Transcript document

E3. Innate and learned behavior
 E.3.1 Distinguish between innate and learned behavior. Innate
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behavior develops independently of the environmental context,
whereas learned behavior develops as a result of experience.
E.3.2 Design experiments to investigate innate behavior in
invertebrates, including either a taxis or a kinesis. EG. Taxis –
Planaria move towards food (chemotaxis) and Euglena move
towards light (phototaxis)
kinesis- woodlice move about less in optimum (humid)
conditions and more in an unfavorable (dry) atmosphere.
E.3.3 Analyse data from invertebrate behavior experiments in
terms of the effect on chances of survival and reproduction.
E.3.4 Discuss how the process of learning can improve the
chance of survival.
E.3.5 Outline Pavlov’s experiments into conditioning of dogs.
E.3.6 Outline the role of inheritance and learning in the
development of birdsong in young birds.
E.3.1 Distinguish between innate and
learned behavior
 Innate : Developmentally fixed.
 Instinctive (have survival value)
 All individuals of a species exhibit virtually
the same behavior despite the inevitable
environmental differences within and outside
their bodies during development and
throughout life.
 Species specific behavior.
 Inherited
Examples of Innate Behaviors
 E.g. Kittiwake gulls show cliff edge
aversion
 E.g. Any example of invertebrate
taxis or kinesis
 E.g. “Rooting” behavior in human
babies
Learned Behavior
 Learned behavior reflects conditions
experienced by individuals during
development.
 Types of Learned Behaviors:
Classical and Operant Conditioning (Pavlov
and Skinner)
“Trial and Error Learning” (avoiding bad
tasting caterpillars)
Habituation (e.g. hydra stop contracting with
persistent water current)
Imprinting (e.g. graylag geese and Lorenz)
E.3.2
Design experiments to investigate innate behavior
in invertebrates including either taxis or kinesis.
 Two types of behaviors involving movement
have been defined:
A) Taxis: movement towards or away from a
directional stimulus. (Positive or Negative
chemotaxis (gradient), phototaxis,
thigmotaxis – wall-hugging behavior)
A) Kinesis: response to a non-directional
stimulus, in which the rate of movement or
the rate of turning depends on the level of
the stimulus, but the direction of movement
is not affected.
B) Examples include the number of turns and
the speed of movement of woodlice (also
called slaters) with changes in relative
humidity. Other factors: temperature,
oxygen concentration…uniform distribution
of any factor).
Design an Experiment: Examples
 To evaluate the response of a terrestrial organism to
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differences in humidity.
To evaluate the response of an aquatic organism to
light.
To evaluate the response of an aquatic organism to a
gradient of salinity.
To evaluate the response of a terrestrial organism to
differences in temperature.
To evaluate the response of a terrestrial organism to
odors produced by the same gender vs. different
gender.
EG Invertebrates
Design of Experiment: Give yourself
1 mark if….
 You stated the problem to be investigated.
E.g. The effect of water current speed on the
behavior of aquatic invertebrates.
E.g. The effect of light on the behavior of
terrestrial arthropods.
 Specified the null hypothesis: There will NOT
be a response to this stimulus.
 Specified the alternative hypothesis. There
WILL be a response – avoid/ move
toward/slow down.
Design of experiment: Choices
 Invertebrate species to use? E.g. aquatic? –
planaria, hydra; terrestrial? Isopods, land
snails, insects.
 Source of animals: captured in wild vs.
laboratory reared (biological supply company)
 Variable investigated (independent variable)
or manipulated
 Variable measured quantitatively (speed, #
turn, presence or absence in choice
chambers)
 Controls: temperature, humidity, light, size
Other considerations
 Experimental set up
 Sample size ###
 Replicates###
 Analysis of data Comparison
 What will results mean? If this happens, then…, if
this other thing happens, then….
 Kept for a short time only. Safety issues
 Protected from suffering during experiments and then
returned to habitat.
 Endangered species should not be used.
Analyze data from invertebrate behavior experiments
in terms of the effect on chances of survival and
reproduction.
 An experiment was
conducted to test the
response of invertebrates to
scents. The animals are
placed in the syringe with a
pump attached to the tube to
draw air gently through two
Y shaped arms.
 The apparatus was used to
test whether woodlice were
attracted to the smell of other
members of their own
species. 3 species were
tested. In each case, air was
drawn through a container of
the woodlice into one of the
2 arms. This air was
therefore scented with the
woodlice. Unscented air
was drawn into the other
arm. The number of
woodlice that moved from
the syringe into each arm
was counted.
Results:
Species
Numbers collecting in each arm
Scented
Unscented
Oniscus asellus 148
69
Porcellio scaber 101
62
Armadillidium
115
55
vulgare
1) Outline trends in data. 2) type of receptor that the
woodlice must have 3) discuss in terms of survival
and reproduction, the possible reasons for the
woodlice entering:
a) the scented arm of the apparatus
b) the unscented arm of the apparatus
4) What else might encourage the woodlice to move
out of the syringe into one of the arms?
 The graphs below show the associations between head width
and courtship and aggressive success of D. heteroneura.
 [Source: Boake et al., Proceedings of the national Academy of
Science, USA, (1997), 94, pages 12442–12445]
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What does this data suggest about male head width and
reproduction?
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What does this data suggest about male head width and
survival?
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Key:
best fit line
line of equal size flies
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0
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2.5 2.7 2.9 3.1
Male head width / mm
Aggressive success
Head width, winning male / mm
Number of copulations
Courtship success
3.1
3.0
2.9
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2.3 2.5 2.7 2.9 3.1
Head width, losing male / mm
E.3.4.Discuss how the process of learning can
improve the chance of survival.
 In diverse and changeable environments, animals can improve
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their chances of survival by learning new behavior patterns.
Examples
Chimpanzees learn to catch termites by poking sticks into
termite mounds. (Take advantage of a new food source.)
Birds learn to avoid eating orange and black striped cinnabar
moth caterpillars, after associating their coloration and
unpleasant taste. Learn to avoid potentially toxic substances.
Many bird species learn to take avoiding action when they hear
alarm calls warning them of a predator. (Avoid being THE meal)
Foxes learn to avoid touching electric fences after receiving an
electric shock.
In Britain, hedgehogs have learned to run across busy roads,
instead of rolling up into a ball.
E.3.5 Outline Pavlov’s experiments
into conditioning of dogs.
 Organisms learn to associate one stimulus
with another = Associative learning
 One type of associative learning is classical
conditioning
 Pavlov’s Experiments
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Spray powdered meat into dog’s mouth
causing salivation
Ring bell just before meat spray
Eventually dogs salivated at the sound of the
bell with no meat spray present
 Unconditioned stimulus is the natural stimulus
 Unconditioned stimulus = meat spray, or
smell or sight of food.
 Conditioned stimulus = Bell ringing, or
flashing of a light, a metronome ticking or a
musical box playing.
 Unconditioned stimulus yields an
unconditioned response
 Unconditioned response = salivation
 After pairing conditioned stimulus yields
conditioned response
 Conditioned response = salivation for the bell
E.3.6 Outline the role of inheritance and learning in
the development of birdsong in young birds.
 3 different strategies:
Strategy 1: entirely innate (inherited); New World Flycatchers; reared
away from adults and still acquire the species specific song.
Strategy 2: partially innate (ability to learn only song of same species)
but also learned (imprinting – sensitive period of development)
White Crowned Sparrow
 Has sensitive period for developing their songs.
 If isolated for the first 50 days of life and unable to hear either real
sparrows or recordings of sparrow songs, it fails to develop the
adult song of its species.
 Young sparrows do not sing, but they listen and memorize the
song of its species. During their sensitive time, fledglings seem to
be stimulated more by the songs of their own species than by
songs of other species.
 Thus, they learn the songs they will sing as adults, but learning
appears to be bounded by genetically controlled preferences.
Chaffinch
 Male chaffinches use their song to keep other males
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out of their territory and to attract females.
The song varies a little between males, allowing
identification of individuals.
It also has recognizable features to show that it is a
chaffinch singing.
Reared in isolation, a male chaffinch’s song has
some features of the normal song, including the
correct length and number of notes, which must have
been innate.
However, there is a narrower range of frequencies,
and fewer distinctive phrases. These must be
learned from other chaffinches.
E.4 Neurotransmitters
 E.4.1 State that some presynaptic neurons excite postsynaptic
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transmission and others inhibit postsynaptic transmission.
E.4.2 Explain how decision-making in the CNS can result from
the interaction between the activities of excitatory and inhibitory
presynaptic neurons at synapses.
E.4.3 Explain how psychoactive drugs affect the brain and
personality by either increasing or decreasing postsynaptic
transmission. Include ways in which synaptic transmission can
be increased or decreased.
E.4.4 List 3 examples of excitatory and 3 examples of inhibitory
psychoactive drugs. Use: nicotine, cocaine and amphetamines
for excitatory and benzodiazepines, alcohol and
tetrahydrocannabinol (THC) for inhibitory.
E.4.5 Explain the effects of THC and cocaine in terms of their
action at synapses in the brain. Include the effects of these
drugs on both mood and behavior.
E.4.6 Discuss the causes of addiction, including genetic
predisposition, social factors and dopamine secretion.
E.4.1 State that some presynaptic neurons excite postsynaptic
transmission and others inhibit postsynaptic transmission.
Open Na+/K+/Cl- channels
E.4.2 Explain how decision-making in the CNS can result
from the interaction between the activities of excitatory and
inhibitory presynaptic neurons at synapses.
Summation
 A typical neuron in the CNS receives input from 1000 to 10,000
synapses.
 Integration of these inputs is known as summation and occurs at
the trigger zone.
 The greater the summation, if it is a depolarization, the greater
the probability a nerve impulse will be initiated. Usually, a single
release of neurotransmitter from one of the pre-synaptic neurons
is insufficient to trigger an action potential. Either one presynaptic neuron must repeatedly release neurotransmitter, or
several different pre-synaptic neurons must release
neurotransmitter together. The additive effect from multiple
releases of neurotransmitter is called summation.
 A single postsynaptic neuron receives input from many
presynaptic neurons. Some produce excitation and some
produce inhibition. The sum of all of the effects determines the
effect on the postsynaptic neuron.
E.4.3 Explain how psychoactive drugs affect the brain and
personality by either increasing or decreasing postsynaptic
transmission. Include ways in which synaptic transmission
can be increased or decreased.
 Over 100 different brain neurotransmitters are
known.
 Psychoactive drugs affect the brain and
personality by altering the functioning of
some of the synapses. These drugs can be
ingested, injected, inhaled, or put into the
body in some other way.
 Some drugs are excitatory because they
increase post-synaptic transmission. Others
are inhibitory because they decrease it.
Psychoactive Drugs
Disrupt synaptic transmission in the brain
by
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Mimicking a neurotransmitter and binding to receptors for that
neurotransmitter in post-synaptic membranes. They block
receptors and so neurotransmitter cannot have its usual effect.
These drugs are chemically similar to a neurotransmitter. E.g.
Heroine and morphine combine with endorphin receptors.
Block activity of endorphins.
2.
Mimic a neurotransmitter with same effect, but are not broken
down so that effect is much longer lasting. Again, chemically
similar to the neurotransmitter.
3.
Interfere with the breakdown or reabsorption of
neurotransmitters in synapses and so prolong the effects. E.g
cocaine prevents dopamine reuptake, causing build-up of
dopamine in the synapse. E.g. prozac is a selective serotonin
reuptake inhibitor…increasing serotonin levels and a treatment
for depression.
E.4.4 List 3 examples of excitatory and 3 examples of inhibitory
psychoactive drugs. Use: nicotine, cocaine and amphetamines for
excitatory and benzodiazepines, alcohol and tetrahydrocannabinol (THC)
for inhibitory.
 Nicotine
 Benzodiazepines (e.g.
 Cocaine (Crack form)
valium, temazepan,
tranquilizers)
 Alcohol
 THC (active chemical
associated with
cannabis)
 Often accentuate the
effects of inhibitory
neurotransmitter GABA.
 Amphetamines
(Ecstasy is a derivative)
 Often accentuate the
effects of dopamine
E.4.5 Explain the effects of THC and cocaine in terms of their
action at synapses in the brain. Include the effects of these drugs
on both mood and behavior.
 Mixture of chemicals, one of which is THC which
binds to cannabinoid receptors in various parts of
brain (cerebellum, hippocampus and cerebral
hemispheres), blocking synaptic transmission.
 Strong evidence that the ability to concentrate,
control muscle contractions and judge times and
distances is so much reduced that it is unsafe to drive
vehicles or operate machinery.
 Users report feelings of emotional well-being and
clear thinking of complex ideas.
 Evidence for short-term memory impairment,
intoxication and stimulation of appetite.
 THC affects transmission at an unusual type
of synapse, where the postsynaptic neuron
can release a signalling chemical that binds
to receptors in the membrane of the
presynaptic neuron. (Retrograde signalling)
 THC binds to these presynaptic receptors.
 When THC binds to these cannabinoid
receptors, it blocks the release of excitatory
neurotransmitter. Therefore, THC is an
inhibitory psychoactive drug.
Mode of Action of Cocaine
Cocaine: Excitatory
Cocaine: stimulates transmission at synapses in brain
that use dopamine as a neurotransmitter.
Cocaine: binds to membrane proteins that pump
dopamine back into the presynaptic neuron.
Cocaine: blocks these transporters, causing a build-up
of dopamine in the synapse causing increased
energy, alertness, and talkativeness.
Intense feeling of euphoria.
Absorbed through skin of nostrils where it causes
constriction of blood vessels, delaying absorption.
Crack: forms a vapor when heated. Inhaled
and absorbed more rapidly; more intense
effects. Causes greater addiction and
overdose problems than other forms of
cocaine. Effects last about 40 minutes.
E.4.6 Discuss the causes of addiction, including genetic
predisposition, social factors and dopamine secretion.
The American Psychiatric Association has defined
addiction as:
“a chronically relapsing disorder that is characterized
by three main elements:
a) compulsion to seek and take the drug
b) loss of control in limiting intake and
c) emergence of a negative emotional state when
access to the drug is prevented
 Dopamine: primary neurotransmitter used by neurons in
the brain’s reward system.
 All drugs of abuse target the brain’s pleasure center.
 All drugs of abuse increase dopamine release from
the dopamine-containing axon terminals in the
nucleus accumbens region of the brain.
 Typically, dopamine increases in response to natural
rewards, such as food, music, art, and sex.
 When cocaine is taken, dopamine increases are
exaggerated, and communication is altered.
 1. Dopamine secretion: some drugs stimulate at
synapses using dopamine as the neurotransmitter.
Involved in reward pathway, giving feelings of wellbeing and pleasure. Cocaine, amphetamines,
methamphetamines, etc. Users become dependent
on the feelings that dopamine promotes.
 2. Genetic predisposition: alcoholism, chemical
dependency, have genetic components. Twins
studies and studies of children reared apart from
addictive parent indicate increased risk for
developing addiction if a first degree relative is
affected. (15% of children of alcoholics become
alcoholics) Allele of DRD2 gene that codes for the
dopamine receptor protein correlated with alcohol
intake.
Causes of addiction
 3. Social Factors: Cultural traditions explain
why different drugs cause problems in
different parts of the world.
 Peer pressure, poverty, social deprivation,
traumatic life experiences and mental health
problems may also contribute to encouraging
addiction.
 Even if genetically predisposed, social factors
(religion, culture, etc.) can also prevent
addiction.