Sensorimotor Disorders Flashcards
1
Q
2 different causes of movement
A
- Top-down: you are voluntarily initiating movement (ex. Moving eyes to look for keys)
- Bottom-up: involuntary, automatic movement (ex. Automatically looking at bright, flashing light)
2
Q
Movement pathway
A
- Intention/decision/goal (ex. Make dinner) ->
- Motor plan (ex. Pick up onion, chop with knife) ->
- Motor signal (delivering components of the motor plan to places that will execute them) ->
- Movement ->
- Sensory feedback that influences motor plan and motor signal (ex. Were we chopping the onion well enough?)
3
Q
sensory feedback: what does it include? Case study?
A
- Includes proprioception (knowing where your body is in the world – ie. My legs are crossed)
- Case study: G.O. had damage to somatosensory nerves in arms -> could not get feedback -> numerous problems with movement
4
Q
Hierarchal control of movement
A
- Association cortex ->
- Secondary motor cortex ->
- Primary motor cortex ->
- Brainstem motor nuclei ->
- Spinal motor circuits ->
5
Q
3 main assertions of central sensorimotor program theory
A
- Lower levels of hierarchy possess “sensorimotor programs” that represent particular patterns of activity
- A particular movement is produced by activating the appropriate combination of these sensorimotor programs
- Once a particular level of the sensorimotor hierarchy is activated, it is capable of operating on the basis of sensory feedback without direct control by higher levels (becomes automatized, doesn’t need cortex and higher-level structures anymore)
6
Q
Planning out movements - variations
A
- There is more than one way to carry out movement (ex. Signing your name with your toe)
- Primary motor cortex will be different, but secondary motor cortex should be the same
7
Q
practice and sensorimotor programs
A
- Practice can create and/or modify sensorimotor programs
- Most theories talk of two sorts of processes that influence the learning of sensorimotor programs:
- Response chunking
- Shifting control to lower levels
- Basal ganglia heavily involved
8
Q
2 major areas of sensorimotor association cortex and their function
A
- dorsal-lateral prefrontal cortex
- posterior parietal cortex
9
Q
dorsal-lateral prefrontal cortex
A
- Receives projections from posterior parietal cortex
- Projects to secondary motor cortex, primary cortex, and frontal eye field
- Involved in assessments of external stimuli
- May work with posterior parietal cortex in decisions regarding voluntary response imitation
- Fires first in the motor chain
- Decision-making, voluntary movement
- Critically involved in many other functions (ie. Problem-solving, math, working memory, learning)
- Damage here affects a number of sophisticated cognitive functions
10
Q
posterior parietal cortex
A
- Provides information on where body parts are in relation to the external world
- Receives input from visual, auditory, and somatosensory systems
- Output goes to secondary motor cortex
- Stimulation of this area makes the subject feel they are performing an action (even though they aren’t)
11
Q
2 outcomes of damage to posterior parietal association cortex
A
- apraxia
- contralateral neglect
12
Q
apraxia
A
- inability to perform movements on command, imitate gestures – especially non-sensical ones, and use tools
- Occurs when posterior parietal association cortex is lesioned
- Associated with left hemisphere damage
- Symptoms are bilateral
13
Q
contralateral neglect
A
- fail to respond to visual, auditory, or somatosensory stimuli
- Produced by very large right parietal lesions
- Individuals only attend to right side of body or items in environment
- Individuals are capable of unconsciously perceiving objects on the left
14
Q
secondary motor cortex
A
- Eight areas of secondary motor cortex
- Two areas of premotor cortex
- Three supplemental motor areas
- Three cingulate motor areas
- Projects to primary motor cortex, each other, and brainstem
- Produce complex movements (before and during voluntary movements)
- Exact role of these areas is unclear
- Premotor areas encode spatial relations and program movements
15
Q
organization of primary motor cortex
A
- Aka: precentral gyrus, M1
- Somatotopic organization: homunculus (Dr. Penfield played a large role)
- Receives feedback from muscle and joints
- Neurons code for preferred direction
16
Q
what happens when there is damage to primary motor cortex
A
- Damage is not as disruptive as you might think
- Independent movement
- Astereognosis (inability to know what an object is when it’s in your hand)
- Reduced speed/accuracy/force
