BIOL 3322 1nd Edition Lecture 16Lecture 10/28Hierarchy of movement control a. Major components of the motor system i. Cerebrumii. Brainstem iii. Spinal cordb. Other regions of the motor system i. Subcortical basal ganglia ii. CerebellumII. Initiating a motor sequencea. Motor sequence i. Movement modules preprogramed by the brain and produced as a unit ii. Frontal lobe (prefrontal cortex, premotor cortex, and primary motor complex)III. Animals with damage to the premotor cortex cannot put motor sequences togetherIV. Experimental evidence for the movement hierarchy a. Frontal lobe regions in each hemisphere that plan, coordinate, and execute precise movements are hierarchically related i. Prefrontal cortex formulates a plan of action ii. Prefrontal cortex instructs premotor cortex to organize the appropriate sequence of behaviors iii. Primary motor cortex executes the movements V. The forebrain and initiation of movement a. Prefrontal cortex plans movement b. Premotor cortex organizes movement sequences c. Motor cortex produces specific movementsVI. Muscles and their movements a. Antagonistic muscles are necessary for moving limbs in opposite directions b. Limb muscles are arranged in pairs i. Extensor – moves extends the limb away from the trunkii. Flexor – moves the limb toward the trunk c. Proprioceptor – stretch reflex – muscle spindle – golgi tendon organd. Fast twitch fibers… produce fast contractions but fatigue rapidly e. Slow twitch fibers… produces less vigorous contraction without fatiguef. Neurotransmitter junction g. Motor unitsi. A motor neuron plus muscle fibersii. All fibers contract when motor neuron firesh. # of fibers per unit varies i. Fine control These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.ii. Fewer neurons i. Muscle i. Muscle fibers bound together by a tendon j. Reflexes are involuntary k. Consistentl. Automatically respond to stimuli i. Spindals and golgi fibers VII. Brainstem control of muscles and movement a. Motor nuclei in the brainstem control muscles of the head and neck (deep in the brain almost reflex like)b. Species typical movement i. Stalking (cat like)ii. Grooming (fixed action potential)iii. Nest building c. Maintaining posture, standing upright, coordinating movements of the limbs i. Locked in syndrome (only able to move eye)ii. Cerebral palsy (damage to brainstem nuclei can result in paralysis from limiting to completeVIII. Organization of the motor system (motor cortex)a. Homunculus – little person b. Topographic organization c. Evolution has imbued each species with a cortical representation consistent with the appropriate sensorimotor demands of the animal d. Distorted version of has body actual looks b/c of sensory motor demandsIX. Organization of the motor system corticospinal tracts a. Corticospinal tract i. Bundle of the nerve fibers directly connecting the cerebral cortex to the spinal cord ii. Branches at the brainstem into opposite side lateral tract that controls movement of limbs and digits and a same side ventral tract that informs movement of the trunk iii. Also called the pyramidal tract (in BS)iv. Afferent pathways voluntaryX. Control of muscles a. Connections between interneurons and motor neurons ensure that the muscles work together so that when one muscle contracts the other relaxes i. Triceps (extensor muscle) – extends the lower arm away from the bodyii. Biceps (flexor muscle) – moves the lower arm toward the bodyiii. Acetylcholine is the neurotransmitter at the neuromuscular junction XI. Basal Ganglia Connections a. Receives input from all areas of the neocortex and limbic cortex as well as the dopaminergic system b. Project back to the motor cortex and substantia nigra c. Damage to the basal ganglia i. Hyperkinetic symptom – excessive involuntary movementsii. Hypokinetic symptom – parkinsons diseaseXII. Basal ganglia and movement force (2 pathways)a. Direct – inhibitory b. Indirect – excitatory XIII. Cerebellum and movement skilla. 2 main motor functionsb. Timing c. Maintaining movement accuracy (error correction)XIV. Organization of the somatosensory system a. Tells us what the body is up to and whats going on in the environment by providing bodily sensations i. Temp, touch, pain , position in space, movement of joints XV. Sensory receptors a. Nocioception b. Hapsis c. Proprioception d. Rapidly adapting receptor e. Slowly adapting receptorXVI. Organization of the somatosensory system dorsal root ganglion neurons a. Dorsal root ganglion neuron XVII. Somatosensory pathways to the brain a. Haptic proprioceptive axons for touch and body awareness ascend the spinal cord ipsilateralb. Nociceptive (pain, temp, itch) nerve fibers synapse with neurons whose axons cross to the contralateral side of the spinal cord before ascending to the brain XVIII. Perceiving pain a. Ventral spinothalamic tract is main pain pathway to the brain b. Other pathways may carry pain info from the spinal cord to the brain i. Reticular formation ii. Amygdalaiii. Hypothalamusc. Pain is necessary d. Treating paini. Periaqueductal gray matter (PAG)ii. Provide relief from pain iii. Inhibit neurons that form the ascending pain pathways XIX. Vestibular system a. Static (still) or dynamic (moving )b. Vestibular organ containsi. 3 semicircular canals ii. Otolith organs (utricle and saccule)iii. Position of gravity iv. Signal changes and speed of