Topic E:

E1 Stimulus and response

E2 Perception of stimuli

E3 Innate and learned behaviour

E4 Neurotransmitters and synapses

E5 (HL) The human brain

E6 (HL) Further studies of behaviour

E1

Stimulus and response

Stimulus: change in the environment (internal or external) that is detected by a receptor and elicits a response

Response: An action resulting from the perception of a stimulus. Reaction to a change perceived by the nervous system. Total of responses to stimuli often called behaviour

Reflex: A rapid, unconscious response

Receptors, (internal, external), energy.

action potentials

photoreceptors, chemoreceptors, thermoreceptors

The bird latin:______ ______ (_______) breeds during summer in Germany, and until recently flew to Spain or the Mediterranean for winter. However, recently ____ of blackcaps migrate to the UK instead.

To test whether this change is _______ determined or not (and was therefore a consequence of _____ ______ or not), eggs were collected from birds who flew to both the UK and Spain. The direction the hachlings flew for winter was recorded. Birds whose parents migrated to UK tended to fly west, and birds whose parents went to Spain flied south-west.

This suggests blackcaps are genetically programmed to respond to ______ when they migrate, so they fly in a particular direction. 

The increasing number of blackcaps flying to the UK might be due to warmer winters and greater survival rates there.

When winters were colder, there was a lot of ______ _____ against the genes that caused birds to fly west. This means they were more likely to die in the winter. 

Now that the winters are warmer, the survival rates in the UK have increased, reducing natural selection against them and hence against the behaviour.

Hedgehogs roll into a ball when threatened. When at night hedgehogs cross roads, they treat approaching cars as predators, so they roll up and die. 

However, it has been suggested that some hedgehogs run away from cars. This is more likely for them to survive, and produce more offspring carrying on this gene.

E2 

Rod cells are found all through the ______, except in the ______. The pigment in the rods is called _______ or visual ______. Several rods are linked to one ______ ______. This means that their impulses are "_____ up" and this explains their higher light sensitivity. However, it also reduces ______.

When light has caused an ______ _______ in rods or cones, it is passed on to the _____ _______. Here, the presence of action potentials of other cells may inhibit or further excite the _____ cell. An action potential may then be passed on to the ______ cell and from here to the ______ ______.

Retina, fovea. rhodopsin, purple. Bipolar neuron. added. Accuracy.

Action potential, bipolar neurons. Bipolar. Ganglion, optic nerve.

Processing visual stimuli already starts in the eye. It has been found that _____ cells send impulses to the brain, even when light is completely ______. Diffuse, low intensity light does not affect this process. 

However, when a small spot of light shines on the retina, _______ may greatly ______ the number of impulses sent to the brain or may _____ sending impulses, depending on where the light shines.

Ganglion, absent.

ganglions, increase, stop

Rods are grouped together in _____ _____. Those in the ______ of a ______ area are _______ and will respond to light by sending an impulse to the ______. Those near the ______ of the ______area are ________ and will stop the ______ from sending impulses to the brain. 

If light shines on ________ _________, in the ______ of a receptive area, the ganglions send more _______. If the light shines on the _______ ________, the ganglion will _____ sending impulses. If the light shines on ________, there will be ___ ______ in the frequency of sending impulses, i.e. it remains the same as in the dark.

receptive areas. centre, receptive, excitatory, ganglion. Outside, receptive, inhibitory, ganglion.

Excitatory photoreceptors, centre, impulses. Inhibitory photoreceptors, stop. Both, no change. 

The explanation for this is that the nerves are not just passing information about the light ______ perceived to the brain. They are processing details about light and dark and informing the brain about _____ which tells us a lot about shapes.

TVs and cameras use this concept and can do the same thing. It is called ______ _______. It makes the edge of something ____ even ______ and creates a "halo" of light around it, enhancing the ______. This also happens within the _____ (and is also known as lateral inhibition), and can be demonstrated by looking at the _______ _____ ______.

intensity, contrasts.

Edge enhancement. Dark, darker, contrast. retina. Hermann grid illusion.

Receptive areas.

[image]

_____-______ ________ refers to the fact that some of the nerve fibres in the optic nerve will cross before reaching the brain. The information of the left half of the _____ _____ arrives on the ____ side of the retina in the _____ eye. The nerves from this section are processed from the _____ side of the brain. 

Information from the ____ half of the visual field arrives on the ____ side of the retina in the ____ eye. The nerves from this section are processed by the _____ side of the brain. Vice versa occurs for the right eye.

Contra-lateral. Visual field, right, left. Right.

Right, left, left. Right.

Overall, information of the right side of the visual field is processed by the ____ side of the brain, and information from the ____ side of the visual field is processed by the _____ hemisphere.

left, left, right.

It does NOT mean info from right eye is processed by left hemisphere and vice versa.

• eardrum
• frequency, amplitude
• bones of the middle ear, ossicles, magnify
• Hammer, anvil, stirrup
• Ossicles, oval window, cochlea
• Fluid, cilia, action potentials
• Hair, Length, frequency
• nerve, auditory nerve
• Cochlear, Round window

Innate behaviour develops independently of environmental context.

Learned behaviour develops as a result of experience.

Taxis is a change in movement in response to a stimulus

Kinesis is a change in activity rate in response to a stimulus

Example experiment for taxis, in this case phototaxis: 

Euglena is a photosynthetic unicellular organism that requires light as a source of energy

• Step 1:  Place ____ in a ____ _____ with appropriate environmental conditions
• Step 2:  Cover dish with ______ ___, excluding a few small exposed sections
• Step 3:  With a ____ source placed above, Euglena should aggregate towards holes

• Euglena, light
• Euglena, Petri dish
• aluminium foil
• light

Experminent for kinesis (kinesis to humidity):

Woodlice have  ______ for respiration that will tend to dry out in dry conditions

• Cut a _____ paper in half. Place one half in a _____ ____. Wet the other half and also put it in. 
• Put 5 woodlice in, and record their positions every minute for 10 minutes. 
• They should move more on the ___ paper than the ___ paper.

gills.

• filter. petri dish. 
• wet, dry

______ behaviour is suited to conditions that do not change, e.g. in bees. They know innately to search for nectar in brightly coloured flowers. A positive experience with a flower will cause the bee to _____ look for this flower next time. 

Animals can also learn how to catch their food by practice, for example grizzly bears practicing catching salmon. 

Pavlov. Conditioned. Unconditioned.

[image]

All birds have a genetic component to their birdsong. For the _____ bird, it is completely innate. They can sing their song when raised in complete isolation. 

Many songbirds, e.g. the ______, have an innate component to their song and expand it by learning from other warblers. They sing a simplified song if not taught by older birds.

Others, like the ______, incorporate sounds it hears into their song, eg sound of mobile phones. 

Phoebe.

Warbler.

Starling.

-70mV. +50mV.

post-synaptic membrane. Sodium (Na⁺), sodium. excitatory post-synaptic potential (EPSP), depolarise. action potential.

Post synaptic transmission.

They can do things like release neurotransmitters, mimic their effect, reduce or delay re-uptake of neurotransmitters, block the receptors on the postsynaptic membrane or bind to the neurotransmitter receptors, but with the opposite effect

How cocaine works: 

Cocaine stimultes the ____ and creates a sense of ______. It blocks re-uptake of ______, which therefore _______. It makes the user feel less ____ or _____, and enhances endurance. _______ is part of the brains reward system, makes us feel happy, and anything increasing its effect will be potentially addictive. 

When the circular muscles ______, and the _____ muscles _______, the pupil becomes _______.

When the circular muscles _______, and the ______ muscles _______, the pupil becomes _______.

contracts, radial, relax, smaller.

relaxes, radial, contract, larger.

[image]

Due to modern life support equiptment, we can maintain the bodily process of someone who doesnt respond to any signal for a long time. If there is no measurable brain activity, it is persumed that there is no form of _______, and the doctors are allowed to declare the patient dead and switch off life support equiptment.

The absence of a ______ _____, pain and gag-reflex, are indicators that cranial reflexes are absent. Many such tesets have to be done before declaring someone brain dead.

Brain death is not to be confused with vegetative state or coma.

The _____ ____ ____ have a social structure unusual for mammals. They live in _____ underground, in burrows and tunnels. The _____ is the only female that reproduces, with a few males. Other females are _____ with a specific task: ______, ______ or ____-_______.

The queen nurses the _______ for a little, but this is soon taken over by the _____, until they are capable of playing a role in the colony. Should the queen die, other female workers fight until it is clear who is the new queen. The _____ of the workers is not _____, but maintained by the queen, possibly by _______.

naked mole rat. colonies. queen. workers, tunnelers, defenders, food-gatherers.

young, workers. sterility, genetic, pheronomes.

If the benefit to the recipient multiplied by the degree of relatedness to the performer is greater than cost to the performer, the behaviour is likely to spread by natural selection. 

This means: animals are more likely to perform altruistic acts that benefit closely related members of the species

• When presented with either species alone, bluegill fish eat more _____ than ______.
• When presented with both, the bluegill will only eat _______.

This is an example of _____ behaviour that ______ food intake.

• D. pulex, D. lumholtzi
• D. pulex

Foraging, optimizes

• Females often choose their mate (they choose best genes, so offspring gets best genes and survival chances)
• Males need to attract attention in order to mate (by using ornaments or attracting attention otherwise)
• Males may fight other males to establish dominance (strongest genes fight best, but establishing dominance by showing off ornaments is more desirable, as no male gets hurt)