Sensiormotor system Flashcards
What is the first principle of the sensiormotor system?
1) Hierarchally organised
- higher levels plan movements, and the lower levels execute these planned movements
- the highest levels are the association areas of the brain
- The lowest levels are muscles to execute the movement
- Infomation is sent through the brain stem`
2) Functional segregation
- Each level is divided into sub-levels which perform different functions
3) Parallel structure
- Signals flow across the levels through multiple paths
- Provides some robsutness against damage
What is the second principle of the sensorimotor system?
**Motor outputs **(production of movement) which are guided by sensory inputs
- Sensory motor system receives infofrom different sensory systems which guides motor output
- Info from these systems are used to finetune the body’s movements.
Tell me about the study for motor outputs
(Rothwell et al., 1982)
Second principle
- Patient lost sensations in the sensations in the limbs
- Found that the patients motor power was unaffected
- NO muscle weakness - could just feel nothing
- DIFFICULTY when** grasping** an object as they did not know how much pressure to aply to an object
- Shows the role of** sensory feedback** on motor outputs
What is the role of the third principle of the sensiormotor system?
Learning changes the nature of the motor output
- Learning changes motor outputs automatic movements
- A learnt behaviour is NO longer under pre-frontal and conscious control; therefore it becomes difficult to change
Areas of sensiormotor hierarchy
Tell me about the role of the posterior parietal assocation cortex (PPC)
Provides infomaton about spatial infomation
- Integrates infomation about body part location and external objects both which are needed to initiate movement
- It outputs infomation to motor cortex - Dorsolateral prefrontal cortex & secondary motor cortex
Areas of sensiormotor hierarchy
Tell me about the role of the Dorsolateral prefrontal cortex (DPC)
This is the second association area
- it talks to the PPC
- sends signals to the secondary motor cortex
- involved in motor planning
Damage to this area leads to disorder of voluntary movements
Tell me about the secondary motor cortex
It receives info from both association areas (PPC and DLC) and sends info to the primary motor cortex
What is the secondary motor cortex divided into??
- Supplementray motor areas
- Premotor areas
- Cingulate motor areas
What are the functions of teh secondary motor cortex?
It puts a plan from the DPC into action
- Coordinates movement sequences and projects towards the primary motor cortex
Tell me about the monkeyb study by Brinkman., 1984) regarding the secondary motor cortex.
Brinkman 1984
- one group had an intact SMC; one group had lesions to SMC
Did a coordination task
- Retriveing a food pellet from wedged hole in a table using their index finger and the other hand to retrive the pellet
Findings
- In tact SMC had no trouble with co ordination task
Leisoned group couldnt coordinate their hands to retrive the food pellet
Shows SMC puts a plan into action to achieve a goal
Tell me about the primary motor cortex
Tells the muscle to produce the movement
- found in the frontal lobe - located in precentral gyrus
- receives input from secondary motor cortex
Describe the function of the cerebellum?
Receives info from different sensory systems and uses that infomation to fine tune the movements; regulates precision of the movements
Describe the location of the cerebellum
- Part of the hindbrain (most posterior part if brain)
- Vemis holds the hemispheres together
What happens when there is damage to the cerebellum?
Cerebellar ataxia
= movements becomes uncoordinated and less accurate
- Dyssynergia = Difficulty coordinating movements, so movements broken down into single joint movements
- Dysmetria = Tendency to over/undershoot when moving
Tell me about Park et al., 2009 ; Park et al., 2012 study..
(Measuring cerebellar volume of athletes and non-athletes)
- Examined cerebellar volume of athletes and non athletes (basket ball and speed skaters)
- Both sports have precise training
Findings
- Larger volume of cerebellum in athletic groups
- Presents extent to which it plays a role in movement
Be critical about Park et al., 2009 ; and Park et al., 2012 study…
Takes on a reductionist approach!
Question of ..
- Whether the larger cerebellum is a cause or consequence of this activity (correlational research)
- Does a larger cerrebelum make you better at sport or being better at sport enlarges cerebellar volume?
Tell me about Ivry and Keele (1989) research into demonstarting the function of the cerebellum..
- Patients with cerebellar damage to perform two tasks
- Rhythmic tapping task - tap finger to a tone
- Perception task - two pairs of tones play and identify if the 1st or 2nd had a longer duration
Findings
- Cerebellar damage made many errors with the rhythmic tapping task
Suggests:
- The cerebellum plays an important role in time perception too
Describe the role of the basil ganglia
Role in:
- Movement coordination
- Habit learning for it to become automatic
- It loops with the cortical structures
Tell me where the basil ganglia is located
In the forebrain (subcortical)
Tell me about the collection of structures that make up the basil ganglia
- Globus Pallidus
- Putamen
- Caudate Nucleus
These are all part of the dorsal striatum
What are the two disorders of movement?
- Parkinsons disease
- Huntingtons disease
What are the symtoms of Parkinsons disease?
- Rigitity
- Muscle tremors
- Slow movements
- Difficulty initiating physical and mental activity
What are the immediate causes of Parkinsons disease?
When the substantia nigra (in midbrain) starts to lose neurons, this affects the communication/loop between substantial nigra & the basal ganglia
- The loop when talking between cortex is affected, which slows the movement disorders (motor coordination connections are deteriorated)
