The Motor System Flashcards
What are the 5 facets of hierarchical movement control?
Decision, sequencing, production, timing and error
What are the major components of the motor system?
Forebrain, brainstem and spinal cord
What is the role of the forebrain in the motor system?
Complex voluntary movements
What is the role of the brainstem in the motor system?
Timing and control
What is the role of the spinal cord in the motor system?
Reflexes, somatosensory direction of movement
What is the role of the basal ganglia in hierarchical movement control?
Production of appropriate movement force
What is the role of the cerebellum in hierarchical movement control?
Timing and accuracy
How does the forebrain organize movement?
Motor sequences
What are motor sequences?
Movement sets produced as a unit by the brain
What brain region is responsible for planning and initiating motor sequences?
Frontal lobes
What are the 3 motor regions of the frontal lobe?
Prefrontal cortex
Premotor cortex
Primary motor cortex
What is the role of the prefrontal cortex in movement?
Planning movements
What is the role of the premotor cortex in movement?
Sequencing and organizing movements
What is the role of the primary motor cortex in movement?
Producing specific movements
The PFC does not specify the precise movements to make, what does it do?
Decides the goal of the movement (planning)
How would damage to the prefrontal cortex show in motor systems?
Unable to plan how to direct the goal of the movement– eg. how can i reach this water bottle?
What would damage to the premotor cortex look like?
Motor sequences could not be accomplished (think monkeys who cannot complete motor sequences to get food)
What evidence is suggestive of a movement hierarchy in the Frontal Lobe regions?
Directionality of blood flow
What is the role of the brainstem in controlling motor behaviour of species?
Responsible for species-typical behaviours
What are species-typical behaviours
Innate actions produced by every member of a species (eg. hissing in felines)
Grooming behaviours are controlled by what region of the brain?
Brainstem
Damage to the brainstem results in difficulties with what type of movement?
Voluntary
What is locked-in syndrome? What region of the brain causes locked-in syndrome?
Condition where patient is aware and awake but all voluntary muscled are paralyzed other than the oculomotor cranial nerves of the eyes (vertical movement)
What is cerebral palsy?
Condition where voluntary movements are difficult, atonia and poor posture– caused by brainstem trauma before or after birth
What is quadripalegia?
Paralysis and loss of sensation in both the legs and arms (C1-T1)
What is parapalegia?
Paralysis and loss of sensation confined to lower body and legs (after T1)
What is the homunculus (body map)?
Representation of the human body in motor cortex; bilateral, contralateral control
What region of the motor cortex controls lower limbs?
Dorsal
What region of the motor cortex (M1) controls upper body, hands and face?
Ventral
The motor cortex represents not specific muscles, but rather what?
A grouping of movement categories.
True or false: M1 neurons are activated not just while performing a particular movement but also when imagining those movements as well
True
What are corticospinal tracts/pyramidal tracts?
Efferent pathways from the motor cortex to the brainstem and then to the spinal cord to produce movements
Why are there two corticospinal tracts, one crossed (lateral) and one uncrossed (anterior)?
Axons descend from the motor cortex into the brainstem, then half cross over to the opposite side of the brainstem.
What is the role of the crossed/lateral corticospinal tract?
Moving limbs on opposite side
What is the role of the uncrossed/anterior corticospinal tract?
Moving muscles at the midline of the body on the same side
What are lateral neurons in the spine?
Neurons that project to limbs to produce movement
What are medial neurons?
Neurons that control the body’s trunk
How do motor neurons produce body movement?
These motor neurons will eventually synapse with the muscles that ultimately produce the body movement
What are the 3 motor nuclei of the basal ganglia?
Caudate nucleus and putamen (striatum)
Subthalamic nucleus
Globus pallidus
Where does the basal ganglia receive input from?
Cerebral cortex (motor cortex) and dopaminergic system (substantia nigra)
What is the role of the basal ganglia in the force of movement?
Control and coordination
What damaged region to the basal ganglia causes hyperkinetic movements and dyskinesias?
Striatum (Caudate and putamen)
What damaged region to the basal ganglia causes hypokinetic movements?
Substantia nigra
What is the associative cause of parkinson’s disease?
Associated with dopamine depletion in the basal ganglia and its connections with the substantia nigra
What is parkinsonism?
an umbrella term referring to the common motor disorder symptoms, which may occur in conditions outside of just PD
What is true about disposition to Parkinson’s?
Can be idiopathic or non-idiopathic
What is an effective treatment for early PD symptoms?
Deep brain stimulation of the substantia nigra and other areas of the basal ganglia
What is Huntington’s disease (Huntington’s chorea)?
A genetic condition in which there is a build of the huntingtin protein which causes neurodegeneration of the basal ganglia
What is true about the development of Huntington’s disease?
It is autosomnal dominant– If you have the allele you will develop the disease.
Onset is around 30-40yrs
What is the time course of HD?
Progressive 10-15 years
What are symptoms of HD?
Triad of symptoms:
A progressive motor disturbance
Cognitive impairment
Psychiatric symptoms (anxiety, depression, late-stage psychosis)
What is dysarthria?
A motor speech disorder; characterized by difficulties controlling the tongue and speech muscles/structures
What is dysphagia?
Difficulties with swallowing; leads to difficulty with eating
What happens when we practice or neglect to practice a motor skill?
We lose or gain the skills – cerebellum does this work
What is the anatomy of the cerebellum?
Flocculus and two hemispheres (lateral and medial)
What is the Flocculus (floccular lobe)?
Small but dense lobe; projects from the ventral surface
Involved in eye movements and balance (input from the vestibular system)
What are the hemispheric roles of the cerebellum?
Lateral parts
Controls movement of limbs, hands, feet, and digits
Medial parts
Controls movement of face and midline of body
How does the Cerebellum improve movement control?
Timing
Maintaining movement accuracy (correction of errors)
How does the cerebellum correct movement errors?
Involved with balance and orientation
