The relationship between the brain and behaviour
Techniques used to study the brain in relation to behaviour: Study one technique used to understand the brain and behaviour.The choice of techniques used to correlate the brain with behaviour is based on a variety of factors including opportunity, available technology and cost. There are strengths and limitations to the different techniques used to study the effects of the brain on behaviour; however, the contribution of different techniques has helped to understand behaviour. Examples of techniques include fMRI, MRI, EEG, CAT, and PET.
Localization of function: Study one example of localization of function.Localization of function is the theory that certain parts of the brain correspond to certain functions and reflects the idea that behaviour, emotion, and/ or thoughts originate in specific regions of the brain.
Neuroplasticity: Study one example of neuroplasticity.The development of neural networks through repetition and neural pruning is both genetic and subject to environmental influences. Neural networks can change developmentally, over time or after injury. 
Study all of the following. • Neural network • Neural pruning • Neuron
Neurotransmitters and their effects on behaviour: Study one neurotransmitter and its effect on behaviour.Neurotransmitters mediate the events at the synapse and are affected by agonists that amplify their effects and antagonists that reduce their effects. Neurons working together can produce a large variety of effects, resulting in a complex repertoire of behaviours. As a result, any claim of cause and effect should be treated with caution. 
Study all of the following. • Synapse (how these relate to excitatory and inhibitory neurotransmitters) • Agonist • Antagonist
Hormones and pheromones and their effects on behaviour
Hormones and their effects on behaviour: Study one hormone and its effect on behaviour.Hormones are chemicals released by specific glands in the body to regulate medium- and longterm changes in the body. Some hormones, like adrenaline, also act as a neurotransmitter and can produce instantaneous effects on mood and attention.
Pheromones and their effects on behaviour: Study one pheromone and its effect on behaviour.Arguments for and against the influence of pheromones on human behaviour
The relationship between genetics and behaviour
Genes and their effects on behaviour: Study one gene and its link to behaviour.Genes are made of DNA providing the blueprint for the structure and function of the human body, including behaviour.
Genetic similarity: Study genetic similarity (twins, siblings, parents, adopted children) for one behaviour.Genetic similarity is referred to as relatedness. The greater the genetic similarities between two individuals or a group of individuals the higher the degree of relatedness. 
Study the following. 
• Twin and kinship studies
Evolutionary explanation for behaviour: Study one example of an evolutionary explanation for behaviour.Genes are constantly being switched on and off by signals from inside and outside the body. Internal signals include the presence of hormones or other chemicals, or indeed other genes. Hormones are frequently produced as a result of environmental events and work by altering gene expression. There are countless environmental events that also affect gene expression. The signal activates special proteins that can promote or block the expression of a gene. Sometimes genes are permanently switched off through methylation of the DNA molecule as part of the developmental process. This effect on genes is sometimes referred to as epigenetics as there is no alteration in the actual structure of the DNA. Mutations occur when there is an actual alteration of the DNA.
HL Extension
The role of animal research in understanding human behaviourFor all three topics in the biological approach, and with reference to research studies, HL students should study the following:
• The value of animal models in research to provide insight into human behaviour 
• Ethical considerations in animal research