Week 1: Touch, Proprioception and Vision

Question 1

Describe the role of sensory information in motor control (2 points)

Answer 1

• Touch, proprioception and vision contribute to motor control skills in significant ways
• Touch and proprioception are included as senses in the somatic sensory system, whereas vision is the sense associate with the visual sensory system

Question 2

Describe touch (3 points)

Answer 2

• Relates to the contact we have with objectss
• Provided by cutaneous receptors in the skin
• Important in skills that involve contact with external objects

Question 3

Describe the role of touch in motor control (6 points)

Answer 3

• There are five movement-related influenced by tactile sensory information the CNS receives from touch
  
  • Movement accuracy
  • Movement consistency
  • Movement timing
  • Movement force adjustments
  • Estimate movement distance

Question 4

Describe the role of touch in movement accuracy (9 points)

Answer 4

• The ability to perform accurate movements is heavily affected by tactile feedback, or touch.
• Movement accuracy decreases when tactile information is not available, especially at the fingertips
• Poorer accuracy in serval skills is demonstrated when tactile feedback is removed or minimized, such as
  
  • Pointing
  • Reaching and grasping
  • Typing on a keyboard
  • Maintaining a precision grip
  • Rhythmically tapping a finger to an auditory stimulus
  • Playing a sequence of notes on a piano

Question 5

Describe the role of touch in movement consistency and movement timing (3 points)

Answer 5

• Experiments have shown without tactile sensory feedback from the finger, not only does accuracy decrease, but so does movement consistency
• Movement timing can be influenced by tactile feedback, particularly in rhythmic movements that involve intermittent contact with the environment such as juggling and locomotion
• Experiments have shown that including a tactile event as a timing cue improved timing accuracy

Question 6

Describe the role of touch in movement force adjustment and estimating movement distance (4 points)

Answer 6

• Movement force adjustments while holding and using an object also depend tactile feedback
• For example, when grasping and lifting a cup, an individual must regulate the amount of grip force as they move the cup and properly position it to drink from.
• Researchers have shown that the sensory feedback from the grasping fingertips intermittently updates the movement command in the CNS to adjust grip forces as necessary (closed-loop)
• Tactile feedback could be used to improve the use of proprioceptive feedback to estimate movement distance when the beginning and end of a pointing movement involved touching a surface

Question 7

Describe proprioception (10 points)

Answer 7

• AKA kinaesthesis
• The sensation and perception of limb, body, and head position and movement characteristics and the force and effort associated with muscle contraction.
• Afferent neural pathways send to the central nervous system proprioceptive information about characteristics such as limb movement direction, location in space, velocity, and muscle force.
• Relates to balance and knowing where you are in relation to the environment
• Provided by:
  
  • proprioceptors, or sensory receptors, in the muscles, tendons and joints
  • vestibular system in the inner ear
• Important in:
  
  • determining the position of our body and our limbs in performing skills
  • maintaining equilibrium and balance

Question 8

Describe the neural basis of proprioception (7 points)

Answer 8

• The CNS receives proprioceptive information from afferent neural pathways that begin in proprioceptors, sensory neurons located in the muscles, tendons, ligaments, and joints.These neurons pick up information about body and limb position and changes in position.
• There are several types pf proprioceptors, each of which detects specific characteristics of body and limb position and movement
• Some examples of proprioceptors are:
  
  • Muscle spindles, found within the fibers of most skeletal muscles, detect changes in muscle length and velocity
  • The Golgi-tendon organs, located in skeletal muscles near the insertion of tendons into the muscle, detect changes in muscle tension or force
  • Joint receptors, located in the joint capsule and ligaments, respond to changes in force and rotation applied to the joints
• Alcohol can affect proprioception, hence why police officers conduct sobriety test that test the driver’s proprioception

Question 9

Label the following image (8 points)

Answer 9

Question 10

Describe the methods of investigating the role of proprioception in motor control (9 points)

Answer 10

• Research studies have examined the role that proprioception plays in motor control. These studies have examined the effect when proprioception information was removed or was not available.
• One of those studies, conducted by Bizzi and Polit (1979), involved afferent neural pathways of silver spring monkeys being removed through surgical deafferentation.
• This procedure was conducted so the proprioceptive information was not able to make its way to the monkey’s central nervous system.
• This resulted in a decrease in the performance of grooming, climbing and grasping of food in those monkeys
• A study by Blouin et al (1993) that involved humans compared the participants with normal nerve function to participants with the medical condition known as sensory neuropathy, where nerve damage is present and causes proprioceptive information to not make it the CNS.
• This study required participants to complete a pointing task with and without vision of their hands. Those with sensory neuropathy performed just as well in the pointing task when vision was available but performed significantly worse when vision was not available.
• Studies have also been conducted where proprioceptive info was impaired through blocking the nerve info by placing a blood pressure cuff on to participants, inducing “arm sleep”.
• There has also been studies where vibrating a tendon in participants arms has been conducted. The tendon vibration study involved the participants performing an arm positioning task. The participants perform this task with no vision of their arm available.
• When the participants bicep brachii tendon was vibrated, it was found that the performance level of this task was decreased. The experimenter concluded that the muscle spindles in the bicep brachii are an important source of dynamic position and velocity information used by the central nervous system to coordinate arm positioning task

Question 11

Describe the role of proprioception in motor control (6 points)

Answer 11

• The role of proprioception in motor control is important in closed loop control
• Studies have shown that movement coordination is affected by a lack of proprioceptive info. While certain movements can still be carried out studies have shown the quality of these movements decrease
• Lack of proprioceptive info can decrease the accuracy of movements, as shown in the sliver spring monkey experiment.
• It has also been identified that proprioception impacts coordination control.
  
  • It has been suggested that postural control, more specifically our ability to maintain correct upright stance posture, is affected by proprioception info.
  • Spatial temporal coupling research has shown that proprioception is important when different limbs are involved in movements, as well as when two segments of the same limb, for example the upper arm and the forearm, are involved in a movement.

Question 12

Describe vision (3 points)

Answer 12

• Relates to what people can see
• Provided by photoreceptors in the eye
• Important in providing information about the environment and our body in relation to the environment that we use in planning, performing and evaluating movement

Question 13

Describe the role of vision in motor control and methods of investigating the role (10 points)

Answer 13

• Research findings have identified that we tend to utilize and trust our vision more so than the info we receive from our proprioceptive and vestibular system
• This can be demonstrated clearly when watching someone learn to dance or play piano. The novice dancers will tend to want to look directly at their feet and those learning to play the piano will spend a large amount of time looking directly at their hands and their fingers.
• One famous study conducted by Lee and Aronson in 1974 demonstrated the faith we place in our vision.
  
  • This experiment involved an experimental room which had walls that could move up and down forward and back while the floor remained stationary.
  • When participants were in this room and the walls were moved their vision told them that the walls were moving towards them. In contrast the proprioceptive info they were experiencing would have been telling them that they were standing still.
  • Because their vision was telling them that the walls were moving towards them they would have interpreted this that they were falling towards the wall. These participants trusted their vision more than their proprioception and they made postural corrections that were not needed, such as leaning forward or back.
  • These findings show that vision predominates our other senses.
• Eye movement recording technology has shown that vision plays an important role in elite sporting performance. When observing soccer players, more experienced athletes are able to use their vision to identify what their opponents are going to do next by looking at pre cue information. Less experienced players are unable to do this because they need to focus their attention on the ball to ensure that they are able to maintain possession of the ball.
• Another piece of technology that has examined the role vision plays in motor control is temporal occlusion technology. These specially designed goggles are designed to block the participants vision of an outcome of a movement. These goggles can be used to examine how long a person needs to be able to see something, for example an approaching ball, to execute a skill.
• Another example of temporal occlusion technology that has been used in training is showing tennis players video footage of an opponent serving that has been filmed from the perspective of the receiver. The footage is paused at the point of contact and the viewer has to identify which direction they think the serve is going. This type of training helps the learner to start to identify pre-contact cues such as the racket head angle or ball toss position so that when they are in a game situation they can anticipate the direction of the serves.

Question 14

Describe the relationship between vision and locomotion (6 points)

Answer 14

• Vision is important when performing locomotion skills.
• For example when you’re running across the road there may be potholes that are full of water because of recent rains. You want to avoid those puddles. To do this your vision provides feed-forward information that helps you contact the dry ground.
• In a sporting example, a baseball or softball player will use visual information to adjust their stride lengths to ensure they contact the bases as they are running around the diamond.
• A study by Lee, Lishman and Thompson (1982), which examines stride length adjustments in elite long jumpers, found that visual info was used to adjust stride length so that the jumpers were able to contact the takeoff board in an appropriate manner.
• Because the measurement of long jumping is taken from the end of the take-off board, long jumpers want to make sure that they are taking off as close to the end of the take-off board as possible. Otherwise they would be wasting some of their jump
• When observing the stride lengths, it can be seen that they increase in a consistent manner for the first six or so strides. The next six maintain a consistent length but the last six are very inconsistent. This is because the jumper’s visual to time and contact information has told him that he needs to make adjustments so that he will be contacting the board appropriately.

Question 15

Describe the relationship between vision and balance (6 points)

Answer 15

• We receive balance and stability information from our proprioceptors and the vestibular apparatus in our inner ear as well as our vision.
• People tend to put more faith in the visual info they receive, identified in the moving room experiment.
• Physical education teachers coaches and other practitioners need to understand how vision affects balance so that they can help people they are working with
• One specific practical implication of this relates to the importance of keeping your head still when performing striking skills in sports like golf, cricket and baseball. If a player is able to keep his head still it will help in the performance of these striking skills.
• For example a golfer who keeps his head still will be more likely to make good contact with the ball compared to a golfer who sways his upper body and head during the swing.The reason for this is even a small amount of head movement can result in unwanted postural adjustments and swing angle changes.
• In other sports where rotational movements are performed, sports like gymnastics, aerial skiing and weight boarding, these movements can cause confusion between vision proprioceptors and the vestibular apparatus. This confusion can lead to dizziness and sometimes nausea. One way this can be overcome is using a technique called spotting. This technique involves focusing your vision on one spot while spinning so that you’re able to hold your head steady for as long as possible. Then at a certain point when you have to turn your head you quickly snap your head around and focus your vision on that same spot again.

Question 16

Describe the relationship between vision and catching (10 points)

Answer 16

• Catching involves intercepting or taking hold of a moving object and is a skill that is very important in lots of sports.
• When discussing the importance of vision in performing a caching skill, Magilla identified catching as a complex perception action skill.
• Perception action coupling involves perceiving or detecting information, for example how long until the ball is going to be within reach, and the action part involves the performing of the planned movement.
• Vision is clearly the dominant sense that delivers the information involved in the perception task. Research conducted by Williams and McCreary (1988) that examined eleven-year-old boys catching demonstrated three phases of catching.
• Movement analysis showed that for the first 160 to 240 milliseconds of the ball’s flight there is no arm or hand movement. Then at 25% of the balls flight the beginning of elbow flexion and finger extension can be seen. At about 50% of the balls flight the hands begin to withdraw from the ball to cushion the impacts when the ball meets the hands. At the point of 75% of the balls flight path, the catcher’s final finger positioning has been achieved so that the hands are in the correct position to take the catch.
• This phase information shows that vision delivers advanced spatial and temporal info that enables a motor control system to get the hands and fingers in the correct position to successfully catch the moving objects.
• Proprioceptive info and tactile info become involved from the point of ball contact.
• One area of catching research that has been examined relates to the amount of time of visual contact time is needed to successfully catch a moving object.
• Research has not established an exact time that is needed. This is very much dependent on the catching situation. Research has suggested though that constant visual contact is needed during two critical periods of the object’s flight path. The first being the initial flight to get an idea of the direction and distance of the flight path and the second being the period just before the ball contacts the hands. This gives a better understanding of the time to contact.
• A study by Savelsberg and co in 1993 demonstrates the importance of seeing the ball late in its flight path. Through the use of occlusion goggles, this study showed that when visual contact was available during the last 200 to 300 milliseconds of the object’s flight path, catching significantly improved, showing time to contact information allowed participants to get their hands in the correct position and it also told them when to grasp.

Question 17

Describe the relationship between vision of the hands and catching (6 points)

Answer 17

• One question that has received previous research attention is do we need to be able to see our hands to be able to catch successfully.
• An early study by Smyth and Marriott (1982) involved participants trying to catch an oncoming ball. Some trials allowed them to see their hands and in other trials participants could see the balls flight but the vision of the hands was blocked by a screen.
• The results showed that when they could see their hands they caught on averaged 17.5 out of 20 catches. When the screen blocked the view of their hands they are only able to catch on average 9.2 out of the 20 catches
• Similar research conducted since this study has resulted in general agreement that experience and skill level are factors that affect whether or not catchers need to see the hands to be able to catch successfully.
• More experienced and more skilled catchers do not need to see the hands but less experienced less skilled catchers will benefit if they can see their hands.
• The vision of their hands provides visual information that complements that catches proprioceptive feedback to help them get the hands in the correct position to catch the ball

Question 18

Describe the relationship between vision and hitting a moving object (6 points)

Answer 18

• Hitting a ball involves spatial and temporal interception of the ball.
• The motor control of the hitting action is based on the visual information available to the hitter or the batter.
• A study conducted by BaHill and LaRitz (1984) examined eye and head movements of a major league baseball player and several college baseball players. The findings showed that the more experienced major league player visually tracked the ball for longer than the college players
• The major league player maintain visual contact to a point 5.5 feet in front of the plate compared to the college players who lost visual contact earlier when the ball was 9 feet in front of the plate
• It is worth mentioning that these findings and the findings of other visual info research conducted on various sports have shown that the speed of the ball means athletes are often not over keep visual contact until the ball hits their hands or their bat
• For example, in Australian rules football, a player may not be able to keep visual eye contact on the ball all the way into his arms. So when giving advice it is generally more accurate to tell players to keep an eye on the ball for as long as possible