Motor Control Flashcards
How are action plans generated?
Through the affordance competition hypothesis; motor plans and actions are activated at the same time.
What is the affordance competition hypothesis?
Action plans and specification occur simultaneously.
Optic ataxia
Inability to use visual information to guide movement.
Ideational apraxia
Inability to comprehend the meaning or purpose of an action; an action can be performed but incorrectly.
Damage to the association motor cortex can lead to:
Optic ataxia and ideational apraxia
IV in the single unit monkey study for action plans
Target location
Does the parietal cortex have topographic organization?
Yes
Eye cortical representation in parietal cortex
Lateral intraparietal area (LIP)
Arm cortical representation in parietal cortex
Medial intraparietal area (MIP)
The parietal cortex has distinct subregions for ____, _____, and ____ movements.
Arm, hand, eye
What are the major parts of the basal ganglia?
Caudate nucleus, putamen, globus pallidus, subthalamic nucleus, substancia nigra
What is the striatum?
Caudate nucleus and putamen
Is most of the circuit of the basal ganglia inhibitory or excitatory?
Inhibitory
Globus pallidus (GP) has a ____ baseline firing rate which produces __________ of the motor system.
High, tonic inhibition
What are the two pathways of the basal ganglia?
Direct and indirect
What is the direct pathway?
Fast, striatum to GPi
What is the indirect pathway?
Slow, striatum to GPi via GPe and STN
SNc
Substancia nigra, pars compacta
SNr
Substancia nigra, pars reticulata
GPe
External segment of globus pallidus
GPi
Internal segment of globus pallidus
STN
Subthalamic nucleus
SC
Superior colliculus
What is the primary neurotransmitter in the basal ganglia circuitry?
Dopamine; D1 and D2
SNc ______ direct pathway
Excites
SNc ______ indirect pathway
Inhibits
D1 is for the _____ pathway and D2 is for the ______ pathway.
Direct, indirect
Symptoms of Huntington’s Disease
Clumsiness, balance problems, involuntary movements
Result of Huntington’s Disease is ________.
Hyperkinesia
What is hyperkinesia?
Excessive movement
What does Huntington’s Disease change in the basal ganglia circuit?
The inhibitory neurons of the indirect pathway
Results of Parkinson’s Disease are _______ and ______.
Hypokinesia, bradykinesia
What is hypokinesia?
Reduction of motion
What is bradykinesia?
Slow/delayed motion
What does Parkinson’s Disease change in the basal ganglia circuit?
Loss of neurons in the SNc
How is Parkinson’s Disease treated?
DBS
Sensorimotor Adaptation
Use of sensory inputs to learn to make motor movements
IV in Human tDCS study with visuomotor adaptation task
Stimulated regions, three conditions in the visuomotor task
In the Human tDCS study with visuomotor adaptation, stimulation of the _______ speeds adaptation _______, but stimulation of _____ maintains adaptation _________.
Cerebellum, short term, M1, long term
What area in the brain supports new learning?
Cerebellum
The motor system is _______.
Hierarchical
Effector
Part of the body that can move
Effectors are controlled by ______.
Muscles
Muscles control _______.
Effectors
Muscles are composed of _______ fibers.
Antagonist
_________ of a fiber group causes _______ in the other.
Contraction (shortening), extending (lengthening)
Muscles are controlled by ___________.
Motor neurons
Order of control in muscles
Motor neurons, muscles, effectors
Alpha Motor Neurons
Produce contractions
Gamma Motor Neurons
Support proprioception
Alpha motor neurons synapse on __________ not ________.
Muscle fibers, other neurons
Alpha motor neurons release __________.
Acetylcholine
How do alpha motor neurons determine the force of a muscle?
Number and frequency of action potentials
Alpha motor neurons receive input from __________.
Muscle spindles
Muscle Spindles
Stretch receptor, indicate the current status of the muscle
Dorsal Root
Sensory neuron
Central Pattern Generators
Ability to produce motions without commands or external feedback signals.
When the cat’s spinal cord was disconnected from the cortex and subcortex, what happened to the reflexes?
It was maintained and exaggerated
Why was the cat’s reflexes exaggerated?
Lost the inhibition ability to control strength of movement
__________ and ___________ are central pattern generators
Spinal cord, alpha motor neurons
Cerebellum has ______ organization not _______.
Ipsilateral, contralateral
The cerebellum has _____ nuclei.
3
The 3 nuclei of the cerebellum
Vestibulocerebellum, spinocerebellum, neocerebellum
Vestibulocerebellum
Balancing and coordinating eye movements with body movements
Spinocerebellum
Auditory and visual inputs
Neocerebellum
Inputs from frontal and parietal lobes; outputs to motor regions through the thalamus
Damage to vestibulocerebellum
Vestibulo-ocular reflex; eyes can remain fixed on an object despite head/body movements
Damage to spinocerebellum
Unsteady gait and balance disturbances
Damage to neocerebellum
Ataxia; disruption of fine coordination; intention tremor
Signals from the spinal cord travel to the primary motor cortex through the _____________ through the brain stem.
Pyramidal tracts
Cerebellum function
Balance, gait, fine coordination
Lesion in primary motor cortex
Hemiplegia
Hemiplegia
Loss of voluntary movements on contralateral side of the body
Primary motor cortex has _______/______ organization
Rostral, caudal
True or False: The rostral area in primary motor cortex is present in many species
True
True or False: The caudal area in primary motor cortex is present in many species
False; present in humans and some primates
Neurons in caudal area terminate directly on ___________.
Alpha motor neurons
True or False: Primary motor cortex has motor homunculus
True
2 hypothesis of how M1 codes actions and commands
Trajectory based, location based
Trajectory Based Hypothesis
Path that transports an effector from one location to another; path/direction specific
Location Based Hypothesis
Goal location and command needed to move effector to that location; location/goal specific regardless of path
Center-out Task
Moving a lever to the center to a target indicated by light
IV in center-out task
Target location, direction of movement
DV in center-out task
Firing rate of neurons in primary motor cortex
Center-out task showed that neurons prefer _________ hypothesis.
Trajectory based
Function of primary motor cortex (M1)
Voluntary motion
Neurons are tuned to _______ and can respond in _____ and _______.
Direction, planning, execution
Secondary motor cortex is broken down into ___________ and _________.
Supplementary motor area (SMA) and premotor cortex (PMC)
SMA and PMC have _____ of the body.
Maps
True or False: SMA and PMC have somatotopic organization
True
SMA
Supplementary Motor Area
PMC
Premotor cortex
Apraxia
Loss of motor planning
Ideomotor Apraxia
Have a sense of desired action but unable to execute the action itself
PMC Function
Externally guided movements through parietal connections
SMA Function
Internally guided movements through prefrontal connections
Lesion in secondary motor cortex cause
Impair in motor planning and not hemiplegia