Motor Loops_PL Flashcards
List the 2 ways movements are broke down
- Open loop control (bottom up)
- Closed loop control (top down)
Describe the “loop”
The loop is a cycle or circuit of action and evaluation. If the loop is closed feedback becomes a critical part of the loop. If the loop is open feedback can only be applied to future action.
Type of Loop: The instructions are structured in advance and are executed without regard to the effects that they may have on the environment
Open loop
Ex. like using a fire to try and keep a consistent temp in your house
List the Key Features of Open Loop Control (3)
- RAPID, less than 150 ms
- CANNOT use sensory feedback to alter current movement
- PROGRAMMED movement
Describe central pattern generators (CPGs) (2)
CPGs are a network of neurons in the SC that produce rhytmical movements in the limbs even when the brain is not receiving sensory feedback from the periphery
Flex/ext mm groups are alternately activated when the SC is stimulated
List the important concepts about CPGs (6)
- Prewired in SC
- Turned on in various ways and continue until shut off
- Patterns can me modified based on sensory input
- Basic relfexes are still active and can influence CPG output
- Reflexes are not stereotyped (reflex-reversal phenomenon)
- The GOAL of movement is MAINTAINED
Term: restructured set of central commands and capable of carrying out movement
Motor program
List the evidence for the exists of motor programs (3)
- Some movements are performed faster than feedback can be processed
- Reaction time is longer for complex movements compared to simple movements
- Individuals who can’t receive sensory input can still perform some skilled movement
List the 2 types of errors seen in motor programs
- Program selection
- Program execution
These errors occur b/c we can’t/don’t have a motor program for every possible situation
Type of error: from a misperception of the environment
Program selection
Type of error: from an unexpected difference or alteration in environment
Program execution
Type of Loop: the system can recieve and process feedback information
Closed Loop Control
ex. Modern thermostat
List the Key features of closed loop control (3)
- SLOW, 120-180, up to 250 ms
- FEEDBACK allows for online adjustment
- CONTINUOUS or longer movements
Describe hierarchical levels of control
This concept of control adapts open loop control to allow for the know influence of sensory feedback
List the 2 concerns with the concept of a motor program and what idea have they led to?
- How does the brain store all these programs?
- How do we produce the movemes that we have never done before?
Generalized motor programs (GMP)
Describe how the GMP solves the concerns with motor progams
- They would have invariant features i.e. fixed features and actions that are identified as coming from that motor program
- They can be parameterized i.e. certain features of the template can be adjusted to meet the demand
List the invariant features of the GMP (3)
- order of events
- relative timing of components of movement (duration can change but percentage by component is the same)
- relative force of components
List the parameters of GMP that can be altered (3)
- Duration of movement
- Overall force that will be required
- Selection of mm to complete the movement
List the 3 groups of sensory information
- interoceptors (i.e. hunger)
- Exteroceptors (i.e. vision, audition, smell)
- Proprioceptors (i.e. vision, audition, vesitbular system, mm/joint/cutaneous receptors)
List the key features of reflexive corrections (4)
- VERY rapid, as little as 30 ms
- May NOT require conscious attention
- Mediated at spinal level
- 2 kinds: myotatic and long loop
