* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Motor Systems - People Server at UNCW
Survey
Document related concepts
Synaptic gating wikipedia , lookup
Neuroscience in space wikipedia , lookup
Optogenetics wikipedia , lookup
Cognitive neuroscience of music wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Caridoid escape reaction wikipedia , lookup
End-plate potential wikipedia , lookup
Proprioception wikipedia , lookup
Electromyography wikipedia , lookup
Microneurography wikipedia , lookup
Synaptogenesis wikipedia , lookup
Embodied language processing wikipedia , lookup
Central pattern generator wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Transcript
Goal-Directed Behavior and Reflexive Behavior Goal-Directed Reflex Relatively Complex Relatively Simple Consciousness? Intention Automatic Plastic Relatively Inplastic Requires Cortex Cortex not required Learning /experiences are major influence Genetics are major influence Goal-Directed Behaviors Require: • Goal selection and prioritization • Resistance to distracters -Cross-modal Sensory integration – Perception of target – Awareness of location of movable body part – Ability to aim movement of body part – Ability to detect errors and re-adjust, (use feedback) – Ability to use feedback to control movement of body part Sensory-Motor Integration in the frontal lobes THE DLPFC: “The conductor” Integrates cross modal input- may initiate goal-directed behaviors Lesions of the dorsolateral frontal areas results in a number of “executive” motor impairments. These include perseveration, incoordination, motor impersistence, apraxias and hypokinesia. http://www.youtube.com/watch?v=p_uhP1vDfoo The premotor and supplementary motor ctx: “The sections” Stimulation= complex sequences of behavior (aimless behavior) Damage to the secondary Motor Cortex? • Ideomotor Apraxia • This apraxia is associated with great difficulty in the sequencing and execution of movements. A common test of apraxia is to request the patient to demonstrate the use of a tool or household implement (e.g., "Show me how to cut with scissors"). Difficulties are apparent when the patient moves the hand randomly in space or uses the hand as the object itself, such as using the forefinger and middle finger as blades of the scissors. They have additional trouble sequencing the correct series of movements and make errors in orienting their limbs in space consistent with the desired action. Imitation of the movements of others will usually improve performance but it is still usually defective. • Memories for skilled acts are probably stored in the angular gyrus of the parietal lobe in the left hemisphere. • http://www.youtube.com/watch?v=gewP1T7GYcc The primary motor cortex; “the instrument” Stimulation = relatively simple fragments of behavior TWO MAJOR DESCENDING PATHWAYS FROM THE PRIMARY MOTOR CORTEX: The Dorsolateral pathway And the VM Path. • The VM pathway does not discretely decussate, but does branch and innervate contra lateral segments in the spinal cord. DL vs VM descending motor paths • Dorsolateral • Ventromedial • Decussates at medullary pyramids • Distal muscle groups • More direct • More volitional control • Higher resolution of control • Does not cross • Medial muscle groups • Gives off spinal collaterals • Yoking • Lower resolution of control Other Motor Pathways • In addition there are other motor paths that have relays in the brainstem • These other paths innervate nuclei of the RAS, cranial nerve nuclei, etc… Descending paths get additional inputs Both pathways terminate in spinal cord segments According to part of the body they control On lower motor neurons (alpha motor neurons) Amyotropic lateral sclerosis (ALS) disease of the alpha motor neurons ALS Alpha motor neurons project to form part of spinal nerve pairs Terminate on muscle fibers At each spinal segment Muscle groups are complex; attach bone to bone via tendons and ligaments A muscle group has many fibers The motor unit helps us understand “resolution” The motor unit: If ratio is high=low resolution The Neuromuscular junction (NMJ): The receptive portion of muscle-the motor end-plate The NMJ ( sometimes called the motor end-plate) nACHr End-plate potential • Larger • Longer • Leads to Ca+ influx in sarcolema of muscle – Ca+ causes muscle contraction muscle fibers encase myofibrils. The casing is called the sarcolema Muscle group myofibril Muscle fiber End-plate potential causes ca+ influx into sarcolemma Myofibrils in turn contain “Actin and Myosin” filaments When the NMJ is activated Actinmyosin interact to shorten the length of a muscle fiber Sliding filament model of muscular contraction Muscle shortens=work Disease of the NMJ? MG MG MG Cortical vs Spinal control of behavior • Goal-directed • Reflexive • Complex • Higher levels of control • Plastic • Numerous reflexive behaviors are involved • Simple • Automatic • inplastic Spinal reflex ARCs • Monosynaptic – stretch • Polysynaptic – Withdrawal – Antagonist muscle groups – Synergistic muscle groups – Polysegmental relexes – Cross-spinal reflexes A “monosynaptic” spinal reflex arcthe Stretch reflex The stretch reflex involves neuromuscular “spindles” Stretch reflex regulates muscle tension in every muscle group The polysynaptic part of stretch reflexes: inhibition of Antagonist muscles Spinal inhibition of antagonist muscles require inhibitory interneurons The “withdrawal reflex arc” a polysynaptic spinal reflex Also involves interneurons And may involve more than one spinal cord segment And/or Cross spinal reflex arcs The Goli tendon organ (GTO) reflex Neural activity of spinal neurons related to whole muscle group activity Lower motor neurons “the final common pathway” “the final common path: