Section 1 Notes Flashcards
Define: motor behaviour
Includes individual movements and motor skills
Define: motor skill
– A goal-directed task that is made up of a series of movements
– E.g., shooting a basketball into a hoop; passing the puck in hockey to another player
Define: movement
– Make up the components of a motor skill and are defined by the behavioural
characteristics of the limb or a combination of limbs
– E.g., extending at the elbow when shooting a basketball
Reasons to distinguish movements from skills
- People learn movements when beginning to learn a skill
- Different movements can produce the same skill (bowling between legs and bowling with one arm)
- Motor skills and movement are measured differently (skills are tied to outcome and movement is tied to specific characteristics)
How is motor behaviour controlled?
a combination of feedforward and feedback control
Define: feedforward control and give an example
– Uses sensory information prior to the execution of movement rather than during the movement
– Can use what was learned through trial and error during previous movements
– This type of control is often rapid
– Example: the movement to swat a mosquito on your arm may be too fast for you to make corrections based on where you see or feel your arm.
Define: feedback control and give an example
– Uses sensory information (“sensory feedback”) during the execution of movement
– Involves modification of ongoing movement to produce high accuracy
– Allows for error detection and thus movement correction
– This type of control is often slower
– Example: correcting the trajectory of your arm/hand to catch a ball that is curving away from you because of the wind based on visual feedback
List 4 sensorimotor control problems the nervous system must deal with
- Degrees of freedom (DOF) problem
- Serial-order problem
- Sensorimotor integration problem
- Motor learning problem
Describe the degrees of freedom problem that the nervous system must deal with
The DOF problem relates to the fact that the nervous system must control and coordinate many neurons, muscles, and joints to perform a particular motor behaviour
Define: DOF
DOFs refers to all of the independent variables in a system (which in this case is one’s body).
- joints, muscles, even individual neurons depending on the level of analysis
- controlled by groups of neurons that can fire in different patterns
How many muscles and bones are in the human body
640 muscles
206 bones
How many DOFS does the arm have not including fingers? Describe them
7
Shoulder: 3 (up-down, side-side, twist)
Elbow: 2 (flexion/extension and twist)
Wrist: 2 (flexion/extension and side-side)
What is the advantage of having so many DOFs
- provides greater flexibility
- can perform the same action different ways (important if you suffer an injury/ are an athlete)
What are some of the solutions to the DOF problem that the nervous system can use? (4)
- can ensure efficiency by avoiding extreme joint angles and moving smoothly
- use muscle synergies. A muscle synergy is a group of muscles activated by a common command (and thus working together)
- determine the task relevant DOFs. Thus, rather than reducing the number to control, the nervous system can coordinate only the DOF that are most relevant to the motor behaviour
- exploit the mechanics of the joints and muscles (e.g., inertia, gravity). The nervous system might be able to activate the muscles less if inertia causes a limb to move (or continue moving). As for gravity, if you have an arm out to the side, why activate muscles to bring it back down when you can use gravity to assist (and thus use less muscle activity).
give an example of a use of muscle synergy
One example of using a muscle synergy is to “freeze out” a portion of the DOF, which means introducing temporary, rigid couplings between multiple DOFs, thus reducing the number of DOFs to control. For instance, when learning to ice skate, many people lock (or freeze out) their knee joints. Over time, they learn to bend the knees. Locking the knee joint means that the nervous system doesn’t have to worry about complex coordination of the knee with the rest of the leg joints.
Describe the serial-order problem that the nervous system must deal with and how it solves it
- the nervous system must sequence a movement or series of movements by activating the correct muscles in the correct order
- forms a motor plan
- use co-articulation: simultaneous motions of different effectors (body parts, trunk, head, eye, etc) to help achieve a task that unfolds over an extended period; the activity of one muscle begins before the other ends to allow smooth movement at different joints
Describe the sensorimotor integration problem that the nervous system must deal with
- aka perceptual-motor integration problem
- the nervous system needs to integrate sensory information to form a perception, which it can then use to act on (i.e., execute a motor behaviour)
- issue: sensory information is encoded by different receptors in different parts of the body and thus, in different co-ordinate systems; sensory information must be converted into a signal the motor regions can understand
Describe the motor learning problem that the nervous system must deal with
- To what extent are we born with a selection of motor skills and to what extent are motors skills learned?
- How do we acquire skills that we must learn?
- How do we adapt our movements to changes in the sensorimotor system?
- How is motor memory represented and maintained?
What factors affect postural sway (5)
- Physical characteristics and condition of the individual (sway is usually increased with age and fatigue)
- Stance posture (position of feet can change amount of sway)
- Support surface characteristics (sway increases when standing on compliant terrain; E.g., standing on a bed or couch, snow, sand)
- Availability of sensory information (sway is smaller when all three relevant sensory systems are available)
- Psychological factors (fear, multitasking, etc., can affect the amount of sway)
Define: postural stability
keeping the body’s centre of mass within the base of support
Define and give the location of the COM
point that is at the centre of the total body mass; located roughly at the location of your belly button
Define: base of support (BOS)
area of the body that is in contact with the support surface plus the space on the ground between the contact points
Define: centre of pressure (COP)
centre of the distribution of the total force applied to the supporting surface; helps keep COM inside BOS
Define: anticipatory postural adjustments
- also state its purpose
- postural changes caused by muscle activation that occur prior to or at the same time as the onset of the postural disturbance due to self-movement (ex: raising hand)
- meant to minimize the potential disturbance that the movement may cause
