NEUR30003 Lecture Notes - Lecture 27: Agnatha, Chondrichthyes, White Matter
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How best to measure brain size: brain weight, brain as percentage of body weight, encephalization factor. In what way have brains changed: overall size. Birds, mammals and cartilaginous fish have increased relative brain size. Lowest performers = jawless fish simple vertebrates: relative regional size increase esp. neocortical scaling. Mammals have a lot of cerebral hemisphere. A rat is a monkey is a human ->>> Similar design of structures: brain architecture design (lamination, migration, segregation, mappings) esp neocortical parcellation. Are bigger brains more sophisticated brains: human brain has more sophistication even though smaller 6 cortical layers. Are smaller brains less sophisticated brains: fish brain is even more intricate, lobes 15 layers, cellular architecture is more complicated. Our brain is 2% of our body, a mouse brain is 0. 2% What hasn"t changed: cortical thickness is relatively constant (basic design is similar across mammals 6 layers) Bigger brains (in relation to body size)