motor control Flashcards
neuromuscular junction
specialized synapses between the nervous system and muscle fibers
lateral corticospinal motor tract
involved in fine movement of distal limb muscles (arms, hands, fingers, lower leg and foot)
tract crosses entirely from one side of the brain to the opposite side of the body (contralateral)
medial motor tract
involved in control of movements of the trunk and proximal limb muscles
involved in posture and bilateral movements
projects both contralaterally and ipsilaterally
cerebellum motor control
plays an important role in coordinating timing of muscle movement, planning movement and learning motor skills
organized into 3 main divisions that each receives a distinctive type of info a sends out input to distinct portions of the nervous system
info flowing through these cerebellar loops allows it to modulate motor processing
movements that are not modified once they have been started
vestibulocerebellum
damage causes difficulty with balance and postural instability
spinocerebellum
damage causes difficulty with smooth muscle control of movement and movement of proximal muscles
cerebrocerebellum
damage causes difficulty with the regulation of highly skilled movement that requites sensorimotor learning
cerebellar ataxia
difficulties in coordinating movement after cerebellar damage
tradition test: patient touches their nose and then neurologist’s finger
occurs when activity of agonist and antagonist muscles are not coordinated
disrupts coordination of multi-joint movements. to compensate patients will move of join at a time in serial manner
difficulties in sensory motor learning after damage to lateral portions of the cerebellum.
agonist
contracts during movement
antagonist
relax/lengthen during movement
forward model theory of cerebellar function
theory argues that the cerebellum helps predict the sensory consequences of motor plans
forward models not influenced by feedback from periphery
subcortical nuclei in the basal ganglia
caudate nucleus
putamen
nucleus accumbens
globus pallidus
substantia nigra
subthalamic nucleus
roles of the basal ganglia
setting the motor system with regard to posture
preparing the nervous system to accomplish a voluntary motor act
acting as an autopilot for well-learned sequential movements
controlling the timing and switching between motor acts
because they receive both motor and nonmotor info, the basal ganglia are also thought to assist in motor planning and learning
movements that take time to initiate or stop
theories of the basal ganglia function
- the basal ganglia facilitate the synchronization of cortical activity underlying the selection of appropriate movements while inhibiting inappropriate ones
- the basal ganglis chunch individual actions into coordinated, stereotyped and habitual units of action
- the basal ganglia aid the ability to execute movements with varying levels of vigor
direct route of the basal ganglia
contributes to sustaining/ facilitating ongoing action
indirect route of the basal ganglia
important for supressing unwanted movement
works in opposition of the other
parkinsons
results from damage to the cells of the substantia nigra
loss of dopamine neurons
tremors - rythmic, oscillating movements
akineria - inability to initiate spontaneous movement
bradykinesia - slowness of movement
what does neuron death in the substantia nigra cause
inadequate input to the basal ganglia
causes overactivation of th indirect pathway
increases activity in the internal portion of the globus pallidus
inhibits the thalamus and decreases motor activity
treatment for parkinsons
levodopa
deep brain stimulation
levodopa
cannot give dopamine directly
monoamine oxidase (MOA-B) inhibitors
deep brain stimulations (DBS)
aerobic exercises and behaviour intervention
thalamonoty or pallidotomy
grafting of fetal tissue to the striatum