Mod 2 Theories of Motor Control Flashcards
What is a theory of motor control?
a group of abstract ideas about the control of movement
What is a theory?
a set of interconnected statements that describe unobservable structures or processes and relate them to each other and to observable events
What is the blueprint analogy?
- just as a blueprint provides structure that transforms stones into a house, theory gives meaning to facts
- just as the same stones can be used to make different houses, the same facts are given different meanings/interpretations by different theories
How do theories of motor control influence rehab?
- framework for interpreting behavior
- guide for clinical action/intervention
- new ideas and approaches to assessment and intervention
- working hypotheses for assessment and intervention
What is reflex theory?
the integrative power of the CNS is due to a set of reflexes coordinating the activities of different organs
What are reflexes considered as?
the building blocks and most basic functional units of complex behavior
Individual reflexes _______ give rise to complex behavior
chained together
_________ to one stimulus serves as the _______ for the next
response; stimulus
What is an example of complex inter limb coordination being mediated reflexively?
frog has paper placed on forelimb and back limb makes an upward wiping motion trying to wipe away stimulus
- when forelimb is placed in different location, back limb responds with different movement
Different movement trajectories and muscle synergies depending on ________________ not just the stimulus in frogs
position of forelimb
How do we see reflex theory in humans?
flexor withdrawal - crossed extension reflex
What does flexor withdrawal - crossed extension reflex provide a building block for in humans?
pattern formation in human gait
extension of support limb results in stretch of hip flexors which is stimulus for switching to swing phase
What are limitations of reflex theory?
does not account for
- voluntary movements not “activated by outside agent”
- movements that occur in absence of sensory input
- fast movements that occur to rapidly for sensory feedback
- same stimulus can result in different responses depending on context
- novel movements: unique combos of stimuli and responses
How is reflex theory used to interpret patient’s behavior and serve as guide of treatment?
- test reflexes to predict function
- motor behavior attributed to presence/absence of reflexes
- interventions focused on enhancing or reducing effects of reflexes
What is hierarchical theory?
- nervous system is top down, segments at top control next segment below
How is the nervous system organized in hierarchy?
higher(association areas)
middle (motor cortex)
lower (spinal)
What is important to remember about the direction of hierarchical theory?
no bottom up control
What did Hughlings Jackson find about hierarchical theory?
- NS compose of phyiologically discrete organs, with single function each
developed somatotopic representation
- claimed NS is evolutionary hierarchy
What did Rudolf Magnus propose about hierarchical theory?
- reflexes controlled in lower levels of neural hierarchy are present only when cortical areas are damaged
- higher centers typically inhibit reflexes
What is reflex/hierarchical theory?
motor control emerges from reflexes that are nested within hierarchically organized levels of nervous system
What did Georg Schaltenbrand use hierarchical theory for?
used Magnus’s concepts to explain motor development
What did Shaltenbrand conclude about hierarchical theory?
appearance and disappearance of hierarchically organized reflexes can determine neural age of child and damage to the brain could result in re-appearance of primitive reflexes
What did Stephan Weisz use hierarchical theory to tell us about development?
hierarchical organized reflexes as bases for balance and maturation corresponds to developmental progression from sit to stand to walk
What did Gesell and McGraw suggest by using hierarchical theory?
normal motor development due to increasing corticalization of CNS
emergence of higher levels over control over lower level reflexes
What is neuromaturational theory of development?
assumption that maturation of central nervous system is primary driver of motor development
What are the current concepts of hierarchical theory?
- elements of hierarchical organization but not strict top down manner
- each level of NS can act on other levels depending on tasks
- reflexes not considered sole determinant of motor control, but one of many processes
What are the limitations of reflex hierarchical theory?
- can’t explain dominant reflex behaviors that occur in intact adult
- low level reflexes are not all primitive and high level behaviors are not all mature
How might reflex hierarchical theory be used in clinic to guide treatment?
- abnormalities in reflex organization used to explained disordered motor control
What is motor programming theory?
- focus on actions rather than reactions: movement patterns occur in absence of stimulus or afferent input
motor program
What are central pattern generators in motor programming theories?
when sensory nerves cut, nervous system could generate movement with no sensory input(slow movement)
sensory input not essential but still important in modulating action
What was found in studying CPGs in cats?
spinal neural networks could produce locomotor rhythm without sensory input
changing intensity of spinal cord stimulation could change pattern from walk to trot to gallop
What is a motor program considering CPGs?
neural connections that are hardwired and produce stereotyped behaviors