UNC EXSS 380 Exam Review

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25NA motor control researcher estimates grip force during a task where the goal is to pick up a mass object for which the appropriate grip and lifting forces are unknown (i.e. the weight is unknown). During the first trial, the subject produces a force of 1N in the finger flexors, and 5N in the thumb flexors, but is unsuccessful in picking up the object. If in the second trial the subject increases the force produced by the finger flexors to 5N, what force would we expect to see in the thumb flexorsthe spinal cordThe central pattern generator for gait is located in ________.somatosensory inputIn the absence of electrical stimulation, treadmill walking in the spinalized cat with intact dorsal roots is initiated by ___________.the amplitude of electrical stimulation of the spinal cordIn the spinalized cat with transected dorsal roots, the velocity of walking gait on a treadmill is determined by _____.Task 2For a simple reaction time experiment, subjects must perform two different tasks in response to the same stimulus. The first task (Task 1) involves flexing the elbow as quickly as possible. The second task (Task 2) involves flexing the elbow as quickly as possible to bring the index finger to a target. For which task would we expect a longer reaction time?Response programmingA motor control researcher asks subjects to perform two tasks. The primary difference between the two tasks is that one involves more "movement parts" than the other. Though the stimulus for each task is identical, and the subjects are aware of the movement they are to perform, the researcher notices that the reaction time increased as the number of movement parts increased. What stage of information processing is most likely influenced by this experiment?Simple reaction time testsAccording to Donder's subtractive method, which of the following experimental conditions produces the shortest reaction time?ParallelIf multiple sensory inputs are processed simultaneously, they are said to be processed in _____.upright standingIn which of the following positions would we expect to see the smallest spinal stretch reflex?ability to step over an obstacle noted in the visual fieldA lesion/injury to the motor cortex would likely have the greatest effect on which of the following locomotive functions?overall durationAll of the following are invariant features of motor programs except _____.5 & 6Which of the scenarios depicted above is/are indicative of vestibular function?4 & 6Which of the conditions listed are reflective of altered/incorrect somatosensory information?static postural controlThe ability to maintain the body's COM within a stable base of support refers to _____.eyes closed, foam support surfaceWhich of the following scenarios would isolate the influence of the vestibular apparatus on postural stability?Choice reaction time with 5 stimulus-response alternativesIn which of the following scenarios would we expect the longest reaction time?short-term memoryThe response selection stage of information processing takes place in _____.Where the body or body segment is in spaceJoint position sense refers to _____.AtaxiaWhich of the following would likely be present during gait following lesions in the cerebellum?rhythmicityThe key defining feature of locomotor activity is _____.diminished visuo-motor coordinationInjury to the motor cortex would result in _____ during gait.relative forceAll of the following are parameters of motor programs except _____.deafferentationThe absence of sensory input refers to _____.Postural controlWhich of the following does not likely involve a central pattern generator?Stimulus identificationA subject is required to respond to one of two stimuli: a "Go" light or a "No-go" light. The researcher finds that when compared to a simple reaction time test in which the subject responds to a single stimulus, the reaction time is greater. This increase in reaction time is likely due to increases in which stage of information processing?Ankle (1): small perturbations (1), firm support surface (1), distal to proximal strategy (2) Hip (1): hard/fast perturbations (1), small/unstable support surface (1), proximal to distal strategy (2)What are the two primary stationary (i.e. non-moving) strategies to maintain postural control following an external perturbation in the sagittal plane. List when each strategy is used and the general muscle synergy/pattern used during each strategy.1) Injury damages some of somatosensory receptors in and around the knee resulting in less somatosensory information being sent to the CNS 2) The knee sleeve compresses the cutaneous receptors causing them to send more information to the CNS. The CNS uses this additional information to better triangulate where they are in space and improves proprioception 3) Ensemble coding refers to taking all sources of sensory input and combining them into a single stream (instruments into an orchestra). In this example, some of the articular receptors are removed (diminished JPS) but cutaneous receptors are added (improved JPS). The elements of the code differ but the overall code is similar to an uninjured scenario.An otherwise healthy soccer player has sprained the medial collateral ligament (MCL) of her right knee. During the rehabilitation process, the clinician she's working with finds that her knee joint position sense is diminished. Surprisingly, when the soccer player begins wearing a neoprene knee sleeve, her knee joint position sense is improved. 1) Why does the injury result in diminished joint position sense, 2) how is the knee sleeve capable of improving joint position sense, and 3) how do these alterations relate to ensemble coding, if at all?1) Progression, postural control, adaptation 2) Stimulation generates stepping like behaviors. However, the stimulation does not reconnect the brain to the spinal cord and the brain is needed to maintain postural control and adapt while walking.We provided evidence for the existence of a gait central pattern generator in humans in that electrical stimulation produces stepping patterns in spinal cord injured patients. What 3 things are needed for locomotion and why can't stimulation produce locomotion?Short term sensory store: large capacity, short duration Short term memory (working memory): limited capacity, short duration Long term memory: large capacity, long durationWhat are the stages of memory? What is the general capacity and duration of each stage?Voluntary contraction / reaction time / conscious controlWhat is denoted by arrow B in the figure above?Long-loop reflex / functional stretch reflexWhat is denoted by arrow A in the figure above?Primary muscle spindle / IaWhat sensory neuron is responsible for the initial, small burst of activity denoted by arrow C in the figure above?Sensation of joint motionKinesthesia refers to _____.closed; openWhereas a(an) __________ loop system utilizes peripheral information/feedback in the refinement of appropriate motor responses, a(an) ____________ loop system is preprogrammed in nature.Anticipatory postural adjustmentsWhich of the following is an example of an open loop system?150msAn elbow flexion task is completed over a 100ms interval during which the biceps brachii is active for 50ms. If the duration of the activity is increased to 300ms, for how long would we expect to see the biceps brachii active?24NA motor control researcher is studying grip force by having participants lift an object of unknown weights. During the first trial, the subject produces a force of 2N in the finger flexors, and 6N in the thumb flexors, but is unsuccessful in picking up the object. If in the second trial the subject increases the force produced by the finger flexors to 8N, what force would we expect to see in the thumb flexorsensemble codingCombining multiple sensory inputs in a single stream refers to _____.trigger responseWhich of the following involves the highest level of processing by the CNS?It is non autogenic / it has the longest latencyRelative to the other options, what is it about your response to question #10 that tells you your answer has the highest level of processing by the CNS?parametersCharacteristics of a generalized motor program that can be altered are referred to as _____.PhasingWhich of the following is an invariant feature associated with generalized motor programs?Reaction time increases as the number of stimulus and response alternatives increaseWhat is Hick's Law?Highly natural and highly practicedExceptions to Hick's Law can generally be described as?motor unitThe smallest component of the nervous system that contributes to muscle contraction is the __________.Type IIbWhich type of muscle fiber is activated last during muscle contraction?Innervation ratioThe number of muscle fibers innervated by a single motor neuron is identified by the _____________.the relative refractory periodThe interval following generation of the action potential when a neuron can be depolarized only by an extraordinarily large EPSP refers to _____.AfferentWhich type of neuron conducts nerve impulses toward the central nervous system?move K+ out of the cellThe concentration gradient force has a tendency to _____.Myelin sheathThe _____ is/are responsible for increased nerve conduction velocity.Dendrite; axonInput to the soma is achieved via the _____, while output is achieved via the _____.AcetylcholineThe neurotransmitter associated with skeletal muscle depolarization is _____.Association neuronsThe majority of neurons are _____.TractA bundle of nerve fibers in the central nervous system is referred to as a _____.Na+In general, a change in selective membrane permeability to _____ begins the chain reaction that results in membrane depolarization.a-motorneuronsThe cerebellum has connections to all of the following except _____.Sensory neuronsThe dorsal roots of spinal nerves contain ____.CerebellumMore than half of the neurons in the brain are located in the _____.NegativeThe spinal stretch reflex is an example of a(an) ________ feedback loop.ANeurons A and B are both Type Ia. Neuron A has an axonal diameter of 25 microns, and neuron B has an axonal diameter of 18 microns. Which neuron has the highest conduction velocity?Type IbA neuroscientist is measuring activity from a sensory neuron associated with the biceps brachii. During isometric muscle contraction, this neuron displays high-frequency activity. What type of neuron is the researcher measuring?increase reciprocal inhibitionExcitation of the Ia inhibitory interneuron would _____.decreases permeability to Na+Excitation of the Ia inhibitory interneuron _____ in the antagonist alpha motor neuron.decrease reciprocal inhibitionExcitation of the Renshaw cell would _____.Somatosensory associationThe ________ area of the cerebral cortex is responsible for integration and interpretation of information from peripheral receptors.Muscles of the palmar surface of the handWhich of the following would be represented by the largest area of the primary motor cortex?CerebellumThe _____ is associated with integration of sensory and motor information to produce smooth movement.Type IaA neuroscientist is measuring activity from a sensory neuron. During rapid eccentric contraction, she notices that the activity of the neuron displays high frequency activity. What type of neuron is the researcher measuring?temporal summationThe mechanism by which a single presynaptic neuron is capable of increasing the EPSP in a postsynaptic neuron is _____.Type IIThe _____ neuron is sensitive to static muscle length.DisinhibitionInhibition of an inhibitory neuron refers to _____.Reciprocal inhibitionWhen contraction of the agonist causes inhibition of the antagonist, _____ is occurring.The net effect of recurrent inhibition is _____.inhibition of the agonist and disinhibition of the antagonistType Ib neuronAutogenic inhibition is initiated by the _____.Renshaw cellThe strength of recurrent inhibition is governed by the _____.presynaptic inhibitionA form of inhibition that decreases the post synaptic neuron's sensitivity to selective inputs is _____.the time interval between the onset of neural activation of a muscle and force productionElectromechanical delay refers to _____.Triceps brachii contraction of a male cheerleader supporting a female cheerleader above himUnder which of the following scenarios would we expect EMG amplitude and muscle force to be related?reciprocal inhibition and autogenic inhibitionThe "Slow-Reversal" method of PNF stretching utilizes _____ to improve range of motion.autogenic inhibitionThe "Contract-relax" method of PNF stretching utilizes _____ to improve range of motion.FeedforwardMuscle activity that produces quick voluntary movement patterns, independent of sensory input, during the task, is derived from ______ command signals from the CNS.hamstringsArticular receptors in the anterior cruciate ligament produce a stress-elicited reflex response in the ____ muscles.Type IaThe tendon-tap reflex is initiated by the _____ neuron.IWhat type of muscle fiber would be innervated by Motor Unit 1?5Which of the motor units depicted will produce the greatest force?1Which of the motor units depicted above possess the greatest ability to resist fatigue?Ballistic stretching calls for rapid movements that involve momentum. As a result, ballistic stretching causes repeated spinal stretch reflexes (i.e. muscle contractions) as opposed to reflexing a muscle (1). Passive or PNF stretching techniques take advantage of autogenic and reciprocal inhibition pathways that cause a relaxation of a muscle and greater flexibility (1). The sustained stretch allows for a consistent signal from the GTOs to be interpreted as a safe tension and overrides the initial spinal stretch reflex that occurred when the muscle was initially put into a position of stretch (1).Briefly (i.e. 2-3 sentences) explain why ballistic stretching techniques are not as effective as passive stretching or PNF stretching.Rate Coding (1/2) = the number of action potentials sent to the muscle (1). The higher the code, the more force (1) Motor Unit Recruitment (1/2) = the number of M.U. recruited (1). The more motor units recruited, the more force (1)We discussed in detail the two manners in which the nervous system controls muscle force. A) Name these two factors (1). B) Define each factor (2). and C) What does a change mean in each factor due to muscle force?Autogenic = Reflex is trying to stop the action (inhibit the biceps) because of the increased tension on the muscle (1). Command is over riding the reflex because we want to complete the task and know that we can (1). Reciprocal = Reflex is inhibiting the tricep/antagonist to reduce resistance to the contraction (1). Command is facilitating/helping the reflex to reduce the resistance to the contraction (1). Recurrent = Reflex is inhibiting the biceps to stabilize the firing rate (1). Command is overriding the reflex by inhibiting the Renshaw cell so that the firing rate is not stabilized but instead allowed to go towards maximum effort (1).An individual wishes to produce a strong contraction of the biceps brachii during a "biceps curl" exercise (e.g. a 3 repetition max). During this motor task, the individual's reflexive inhibitory pathways are active but because this is a voluntary movement, so are the individual's descending commands. List (bullet points are fine) what is happening to both the (reflexes and commands) during the task and why.accuracyAll of the following are examples of process measures used to assess motor learning except _____.The specificity of learning principleThe best practice approximates the movements of the target skill and the environmental conditions of the target context. This statement is known as _____.Verbal-cognitive stageDuring which stage of motor learning would we expect to see large, rapid improvements in performance?distributedA motor learning researcher has subjects perform practice trials for a period of 10 minutes, followed by a 10 minute rest period, followed by another 10 minutes of practice trials of the same task. This is an example of _____ practice.randomA motor learning researcher has subjects perform 10 practice trials during which the task being practiced alternates continuously from Task 1 to Task 2 in no particular order. This is an example of ____ practice.variedA physical therapist has a stroke patient perform 12 trials of a task during which the patient is required to pick up an object. The therapist continuously changes the characteristics of the object being grasped (e.g. weight, width, etc.). This is an example of ____ practice.50 trials of isometric quadriceps contraction to 20, 40, 60, and 80%max (200 total trials)A motor learning researcher is interested in determining the optimal practice methods for improving transfer of learning. If the transfer test involves an isometric quadriceps contraction to 50%max, which of the following practice scenarios would result in the greatest performance on the transfer test?reproducing 35° of knee flexionA motor learning researcher is interested in evaluating the effects of variable vs. continuous practice on motor skill acquisition. Subjects practice a joint position reproduction task that involves reproducing an angle of 35° of knee flexion. If she assesses the extent of learning following the acquisition phase, which of the following should she use at the retention test?They have the same absolute retention because they both lost 4N of precision. #1 has better relative retention. RR = difference score divided by amount acquired during practice. Difference score = last acquisition minus first retention. Amount acquired = last acquisition minus first acquisition. #1 = difference score of 4 and an amount acquired of 10 (20-10). 4 / 10 = 40% lost or 60% retained. #2 = difference score of 4 and an amount acquired of 8 (16-8). 4 / 8 = 50% lost or 50% retained.Two individuals are learning a novel task that involves producing a specified grip force. Performance on the task is measured as the difference (error) between the specified force and the force the subject produces during each trial. Individual 1 starts the practice/acquisition phase with an error of 20N but improves to an error of only 10N on the final practice trial. Individual 2 starts the practice/acquisition phase with an error of 16N but improves to an error of only 8N on the final practice trial. If both individuals "lose" 4N of precision on a retention test, who learned the task better? Who has better absolute and relative retention?