Biological Bases of Behaviour. Lecture 1: Biology & Behaviour.

1. Biological Bases of Behaviour. Lecture 1: Biology & Behaviour.

2. Learning Outcomes. • At the end of this lecture you should be able to: • 1. Explain 3 approaches used to answer causal questions concerning biology and behaviour. • 2. Outline the usefulness of the 'comparative approach'. • 3. Explain what is meant by the 'mind-body problem'. • 4. Describe Tinbergen's '4 why's'.

3. What is Biological Psychology? • According to Kalat (2001) "Biological psychology is the study of the physiological, evolutionary, and developmental mechanisms of behaviour and experience". • The biological psychologist explains behaviour in physiological terms, because physiological mechanisms can inform us about psychological processes. • Carlson (1994) provides the following example: • Brain damage produces language impairments, if such damage produced exactly the same impairment this would tell us little. • However, damage to specific regions of the brain leads to particular deficits in language use, the precise nature of these impairments tells us how such abilities are organised.

4. Problems of Correlating Behaviour with Physiology • Identical behaviours may occur for different reasons. Carlson (1994) cites the following example: • Mice build nests under 2 conditions: • 1. When the temperature is low. • 2. When the animal is pregnant. • A non-pregnant mouse will not build a nest if it is warm, but a pregnant mouse will build a nest regardless of the temperature. • Not surprisingly, these behaviours are initiated by different physiological mechanisms - one hormonally based, and the other based on changes in the sensation of temperature.

5. The ‘Causal Approach’. • Toates (2001): the key element of biological psychology is that behaviour is caused by identifiable events within the nervous system. • This demonstrates a 'causal approach' of the form 'if X then Y'. E.g: • 1. Does the regular use of ecstasy produce long-term impairments in memory? • 2. Do mobile phones affect brain function? • 3. Is the hormone testosterone responsible for male aggressive behaviours? • 4. Does alcohol impair driving performance? • 5. Is homosexuality genetic? • 6. Can the effects of brain damage be reversed?

6. The ‘3 Approaches’. • According to Rosenzweig et al., (1996) to answer the previous questions we can use 3 approaches: • 1. Somatic Intervention: The investigator can alter a structure or function of the brain or body in order to see how a particular change alters behaviour. Examples: • A hormone is administered to some animals but not to others, various behaviours are then compared. • One region of the brain is electrically stimulated and behavioural effects are observed. • A group of people take ecstasy and another group take a placebo, their subsequent cognitive performance is then compared.

7. 2. Behavioural Intervention. • This is the opposite approach. Here the behaviour of an individual is altered, and any changes in neural structure or function are noted. Examples: • Exposing an individual to a visual stimulus provokes changes in electrical activity and blood flow in certain brain regions. • Ecstasy administration leads to observable changes in the concentration of certain neurotransmitters. • Learning produces alterations in the number and connectivity of certain neurons in the brain.

8. 3. Correlation. • This approach consists of finding the extent to which a given bodily measure varies with a given behavioural measure. Examples: • Are people with bigger brains more intelligent? • Do regular users of ecstasy experience cognitive/behavioural problems? • Is the severity of schizophrenia correlated with the magnitude of changes in brain structure?

9. However.. • 1. We must remember that the nervous system does not exist in isolation - it receives input from the external world and is influenced by bodily events outside of the nervous system (e.g. temperature). These can alter behaviour. • 2. Behaviour also has consequences for the environment, and can thus change subsequent behaviour. • 3. There are also many methodological and ethical issues to consider. • 4. Correlations are not proof of causality.

10. The Comparative Approach. • Most of what we know about how the brain and nervous system functions stems from animal research. • What can the study of animals tell us about the human brain and behaviour? • Kalat (2001) argues that animals are studied for 4 reasons: • 1. Animal and human brains are structurally and functionally similar. • 2. Knowledge of animal physiology and behaviour can be used to improve animal welfare and preserve endangered species. • 3. Understanding our near relatives (e.g. chimpanzees) can shed light on human evolution. • 4. Some medical and psychological experiments cannot use human participants due to ethical and legal problems.

11. Vertebrate Brains. cerebrum cerebellum cerebrum cerebellum Brain stem Brain stem cerebrum cerebrum cerebellum Brain stem cerebellum Brain stem Kalat, 2001, p21

12. Brain, Mind, and Behaviour. • Most people have no difficulty in explaining animal behaviours in terms of genes, hormones, neural activity etc. • Many are uncomfortable using such explanations for complex human behaviours such as love, religious experience, morality, aggression, consciousness etc. • Biological psychologists tend to be 'deterministic' i.e. they believe than we can identify physical causes for all observed behaviours. • The extreme form of this is known as 'reductionism' in that very complex processes (e.g. consciousness) can be reduced to events at a lower level (i.e. the actions in specific neurons).

13. Problems with Reductionism. • It may not always be possible to employ this approach, Toates (2001) points out that the assumption that the mind needs a physical body does not necessarily mean that the laws applicable to mental states can be reduced to those of biological structure. • He uses the argument of liquid water (the product of combining oxygen with hydrogen). • The final product does not resemble either of the original components, and cannot be reduced to the sum of the properties of each. • The property of liquid water only emerges from their combination.

14. Mind/Body Problem • Many philosophers have addressed the 'mind-body problem’ by asking 'How are the mind and brain related'? • Some argued that the mind and brain are separate entities - this is called ‘dualism’, the most famous exponent being Descartes who stated “cogito ergo sum” - ‘I think therefore I am’ • He argued that while animals were simply 'machines' lacking a higher form of consciousness, humans possessed souls that controlled the body via the pineal gland in the brain. • BUT, if the mind is not part of the material world then how can it exert a force that can influence physical matter? • Many people still hold dualist views - e.g. the survival of the mind after the physical death of the body.

15. Monism. • Most philosophers and neuroscientists now reject dualism in favour of 'monism'. • This argues for the singularity of mind and brain; that human thoughts, feelings, experiences, etc are simply the product of complex neurological / neurochemical / neuroelectrical / neurohormonal activity. • Many human behaviours can be explained in such terms, but others remain mysterious. • The fundamental question of why humans possess self-consciousness and what kinds of physical activity is necessary to produce a conscious being remain unanswered.

16. Can We Explain Consciousness? • Chalmers (1995) proposed that consciousness is a fundamental property of living matter which cannot be reduced to specific physiological events. • Dennett (1991) argued that one day we will be able to explain consciousness at a physiological level. • Are animals conscious? If so should they be treated the same as humans? • Are brain-damaged humans conscious? If not, then are they human? • Sperry (1987) developed the notion of 'emergent interactionism' : • 1. Consciousness is an emergent property of millions of neurons. • 2. The activity of individual neurons can only be understood in terms of their participation in the whole system.

17. Biological Explanations of Behaviour. • These fall into 4 categories originally prposed by Tinbergen (1951) and are thusreferred to as 'Tinbergen's 4 whys': • 1. Physiological. • This explanation relates a specific behaviour to the activity of certain regions or structures of the brain, or other organs. It covers cellular, chemical, and hormonal influences. • E.g the ability to learn information, memorise it, and then recall it appears to be governed by the hippocampus and its connections to other brain regions. • Damage to this area of the brain severely impairs the ability to transfer short-term memories into long-term ones. • Individuals with hippocampal damage can only retain information over a short delay.

18. Biological Explanations of Behaviour. • 2. Ontogenetic (developmental): ‘Ontogeny’ is the process whereby an individual changes and develops through their life span. • This type of explanation tries to explain how a certain behaviour develops throughout life. • It covers genetic and environmental (nature versus nurture) influences and their interactions. • E.g intelligence is a complex set of skills that are partially determined be genetic factors, but the expression of these genes is also determined by the environment i.e. nutrition, stimulation etc.

19. Biological Explanations of Behaviour. • 3. Evolutionary: This examines a structure or behaviour in terms of the evolutionary history of the species ('phylogeny'). • Certain physical and behavioural features have emerged over evolutionary time because they have solved certain problems in a way that have improved the reproductive capability of the individual showing that feature (they are 'adaptive'). • E.g when certain species of animals are threatened, they respond by erecting their body hairs making them look bigger and more intimidating (piloerection). • When humans are frightened they also erect their body hairs, but as humans have lost most of their body hair this results in the sensation known as goose bumps.

20. Biological Explanations of Behaviour. • 4. Functional: This tries to answer how a particular behaviour has evolved - i.e. what is its purpose, what genetic/survival advantage might a particular behaviour have for an individual? • Darwin's theory of 'natural selection' emphasised that all of the physical and behavioural characteristics of an organism have (or had) a functional significance. • E.g some species can change the colour of their skin to match their surroundings, the functional significance of this ability to hide from predators is obvious. • We thus need to understand the natural history of a species, so that the behaviours can be seen in the correct context. • The evolutionary and functional explanations are often difficult to separate and are often discussed together.

21. Example: Birdsong • Catchpole & Slater (1995) illustrated these different types of explanations by considering birdsong: • Physiological explanation: Birdsong depends upon 2 areas of the brain - the caudal nucleus of the hyperstriatum ventrale and the robust nucleus of the archistriatum. • These areas are larger in songbirds than in non-singing species, in males than females, and in breeding males than immature males. • The size of these regions depends upon the hormone testosterone, which is secreted in higher levels in males of a breeding age, at certain times of the year.

22. song Spring Autumn Testosterone Level and Size of the Song Production Areas. Testosterone level Size of song-production area

23. Ontogenetic Explanation. • In certain bird species, a young male learns a song by listening to and copying adult males. • Development of his singing ability requires the genetic program that prepares him to learn the song and the actual experience of hearing a song during a sensitive period in early life. • Interestingly, although the song is learnt at a young age the individual will not get a chance to practice it until later in life. • Birds that do not sing (e.g. pigeons) do not have a sensitive period; they make the noises throughout their development.

24. Time of first vocalisation Birth Sensitive period Time Bird must hear song here Sensitive Periods and Singing.

25. Evolutionary Explananation. • Closely-related bird species have similar vocalisations, suggesting that they share a common ancestor. • We can investigate this by analysing changes between the evolutionary relationships ('taxonomy') of different bird species. • E.g although Baird's sandpiper looks physically like other sandpipers (and was originally named as one), its song is more like that of the Dunlin. • Genetic analysis revealed that it is indeed more closely related to the Dunlin.

26. Functional Explanation. • We have already seen that: • Genes + appropriate environment = song. • This combination must have some adaptive benefit to the individual. The following have been proposed: • 1. Singing songs is a feature of mate value - males sing during the breeding season to attract females. • Only males with the best singing voices, or who can sing the most complex songs, will be selected as mates and pass their singing ability to their offspring. • 2. Singing a song helps to establish a territory, it also gives honest signals about the age and size of the singer.

27. References and Bibliography. • Carlson, N.R. (1994). Physiology of Behaviour. Allyn & Bacon. • Catchpole, C.K., & Slater, P.J.B. (1995). Bird Song: Biological Themes and Variations. Cambridge University Press. • Chalmers, D.J. (1995). Facing up to the problem of consciousness. Journal of Consciousness Studies, 2: 200-219. • Dennett, D.C. (1991). Consciousness Explained. Little Brown & Co. • Kalat, J.W. (2001). Biological Psychology, 7th edition, Wadsworth. • Rosenzweig, M.R., Leiman, A.L., & Breedlove, S.M. (1996). Biological Psychology. Sinauer Associates. • Sperry, R.W. (1987). Structure and significance of the consciousness revolution. Journal of Mind and Behaviour, 8: 37-66. • Tinbergen, N. (1951). The Study of Instinct, Oxford University Press. • Toates, F. (2001). Biological Psychology: An Integrative Approach. Prentice Hall.