Other Minds - Chapter 2 Flashcards
action potential definition
- mode through which a neuron transports electrical signals.
- defined as a brief change in voltage across the membrane due to the flow of certain ions in and out of the neuron
How much energy we take in is spent on running the brain?
Nearly a quarter
What is the original function of the nervous system?
To link perception with action
Where did action potentials exist before?
inside cells before animals evolved and now they exist within animals
evolution transformed cell-cell signalling into …
an organised network: the nervous system
Sensory-motor view of nervous systems
- nervous system evolved in order to produce actions in response to what is perceived EXTERNALLY
Action-shaping view of nervous systems
- Chris Pantin developed this view in 1950s
- internal coordination
- idea that first nervous system came to exist as solutions to a problem of pure co-ordination within the organism
- nervous systems came into existence to coordinate micro-acts of parts of the body into macro acts of the whole
When and where and who by was the first Precambrian fossil found?
1946 Reginald Sprigg (Australian geologist) abandoned mines in outback South Oz
discovered EDIACARA BIOTA
Characteristics of ediacaran animals
+ 2 examples
not tiny (several inches in length)
lived mostly on sea floor - motionless
nervous systems present (second half of ediacaran)
kimbrella, dickinsonia
What is the big question about ediacaran cnidarian jellyfish?
why did they have stingers when no other animal had any form of defense?
AKA Why did cnidarian stings evolve so early?
What do some biologists argue about animals in the Ediacaran period?
They weren’t proper animals
Two views for role of the nervous system?
1) action-shaping view
2) sensory-motor view
What point might the role of the nervous system been action-shaping and why?
Ediacaran, then animals were not alert and aware of their environment because no predation and they lived alone. No need sense much of the surroundings and act on what they perceived.
Their nervous systems were for shaping movements, maintaining rhythms and crawling which would have included some sensing of the environment but perhaps not that much.
Bilaterian
evolved before the Cambrian era, allows for mobility and walking
eg. Kimbrella in Ediacaran period was believed to be bilaterian
Cambrian organisms
- definitely predation (fossils have eyes, antennae, claws)
Box jellyfish
24 eyes
navigate by watching external landmarks on the shore
Radial symmetry
top and bottom but no left or right
eg. jellyfish
What did the bilateral body plan do?
created new possibilities for the nervous system
What two types of eyes evolved in the Cambrian era and what did this mean?
Camera (us)
Compound (insects)
With an influx of sensory information comes the need for complex internal processing.
How did minds, senses and nervous systems evolve?
in response to other senses + nervous systems. INTERACTION led to EVOLUTION
How did predation arise?
feeding on microbial mats –> feeding on the dead –> feeding on the living
(scavenging became predation)
Complex Active Bodies
- move quickly, seize and manipulate objects
- appendages that can move in any direction
- senses, eyes, can track distant objects
Which three major animal groups produced some species which are classed as CABs?
arthropods, chordates, cephalopods
What did biologist Detlev Arendt believe?
nervous systems originated twice in the same animals (at different places in the body)
LINK - brain gut
E.g. jellyfish: one nervous system evolves on top – it tracks light to control bodily rhythms and regulate hormones.
A second nervous system evolves to control movement.
At some point, the two systems start working together in the body - crucial event in Cambrian era than took bilaterians forwards
