8459225
Description
Flashcards by Linda Lummer, updated more than 1 year ago
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Created by Linda Lummer
about 7 years ago
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| Question | Answer |
| What are the principles of sensorimotor control? | 1) Sensorimotor system is hierarchically organized 2) Motor Output is guided by sensory input 3) Learning can change the nature and the locus of sensorimotor control |
| functional segregation | each one of the sensorimotor system is composed of different units (neural structures), each of which performs different function |
| sensory feedback | eyes, organs of balance, receptors in the skin, muscles and joints all monitor the body's responses and feed their information back into sensorimotor circuits - important in directing continuation of the responses that produce it |
| ballistic movements | responses that are normally influenced by sensory feedback - brief all-or-none, high speed movements (swatting a fly) |
| posterior parietal association cortex | important role in integrating information, in directing behavior by providing spatial information and directing attention |
| association cortex | receives input from more than one sensory system (visual, auditory, somatosensory systems) |
| Apraxia | disorder of voluntary movement - difficult with specific movements out of context - can perform such movements under natural conditions when not thinking about them |
| Contralateral neglect | disturbance of ability to respond to stimuli on the side of the body opposite to the side of the brain lesion, in the absence of simple sensory motor deficits - most of the time, deficits in responding occur for stimuli to the left of their body, referred to as egocentric left |
| dorsolateral prefrontal association cortex | receives projections from the posterior parietal cortex and sends projections to areas of the secondary motor cortex, primary motor cortex and frontal eye field |
| secondary motor cortex | receive much of their input from association cortex and send much of their input to primary motor cortex |
| mirror neurons | neurons that fire when an individual performs a particular goal-directed hand movement or when she or he observes the same goal-oriented movement performed by another |
| functions of mirror neurons | - provide a possible mechanism for social cognition which would facilitate social understanding, cooperation an imitation - mirror neurons respond to the understanding of the purpose of an action |
| primary motor cortex | located in the percental gyrus of the frontal lobe and is the major point of convergence of cortical sensorimotor signals and a major point of departure of sensorimotor signals from the cerebral cortex |
| astereognosia (deficits in stereognosis) | large lesions to the PMC disrupt ability to move one body part independently of others and may reduce speed, accuracy and force of a movement - such lesions do not eliminate voluntary movement because there are parallel ways that descend directly from secondary cortex without passing through primary cortex |
| dorsolateral corticospinal tract | 1 group of axons that descends from primary motor cortex through medullary pyramids |
| dorsolateral cerebrospinal tract | synapses on the interneurons that synapse on motor neurons that project to the distal muscles of the arms and legs (descends from red nucleus) |
| ventromedial corticospinal tract | direct ventromedial pathway - axons that descend here branch diffusively and innervate neurons circuits in several different spinal segments on both sides of the spinal grey matter |
| ventromedial portico-brainstem spinal tract | indirect ventromedial pathway - each side carries signals from both hemispheres and each neuron synapses on interneurons of several different spinal chord segments that control the proximal muscles of trunk and limbs |
| brain stem structures that with the ventromedial portico-brainstem spinal tract | 1) tectum 2) vestibular nucleus 3) reticular formation 4) motor nuclei of carnival nerves that control face muscles |
| tectum (brain stem structure interaction with the ventromedial cortico-brainstem spinal tract) | receives auditory and visual information about spatial location |
| vestibular nucleus (brain stem structure interaction with the ventromedial cortico-brainstem spinal tract) | receives information about balance from receptors of inner ear |
| reticular formation (brain stem structure interaction with the ventromedial cortico-brainstem spinal tract) | contains motor programs that regulate species-typical movements such as walking |
| motor unit | smallest unit of motor activity, that compromises a single motor neuron and all of the individual skeletal muscle fibers that it innervates |
| motor unit (functions) | - when motor neuron fires, all muscle fibers of its unit contract - units with fewest fibers permit the highest degree of selective motor control - Acetylcholine activates the motor end-plate |
| motor end-plate | causes the fibre to contract |
| motor pool | all of the motor neurons that innervate fibers in a single muscle (fast and slow muscle fibers) |
| fast muscle fibers (white) | contract and relax quickly, fatigue quickly because they are poorly vascularized (few blood vessels) |
| slow muscle fibers (red) | slower, weaker, capable of more sustained contraction because they are richly vascularized |
| flexors | bend or flex a joint (biceps) |
| extensors | straighten or extend a joint (triceps) |
| synergistic muscles | muscles whose contraction produce the same movement, be it flexion or extension |
| antagonistic muscles | those that act in opposite (biceps and triceps) |
| isometric contraction | when activation of a muscle increases the tension that it exerts on two bones without shortening and pulling them together |
| dynamic contraction | when activation of a muscle shortens and pulls two bones together |
| tension in a muscle | can be increased by increasing the number of neurons in its motor pool that are firing, by increasing the firing rates of those already firing or by a combination of both |
| Golgi tendon organs | embedded in tendons which connect each skeletal muscle to bone |
| Golgi tendon organs (functions) | - respond to increase in muscle tension - provide the CNS with information about muscle tension - protective function; when contraction is too extreme, they exit inhibitory interneurons in spinal chord that causes the muscle to relax |
| muscle spindles | embedded in the muscle tissue itself - respond to changes in muscle length |
| patellar tendon reflex (stretch reflex) | elicited by a sudden external stretching face on a muscle |
| withdrawal reflex | not monosynaptic; first responses to painful stimulus are recorded in motor neurons of arm flexor in about 1.6ms later, about the time it takes a neural signal to cross two synapses -> the shortest route in the withdrawal route involves one interneuron |
| reciprocal innervation | antagonistic muscles are innervated in a way that permits a smooth, unimpeded motor response; when one is contracted, the other relaxes |
| cocontraction | smooth movements that can be stopped with precision by a slight nacres in the contraction of the antagonistic muscles |
| recurrent collateral inhibition | the inhibition on produced by this (motor neuron) local feedback |
| Renshaw cells | small inhibitory interneurons that mediate recurrent collateral inhibition |
| Sensorimotor system comprises a hierarchy of central sensorimotor programs | ...? |
| motor equivalence | the fact that the same basic movement can be carried out in different ways involving different muscles - general programs are stored higher in sensorimotor hierarchy and then are adapted to situation as required |
| motor equivalence (details) | - conscious perception and sensory control of behavior are separated - Central sensorimotor programs for many species-typical behaviors are established without explicit practice of the behaviors - sensory feedback in operation of central sensorimotor program is important |
| response chunking | practice combines the central sensorimotor programs that control the individual response into programs that control sequences (chunks) of behavior (eg. in an unpracticed typist, the word is individually triggered, in a skilled typist, the sequel of letters are activated as a unit which is shown in speed and continuity) |
| response chunking (details) | - control is shifted from higher levels of hierarchy to lower levels of hierarchy which has two advantages 1) frees up higher levels of the system to deal with more esoteric aspects of performance 2) permits great speed because different circuits at lower levels of the hierarchy can act simultaneously, without interfering with each other - the involvement of the cerebellum and association areas diminishes when sequences are well practiced |
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