Lecture 29: Somatic Control Flashcards
What is somatic control?
Control of skeletal muscle; reflex movements, precise, voluntary movements, automatic movements.
What is the definition of a reflex?
“A predictable, reproducible automatic response to a particular sensory stimulus.”
How many neurons are involved in a typical withdrawal reflex?
3: Afferent, interneuron, efferent.
Explain what happens in a withdrawal reflex.
Stimulus causes AP to travel up to spinal cord, where signal is sent back down to withdraw limb (ipsilateral). The signal also crosses to the other side of the body at the spinal cord and sends a signal to stabilise that side of the body (contralateral).
What are the 3 parts of the motor cortex and what are their functions?
Prefrontal cortex: Goal
Premotor cortex: Motor program
Primary Motor Cortex: Activation of specific motor units.
How many neurons are in the corticospinal pathway?
2
Name and describe the 2 neurons in the corticospinal pathway.
Upper motor neuron:
- Primary motor cortex
- crosses over at the medulla.
- corticospinal tract in spinal cord
- excitatory synapse to lower motor neuron
Lower Motor Neuron: Controls precise movement of hands and feet.
What is the purpose of the basal ganglia?
Modify movement using a loop system with the cortex, helps select an appropriate movement.
INHIBITS inappropriate movement.
What is the purpose of the cerebellum?
‘little brain’
- Ensures selected movement is coordinated, guided by sensory feedback.
- intention//result
- maintains posture.
What is procedural memory?
The development of automatic movements / motor programmes.
Explain ‘inhibition of inhibition’.
At rest, the basal ganglia inhibits the cortex from making movement. When active, the basal ganglia inhibits its own inhibition, allowing the movement to occur.
Explain integration between the motor and sensory systems.
Cerebellum receives sensory feedback and goals, compares them and signals an adjustment to the cortex. The motor cortex signals to the lower motor neurons via thalamus. At the same time, the motor cortex signals this goal to the cerebellum.
