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Motor Control and Learning (Spinal Cord (Lower level-PNS (proprioceptors:…
Motor Control and Learning
Neuromuscular control of movement
motor control and learning related to neuroscience, psychology and biomechanics
nervous system controls the movement
The brain: weights about 3 lbs
consumes 20-25% body's energy
86 billions neurons
is 75% water
we use all of our brain
losing consciousness for 4 seconds you will pass out
losing consciousness for 4 minutes results in brain damage
Motor Cortex-responsible for voluntary movement
motor neurons effect the contralateral (opposite) side of which they reside
Motor homunculus
representation of which areas control which bodily movements
order is reversed- feet at top, lips at bottom
areas of body with more complex connection are represented as larger, smaller connections represented as smaller-->results in a disproportionate figure of homunculus
premotor area: supplementary motor cortex, premotor cortex
-areas anterior to motor cortex have premotor functions
somatosensory cortex- receives sensory info
-front portion of parietal lobe
-Penfield & Boldney found area
cerebellum (little brain): regulates and fine tunes movement, works in continuous loop
-controls posture and balance
-makes modification in motor commands
basal ganglia: initiation and intensity of movement
-plays a role in Parkinson's disease due to production of dopamine
efferent neurons: carry info away from CNS
afferent neurons: carry info to CNS
Spinal Cord
efferent pathways
Upper motor neurons: originate in cerebral cortex or motor centers of the brainstem
Local circuit neurons: lie in the spinal cord near the cell bodies of the lower motor neurons, integrate info from somatic sensory receptors to coordinate movement
lower motor neurons: extend from the spinal cord via anterior roots to innervate skeletal muscles
afferent pathways
1st order neurons: connect somatic sensory receptors to the spinal cord via dorsal nerve roots
2nd order neurons: connect spinal cord to thalamus
3rd order neurons: connect thalamus to ipsilateral portion of somatosensory cortex
bundle of nerves, can operate independent of brain, 17-18 in long, 1/2 inch diameter, stops growing age 5, passes through 33 vertebrae
damage to cord can cause paralysis
complete: almost all sensory feelings and ability to control movement are lost below spinal cord injury
incomplete: when there is still some sensory and motor function below injury
quadriplegia or tetraplegia: injury above the first thoracic vertebrae, some paralysis in all 4 limbs
the higher up on the spine the injury is, the more extensive it will be
paraplegia: damage to cord below first thoracic spinal level, able to use arms and hands, leg damage varies
injury to lumbar area can cause caudiequina syndrome, interferes with bladder, sexual, leg function
spinal column
corticospinal tract-major efferent pathway
dorsal column: afferent pathway
central pattern generator - when brain is take out of equation, this can still work to generate locomotion
stimulus input-->travel through neurons-->neurons contract/relax muscles (reciprocal inhibition)
Motor neurons
efferent, relay impulses from CNS to organs, muscles, glands
sensory neurons
afferent, convert sensory info to CNS
interneurons
association, bridge gap between sensory and motor neurons
reflex arc
receptor-->integrator-->effector
reciprocal inhibition
agonist/antagonist
Lower level-PNS
proprioceptors: sensory receptors that receive stimuli from within body
motor units: motor neuron and muscle it innervates
Golgi tendon organs: sensory receptors that respond to muscle tension
muscle spindles: stretch receptors in muscle that respond to changes in length, responsible to stretch reflex
Hick's Law
states that the amount of time it takes someone to make a decision increases as the amount of possible choices increases
reaction time: time between onset of stimulus and start of response
simple reaction: single stimulus, single possible response
choice reaction time: several stimuli, single/multiple possible responses
age, gender, stimulus intensity, height, level of alertness can effect reaction time
on avg. men have faster reaction times than women , taller people have slower reaction times , being more alert improves time
calculation: movement time + processing speed [(log2)(n)]
movement time: time it takes to complete onset of a movement
response time: time it takes to process info and then make a response
reaction time+movement time=response time
Fitt's Law
"haste makes waste" -doing things too quickly makes it less accurate
movement speed- speed of movement from start to finish
movement distance- distance body parts travel or range of motion
motion time related to index of difficulty
more difficult task, longer motion time
movement distance and movement time can be traded off to maintain accuracy
increase movement distance by increasing move time to maintain accuracy , or shorten distance and keep movement time the same
slow is smooth , smooth is fast
less time and more range of motion = more error
too fast over long distance = error
forces in muscle increases, variation increases
HOWEVER: rapid and slow movements have better accuracy because of the force in muscle that decreases variation