Biological Psychology

Localisation of Function (LOF)

Localisation of function is the theory that specific brain areas control specific behaviours.
It assumes a biological basis for behaviour and is supported by brain imaging techniques like MRI, fMRI, and PET scans.

The amygdala plays a key role in:

• Emotional processing (esp. fear, anxiety, jealousy)

• Survival instincts (triggers fight or flight)

• Emotional memory (stores vivid emotional events)

• Social interaction (recognising emotional expressions)

• Emotion regulation (balancing emotional responses)

Localisation of Function (LOF) - Feinstein et al. (SM)

Aim:
To investigate the role of the amygdala in the experience and recognition of fear.

Procedure:

• SM was a woman with bilateral amygdala damage due to a rare genetic condition.

• Researchers exposed her to fear-inducing stimuli (e.g. snakes, haunted house, scary films).

• Her reactions were recorded through self-reports and questionnaires.

Results:

• SM showed no emotional response of fear, even in highly threatening situations.

• However, she did show some physical signs (e.g. increased heart rate).

Conclusion:
The amygdala is essential for the experience and recognition of fear.
Damage to it results in an inability to feel or process fear properly.

Neurotransmission

Neurotransmitters are chemical messengers that travel across the synaptic cleft from the presynaptic neuron to the post-synaptic neuron, triggered by an electrochemical action potential.

• An action potential begins at the dendrites, travels down the axon, and releases neurotransmitters from synaptic vesicles at the terminal buttons.

• Excitatory synapses increase the chance of a post-synaptic neuron firing.

• Inhibitory synapses decrease that chance.

Key neurotransmitters:

• Serotonin: can be both excitatory and inhibitory, but is mostly inhibitory. Regulates mood, sleep, and body temperature. Linked to depression and anxiety when levels are low.

• Glutamate: A major excitatory neurotransmitter important for learning and memory. Too much can cause neurodegeneration (e.g. Alzheimer’s, Huntington’s).

Neurotransmission - Crockett et al. (2010)

Aim:
To investigate how serotonin affects prosocial behaviour, especially decisions involving personal harm.

Method:

• 30 healthy participants (mean age: 26), repeated measures design.

• Condition 1: Given citalopram (SSRI, increases serotonin).

• Condition 2: Given a placebo.

• Participants responded to moral dilemmas:

  • Personal (e.g. pushing a man off a bridge to save five lives)

  • Impersonal (e.g. flipping a switch to divert a train)

Findings:

• Citalopram had no effect on impersonal decisions.

• Participants were less likely to choose personal harm (e.g. push the man) when on citalopram.

Conclusion:
Serotonin increases prosocial behaviour by reducing the acceptability of personal harm.
It influences moral decision-making in emotionally intense situations.

Neurotransmission - Feder et al.

Aim:
To test whether ketamine is effective in reducing symptoms of PTSD and depression.

Method:

• Participants diagnosed with PTSD received ketamine or another antidepressant (repeated measures, 2 weeks apart).

• Symptoms were measured before and after treatment using questionnaires.

• Study used randomised order and double-blind procedure to prevent bias.

Findings:

• Ketamine significantly reduced symptoms of PTSD more than the other antidepressant.

Conclusion:
Ketamine is effective for treating PTSD and depression.
It works as a glutamate antagonist, suggesting blocking glutamate receptors may help manage these disorders.

Inhibitory Neurotransmission

• During neurotransmission, vesicles release neurotransmitters into the synapse, where they bind to receptors on the post-synaptic neuron.

• Inhibitory neurotransmitters (like serotonin) decrease the likelihood of a post-synaptic neuron firing.

• Serotonin regulates mood, sleep, and body temperature, and is linked to depression and anxiety when levels are low or irregular.

Inhibitory Neurotransmission - Crockett et al. (2010)

Aim:
To investigate how serotonin affects prosocial behaviour, especially decisions involving personal harm.

Method:

30 healthy participants (mean age: 26), repeated measures design.

Condition 1: Given citalopram (SSRI, increases serotonin).

Condition 2: Given a placebo.

Participants responded to moral dilemmas:

Personal (e.g. pushing a man off a bridge to save five lives)

Impersonal (e.g. flipping a switch to divert a train)

Findings:

Citalopram had no effect on impersonal decisions.

Participants were less likely to choose personal harm (e.g. push the man) when on citalopram.

Conclusion:
Serotonin increases prosocial behaviour by reducing the acceptability of personal harm.
It influences moral decision-making in emotionally intense situations.

Excitatory Neurotransmission

• In neurotransmission, vesicles release neurotransmitters into the synapse, where they bind to receptors on the post-synaptic neuron, triggering a response.

• Glutamate is a major excitatory neurotransmitter.

• It plays a key role in learning, memory, digestive health, and immune system function.

Excitatory Neurotransmission - Feder et al.

Aim:
To test whether ketamine is effective in reducing symptoms of PTSD and depression.

Method:

• Participants diagnosed with PTSD received ketamine or another antidepressant (repeated measures, 2 weeks apart).

• Symptoms were measured before and after treatment using questionnaires.

• Study used randomised order and double-blind procedure to prevent bias.

Findings:

• Ketamine significantly reduced symptoms of PTSD more than the other antidepressant.

Conclusion:
Ketamine is effective for treating PTSD and depression.
It works as a glutamate antagonist, suggesting blocking glutamate receptors may help manage these disorders.

Agonist Transmission

• An agonist is a molecule that binds to a synaptic receptor and activates it, mimicking or enhancing a neurotransmitter’s effect.

• Drugs can act as agonists.

• For example, SSRIs (Selective Serotonin Reuptake Inhibitors) are serotonin agonists:

  • They increase serotonin levels by blocking reuptake into the presynaptic neuron.

  • Commonly used to treat depression, PTSD, OCD, and anxiety disorders.

Agonist Transmission - Crockett et al. (2010)

Aim:
To investigate how serotonin affects prosocial behaviour, especially decisions involving personal harm.

Method:

• 30 healthy participants (mean age: 26), repeated measures design.

• Condition 1: Given citalopram (SSRI, increases serotonin).

• Condition 2: Given a placebo.

• Participants responded to moral dilemmas:

  • Personal (e.g. pushing a man off a bridge to save five lives)

  • Impersonal (e.g. flipping a switch to divert a train)

Findings:

• Citalopram had no effect on impersonal decisions.

• Participants were less likely to choose personal harm (e.g. push the man) when on citalopram.

Conclusion:
Serotonin increases prosocial behaviour by reducing the acceptability of personal harm.
It influences moral decision-making in emotionally intense situations.

Antagonist Transmission

• An antagonist is a molecule that binds to a receptor but blocks or reduces the effect of a neurotransmitter.

• Drugs can act as antagonists by inhibiting normal neurotransmitter action.

• For example, ecopipam is a dopamine antagonist.

• Glutamate, a major excitatory neurotransmitter, is also affected by some antagonists — blocking its action may help with disorders like PTSD and depression.

Antagonist Transmission - Feder et al.

Aim:
To test whether ketamine is effective in reducing symptoms of PTSD and depression.

Method:

• Participants diagnosed with PTSD received ketamine or another antidepressant (repeated measures, 2 weeks apart).

• Symptoms were measured before and after treatment using questionnaires.

• Study used randomised order and double-blind procedure to prevent bias.

Findings:

• Ketamine significantly reduced symptoms of PTSD more than the other antidepressant.

Conclusion:
Ketamine is effective for treating PTSD and depression.
It works as a glutamate antagonist, suggesting blocking glutamate receptors may help manage these disorders.

Neuroplasticity

Neuroplasticity is the brain’s ability to adapt and change due to learning, experience, or injury. It forms or strengthens neural connections to help the brain "rewire" itself.

• Structural plasticity: Physical changes in the brain (e.g. more grey matter or synapses)

• Functional plasticity: Brain shifts functions from damaged areas to undamaged ones

It’s supported by:

• Learning

• Recovery from trauma

• Repeated use of neural pathways (LTP)

Neuroplasticity - Draganski et al. (2004)

Aim:
To investigate whether the human brain can change its structure in response to learning new skills.

Method:

• Volunteers with no prior juggling experience were split into jugglers and non-jugglers.

• All had a baseline MRI scan.

• Jugglers practiced a 3-ball routine for 3 months, then had a second scan.

• They stopped juggling for another 3 months, then had a third scan.

Findings:

• No initial differences in brain structure.

• After practice, jugglers showed increased grey matter in the mid-temporal area (linked to movement and visual memory).

• After stopping, grey matter decreased, but not back to the original level.

Conclusion:
Learning new skills changes brain structure, supporting neuroplasticity.
Changes can reduce when the skill isn’t used but may not disappear completely.

Synaptic Pruning

• Neural networks: Groups of interconnected neurons that combine to produce specific neurological functions or processes.

• Formation: Neural networks form when new behaviors are learned. With time and practice, these pathways strengthen and become more embedded.

• Decline of unused networks: Neural pathways that are not frequently used may stop functioning over time.

• Synaptic pruning: The process by which the brain eliminates synapses and neurons that are no longer needed or used, improving efficiency.

• Neuroplasticity: Synaptic pruning is a key aspect of neuroplasticity, the brain’s ability to reorganize itself by eliminating outdated neural pathways.

Synaptic Pruning - Draganski et al. (2004)

Aim:
To investigate whether the human brain can change its structure in response to learning new skills.

Method:

• Volunteers with no prior juggling experience were split into jugglers and non-jugglers.

• All had a baseline MRI scan.

• Jugglers practiced a 3-ball routine for 3 months, then had a second scan.

• They stopped juggling for another 3 months, then had a third scan.

Findings:

• No initial differences in brain structure.

• After practice, jugglers showed increased grey matter in the mid-temporal area (linked to movement and visual memory).

• After stopping, grey matter decreased, but not back to the original level.

Conclusion:
Learning new skills changes brain structure, supporting neuroplasticity.
Changes can reduce when the skill isn’t used but may not disappear completely.

Neural Networks

• Neural networks are interconnected neurons that work together to produce specific functions. These networks form when a new skill or behavior is learned, strengthening the connections between neurons with practice.

• Neuroplasticity allows neural networks to adapt and reorganize over time. The more a behavior is practiced, the more robust and permanent the neural pathways become.

• Unused networks are pruned, meaning connections that aren't regularly activated are weakened and eventually eliminated, allowing the brain to prioritize essential networks.

• This process helps the brain become more efficient, refining cognitive and motor functions by maintaining only the most relevant neural connections.

Neural Networks - Draganski et al. (2004)

Aim:
To investigate whether the human brain can change its structure in response to learning new skills.

Method:

• Volunteers with no prior juggling experience were split into jugglers and non-jugglers.

• All had a baseline MRI scan.

• Jugglers practiced a 3-ball routine for 3 months, then had a second scan.

• They stopped juggling for another 3 months, then had a third scan.

Findings:

• No initial differences in brain structure.

• After practice, jugglers showed increased grey matter in the mid-temporal area (linked to movement and visual memory).

• After stopping, grey matter decreased, but not back to the original level.

Conclusion:
Learning new skills changes brain structure, supporting neuroplasticity.
Changes can reduce when the skill isn’t used but may not disappear completely.

Hormones

• Hormones are chemicals secreted by endocrine glands into the bloodstream to regulate body functions. The pituitary gland controls hormone secretion.

• Hormones act slowly, and their effects can take years to develop, unlike neurotransmitters which act quickly.

• Testosterone is the main male sex hormone, regulating fertility, muscle mass, fat distribution, and red blood cell production. Its levels rise during puberty, leading to the development of secondary sexual characteristics like facial hair and a deeper voice.

Hormones - Zak (2009)

Aim: To investigate the role of testosterone in male generosity and aggression.

Methods:

• A double-blind experiment where half of participants received Androgel (testosterone) and half a placebo.

• Testosterone levels were measured via blood samples.

• Participants played the Ultimatum Game, where a proposer must decide how to split a sum of money with another player; both must agree for the money to be received.

Results:

• Men who received Androgel were 27% less generous toward strangers compared to those on the placebo.

• Men with elevated testosterone were more likely to use their money to punish those who were ungenerous toward them.

Conclusions:

• Men with higher testosterone levels may display less prosocial or even antisocial behavior compared to those with lower levels.

Pheromones

• Pheromones are chemicals secreted by glands to affect others outside the body, in contrast to hormones, which are released internally into the bloodstream by endocrine glands.

• The first research on pheromones was conducted on animals, with strong evidence showing that animals use pheromones for mate selection and territoriality.

• Pheromones communicate signals to members of the same species.

Pheromones - Cutler Et Al (1998)

Aim: To investigate whether synthesized male pheromones increase sociosexual behavior.

Methods:

• A field experiment with male participants who used their own aftershave at least 3 times a week for 2 weeks, tracking their sociosexual behaviors (affection, sleeping next to someone, sex, dates, masturbation) via daily reports.

• After 2 weeks, their aftershave was altered: one group received ethanol only, and the other received ethanol + synthesized male pheromone.

• The altered aftershave was used for 6 weeks, and daily reports continued.

• IV: Presence of synthesized male pheromone.

• DV: Changes in sociosexual behaviors.

Findings:

• The pheromone group showed an increase in the first 4 behaviors (affection, sleeping next to someone, sex, and formal/informal dates), but no change was observed in masturbation.

Conclusions:

• Applying synthetic pheromone increased sociosexual behavior, especially in behaviors where a female partner’s willingness was involved, suggesting it made males more attractive to females rather than simply increasing libido.

Genetics and Behavior

• A gene is the basic unit of heredity in living organisms, carrying the information that influences traits.

• The phenotype is the expression of the genotype, representing physical traits and behaviors.

• While no single gene codes for a specific behavior, some genes may influence particular behaviors or conditions.

• Mutations in the 5-HTT gene (which affects serotonin transport) have been linked to depression and anxiety.

• The 5-HTT gene has long and short allele variants, and variations in these alleles may contribute to disorders like depression.

Genetics and Behavior - Caspi et al. (2003)

Aim: To investigate whether the short allele of the 5-HTT gene, in combination with stressful life events, increases the risk of depression.

Methods:

• A sample of 847 New Zealand 26-year-olds who had been assessed for mental health since age 21.

• Participants were divided into three groups based on their 5-HTT alleles:

  • Group 1: Two short alleles.

  • Group 2: One short and one long allele.

  • Group 3: Two long alleles.

• Participants filled out a "Stressful Life Events" questionnaire covering stressors like financial, employment, health, and relationship issues between ages 21 and 26. They were also assessed for depression.

Results:

• Individuals with short alleles showed more symptoms of depression in response to stressful events.

• The effect was strongest after experiencing three or more stressful life events.

• Inheriting the short allele does not cause depression on its own; however, when combined with stressful life events, the likelihood of developing depression increases.

• People with the short allele were more likely to experience suicidal thoughts after stressful events, and those with two short alleles were most likely to report severe depression and suicidal thoughts or attempts after more than three stressful events.

Conclusions:

• There is an interaction between genetic factors and stressful life events in the development of depression.

• Both nature (genetic predisposition) and nurture (environmental factors like stress) work together to increase the likelihood of depression.

Genetic Similarity (Relatedness)

• Researchers study genetic similarity to understand the role of genes in behavior, with greater genetic similarity suggesting a stronger genetic influence.

• However, scientists can only observe phenotypes (physical traits) rather than genotypes (the underlying genetic makeup), limiting the study to observable behaviors.

• Dizygotic (DZ) twins result from two separate eggs fertilized by two separate sperm, sharing 50% of their DNA.

• Schizophrenia is a chronic and severe mental illness affecting behavior, thoughts, and emotions. Common symptoms include:

  • Delusions: False beliefs.

  • Hallucinations and illusions: Perception of things that aren't present.

  • Disordered thinking.

• Schizophrenia requires lifelong treatment, even when symptoms have subsided, including medications and psychosocial therapy to manage the condition.

Genetic Similarity (Relatedness) - Gottesman and Shields (1966)

Aim:
To investigate the extent to which schizophrenia (SZ) is influenced by genetics.

Method:
Used secondary data from hospital records. From around 45,000 psychiatric patients, 56 same-sex twin pairs (aged 19–64) were selected — 392 twins in total. Researchers compared concordance rates of SZ and related psychoses between monozygotic (MZ) and dizygotic (DZ) twins.

Findings:

• 42% concordance for SZ in MZ twins vs. 9% in DZ twins.

• 54% of MZ twins shared related psychotic disorders vs. 18% in DZ twins.

• For severe SZ: 75% concordance in MZ vs. 45% in DZ.

Conclusion:
SZ is more likely to occur in both twins if they are genetically identical, supporting a genetic basis. However, not 100% concordance → supports the diathesis-stress model (genetic predisposition + environmental triggers). Their results were consistent with 11 other twin studies.

Kinship Studies

• Genetic similarity measures how genetically related individuals are.

• Monozygotic (MZ) twins share 100% of their DNA, as they come from the same fertilized egg.

• Dizygotic (DZ) twins share 50% of their DNA, from two separate eggs and sperm.

• Kinship studies examine patterns of behavior across multiple generations to determine whether behaviors are inherited.

• Twins are especially useful, as they act as control groups for each other when investigating genetic vs. environmental influences.

• Genetic similarity helps identify whether a behavior is due to biological (nature) or environmental (nurture) factors.

Key characteristics of kinship studies:

• Look at the frequency of behaviors across generations

• Examine the frequency within a single generation

• Often longitudinal (conducted over time)

Kinship Studies - Weissman et al. (2005)

Aim:
To investigate the genetic transmission of Major Depressive Disorder (MDD) across three generations.

Method:
Longitudinal family study over 20 years. Original sample of parents (with and without MDD) and their children were interviewed four times. When the children became adults and had their own kids (grandchildren), those children were evaluated by a psychiatrist and psychologist for psychiatric symptoms.

Findings:

• Grandchildren had the highest rates of psychiatric disorders when both their parent and grandparent had MDD.

• If only the parent had MDD (but grandparent did not), there was no significant increase in risk.

• Severity of the parent's depression was positively linked to the child’s risk.

Conclusion:
There is a genetic link in the development of depression. MDD in both parent and grandparent significantly increases the likelihood of psychopathology in grandchildren.

Twin Studies

Definition:
Twin studies are used to examine the influence of genetics on behavior by comparing monozygotic (MZ) twins, who share 100% of their DNA, and dizygotic (DZ) twins, who share about 50%.

Key Concepts:

• Concordance rate: The likelihood that if one twin has a specific trait, the other will too.

• A higher concordance rate in MZ twins compared to DZ twins suggests a genetic basis for the trait.

• Genes are segments of DNA inherited from parents that contribute to the development of behavioral characteristics.

Twin Studies - Gottesman and Shields (1966)

Aim:
To investigate the extent to which schizophrenia (SZ) is influenced by genetics.

Method:
Used secondary data from hospital records. From around 45,000 psychiatric patients, 56 same-sex twin pairs (aged 19–64) were selected — 392 twins in total. Researchers compared concordance rates of SZ and related psychoses between monozygotic (MZ) and dizygotic (DZ) twins.

Findings:

• 42% concordance for SZ in MZ twins vs. 9% in DZ twins.

• 54% of MZ twins shared related psychotic disorders vs. 18% in DZ twins.

• For severe SZ: 75% concordance in MZ vs. 45% in DZ.

Conclusion:
SZ is more likely to occur in both twins if they are genetically identical, supporting a genetic basis. However, not 100% concordance → supports the diathesis-stress model (genetic predisposition + environmental triggers). Their results were consistent with 11 other twin studies.

Evolution and behaviour

Definition:
Explains human behavior through Darwin’s theory of evolution — behaviors are seen as adaptations shaped by natural selection.

Key Concepts:

• Evolution is the process by which species change over time through genetic variation, adaptation, and selection.

• Natural selection favors traits or behaviors that improve survival and reproduction, passing them to future generations.

• Genetic mutation introduces new traits into a species’ gene pool.

• Evolutionary fitness refers to an organism’s ability to survive, reproduce, and pass on its genes.

• Emotions are adaptive responses — strong feelings with physical and expressive components that help individuals respond to environmental challenges.

Evolution and behaviour - Curtis, Aunger, and Rabie (2004)

Aim:
To investigate whether disgust evolved as a protective response to disease risk.

Method:
Survey of 40,000 participants from 165 countries, hosted on the BBC Science website. Participants rated 20 photographs for disgust on a 1-5 scale. They also answered demographic questions and indicated who they would be least likely to share a toothbrush with.

Findings:

• Disease-related images were rated as more disgusting than non-disease-related ones.

• The pattern held across various cultures.

• Females found disease-salient images more disgusting than males.

• Older participants showed a decline in sensitivity to disease-related stimuli.

• Participants were least likely to share a toothbrush with strangers (e.g., postman) and most likely with close family members (e.g., spouse).

Conclusion:
The results support the evolutionary theory that disgust functions as a mechanism to reduce the risk of disease.