4.10 - Evolution of nervous system

Question 1

caenorhabditis elegans (2)

Answer 1

1. nerve networks of just a few hundred neurons
2. neurons spread throughout organism (with some ganglia)

Question 2

lymnaea stagnalis (2)

Answer 2

1. about 20,000 neurons
2. discovery of how a circuit of just 2 neurons can drive a sophisticated form of decision making

Question 3

ventral notochord (2)

Answer 3

1. insects
2. ganglia distributed along body

Question 4

comparisons between neural circuits from insects/vertebrates

Answer 4

fundamental shared computational and organisational principles

Question 5

principles of sensory coding

Answer 5

have to extract information from the same physical and chemical stimuli and solve the same problems

Question 6

ctenophores (3)

Answer 6

1. nervous system forms a syncytium (multinucleate cell, result of multiple unicellular cells or nuclear division without cytokineses)
2. early split of ctenophores from other groups
3. nervous systems/neurons could have evolved at least twice (once within ctenophores, once within lineage of remaining animals)

Question 7

cnidarians (3)

Answer 7

1. radial symmetry
2. fairly simple nerve nets (some degree pf neuronal condensation)
3. jellyfish