Download New Unit Begins today … BOA will not have a comprehensive final

New Unit Begins today …
BOA will not have a comprehensive final exam …
But … remembering and understanding certain concepts
will be expected all semester.
EXAMPLE
BOA will mostly focus on certain familiar groups:
1) “insects” = Phylum Arthropoda
Class Insecta
2) “vertebrates” = Phylum Chordata
Subphylum Vertebrata
Class Osteichthys (bony fish)
Class Amphibia (amphibians)
Class Reptilia (reptiles)
Class Aves (birds)
Class Mammalia (mammals)
EXAMPLE
Evolution by Natural Selection … Know This!!
EXAMPLE
Endothermic Homeotherms – birds & mammals
Ectothermic Poikilotherms – all other animals
Animal Nervous Systems
Nervous systems separate animals from other life.
Life without nervous systems:
plants
single celled organisms
fungi
What advantages are conferred by NS??
Possibilities due to a nervous system:
1) Awareness of the “world” via sensory systems
•
•
•
•
•
•
•
•
Vision
Audition
Senses that humans
Olfaction
can relate to
Gustation
Tactile
Thermoreception
Magnetoreception
Can’t easily relate to
Electroreception
Neurobiology of Sensation
Antenna
Mosquito
Compound eye
More Possibilities due to a nervous system:
2) Memory (short- & long-term)
3) Anticipation
4) Learning
5) Strategy (e.g., stalking strategy of lions)
6) Motor output (body control via muscles)
A Nervous system is an input-output device:
Inputs to brain or cord are “sensory”
Brain processes input (information)
Outputs are “motor” (to muscles)
Input-Output Example: Simple Reflex
“INPUT”
“OUTPUT”
QUESTION: How many types of basic tissues
are there in animal bodies?
What are they?
4 TYPES
-Connective tissue
-Epithelial tissue (e.g. outer skin)
-Muscle tissue
-Nervous tissue
Nervous systems consist of nerve cells called
NEURONS
Neurons are highly specialized for transmitting
INFORMATION
Anatomy of a
typical neuron
Direction
of
Information
(wrong)
Neural Information involves both
(1) ELECTRICAL excitation
(2) CHEMICAL excitation
Electrical excitation is called an Action Potential
Action Potentials are due to Na+ entering the neuron
+
Na
Electrically
Positive
http://www.blackwellpublishing.com/matthews/channel.html
Na+ is entering
the axon
Action potential “flowing”
down an axon
Chemical Information involves the SYNAPSE.
What is a synapse??
A synapse involves 2 neurons and consists of
- an axon end
- the synaptic cleft
- a dendrite beginning
Neurotransmitter
Molecules
SYNAPSE
AXON
DENDRITE
Arriving action potential
Action potential continues
INFORMATION DIRECTION
More Realistic
Number of
Synapses
3 Unsurprising Observations About Nervous Systems
* Simple/primitive animals have simple ones
* Complex/advanced animals have complex ones
* Homo sapiens are the most complex
What makes a nervous system complex?
1) Brain size?
… NO!!
MALES are larger by …
* 7.5% in body size
* 15% in BRAIN size
E
Brain Size: How Important??
Brain
Weight
(g)
Body Size (kg)
Relative
Brain sizes
.
Tarsier
Order Primates
Relative
Brain sizes
ADVICE
.
Never confuse brain mass
with … sophistication or
…… survival probability
H. sapiens
H. neanderthalensis
What makes a nervous system complex?
1) Brain size … NO!!
* ants vs frogs?
* mice vs whales?
2) Neural Circuit complexity … YES!!
* convergence & divergence
* numbers of synapses
* excitatory & inhibitory synapses
* speed of action potentials (e-reserve)
Neural Circuits – pathways of
communication among neurons
simple to horrendously complex
EXAMPLE: Some Circuitry in
the Primate Visual Cortex
Relationships Among Neurons
Convergence & Divergence
10 neurons converging
onto 1 neuron
1 neuron diverging
onto 10 neurons
N N N N N N N N N N
N
N
N N N N N N N N N N
(3:1)
(1:4)
Excitatory Synapse
AXON
DENDRITE
Arriving action potential
Action potential continues
Inhibitory Synapse
AXON
Arriving action potential
DENDRITE
Excitation suppressed!!
CIRCUIT COMPLEXITY
CIRCUIT COMPLEXITY
Moore's law describes a long-term trend in the history of
computing hardware. The number of transistors that can be
placed inexpensively on an integrated circuit doubles
approximately every two years.[note 1] This trend has continued for
more than half a century and is expected to continue until at least
2015 or 2020.[
http://en.wikipedia.org/wiki/Moore's_law
Examples of Animal Nervous Systems
Ultra-simple ………….to …………..Ultra-complex
ULTRA-SIMPLE
Nerve Nets are typical of jellyfish,
corals, and sea anemones
(Note body symmetry)
FAIRLY SIMPLE
Flatworms have the basic components
of advanced systems
(note bilateral symmetry)
Mudworms
BRAIN REGENERATION!!!
How possible??
-Neurons divide to create more neurons
-Synapses form between new neurons
-Circuits appear where none existed
HORRENDOUSLY COMPLEX
Homo sapiens
-Billions of neurons
-Trillions of synapses
-1300 g = 3 lbs
- Jello consistency
- Male brain superiority?
- 15 % larger (7.5% body wt. difference)
- gender difference seen at age 2-3 yrs
Animal brains are specialized for specific
“life styles”
Different brains might be good at ….
•Night vision
•Balance & equilibrium in trees
•Learning
•Coordinating flight muscles
•Interpreting communication
signals
(Rare: no apparent function)
Human
Sensory Worlds
- all animals are different in sensory capabilities
- impossible to truly know about other animals
- senses are matched to specific habitats and life styles
Example of sensory specialization:
star-nosed mole
• lives in tunnels in the soil
• “appendage” is specialized for tactile sensation
• each “finger” is loaded with neurons sensitive to
touch
• brain is disproportionately devoted to touch
interpretation
http://animal.discovery.com/videos/fooled-by-nature-star-nosed-mole.html
Note speed of probing … try to imagine “seeing” with touch
Nares (nostrils)
Cortex
Area
Devoted
to each
Appendage
Tactile Cortex Region
(region where “touch” is processed)
Now think about the HUMAN brain
Human tactile sensation is mapped onto the cortex
of the brain…
If the male brain shows cortical magnification,
what will it look like?
Tactile Cortex Region
(region where “touch” is processed)
Human Cortical Magnification
Q: Which vertebrate can “see” in 2 different ways?
A: Pit Vipers
- about 150 species worldwide
- North America
rattlesnakes
water moccasins
copperheads
Warms when
IR radiation
Is absorbed
Sensory neuron
responds
to a ΔT = 0.003 C
!! Both visible light
vision and infrared
“vision” project to the
Optic Tectum !!
ANIMAL CONSCIOUSNESS
CLASS: What is consciousness??
Dictionary:
1) awareness; especially of something with in oneself
2) being "aware" of external object.
What is "aware"??
Dictionary: Aware = to realize
Realize = to understand
Understand = to grasp the meaning
Are nonhuman animals conscious?
CLASS: Are nonhumans conscious??
At the heart of this question is the concept of SOLIPSISM.
Philosophers have argued that any individual can only be
sure of his/her own consciousness.
Is this concept believable? Useful?
What about "species solipsism"?
How can humans know if animals are conscious?
How would you scientifically deal with it?
CLASS: Think of examples of
animal consciousness (2 min)
Some animal communication suggests a consciousness.
Animals exchange information when communicating Is it accurate/honest??
What if animals intentionally convey inaccurate information??
Is it conscious deception? Maybe.
EXAMPLE: Piping plovers are shore birds that nest on
sandy beaches – nests are hidden.
Plovers have ways of distracting and diverting intruders:
-"peep" and walk just ahead (not deceptive)
-false brooding (appear to be sitting on eggs)
- broken wing displays for 40% of approaches
Risk assessment precedes response.
Consciousness or simply mental flexibility?
EXAMPLE: East African vervet monkeys use
alarm calls to warn others of danger.
The warnings are CONTEXT-SPECIFIC:
- eagle alarm call
- leopard alarm call
- snake alarm call
Are all monkeys equally likely to give the
alarm calls?
Fact: high-ranking individuals alarm call more than subordinates.
Subordinates look for and see danger, but less likely to report it.
Are subordinates "aware" of their rank ....
Do they "assess" their situation and acting accordingly?
Fact: Females give more alarm calls in the presence of their
offspring -- less with unrelated juveniles.
Fact: Males call more when with females -- less if with other males.
Monkey's intent to communicate seems to take into account
immediate social environment.
Are these conscious intentions?
Or simply the workings of a “hard-wired” neural program?
Strong argument for animal consciousness is an
evolutionary one.
Did human consciousness arise with no ancestral
precursors??
If yes, explain how that could happen.
reptiles
birds
primitive mammals
early humans
Other complex traits build on ancestral versions:
learning
memory
vocal communication
problem solving
etc. etc.
humans
Can anything be said about brain size & consciousness???
Dogma: consciousness implies big brains.
Tarsiers (and humans) are primates … rat size
Blue whale: largest animal ever!
Are blue whales more likely to be conscious??
In proposing animal consciousness, avoid imposing
a human type of consciousness.
Perhaps no other animal can step outside of itself and
reflect on its own thoughts.
Perhaps only humans know that they know something.
Perhaps only humans know that they know that they know
something.