without the extrapyramidal system but it is more difficult less accurate people with Parkinson s shuffle Cerebellar damage person doesn t know where their feet are has to look down at feet in order to walk Golgi Tendon Organ squeeze receptors buried inside tendons when muscle contracts i e holding 50lb bag of potatoes the squeezing goes back to sensory receptors in brain to tell you how much pressure is on the tendon Give feedback to how much force is being applied to the tendon tells you how much force to apply GTO s tell you when that muscle has too much force and is about to tear be destroyed When someone jumps off something i e a table in the first milliseconds GTOs try to catch you by applying force when someone jumps off a tall building the first milliseconds go by and you don t have anything to brace the GTOs on to catch you so the GTOs therefore create an inhibitory response saying the muscles are going to tear body needs to relax w suicide etc head hits the ground first b c GTOs allow it Central Control of Movement Premotor cortex working with the motor cortex Parietal cortex plays large role where is my arm body receives info from motor system about what it is going to do so that the parietal isn t confused damage to parietal can cause phantom limb syndrome i e you cant tickle yourself because your parietal knows the action is coming tells you what to expect from the movement of your body Strength can be incentivized strength can be upgraded produce more force if there is emotion tied to it Extra Pyramidal Neurons Pretty much everything that isn t in Pyramidal system Cerebellum purpose is to provide smooth movement takes control of repetitive tasks i e sports and writing ballistic process loss of function is assoc w impaired execution of movement tremors inability to judge distance dysmetria and ataxia tons of GABA receptors in cerebellum which is why walking in a straight line is part of a field sobriety test alcohol overstimulates function of GABA some drugs can influence cerebellar movements alter sensory and motor function smooth body movements i e marijuana Lecture Notes on December 4 2014 Slides 62 80 Extra Pyramidal Continued 90 of neural impulses never leave brain most go to cerebellum to get input on reactions 10 go to UMN in the spinal cord Also contains the caudate nucleus putamen and globulus pallidus make up the basal ganglia good diagram of location on slide 65 caudate talks to frontal lobe