Class 17 - Motor system and cerebellum Flashcards
What are parts of the motor system?
Motor cortex, basal ganglia, cerbellum, brain stem, spinal cord, motor neurons
What does the posterior cortex do?
Specify movement goals and connect to prefrontal cortex
What does the prefrontal cortex do?
Generates movement plans
What does the premotor cortex do?
Recognizes movement of others and selects actions
What does the primary motor cortex do?
Executes movements
What do more complicated movements do to cerebral blood flow?
Increase the blood flow to many different regions
What happened when Wilder Penfield stimulated the precentral gyrus?
Produced movement in different parts of the body
How many homunculi are there in motor and premotor cortices?
10
What are the three types of organization in the motor cortex?
Part of body to be moved, spatial location to which the movement is directed, function
How do neurons increase force?
Increase firing
Are neurons able to plan and initiate movement?
Yes
Motor neurons calculate distance and direction of movement. True or false?
True
In imagined and active movement, is there similar brain activation?
Yes
What are mirror neurons?
Neurons that fire when we see others make a movement. They encode a complete action and fill in banks when part of a movement is absent
What hemisphere are mirror neurons generally located in?
Left hemisphere
What are the two ways the prefrontal and posterior cortex use sensory information?
Make movements in response to sensory stimulation.
Provide information to produce or modify complex movements.
What is deafferation?
Loss of sensory input (Friedreich’s ataxia)
What role does the basal ganglia have?
Modulate the force of movement
What are two disorders of too much movement?
Huntongton’s chorea and tourette’s syndrome. Cell death in caudate/putamen
What happens in Parkinson’s disease?
Loss of dopamine cells in substantia nigra causing muscular rigidity and difficulty performing movements
What are the two pathways in the internal globus pallidus?
Excitatory and inhibitory
What happens if the GPi is inhibited? excited?
Thalamus excitation and inhibition respectively
What does the cerebellum participate in?
Acquiring and maintaining motor skills
What does the flocculus do?
Takes part in balance
What does damage to the cerebellum usually result in?
Loss of timing in movement and perceptions, problems with movement accuracy
What movements are the brainstem responsible for?
Posture, sex, eating and drinking, walking, grooming and making nests
What does the corticobulbar tract do?
Controls facial movements. Projection from cortex to brainstem
What does the corticospinal/pyramidal tract?
Controls limbs and body. Ventral portion controls midline (ipsilateral) and lateral portions moves limbs and digits (contralateral)
What are ventral horns made of?
Spinal cord motor neurons arranged as a homunculus
What is gait ataxia?
Wide based gait, poor turning, staggering to one side “drunk walk”
What is dysmetria of extremities
Lack of coordination of movement (ipsilateral to side of lesion). Cannot do alternating movements (dysdiadochokinesis)
What is dysphagia?
Impaired ability to chew or swallow
What is truncal ataxia?
Problems with the core, lesions to cerebellar vermis
What is appendicular ataxia?
Problems with limb movements, lesions to intermediate cerebellar hemispheres
What is the lateral cerebellar hemispheres for?
Motor planning
What features are affected by cognitive affective syndrome?
Executive functions, visual-spatial functions, language, personality
What is the dysmetria of thought hypothesis?
Cerebellum has functional domains that is an integral node in many neural circuits
What is being suggested results from atrophy of the vermis?
Autism and schizophrenia
What is posterior fossa syndrome?
Lesions to vermis or dentate nucleus causes mutism and personality change (becomes a douche)
