INTRODUCTION TO PSYCHOBIOLOGY

What is Psychobiology?

“[it] is the study of the neural basis of behaviour, but this colourless definition does not do justice to the wealth of scientific expertise that it incorporates.”

Sahagal (1993)

Psychobiology by Any Other Name

• Biopsychology• Behavioural neuroscience• Behavioural biology

Subdivisions of Psychobiology

• Physiological psychology• Psychopharmacology

• Neuropsychology• Psychophysiology• Comparative psychology• Cognitive neuroscience• Behavioural genetics

Human vs. Animal Research

Human:• Relatively cheap• Insight• Extrapolation not

required

Animal:• Expensive• Controlled

environment• Permit procedures that

are regarding as unethical in humans

• Behaviour less complex

• Requires extrapolation

Animals (Scientific Procedures) Act (1986)

• License– Institute– Project– Person

Validity of Animal Models of Behaviour

Willner (1991) stated that, ‘models are tools. As such, they have no intrinsic value; the value of a tool derives entirely from the work one can do with it. Conclusions arising from the use of a simulation of abnormal behaviour are essentially hypotheses that must eventually be tested against the clinical state. An assessment of the validity of a simulation gives no more than an indication of the degree of confidence that we can place in the hypothesis arising from its use.’

Three Facets of Validity

Taken from the world of psychometric testing, an animal model should exhibit:• Predictive validity• Face validity• Construct validity

Willner (1984)

Genetics

• Darwin• Mendel• Crick and Watson

Evolution

• Darwin• Survival of the fittest

– evidence based

• Descent through modification

Mendelian Genetics

• Mendel – a monk– Pea traits

• Can be applied to humans

– Dominant traits– Recessive traits

Seed Colour

Chromosomes

• 23 matched pairs• Genetic material passed on to offspring

– Cellular division• Mitosis• Meiosis

Meiosis

Mitosis

DNA

• Each chromosome contains a double stranded molecule– deoxyribonucleic acid (DNA)

• Each strand of DNA is a sequence of nucleotide bases attached to a chain of phosphate and deoxyribose

DNA

Replication

• Replication is critical for mitosis• The DNA strands unwind• The exposed nucleotide bases attract

complementary bases form the fluid of the nucleus

• Two DNA molecules that are identical are created– Mutations of this process can occur

Replication

Protein Synthesis

• The genetic code produces amino acids

– Making protein and polypeptides

– Transcription

Transcription

• Code taken outside nucleus– mRNA

– RNA is like DNA

• mRNA attaches itself to ribosomes in the cell body

• The ribosomes move along the strand of mRNA and read the code

Transcription