Sensorimotor, Nov 6 Flashcards
what are the 5 components of the hierarchical organization of motor system
- Association cortex
- Secondary Motor Cortex
- Primary motor cortex
- Brainstem nuclei
- Spinal motor circuites
what are the 2 major areas of the sensorimotor cortex?
- Posterior parietal association cortex
- Dorsolateral prefrontal association cortex
What do the posterior parietal association cortex do?
- Integrates information about the current position of body parts with information about external objects you may act upon.
- Stimulation can make the patient feel like that are performing an action.
- Dorsal ventral stream happens here.
What happens if you damage the posterior parietal association cortex? Right vs. Left side of the brain
Right side damage:
- contrlateral neglect: dysfunction of attention.
Left side damage:
- Apraxia: imparied voluntary movement performance (not due to weekness but coordination problems) sympotoms are bilateral (happens on both sides of the body.)
what are apraxic errors
- Imitaion of less meaningful movement
- perfmoance of gestures on command (thumbs up)
- Use of tools and objects (show me hoe you paint but with this screwdriver)
What does the dorsolateral prefrontal cortex (dlPFC) do? (assosication cortex)
Theories say where the decision starts:
- Involved in the evalution of external stimuli and the initiaion of voluntary reactions. (phone is ringing… do I pick it up?)
- First neurons to fire when anticipatin a motor activity > decision to act may begin here.
- Also involved in cognition (e.g., problem solving, math, working memory, learning
What happens when we practice movement?
- First the brain is really active, but overtime it does not need so much activity.
- We begin to response chunk, sequences begin to be treated as units. (like learning a song, 1st chords, 2nd song.)
What are mirror neurons? where in the brain does this happen?
They seem to be active both when doing an action and/or watching someone do an action. (could be like prof son watching row up tape)
- in the ventral premotor cortex.
How do lesions affect the primary motor cortex?
There is less dysfunction that you might think.
- Disrupt a persons ability to move one body part independently of others
- may produce asterognosia (can’t name things by touch.
- may reduce, speed, accuracy and force of movements.
What does the secondary motor cortices do?
produce and guide complex movements in space
What does the cerebellum do for the sensorimotor system?
Recieves inputs from:
- primary and secondary cortex
- information about descending motor signals from the brain stem nuclei
- feedback from motor respines via somatosensory and vestibular systems
Compares intended movements to actual movements
Critical timing and sequences of movement.
What are some effects of cerebellar damage?
- Loss of ability to precisely control the direction, force, velocity, and amplitude of movements (ataxia/ dysmetria - impairment in performing accelerated movements)
- loss of abiilty to adapt patterns of moto output to changing conditions
- difficulties in maintaining steady postures (Rhomburg test - eye closed standing)
- impairments in the learning of new motor sequences
- impairments of measures of attention and executie control, procedural memory, working memory, language and visual-spatial processing.
What role does the basal ganglia (comples group of nuclei) play in the sensorimotor system
modulates motor output like cerebellum
- critical to habit formation
- many cognitive roles
- promotes skill learning
How doe the basal ganglia cause parkinsons and huntingtons disease?
- at rest the basal ganglia inhibits the motor/premotor areas > no movements
-to activate the motor cortex we must inhibit the inhibiton (disinhibition) - excitatory, go, disinhibition
- inhibitory, stop, mainti=ains tonic inhibition
-dopamine in involved in both
pathways but overall creates more GO/less STOP.
What is Parkinsons Disease? what causes it? what are the symptoms?
In PD the go (disinhibtion) increases and the stop (inhibition) decreases
- dopamine neurons in the substantia nigra die.
- results in diminished movement, particularly movement initiation.
- Initial symptoms: stiffness, resting tremor (during inactivity)
- Later symptoms: muscular rigidity, slow movements, masklike face, pain, depression.
- Hard to initiate, but also hard to stop.
