Med Phys Pharm 551 L18 CNS Phys and Motor Control Lecture Notes PDF

Lecture #18: CNS Physiology & Motor Control Julia Hum, PhD Primary Course Instructor Course Meets: Monday/Wednesday/Friday: 2:00-2:50pm Office Hours: Monday/Wednesday/Friday 11:00am-12:00pm (317B or WebEx)  L18: Learning Objecti...

Lecture #18: CNS Physiology & Motor Control Julia Hum, PhD Primary Course Instructor Course Meets: Monday/Wednesday/Friday: 2:00-2:50pm Office Hours: Monday/Wednesday/Friday 11:00am-12:00pm (317B or WebEx)  L18: Learning Objectives 1. Diagram the sensory and motor pathways 2. Detail the roles the four higher control centers play in motor control 3. Illustrate the basal ganglia’s direct and indirect feedback circuits on motor control 4. How are the basal ganglia’s circuits impacted by Parkinson’s and Huntington’s? L18: “Take Home” Slide  Sensory and Motor Pathways Sensory - Afferent Relay sensations to brain Motor - Efferent Dorsal Root From brain to muscle Interneuron Ventral Root Connects sensory and motor to form reflex arc LO1 How does the CNS coordinate motor control of skeletal muscle?  Spinal Cord Tracts Gray Matter Cell bodies, dendrites and unmyelinated axons White Matter Myelinated nerve axons Bundles of nerve fibers with similar origins and destinations Communicate information between the PNS and the brain Ascending Tracts - sensory Descending Tracts - motor LO1  Higher Control Centers Brainstem Cerebellum Basal Ganglia Cerebral Cortex LO2  Planning & Executing Cerebrum Planning & Executing Basal Ganglia Organizes and Relays Info Fine Tuning of Motor Commands Sends Final Command Relays Sensory Signal LO2 Layering of Motor Control Pathways Subdivisions of the Brain and Brainstem A A A A. Cerebrum B B A B. Diencephalon B B C C. Mesencephalon (midbrain) D F D. Pons E. Medulla (medulla oblongata) E F. Cerebellum  Brainstem Function: A Bidirectional passageway for all tracts (axons that share similar origin and A A destination) extending between the B cerebrum and the spinal cord B B A B C Origin of most of the 12 cranial nerves D F E Divided into 3 anatomical areas C - Mesencephalon (midbrain) D – Pons E – Medulla LO3  Brainstem Organization and Function Visual and auditory sensation: processing pathway Sleep wake cycles; Alertness Temperature regulation Autonomic nuclei location Cardiac center- heart rate and Respiration: strength of contraction Regulate rate and depth of Vasomotor center- blood breathing pressure Influence and modify medulla’s Respiratory center- respiration respiration activity rate, influenced by pons Coughing, sneezing, salivating, swallowing, gagging, and LO3 vomiting Cranial Nerves and their functions  Cerebellum – (F) A Coordinates and “fine-tunes” skeletal muscle movement A Cerebrum initiates movement-> sends “rough A draft” to cerebellum, where it is fine tuned B B B A Controls skeletal muscle contractions for patterns B and smooth movement C Stores memories of previously learned movement D F patterns through voluntary and involuntary pathways E Equilibrium and posture Receives proprioceptive information about position from muscles and joints, sends to cerebrum LO3  Cerebellum LO3 http://www.ibens.ens.fr/IMG/jpg/barbour-purkinje_green.jpg  The Forebrain 1. Diencephalon Thalamus Hypothalamus https://kenowapsychology.wikispaces.com/file/ view/forebrain.gif/45305257/301x264/forebrain.gif 2. Cerebrum Basal ganglia Cerebral cortex LO3 https ://upload.wik ime dia.org/wik ipedia/com mons/thum b/1/1b/Bas al_ Ga nglia _ and_Re la te d_ Structure s. svg/490px-Bas al_ Ga nglia _ and_Re la te d_ Structure s. svg.png  Forebrain: Diencephalon - Thalamus Sensory system hub All sensory information passes through the thalamus Except olfactory Required for consciousness Regulates sleep and wakefulness LO3  Forebrain: Cerebrum “seat of human intellect” 1. Cerebral Cortex Thought, language, awareness, learning and memory 2. Basal Ganglia Work with cerebral cortex and thalamus to effect motor control 3 related nuclei LO3  Cerebrum: 1) Cerebral Cortex Function 1. Sensory Receive and process info from thalamus 2. Motor Planning and executing motor commands 3. Associative Most cortical neurons Patterns – color, light, shade, noise Abstract thinking, language, music, math Social interactions LO3  Cerebrum: 1) Cerebral Cortex Planning Voluntary Movement – “when” and “what” 1. Primary Motor Cortex Sends motor fibers via corticospinal tract to interneurons Results in muscle contraction Commands require processing by cerebellum and basal ganglia Execution factors include sensory information from skin and muscle receptors LO3  Cerebrum: 1) Cerebral Cortex Planning Voluntary Movement 1. Primary Motor Cortex 2. Premotor Cortex Planned movements based on visual or sensory input 3. Supplementary Motor Area Retrieves and coordinates motor sequences that have been memorized LO3  Cerebrum: 2) Basal Ganglia “Planning and Executing” – distance, force, timing of movement 1. Gateway by which commands Striatum or Neostriatum from cortex enter GABAergic neurons 2. Output mostly inhibitory LO3,4  Cerebrum: 2) Basal Ganglia “Planning and Executing” – distance, force, timing of movement Inner GP (IGP) – increases motor activity External GP (EGP) – decreases motor activity GABAergic neurons Output inhibitory LO3,4  Cerebrum: 2) Basal Ganglia “Planning and Executing” – distance, force, timing of movement Melanin filled – Dopamine substrate Inhibitory neurons 1. Pars reticulata – GABAergic 2. Pars compacta – Dopaminergic neurons Usually functions with IGP LO3,4  Cerebrum: 2) Basal Ganglia “Planning and Executing” – distance, force, timing of movement Motor Commands from Cortex Link in a basal-nuclei feedback circuit Only primary excitatory Basal Ganglia – feedback circuits center of the basal ganglia Thalamus Primary Motor Cortex Can movement occur in the absence of basal ganglia function? LO3,4  Feedback Circuits Motor Cortex communicates its intents through the B asa l basal nuclei in two pathways within striatum: Direct Ga ngl i on Striatum activated – inhibits IGP (tonically active) Normally suppresses thalamus Thalamus becomes active – stimulates motor cortex Increases motor activity Excitatory Center Indirect Inhibitory Center Straitum activated – prevents EGP signaling EGP normally inhibits subthalamic nucleus Leads to increases activity IGP IGP inhibits thalamus Prevents excitement of motor cortex Acts as “break” for the direct pathway LO3,4 Both pathways end with targeting the thalamus  Feedback Circuits – Disease States Parkinson’s Disease Huntington’s Disease LO3,4  Feedback Circuits – to create movement (Direct) Striatum activated – inhibits Frontal Lobe Cerebral B Cortex IGP (tonically active) -Normally suppresses thalamus Brainstem/Spinal Thalamus becomes active – Cord Striatum - stimulates motor cortex Direct Increases motor activity Thalamus IGP EGP Motor Output Substantia Subthalamic NT: Guide Nigra Nucleus + Glutamate - - Dopamine LO3,4 - GABA  Feedback Circuits – to prevent movement (Indirect) Straitum activated – prevents EGP Frontal Lobe Cerebral B Cortex signaling EGP normally inhibits Brainstem/Spinal subthalamic nucleus Leads to increases activity IGP Cord IGP normally inhibits Striatum - Indirect thalamus Prevents excitement of motor cortex Acts as “break” for the direct pathway Thalamus IGP EGP Motor Output Substantia Subthalamic NT: Guide Nigra Nucleus + Glutamate - - Dopamine LO3,4 - GABA