Toad Prey Capture

Question 1

Nervous System

Answer 1

eyes- optic nerve- tectum- target areas

Question 2

sign stimuli

Answer 2

horizontal= prey
vertical= ignored

Question 3

Ewert

Answer 3

used turn tables to test effectiveness of stimuli

• toad sat in middle and stimuli moved around it
• if interested it would turn and try and follow it
• rate of turning is a proxy measure for stimuli effectiveness
• combination of shape and movement is important
• toad generalizes dark/light and fast/slow
• looked for responsible neuron outside brain

Question 4

Retinal Ganglion Cells (RGCs)

Answer 4

have complex responses to size/movement/colour
2 synapses from retina
detect images such as light/dark dots/edges in larger receptive field

Question 5

Connection scheme

Answer 5

2 RGCs go to pretectum and connect to TH3 neurons which signals danger
2RGCs go to layer 5 and signal movement but not specifically worms
T5(1) excited T5(2) which signals prey
T5(2)s also inhibited by TH3s
Toad with damaged pretectum attack any moving object- evidence of inhibition of t5(2) by TH3

Question 6

Dicke et al (2016)

Answer 6

found that striatum lesioned salamanders had impaired orienting behaviour while spike pattern of tectal cells was unaffected
Dorsal striatum contributes to orienting behaviour but not to an inhibitory feedback signal to tectal neurons