E3. Innate and learned behavior E.3.1 Distinguish between innate and learned behavior. Innate

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 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 UnscentedOniscus asellus 148 69Porcellio scaber 101 62Armadillidium 115 55 vulgare1) 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 apparatus4) 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]

(a) What does this data suggest about male head width

and reproduction? What does this data suggest about male head width and

survival?

.....................................................................................................................................

9876543210

3 .1

3 .0

2 .9

2 .8

2 .7

2 .6

2 .5

2 .4

2 .3

Num

ber

of c

opul

atio

ns

Hea

d w

idth

, win

ning

mal

e / m

m

2 .3 2 .32 .5 2 .52 .7 2 .72 .9 2 .93 .1 3 .1M ale h ead w id th / m m H ead w id th , lo s in g m a le / m m

C o u rtsh ip su ccess A g g ress iv e su ccess

K ey : b e s t f it lin e lin e o f eq u a l s ize flie s

E.3.4.Discuss how the process of learning can improve the chance of survival.

In diverse and changeable environments, animals can improve 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

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 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

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 pre-synaptic 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 brainby

1. 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 Cocaine (Crack form) Amphetamines

(Ecstasy is a derivative) Often accentuate the

effects of dopamine

Benzodiazepines (e.g. valium, temazepan, tranquilizers)

Alcohol THC (active chemical

associated with cannabis)

Often accentuate the effects of inhibitory neurotransmitter GABA.

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 drugb) loss of control in limiting intake andc) 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 well-being 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.