Option E - Neurobiology and Behavior

From KstructIB

[edit] E1-2 Neurobiology and Behaviour

1. State that the behaviour of animals is related to the environmental context. Provide an example.

2. State that innate behaviour develops independently of the experimental context, whereas learned behaviour reflects conditions experienced by individuals during development. Use examples. Innate behaviour is controlled by genes and is inherited from parents. It is developed by natural selection because they make members of a species better adapted to their habitat and increase their survival rates and reproduction. However, learned behaviour mirrors the circumstances that an animal experiences during development.

For example, fly larvae can distinguish the direction of light and move away from it. This is called taxis and is an innate response to a stimulus. This specific movement of the fly larva is negative phototaxis. This movement ensures the larvae remain inside the carcasses, where food is available and predators are less likely to prey on them.

A very famous example of learned behaviour is Ivan Pavlov’s salivation patterns in dogs. Pavlov trained dogs to associate two external stimuli together (bell ringing and the arrival of food), this resulted in increased salivation in the dogs.

3. Explain the role of natural selection in the development of behaviour patterns. Natural selection is how genes and inherited characteristics from parents are controlled. This makes species of organisms better adapted to their environment and increases their chances of survival and reproduction. Taxes and kinesis are behaviour patterns that increase these survival chances in invertebrates.

Examples of this are wood lice. They can distinguish whether or not an area is humid or dry. Response to humid areas includes moving very slowly and changing direction after moving short distances whereas response to dry areas includes moving more quickly and by further movement before changing direction. This innate response in woodlice and a specific type of it called hygrokinesis, ensures that more time is spent in humid areas than dry areas if both are available.

4. Explain, using species of birds or mammals (other than humans), one example of each of the following types of behaviour:[[a) migration -]] Migration is movement of animals between different areas according to seasons of the year. Examples of this are birds called Greater shearwaters that employ migration to avoid cold winters with low food availability. Triggers for migration include shortening day lengths as well as specific smells. [[ b) grooming -]] Grooming is the usage of fingers or tongue to clean the coat of a mammal to remove parasites. Rhesus monkeys spend up to 20% of the day being groomed and this gesture is submissive which reinforces hierarchy in the group. [[ c) communication –]] Communication is the transfer of information from one animal to another and bird-song is an example of this. Male chaffinches use their song to prevent other males from imposing on their territory and attract females. Songs vary slightly between the males to allow individual identification and the song has individual characteristics that make it a chaffinch song. The combined use of the chaffinch’s song can drive away predators as the wide frequency range and repetition allows the source of the call to be located, encouraging other chaffinches to join the attack.

d)courtship and mate selection - Courtship is a behaviour in aim of attracting a mate. An example of this is male green back herons who establish a territory. When a female enters this territory a complex mating relationship begins and involves the following stages. o The birds fly in circles with the male trying to attack the female. o They then fly in undulating circles with bent necks. o The female heron perches and the male flies at her with slow deep wing flaps and his neck plumage displayed. o Then the male heron perches on the nest site and stretches his head and neck upwards, hopping from foot to foot. o The male stretches his neck downwards and snaps his bill. If after all this the male is successful, the female becomes enticed to the nest and coitus occurs.

Mate selection is choosing a partner of the opposite sex for reproduction. An example of this is the red deer. In autumn they try to take possession of the largest group of females they can and have coital relations with them while they are in oestrus. This can include defending the females against rival males by roaring or fighting. The fights are usually brief with the weaker male surrendering. If the male deer isn’t perceived to be aggressive enough, females tend to move to other males’ territories.

e) parental care - Parental care is a behaviour when parents of offspring teach more complex behaviour. Less offspring is produced when this type of parental care is received. Examples of animals that do this are primates, birds and marsupials.

5. Explain the need for quantitative data in studies of behaviour. Studies of animal behaviour usually begin with careful observations from researchers. These careful observations allow us to understand the natural history of a species and often lead to the formation of a hypothesis. From here we can test the hypothesis by collecting quantitative data. Then according to this data we can then establish confidence levels for the data by statistical tests.

6. State that sensory receptors act as energy transducers.All sensory receptors convert energy from the stimulus into the electrical energy of a nerve impulse. Animals behaviour is the response that the animals make to the environment and involves perception of stimuli from this environment. They then use sensory receptors and thus all energy transducers.

7. List the four classifications of human sensory receptors. Mechano-receptors  Chemo-receptors  Thermo-receptors  Photo-receptors

8. Describe each of the receptors listed in Q7 and provide an example of each type of receptor.' ''oMechano-receptors: Mechanical energy in the form of movement, sound pressure or gravity

 Hair cells in the inner ear send nerve impulses to the brain when sounds make them vibrate, different hair cells respond to different frequencies of sound.

oChemo-receptors: Chemical substances

 Nerve cells in the nostrils send impulses to the brain when specific chemical bind to receptors in their membranes

oThermo-receptors: Temperature

 Warm and cold nerve endings in the skin send messages to the brain or spinal cord at a rate determined by skin temperature.

oPhoto-receptors: Electromagnetic radiation, usually in the form of light

 Rods and cones in the eye send messages to the brain, when they absorb light

9. Draw the structure of the human eye (carefully labelled). Discuss the function of each structure labelled.

Aqueous humour- Clear watery fluid that fills the space between the back surface of the cornea and the front surface of the vitreous humour.

Blind spot- An obscuration of the visual field where light detecting photoreceptor cells are lacking.

Choroid – Provides oxygen and nourishment to the outer layers of the retina.

Cornea- The cornea refracts light and helps the eye focus.

Conjunctiva-'' A membrane that covers the white part of eye and the inside of the eyelids. It help lubricates the eye by producing mucus and tears.

Fovea- Responsible for sharp central vision and is involved in any activity that requires extreme visual detail.

Iris- The coloured part of the eye and are made of pigmented fibrovascular tissue (stroma)

Lens- Transparent, biconvex structure that helps the eye refract light to focus on the retina

Optic Nerve- The nerve that transmits visual information from the retina to the brain and it is also called cranial nerve II.

Pupil- Is the black circle in the middle of the iris and regulates the intensity of the light entering the eye.

Retina- Thin layer of neural cells that line the back of the eyeball Sclera- White outer coating of the eye and gives the eye it’s shape and helps protect the delicate inner parts.

Vitreous humour- Fills the space between the retina and lens of the eyeball and it provides a cushioned support for the rest of the eye.

10. Annotate diagrams of the human retina.

11. Distinguish between rods and cone cells. Rods and cone cells are both photoreceptors located in the retina of the eye. Rod cells are more sensitive to light then cone cells and therefore function better in the dim light. However cone cells function better in brighter light as rod cells become bleached in this light. Rod cells absorb all wavelengths of visible light and give monochrome vision. Cone cells are divided into three types and are sensitive to red, green and blue light and produce colour vision.

Groups of up to two hundred rod cells pass impulses to the same sensory neuron of the optic nerve. Cone cells differ as they have their own individual neurons through which messages can be sent to the brain. This results in the cone cells giving greater visual acuity than rod cells. Rod cells give wider fields of vision as they are more widely dispersed through the retina.

12. Outline how visual stimuli are processed in the retina and the visual cortex. In the retina, bipolar cells combine the impulses from rod or cone cells and pass them on to sensory neurones of the optic nerve (ganglion cells). Left and right optic nerves meet at a structure called the optic chasmia and it is here where all the neurones carry impulses from the half of the retina nearest to the nose, cross over to the opposite optic nerve.

This results in the left optic nerve carrying information from the right half of the field of vision and vice versa. Beyond the optic chasmia, the neurones continue to the thalamus where the information is processed. It is then carried to the visual cortex at the back of the brain where more processing leads to the formation of images.