L22 Sensation And Motor Control 2 Flashcards
What does cerebellar injury lead to?
Leads to deficits in the predictive motor responses
What are motor errors signalled by?
By climbing fibres which generate complex spikes in Purkinje cells
What is the cost vs benefit of movement?
Cost - effort/injury/instability
Benefit - strength/speed/accuracy
What is the role of basal ganglia in movement?
The ‘vigour’ of movement is determined by the balance between direct and indirect pathways in the basal ganglia
What are basal ganglia pathways influenced by?
By dopinergic input that signals predicted rewards
Outline a flow diagram for the motor system
Premotor cortex (goals)
->
Motor cortex (controller)
- basal ganglia (cost/benefits)
- cerebellum (predicted consequence)
->
Spinal cord (reflexes)
->
Body and enviroment
What connects the cortex to the muscles?
Motor neurons in the spinal cord
How is the J-receptor reflex initiated?
By pulmonary capillary hypertension and oedema
- this causes dry cough and dyspnea
How is the Golgi tendon reflex initiated?
Initiated to protect against heavy load
- if load is excessive, the Golgi tendon organ is activated to cause relaxation and inhibits motor neurons
What happens when the crossed extensor reflex is initiated?
Pain reflex
- causes the flexors in the withdrawing limb to contract and the extensors to relax
- the opposite happens in the other limb
What happens when the Hering Breuer reflex is initiated?
It is a safety mechanism to prevent over-inflation of the lung
- stretch receptors in the smooth airway muscle will signal via vagus nerve to the medulla
- this causes cessation of inspiration and onset of expiration
What does the knee jerk reflex cause?
Stretch reflex
- causes the quadriceps to contract
- causes hamstring to relax
- results in the swinging forward of the leg
