Talk:Brain Awareness Week 2012

Cerebrum Comparative Anatomy

Primitive vertebrates

• (hagfishes and lampreys)
• cerebrum is a relatively simple structure receiving nerve impulses from the olfactory bulb.

Some fish and amphibians

(Cartilaginous fish (sharks), lobe-finned fish, amphibians)

• remains mainly devoted to olfactory sensation.
• Cerebrum divided into 3 regions.

1. ventral - forms the basal nuclei, and contains fibres connecting the rest of the cerebrum to the thalamus.
2. lateral - forms the paleopallium.
3. dorsal - forms the archipallium.

Ray-finned Fish

• Cerebrum lateral and ventral regions inner surfaces bulge up into the ventricles.
  • these include both the basal nuclei and the various parts of the pallium (complex in structure in teleosts).
• Verebrum dorsal surface is membranous, and does not contain any nervous tissue.

In amniotes, the cerebrum becomes increasingly large and complex.

Reptiles

• paleopallium is larger than in amphibians, and its growth has pushed the basal nuclei into the central regions of the cerebrum.
• Grey matter is generally located beneath the white matter
  • in some reptiles, grey matter spreads out to the surface to form a primitive cortex (anterior part of the brain).

Birds

• enlarged compared to reptiles, due to the basal ganglia.
  • other areas remain primitive in structure.
  • no expansion of the cerebral cortex
• above basal ganglia the HVC develops
  • involved with learning complex tasks, such as song.

Mammals

• cortex covers almost the whole of the cerebral hemispheres (greatest in primates).
  • paleopallium is pushed to the ventral surface of the brain, where it becomes the olfactory lobes
  • archipallium becomes rolled over at the medial dorsal edge to form the hippocampus.
  • corpus callosum connects the two hemispheres.
• surface folding found only in higher mammals.