Flashcards

16. Reflexes and Escape Behaviour

Mimi E Neuroscience Inglês 5,0Avaliação média 5,0 de 5 (1 avaliação) 16 flashcards

Flashcards do conjunto (16)

1Define locomotionThe ability of an organism to move in space in purposeful ways by using efficient mechanisms that are suitable for the purposes of the movement
2What are the specific animal adaptations for locomotion?• Muscles (locomotion requires muscles)
• The nervous system (muscle contraction requires control)
3What makes a good model system for studying the control of locomotion?• The behaviour needs to be, reliable, reproducible and simple
• The underlying control mechanisms need to be simple
• The system needs to be accessible
4Briefly describe crayfish escape behaviour in response to a tail touch. What causes the response?- Touching the tail with a probe triggers a downward tail flip that propels the animal up and away from the stimulus
• It's fast --> the time between the stimulus and the response is 10ms
• Contraction of the tail is caused by the rapid contraction of the flexor muscles
5Describe the crayfish nervous system• The brain: a collection of ganglion fused in the head region
• Subesophageal ganglion complex
• 5 thoracic ganglia (correspond to the 5 thoracic ganglia)
• 6 abdominal ganglia (correspond to the 6 abdominal ganglia)
• Each ganglion is connected by axons
6Where is the circuitry for the tail flip response located?In the abdominal ganglia
7Describe the pathway for the tail flip circuitry• Tail afferents (bipolar sensory cells)
-> Sensory interneurons
-> Lateral Giant Interneuron (LGI)
-> Giant Motor Neurons (MoG)
-> Fast flexor muscles
8[Diagram of tail flip circuitry]The zig-zag lines indicate electrical synapses
9Describe the anatomical organisation of the lateral giant interneurons• There is one LGI per abdominal ganglion
• They are coupled to each other via segmental electrical synapses
[The LGIs essentially operate as a single unit because of how strongly they are connected (ensures rapid spread of activity throughout the ganglia)]
10—• This experiment proves that LGI activity is necessary for the tail flip response
• After electrically stimulating the sensory neuron (mimics tail touch) > depolarisation of LGI > APs in motor neuron
• Injecting negative current leads to hyperpolarisation > no AP in LGI > no AP in motor neuron
11Describe crayfish escape behaviour in response to a head touch. What interneuron is involved in this escape response?• Triggers a tail flip that propels the animal backwards
• The Medial Giant Interneuron (MGI) is involved
12What's the difference between the MGI and the LGI?• MGI is carries sensory information from the head
• LGI carries sensory information from the tail
13What's the difference between how the MGI and the LGI cause the tail flip response?• LGI synapses with MoGs in abdominal segments 1 - 3 so only these muscles contract
• MGI synapses with all segments
14How are escape networks specialised for fast responses?• Neurons have large axon diametres
• Networks have many electrical synapses
15Describe the squid jet propulsion escape response.• It rapidly contracts body and expels water to propel itself away from the stimulus
• It is triggered by the activity of the Squid Giant Axon
16Describe the Drosophila escape jump response.• The fly jumps upwards and backwards and flies away
• Giant Fibres carry sensory information from the eyes to the tergotrochanteral muscles which contract to make them jump