Lecture 9 - Motor pattern generation (1) Flashcards
How is rhythmic output generated, coordinated, and controlled by the nervous system?
- Contractions of numerous muscles
- Posture
- Adjustments to unpredictability
- Sensory feedback
- Proprioceptive feedback
What does stepping require? [2]
- Intravenous L-Dopa
- Electrical stimulation of mesenscephalic locomotor region
How does the central pattern generator work?
Work by providing both flexor and extensor with a signal for rhythmic movement
How does the chain of reflexes work?
- Movement within flexor sends relfex to the extensor causing it move
- A cycle of reflexes happen to ensure rhythmic movement
List two other forms of movement in animals that are rhythmic movements? [2]
- Dogfish swimming
- Flight in locust
How can you study the circuitry and pharmacology of spinal rhythm generation in rats?
- Recordings from ventral nerve roots
- Induce rhythm by bath application of serotonin and NMDA
How do fictive behaviours compare to real behaviours?
- Do not mirror the real thing
- Cycle frequency is often slower
What are the levels of the motor control hierarchy?
> Higher order control centres
Premotor network (CPG)
Motor neurons
What creates the alternating activity for flexors and extensors in the motor control hierarchy?
The premotor network (CPG)
What is the central pattern generator?
A premotor network of neurons that imposes rhythmic activity on motor neurons
What does the output pattern of the central pattern generator depend on? [3]
- Intrinsic properties or neuronal components
- Synaptic interactions
- Network configuration
What does reconfiguration of the central pattern generator cause?
Different output patterns (walking/running)
What are the five intrinsic membrane properties of central pattern generator neurons? [5]
- Excitability
- Endogenous bursting
- Spike frequency adaptation
- Post-inhibitory rebound
- Plateau potentials
What are the properties a synapse needs for rhythm generation?
- Polarity: excitatory vs inhibitory
- Electrotonic vs chemical
- Time course
- Neuromodulatory synapses
- Short term plasticity
What are the two types of network configurations for rhythm generation? [2]
- Reciprocal inhibition (x-y)
- Recurrent inhibition (x-y-z): Allows for 2-phase cycle
