What is a fixed action pattern
an instinctive behavioural sequence that is relatively invariant within the species and almost inevitably runs to completion.
What are the important properties of CPGs?
- intrinsic properties of neurones
- Synaptic properties
- Patterns of neuronal connectivity
What is a network oscillator?
None of the neurones in the CPG have endogenous bursting properties (pacemaker like activity).
Describe the tritonia escape swimming CPG.
- Network oscillator
• sensory input triggers command gating neurones ( trigger-type command neurone tr1 and dorsal ramp interneurone DRI)
• DRI excites dorsal swim interneurone DSI
• DSI excites cerebral neurone 2 C2, and itself.
• C2 have have high thresholds so it takes about 1-4 seconds for firing.
• C2 then excites DRI (positive feedback loop), keeping it firing.
• C2 excites ventral swim interneurone VSI (this is delayed slightly due to an A current), which inhibits DSI and eventually C2. When VSI stops, the cycle repeats.
Briefly outline the sea angel swimming CPG.
CPG creates permanent rhythmic activity, it is constantly swimming.
It does this through a very strongly connected bursting system at the heart of the CPG.
Uses reciprocal and recurrent inhibition.
Briefly outline the Lymnaea feeding CPG.
A network oscillator generating 3 phase rhythm
involves 3 types of CPG neurone
Driven by sensory inputs and higher order modulators
includes the behaviours of protraction, rasp and swallow
