Week 3: the nervous system of octopuses

Question 1

Where does the name Octopus come from?

Answer 1

• ancient Greek
• compound of okto (=eight) and pus (=fuß)
• not latin → plural is NOT octopi

Question 2

What is the family of the octopus?

Answer 2

• Mollusca
• same as snails, clams and chitons

Question 3

What is a brain?

Answer 3

= an organ that is the center of the nervous system

change type A in nervous system → change type B in brain state

Question 4

What is the nervous system?

Answer 4

= the set of all connected neurons plus the cells that support their functioning (glial cells)

Question 5

What are neurons?

Answer 5

cells which transmit electrical impulses in a particular way

Question 6

What is the function of the brain?

Answer 6

• processing information (cognition)
• controlling behavior

Question 7

What is special about the brain function?

Answer 7

• it is adaptive
• cognition is a function from stimulus inputs to behavioral outputs
• function changes over based on prior activation
• it evolves so the resultant behavior is better suited to the environment and the goals of the organism

Question 8

How is the distribution of the nervous system different in humans and octopuses?

Answer 8

human nervous system
- 86 billion neurons in brain
- 100 Billion neurons in peripheral nervous system (PNS)
- Brain ~PNS

Octopus
- 50 million neurons in central brain
- 160 million neurons in separate optic lobes
- 320 million neurons in branchial ganglia in its arms

Question 9

How is an octopus unique in terms of it’s physiology?

Answer 9

• no spine
• no joints
• 1000s of finger-like suckers
• can move, touch themselves and other things in may more ways than humans

Question 10

What characterizes the arms of an octopus?

Answer 10

• highly complex
• contain many interneurons which support cognition and behavioral control

Question 11

What are somatotopic maps?

Answer 11

cortical or subcortical arrangements of sensory inputs and local circuits that reflect the topological organization of the body

Question 12

Where do we find somatotopic maps in humans?

Answer 12

• spinal cord
• cerebellum
• somatosensory cortex

Question 13

Where do we find somatotopic maps in octopuses?

Answer 13

• so far none have been found in their CNS
• possible reason: lack of joint would make them overly complex and redundant
• Grasso suggests it’s because spatial and proprioceptive information can already be represented in the neural networks found in the arm cords

Question 14

Do Octopuses have multiple brains?

Answer 14

• some say they have nine or at least two
• depends on what we mean by brain
• they only have one organ at the center of their nervous system
• other non-central organs also do brain-lie functions

Question 15

What are abilities researches have found octopuses to have?

Answer 15

• good learning capacities
• domain-general cognition
• various visual distinction capacities → implies capability of concept formation
• long-term memory

Question 16

Why are those abilities rather surprising?

Answer 16

• they live a solitary life
• lack a central nervous system