What is the sensorimotor system?
- it is a system where sensory input guides the motor output
- >control of voluntary behavior
Does information in the sensorimotor system flow top down or bottom up?
-it flows top down rather than bottom up
Describe the motor output guided by sensory input in terms of flexibility, sensory feedback and monitoring of ones own activities.
1) it allows for for sensory feedback
- >directs the continuation of responses
- >many responses are controlled unconsciously and reflexively by lower levels
2) Monitors the effects of own activities
3) Allows for flexibility in changing environment
Do ballistic movements require sensory feedback
- no they don’t
- > they are all-or-none
- > it occurs at high speed
- > for example, swatting a fly
How doe s learning change the sensorimotor system involvement in our actions
- initial stages of learning are under conscious control
- after practice
- > responses do not require as much conscious regulation
Describe the movement of signal in terms of the association cortex, motor cortex and the skeletal muscle
-the signal goes from the association cortex to the motor cortex and then ends up at the skeletal muscles
What are the 2 major areas that initiate movement in the sensorimotor association cortex
1) Posterior parietal cortex
2) Dorsolateral prefrontal cortex
What is the posterior parietal cortex(ppc) involved in terms of input
- it integrates info on body position and objects in space
- > it directs attention
- > intention to perform an action or knowledge of having performed that action
-receives input from visual, auditory and somato sensory systems
Where does the output of the ppce go to?
- motor cortex
- secondary motor cortex
- frontal eye field
- > conscious controls eye movements
- dlpfc
What is the PPC specialized for in terms of movement
-it is specialized for the movement of eyes, head, arms and hands
What sensorimotor deficits result when there is damage to the posterior parietal association cortex
- perception and memory of spatial relationships deficit
- reaching and grasping accuracy deficit
- control of eye movement deficit
- attention deficit
How does apraxia affect voluntary movement? Are there bilateral symptoms? Is there bilateral damage?
- can’t make specific movements when requested to do so
- > especially if movement is out of context
- > but can make the same movement when not thinking about it
- there are bilateral symptoms
- > but only unilateral damage
- > damage to the left ppc results in apraxia
What is contralateral neglect
- it is the inability to respond to stimuli on the opposite side of damage
- > often right posterior lobe is the damage
- > so the left side of the world does not exist
Are the motor and sensory systems of people with contralateral neglect intact?Are the items in their left of the bodies processed?
- their motor and sensory systems are intact
- the items to the left of their bodies are not consciously perceived but they are unconsciously processed
- > eg; they can identity incomplete drawings if complete images shown to the neglected side previously
Where does the dorsolateral prefrontal association cortex receive input from? Where does it project this info?
- it receives input from ppc
- it projects this info to
- > secondary motor cortex
- > primary motor cortex
- > frontal eye field
- > ppc
What is the relation of the dpc to external stimuli. Refer to slide 15 for more detail
- it evaluates external stimuli
- it also initiates reactions to external stimuli
Where does the secondary motor cortex receive input from? Where does it send this input?
- it receives input from association cortices
- it outputs this info to the primary motor cortex
What are the 2 major areas of the secondary motor cortex
1) Supplementary motor areas
- >extends into longitudinal fissure
2) Premotor cortex
- >lateral surface of frontal lobe
- >anterior to primary motor
When do mirror neurons fire?
- when observing another individual perform a goal directed hand movement
- > it is a class of ventral premotor neurons
Where is the primary motor cortex? What is it a convergence of?
- it is in the precentral gyrus of the frontal lobe
- it is a major point of convergence for sensorimotor signals
- > therefore, also a major point of departure for sensorimotor signals
Does the primary motor cortex encode for direction or does it encode for location?
- it encodes for location
- there was an experiment regarding the movement of an arm from a centered point
- the firing of movement was closely related to the end point of movement
- > as long as you get close to the target, the neurons will fire
- > direction does not matter
What are the effects of a pmc lesion?Read more on slide 28
- mild effects
- large lesions may disrupt movement of body parts
- result in astereognosia
- may reduce speed accuracy and force of movement
Is the cerebellum part of the sensorimotor hierarchy
- no it is not
- > it interacts with the sensorimotor hierarchy
- > helps with fine tuning and learning of cognitive tasks
- > well connected to other structures as well
Is the cerebellum important for sequence motor learning?
- yes
- >it is involved with the timing of actions
