Vertebrate brain evolution

Question 1

describe nervous system of sponges

Answer 1

lacks tissues therefore has no neurons

evidence fo genes

Question 2

describe nervous system of Cnidaria

Answer 2

hydra have a neural net

medusa/jelly fish have neural net and neural ring (more localized neurons, more precise –> precursor to brain and spinal cord)

Question 3

describe bilateral nervous system

Answer 3

evolution of orientation of head, brain and sense organs in head

Question 4

invertebrates neural system

Answer 4

Cartilaginous notochord , but no vertebrae

Question 5

brain differences between monotremes, marsupials and placentals

Answer 5

placental have corpus collosum while monotremes and marsupials have simple network of nerve fibres that connect the hemisphere

Question 6

describe nervous system of invertebrates

Answer 6

Brain as thick as spinal cord

Hindbrain and midbrain, but lacks telencephalon

Question 7

what are the two main observations made made Ludwig Edinger

Answer 7

1. Greater variation in forebrain while mid and hind brain conserved
2. Brain made of Two main types of tissue (cortical and subcortical)

Question 8

what was the Evolutionary sequence of added structures Ludwig suggest for the variation in the forebrain

Answer 8

Fish and amphibians - basal ganglia, no striatum
I
V

Reptiles - basal ganglia and striatum

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V
Early mammals - basal ganglia and paleocortex

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V

Mammals - basal ganglia, paleocortex, neocortex

reptile –> paleocortex –> neocortex

Question 9

what is Paul Macleans Triune brain view

Answer 9

Suggested that reptile brain had instinctive behaviour

evolution of Paleocortex –> evolution of limbic system (emotions, reinforced learning )

Neocortex –> all above + evolution of cognitive capacities (thinking, decision making, planning)

Question 10

discoveries challenges Macleans and Edingers views

Answer 10

Neocortex found in early mammals and birds –> therefore did not evolve in first mammals

Paleocortex structures found in reptiles –> did not first evolve in early mammals

Striatum found in fish and amphibians –> did not evolve first in reptiles