Lecture 1 Flashcards
Motor Control
Mechanisms essential to the regulation of movement
Area of study dealing with understanding several aspects of movement: nueral, physical, behavioral
Motor Learning
Acquisition of skilled movment as a result of practice
Neuroplasticity
can’t grow new neurons but brain can change its synapses
Brain Plasticity
Degrees of Freedom
Nicholas Bernstein # of independent elements or components of a system that need to be organized to produce a specific result
Kinematic Redundancy
no single solution to a given problem of motor control
Reflex Theory
Sir Charles Sherrington proposed a feedback control system as a way for the CNS to control a limb’s motion
Simple Reflexes were combined to produce actions
Reflex Theory’s definition of a reflex
requiring a receptor, conducting nervous pathway, and effector
Hierarchal Theory
Hughlings Jackson argued that the brain has higher, middle and lower areas equated with higher association areas, motor cortex and spinal levels of motor function.
Reflex/ Hierarchial Combined Theory
Suggests that motor control emerges from reflexes that are nested within hierarchically organized levels of the nervous system`
Reflex/ Hierarchical Theory with brain injury
Reflexes are a part of motor control in which higher centers normally inhibit these lower reflex centers. Pathology of the brain may result in persistance or reappearance of these lower level reflexes
Maturation of Neural Processes with R/H theory
When baby is born functioning at level of brainstem spinal cord with primitive reflex
As nervous system myelinates and baby matures, start getting righting reactions- parachute reflex, propping lateral
As nervous system matures- develop equilibrium reactions- get ambulation
Motor Programming Theory
there is a central memory representation that stores information needed to perform an action
Example of Motor Programming
Writing signature- on board and on paper
Spatial component we hold in our brain to write it and have it look the same
We arent using the same muscles-> proximal shoulder for blackboard and wrist for paper
Motor Programming Evidence
CPG
Deafferentation studies
Reaction Time Studies
Feedback Processing Studies
Spinal Circuits Generate Rhythmic Locomotor Patterns
Central pattern generators control the synergistic, rhythmic pattern of gait.
These generators are innate and built into the architecture of the spinal cord.
Intensity of the Stimulus Modulates Speed
Weak stimulation produced walking gait that increased in speed with the intensity of the stimulation.
Progressively stronger stimulation produced trotting and finally galloping
Control signal - modulated only in intensity -can activate locomotion and cause changes in speed.
Control Signal
modulated only in intensity -can activate locomotion and cause changes in speed
Motor Program- Deafferntation Studies
Deafferaentatiun studies by taub and bizzi
Cut dorsal roots of spinal cord
No afferent info coming in-
Monkey movement was clumsy but could still move- not skilled or coordinated
Reaction Time Studies in Motor Program
Time to start for complex movement was longer than time to start for simple movement
Feedback Processing Studies- in Motor Program
Feedback processing studies- even when they stopped movement the muscles were firing, firing even though no movemnt was taking place
The brain is prepared to move- central processing- muscles were firing even when stopped because there was preparation to move
Generalized Motor Program Author
Richard Shmidt
Generalized Motor Program
A general representation of a class of actions The program stores in memory only some broad features for a particular class of actions Then specific parameters are added in order to execute a particular motion.
Invariant Features of the Movement
Broad features of an action that we store
Characteristics of movement that remain consistent form one to the next
Spatial Order of the Components
Relative Force
Temporal Structure or Phasing -Movements with the same order of contractions, and the same firing ratios have the same temporal structure and are assumed to be produced by the same motor program
Parameters of the Movement
characteristics that are applied to action that make it specific
Addresses novelty issue bc the parameters added to the invariant features that make for novel movements
Overall Duration
Overall Force
Muscle Selection
Movement Direction
Systems Theory
Distributed Model of Control- N. Bernstein 1967
Movements are not peripherally or centrally driven
They emerge as a result of the interaction among many systems
Each part of the system contributing to different aspects of control.
Nervous System, Environment, Musculoskeletal, Sensorimotor
Dynamic Systems Theory
When a system of individual parts comes together its elements behave collectively in an ordered way
Complex systems exhibit a self-organizing principle
Control parameters act to reorganize the system
Dynamic Systems Example
Horse walks- feet individual
Trot- indivudal
Gallop- front legs ttogehter, back elgs together
As velocity increase animal has to change from trot to gallop obecause of biomechanical factors
Not related to peripoheral input, not related ot motor program, related to change of control factors
Dynamic Systems vs Motor Programming
Dynamic systems- one motor program control parameter, biomechanical properties related to velocities
Motor programs- sepatate moror programming, because relative timing is differnt
Task Oriented Approach
best way to learn an activity is to practice that activity
What concepts does task oriented approach draw upon?
Draws on dynamic systems- if you want someone to walk on grass you need to get htem to go walk on grass
Mott and Sherrington
In 1895 Mott and Sherrington demonstrated that surgical deafferentation of a monkey’s limb produced severe movement disorders.
Monkey’s were unwilling to use the limb in any sort of purposeful action.
They concluded that movement initiation requires afferent information.
Edward Taub
Demonstrated that deafferentation does not necessarily abolish the capacity to make purposeful movements
Motor performance, although clumsy and poorly coordinated, was substantially preserved
When deafferentation is bilateral or when followed by retraining
Taub Monkey Experiments Results
The monkey’s could use their deafferented limb when:
a. they were required to move their limb to avoid an electric shock
b. when they restrained the good arm
c. or when the deafferentation was bilateral
Unilateral = did not use extremity unless forced or constrained
Bilateral=used the extremities in a free situation
