Term
| what is a closed loop system of motor control? |
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Definition
| a system of motor control that requires feedback for accurate movement |
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Term
| what is the path of the closed loop? |
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Definition
| you have a reference for movement that is sent from the executive to the effector to create the movement. Feedback about the movement is sent back up to be compared to the reference |
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Term
| is balancing on one foot an open or closed loop and why |
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Definition
| closed loop because you use the feedback from your body to maintain your balance |
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Term
| what does your feedback come from when standing on one foot |
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Definition
| vision, proprioception, sensory receptors, vestibular system |
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Term
| what are the open and closed loop parts of reaching out to grab a cup |
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Definition
| you initially use open loop to reach. When you get close to the cup, you need vision and sensation to be sure you touch the cup and grasp it correctly |
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Term
| is using a cursor on the computer open or closed loop? |
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Definition
| closed: you use visual input to guide movement |
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Term
| what is the path of the open loop? |
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Definition
| executive issues commands, effectors produce movement |
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Term
| is the open loop a feedforward or feedback system |
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Definition
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Term
| is the closed loop a feedback or feedforward system |
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Definition
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Term
| do feedforward systems depend on sensory feedback for accuracy? |
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Definition
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Term
| can feedback be available to a feedforward system? |
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Definition
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Term
| what are examples of feedforward systems |
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Definition
| boxing jab, jumping off a box, baseball bat swing |
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Term
| how is running a hybrid open/closed loop? |
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Definition
| when you execute your program for running, it's open loop. If you intermittently sample the environment for visual, somatosensory = closed loop. If you start to fall, you will have reactions/reflexes enclosed loop to respond |
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Term
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Definition
| a stored set of commands that, when executed, produce movement that does not depend on feedback |
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Term
| is a motor program open or closed loop? |
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Definition
| open loop: feedforward. You just do it |
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Term
| does a motor program require feedback |
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Definition
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Term
| describe the storage limitation for motor programs |
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Definition
| you have an unlimited potential number of motor programs to store. Do we have enough capacity in the CNS for this many motor programs? |
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Term
| describe the novelty limitation for motor programs |
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Definition
| what about movement that you've never been exposed to? You don't already have a motor program for that? |
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Term
| what is a general motor program? |
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Definition
| a motor program for one type of movement that can be varied for different environments |
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Term
| what are some features that make a generalized motor program clearly a part of a gmp? |
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Definition
| order of events, timing, relative force |
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Term
| what are parts of a GMP that can vary? |
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Definition
| overall force, overall duration, muscles used |
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Term
| if you write a sentence with your dominant hand, non-dominant hand, pen gripped with teeth, pen taped to foot, are you still using the same generalized motor program |
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Definition
| yes: there are features that are the same for each task |
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Term
| what does it mean that phasing is the same in a GMP |
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Definition
| each muscle has the same proportion of movement to other muscles |
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Term
| are running and walking the same motor program and why/why not? |
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Definition
| no: they are different because your relative support pattern is different. The phasing is different |
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Term
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Definition
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Term
| how do motor programs work according to the impulse timing theory? |
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Definition
| the motor program tells the muscles when to come on, when to shut off, how many muscles to recruit, how much force to use |
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Term
| what evidence do we have that motor programs work according to the impulse timing theory? |
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Definition
| measurements of onset, duration, and magnitude of EMG activity during movement |
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Term
| what is a central pattern generator |
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Definition
| an isolated 2-3 segments of the spinal cord that can produce a rhythmical output in flexor/extensor nerves in a locomotor pattern |
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Term
| is the CPG model a model of impulse timing |
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Definition
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Term
| what is necessary for the system according to impulse timing |
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Definition
| the system must know where the limb is at the start of movement and must specify appropriate durations and intensities of the muscular impulses |
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Term
| in a force vs time graph, what is the area under the curve? |
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Definition
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Term
| how can you decrease impulse? |
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Definition
| decrease force, decrease time |
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Term
| what are degrees of freedom as applied to human movement? |
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Definition
| independent states that have to be controlled at the same point during a motor at |
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Term
| what is the degrees of freedom problem |
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Definition
| humans have so many degrees of freedom that it would be impossible to control them all individually |
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Term
| is movement optimal or just good enough |
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Definition
| movement is just good enough. Habit is strong. |
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Term
| does the brain maintain and use a currently accurate model of the musculoskeletal plant? |
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Definition
| no. it tries to activate damaged muscles. |
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Term
| Are motor programs computed by optimization or learned and recalled? |
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Definition
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Term
| what is good about motor programs? |
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Definition
| keeps the executive from having to worry about all of the degrees of freedom. Oversimplifies the many degrees of freedom. |
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Term
| what are some innate motor programs |
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Definition
| reflexes that we are born with: sucking, swallowing, grasp, stepping, breathing rooting |
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Term
| how are innate motor programs activated? |
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Definition
| by a stimulus or by central processing |
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Term
| describe rapid movements as evidence for motor programs |
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Definition
| some movements can be faster than the time to process information. Example = study in which people were told to start a motor program, then stop it. If told to stop too late, they can't stop because they've initiated their motor program |
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Term
| why is "reaction time is longer when you're going to do a complex task" evidence for motor programs? |
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Definition
| because the programming is more complicated, it takes longer to load the programming. |
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Term
| how are blocked movements evidence for motor programs? |
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Definition
| if you try to lift a lever that you've lifted before, you will recruit the same muscles at the same times to try to lift the lever even if the lever is blocked and won't move. |
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Term
| how is deafferentation evidence for motor program? |
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Definition
| can still perform the same tasks even without sensory information coming back |
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Term
| how are anticipatory postural adjustments evidence of motor programs? |
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Definition
| EMG shows that muscles are activated prior to movement because the motor program is pre-programmed |
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Term
| what are some things that the motor program theory does not account for? |
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Definition
| biomechanical properties of limbs, such as springiness in muscles; changes in mechanics such as if you change the starting position, environment effects, task characteristics and constraints |
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Term
| are we as focused on reflexes with motor programming as we were initially |
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Definition
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Term
| what are the clinical implications of motor programming |
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Definition
| we know that movement can occur without sensory feedback. We can focus on learning and creating new programs through practice, associations. |
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Term
| what is the speed-accuracy relationship? |
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Definition
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Term
| what are the 2 phases of aiming movements? |
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Definition
| initial open loop movement, final closed loop to use feedback to reach the target |
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Term
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Definition
| movement time is related to task (distance, target size, effector) |
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Term
| what is fitts tapping task? |
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Definition
| varied target width and distance between targets |
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Term
| what is the mathematical relationship for fitts law |
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Definition
| Movement time = a + b[log2(2A/W)] |
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Term
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Definition
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Term
| fitts law says that more processing takes more or less time for movement |
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Definition
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Term
| what determines the slope of the relationship in the fitts law graph? |
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Definition
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Term
| what is on the y axis of the fitts law graph |
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Definition
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Term
| what is on the x axis of the fitts law graph |
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Definition
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Term
| what are the units for the index of difficulty |
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Definition
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Term
| what does the difficulty depend on? |
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Definition
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Term
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Definition
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Term
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Definition
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Term
| can fitts law be generalized to other situations? |
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Definition
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Term
| describe the relationship between force and force variability |
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Definition
| linear: the more force, the greater the variability of the force |
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Term
| how does force variability explain fitts law |
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Definition
| the more force we try to generate with our muscles, the more variable we are. As we move faster, there is more force and more force variability, hence more error. |
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Term
| what are exceptions to speed-accuracy trade off? |
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Definition
| faster movements can be more consistent and more accurate, BUT this is still different from the spatial accuracy tasks examined by fitts law |
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Term
| why does moving slower make you more accurate? |
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Definition
| you can use sensory feedback to improve spatial accuracy |
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