UMass Amherst KIN 470 - Lab 4 - spinal cord reflexes (3 pages)

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Lab 4 - spinal cord reflexes



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Lab 4 - spinal cord reflexes

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3
School:
University of Massachusetts Amherst
Course:
Kin 470 - Exercise Physiology
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Spinal cord reflexes KIN 460 Motor Control Lab Section 2 Lab 4 Spinal cord reflexes Monosynaptic stretch reflex lab The nervous system likes to keep tabs on the state of the body Reflexes provide the nervous system a way to protect the body i e withdrawal reflexes or to restore deviations from intended movements i e a slip of the foot on ice When a difference between the expected position or change in position of a joint occurs stretch reflexes mediate a restoration of the joint to its intended position by activating the muscle that is stretched to contract and increase its tension through a monosynaptic stretch reflex Reflexes provide a rapid error correction process which happens at a latency i e delay that is quicker than we can voluntarily respond This process is a powerful way for us to establish corrective mechanisms that allow the execution of complex coordinated actions like walking in otherwise dangerous conditions i e icy surface Lab objectives 1 To become familiar with anatomical and physiological elements of simple spinal reflexes 2 To examine properties of some simple neuromuscular reflexes commonly tested in physical diagnosis 3 To measure and compare latent periods and reaction times of extensor reflexes 4 To elicit an extensor reflex and compare contractile force vs stimulus strength 5 To make associations between stimulus intensity reflex latency and excitation magnitude Spinal Cord Reflexes Setup 1 Set up each workstation accordingly Make sure you have a EMG electrode lead set b Three disposable vinyl electrodes c Reflex Hammer Transducer 2 Next locate the middle belly of the rectus femoris and place the first electrode pad white negative two inches below this mark on the mid line from the ASIS to the knee mid patella Place the next electrode pad red positive 4 inches above the first pad 3 Plug the EMG lead set into Channel 2 and the Reflex Hammer into Channel 1 4 Select Lesson 20 Spinal Cord Reflexes and type in your name Calibration 1 Set the reflex hammer on a flat surface Subject should sit with legs hanging at 90 degrees 2 When ready click Calibrate 3 Lightly tap the reflex hammer two or three times on a flat surface Subject should extend leg fully to 0 degrees and then return to 90 degrees 4 Check the calibration data to ensure that there are peaks identifying hammer contact and an EMG recording Data Recording 1 Ask subject to close eyes then click Start Wait about half a second before beginning 2 Tendon tap instructions Spinal cord reflexes KIN 460 Motor Control Lab Section 2 a Strike the optimal reflex spot of the patellar tendon forcefully and observe the resulting muscle contraction i Repeat 5 times at three different strike intensities ii Repeat further if reflexes were not elicited b If subject is not responding try another subject 3 When finished click Suspend Review the data If the data looks clean click done a You should have a minimum of 15 clear taps at varying forces of the hammer Repeat this experiment for one or two more people in your group before moving to Part 2 Make sure you extract and save the data from each subject before moving to the next subject Data Extraction 1 Click Analyze current data file and click on the I Beam cursor button to highlight your data for each tendon tap Make sure you are extracting the difference between the onset of stimulus and the onset of the muscle excitation Delta T CONSULT WITH INSTRUCTOR BEFORE SAVING YOUR DATA TO ENSURE YOU ARE EXTRACTING THE CORRECT DATA a Highlight the entirety of each individual hammer tap and emg response one at a time b The top of the screen will be windows where you can extract that max force and max emg measured i You can just type these into excel as you check them c Next you need to get your delta t i Start highlighting the cursor at the base of the force trace at the instant it starts to increase Continue to highlight until you get to the beginning of the emg signal where it becomes positive 2 Copy the data set into excel and save the file This file is what you will be analyzing and graphing in Excel during your write up Data Analysis and Report REFLEX DATA PRESENTATION 1 Present a table with all subject data a Each subject should have the following values for each measure max force max emg delta t 2 Graph 1 relationship between tendon tap force and reflex latency delta t a Create a graph with normalized force data on the x axis and normalized latency on the y axis b Plot the data as a scatter plot dots only c Apply a linear best fit line display the equation for the line and the r 2 d Use proper axis labels for the data 3 Graph 2 relationship between tendon tap force and emg amplitude a Create a graph with normalized force data on the x axis and normalized emg amplitude on the y axis b Plot the data as a scatter plot dots only c Apply a linear best fit line display the equation for the line and the r 2 d Use proper axis labels for the data Lab report questions 1 Define reciprocal inhibition and explain its importance in the context of a monosynaptic stretch reflex 2 Describe the mechanical sequence of a stretch reflex in correct sequence from tendon tap to muscle contraction 3 What is the expected relationship between the tendon tap force and the reflex latency Explain why you would expect this relationship based on your answer to number 2 above Spinal cord reflexes KIN 460 Motor Control Lab Section 2 4 What is the expected relationship between the tendon tap force and the magnitude of the EMG response i e the amplitude Explain why you would expect this relationship based on your understanding of stretch reflexes and neurological factors that contribute to increased force production and how EMG signals are composed WHAT YOU ARE TURNING IN One figure with two graphs Include a figure caption which briefly discusses the contents of each graph without getting into details One table for your raw data o Remember to round your values to reasonable numbers i e if your data is in milliseconds the nearest millisecond is reasonable Include a brief answer to each of the questions above


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