Neural Basis of Posture Control and Gait Flashcards
what parts of the brain are used for automatic, hard wired processes in locomotion
basal gang
brainstem
spinal cord
what happens if there is only spinal cord control of gait (lesion below brainstem)
only rudimentary form of gait
external stimulation is needed
what happens if there is decerebrate control of gait
mesencephalic locomotor region critical
MLR stimulation is helpful
what happens if there is decorticate control of gait
muscle tone, rhythmic stepping and initiation possible
goal directed locomotion
no external stimulation needed
what happens if cortex is intact in terms of control of gait
vision is incorporated and smooth gait is adaptable to the environment
what are some evidence for CPGs
various experiements: cats with severed SC still able to move, rhythmically step, adapt step cycle to clear obstacles, and go from walk to run
what foes CPG formation control
controls level of motor neuron activity
what is evidence of CPGs in humans with SCI
persons can elicit stepping acting with stimulation during PWB support walking
what is evidence of CPGs in humans with regard to development
stepping is observed in newborns before pathways are developed
what are some descending influences on CPGs
visuomotor cortex
cerebellum
basal gang
brainstem
what is the basal gangs role in gait
modulation
muscle tone
gait initiation
velocity and amplitude
what parts of the brain does complex gait use
PMA
SMA
Parahippocampal gyrus
putamen
thalamus
when you walk at increasing speeds, what activates
more prefrontal and premotor along with brainstem
when does visual sampling increase
uneven surfaces, when specific foot placement is required, hazard in path
how can you anticipate modifications needed short term
change foot placement, ground clearance, direction, stop
how can you anticipate modifications needed long term
shortened step length with experience (ex, walking on ice)
describe gait on cognition in healthy young adults
gait isn’t very cognitively demanding in young adults
going from simplest to most complex, list some gait behaviors
sit to stand
standing in tandem romberg
walking
recovery from external preturbations
obstacle avoidance during walking
what model can explain many of our gait actions
passive inverted pendulum model
how is motor programming supported in gait
we can walk without much attention
long rx times in complex situations
embedded neural circuitryw
what happens when we slip
direction specific response
distal -> prox sequence
what happens when we trip
depends on phase in gait cycle
early swing: elevating strategy
late swing: lowering strategy
what happens when we are walking on a slippery surface
shorter strides, lower contact velocities, and reduced stance time
how do we react when walking on a soft surface
stiffen ankle and knee to control posture and stability
increased optic flow = ______ speed
increase
what is very important during locomotion (think vestibular)
head stabilization - usually use VOR to stabilize vision
describe automatic postural responses (SS systems)
direction specific response to platform translations
distal –> proximal activation
includes plantar vibration
describe cutaneous info response in gait (SS system)
reflex modulation: includes crossed extensor reflex and stretch reflex of plantar flexors
both are phase dependent
describe how muscle spindles work in gait (SS system)
stretched hip flexors reset locomotor rhythm which excites ipsi hip flexors and inhibits hip extensors
describe how GTOs affect timing of locomotor rhythm
they excite their own muscle and inhibit antagonists to regulate transition from stance to swing
if you lose the parietal cortex, what happens to gait
lose the ability to avoid obstacles
what does the hippocampus do in regard to gait
code topographical info
what does the MRF in the brain stem do in regard to gait
activates CPGs
target of MLR (initiates and adjusts)
overall, what does the cerebellum do in regard to gait
fine tuning, error correction, adjustments due ot visual cues, multi-joint coordination and locomotor adaptation
what does the medial (vermis) lobe of the cerebellum do for gait
integrate vestibular, visual, and SS system
what does the intermediate lobe do in regard to gait
regulates gait through SS input from limb (muscle spindles and GTO) , receives proprioceptive input from dorsal column
what does the lateral lobe do in regard to gait
adjust gait in novel context when vision is critical, receives info from cerebral cortex (parietal lobe) via pontine nuclei
what is evidence of CPGs in humans with SCI
persons can elicit stepping acting with stimulation during PWB support walking
what is evidence of CPGs in humans with regard to development
stepping is observed in newborns before pathways are developed
when does visual sampling increase
uneven surfaces, when specific foot placement or hazard in path
how can you anticipate modifications needed long term
shortened step length with experience
