Human Cortical Development

Question 1

Describe four ways in which cortex development has been analysed in relation to other species

Answer 1

• Fossil data: skull size and form
• Comparative anatomy
• Comparative genomics
• Fundamental research on cortical development (from mouse to man)

Question 2

Give the:
* Total number of neurons in the brain
* Total number of glia in the brain
* Total number of neurons in the cerebral cortex
* Total number of neurons in the cerebellum:

Answer 2

• Total number of neurons in the brain: 86 bilion
• Total number of glia in the brain: 1000 biljon
• Total number of neurons in the cerebral cortex: 16 bilion (15% of total)
• Total number of neurons in the cerebellum: 67 bilion ( 80% of total)

Question 3

What makes the human brain special?

Answer 3

The human brain is not the largest (elephant). Among primates the human brain is the largest

However, What counts is the absolute amount of interneuronal connections. The primate brain is built in a very economical, space- saving manner

The primate cortex is exceptional in number of neurons per cm3. Still: the human brain holds the record for total number of neurons

Question 4

Compare the human differentiation cycle to mice

Answer 4

Differentiation cycle is similar to mice, however you also get one outer radial glia alongside one inner radial glia. With every division one ORG is producing one intermediate progenitor cell and this producing further intermediate progenitor cells which symmetrically divided into two radial glia.

You also have an outer and inner SVZ; RGs in the VZ produce Neurons, IPCs, ORGs and IRGs. IPCs divide into neurons in the ISVC and ORGs travel up to the OSVZ where they can assymetrically divide into an ORG and IPC twice (2). This increases the number of cells produced.

Question 5

Compare the zones of cortical development in humans and mice