Motor Flashcards
Types of movement
Voluntary(conscious)
Rhythmic(unconscious)
Reflex
Sensorimotor transformations
Turning sensory input into motor output
Reflexes low level voluntary movement high level
Inverse problem in movement
It is the inverse of a forward problem, which starts with the causes and then calculates the effects
Movement planning-inverse kinematics(muscle plan and path)-inverse dynamics(muscle activation)
Internal model
Brain needs to control and predict Inverse model(motor plan) + forward model(end position) Efference copy=How it will work in real life
Experiment for motor task
Ask subjects to point at remembered object in the dark
sensorimotor transformation must be good to point accurately
Computational task
This task is done easiest when based on hand position and speed
Feedfoward control
Is when there is no feedback and Is an open loop meaning it is faster
Feedback control
After motor movement if error is there it is taken into account when trying again
FB is dependent on delay
High gain means big response to small error
Delay magnifies the effect of gain
Stages of the observer model
Previous state estimate- predicted current state- Final state estimate
Role of perception in motor anticipation
size weight illusion shows that action and perception are independent
Motor plasticity
Motor plasticity is defined as the ability of motor neurones and their respective effector muscles to physically and functionally change as a result of failure
Anticipation
Plays an important role in movement
Top down structure for movement
Starts of with conscious processing from motor cortex and brain stem to motor neurones that drive muscles
Cerebellum
Stores coordinated movement
Where are Lower motor neurones
Found at the ventral horn
What does lower motor neurones do?
Innervates fibres in a specific muscle
LMN pool
Each muscle has a LMN pool which is when all the motor neurons innervating a single muscle
Motor unit
muscle fibres+1 motor neurone= motor unit
1 fibre only receives input from 1 motor neurone
fatiguability
susceptibility to fatigue
Marathon runners have a slow fatiguability compared to a sprinter
Muscle tension
This is spike rate dependent and motor units have different threshold so you don’t use all the power in a muscle
What happens when 2 motor neurones receive identical inputs with different sizes
Smaller motor neurones have fewer ion channels and are more excitable
Motor plasticity
Motor neurones when fired can adapt and change there appearance of fibres
What are spindle fibres?
Muscle spindles are stretch receptors within the body of a skeletal muscle that primarily detect changes in the length of the muscle.
Tendon organ
The Golgi tendon organ responds to a tendon stretch, or a muscle contraction, by sending action potentials so that the muscle tension increases
autogenic inhibition
When a muscle is inhibited by a Golgi tendon organ
autogenic inhibition
When a muscle is inhibited by a Golgi tendon organ
reflex arc
The stretch of the muscle spindle causes reflex contraction.
Simple inverse stretch
The stretch of Golgi tendon organ causes reflex inhibition (relaxation).
Gamma motor neurones
Alters the gain of muscle spindle for best tension zone and helps to regulate muscle length and tone
What feature does 1a and 2 axon have
Highly myelinated which allows for high conduction
Alpha motor neurones
They innervate extrafusal muscle fibers of skeletal muscle and are directly responsible for initiating their contraction.
Stretch reflex
When a muscle is stretched , muscle spindles send information to the spinal cord, where it synapses on motor neuron of the same muscle causing it to contract. At the same time, stimulation of an inhibitory interneuron (1a afferent) prevents contraction of the antagonistic muscle
Locomotion
Locomotion is various movements of organisms to propel themselves from one place to another.
central pattern generators
Central pattern generators (CPGs) are biological neural circuits that produce rhythmic outputs in the absence of rhythmic input like walking
Cross inhibition
When you want to move one side of the body the other side is inhibited
What controls lower motor neurones for movement control
Cortical and brainstem inputs control this I the ventral horn
What does the corticospinal do?
Mediates descending control
Ends at the lower motor neurone
Descending pathway in lower motor neurone
Cortex-Midbrain-Middle pons-Middle medulla-Spinal chord
Primary motor cortex(M1)
Directly controls movement
Secondary motor cortex(M2)
Controls high level movement with planning
A population code
Describes the movement vector
cortico motor neurone
A single cortico motor neurone spikes at different points in a task when different muscle are involved
Betz cells
are giant pyramidal cells in motor cortex
Dies in ALS disease
Betz cells
are giant pyramidal cells in motor cortex
Dies in ALS disease
Premotor areas
Areas where movement is planned including M2
Premotor areas
Areas where movement is planned including M2
Mirror movement and ventral lateral premotor cortex
Mirror neurones can learn movement through vision
Monkey see monkey do
