biological

• Biological psychology


  • It is about the mechanisms within our body, in particular the brain, and how they affect our behaviour
• Key assumptions of biological psychology

  • All behaviour is determined by biological factors
  • The central nervous system is a major influence on behaviour
  • Behavioural & psychological development is assumed to be based on changes in the brain and general biology
  • The process of evolution can explain the existence of much human behaviour. Behaviour has evolved so that behaviours that help us survive are more likely to be passed on to future generations
  • Genes influence behaviour
  • There is behavioural continuity between species so it makes sense to study animals and make generalisations to humans
• Central Nervous System (CNS)


  Made up of the brain and the nerves in the spinal cord
• Peripheral Nervous System (PNS)

  Branches out from the spinal cord, a web of nerves carrying information to and from the CNS to the rest of the body
• Role of the CNS in human behaviour

  • Acts as an information processing and control centre for information we receive and responses that we make in our environment
  • When the body receives information from the senses, the PNS sends it to the CNS. The brain processes and integrates all of the information from the senses and generates a response
• Example of CNS processing information

  1. Receptor nerves in shoulder send information to CNS

  2. Information passes through spinal cord and into brain

  3. Sense of touch processed in brain

  4. Brain generates response sending information to muscles to turn around
• The four lobes of the brain

  • Frontal lobe
  • Parietal lobe
  • Occipital lobe
  • Temporal lobe
• Functions of the four lobes

  • Frontal lobe: Planning & organizing, problem solving & decision making, memory & attention, controlling behaviour & emotional impulse
  • Parietal lobe: Integrates sensory information from various parts of body
  • Occipital lobe: Processes visual information, helps with balance & movement
  • Temporal lobe: Processes & recognises sounds, helps with speech & memory
• The two hemispheres of the brain

  • Left hemisphere: Concerned with language, logic, analysis
  • Right hemisphere: Concerned with creativity, intuition, holistic thought
• Corpus callosum


  Massive bundle of neurons that joins the two hemispheres and allows them to communicate
• Limbic system


  Complex system of structures and nerve networks deep inside the brain, linked to instinct and mood, controls basic emotions and drives
• Reductionism is a problem for biological psychology as it oversimplifies the role of the brain and overlooks social and environmental factors
• Structures of the limbic system

  • Thalamus
  • Hippocampus
  • Amygdala
  • Hypothalamus
• Functions of the limbic system

  • Thalamus: Relays sensory information to relevant parts of the cortex
  • Amygdala: Linked to emotions like fear, triggers fight-or-flight response
  • Hypothalamus: Regulates bodily functions via hormone release, also linked to fight-or-flight
  • Hippocampus: Plays key role in forming long-term memories, helps remember things that evoke emotion
• Neuron


  Specialised cell within the nervous system that communicates with thousands of other cells in huge networks
• Structures of a neuron

  • Cell body
  • Nucleus
  • Mitochondria
  • Dendrites
  • Axon
  • Axon hillock
  • Myelin sheath
  • Nodes of Ranvier
  • Axon terminals
  • Terminal buttons/boutons
  • Vesicles
• Neurotransmitters


  Chemicals that pass messages between neurons
• Key neurotransmitters


  • Noradrenaline
  • Dopamine
  • Serotonin
• Functions of key neurotransmitters

  • Noradrenaline: Involved in emotion, sleep, dreaming, learning
  • Dopamine: Involved in emotion, cognition, movement, hormonal regulation
  • Serotonin: Involved in mood, pain, sleep, temperature, hunger
• How cocaine disrupts normal dopamine functioning

  • Cocaine blocks reuptake of dopamine, causing it to remain in synaptic cleft longer

  This prolongs and intensifies stimulation of post-synaptic neuron

  Leads to euphoric feelings as the reward pathways are overstimulated
• How drug addiction develops

  • Drugs alter dopamine neurotransmission in reward pathways

  Brain reacts by reducing natural dopamine production

  This leads to feelings of dysphoria when drug wears off

  Drives compulsive drug use to regain the 'high' and alleviate dysphoria
• VTA


  Ventral tegmental area
• Nucleus accumbens


  Initial and one of the most important factors driving continued drug use and addiction
• Cocaine, heroin etc. increase the amount of dopamine in the reward pathways of the brain
• The brain is a self-regulating system and reacts to this over-production of dopamine by reducing how much dopamine it naturally produces
• Plasticity of the brain


  Allows it to adapt to the changes imposed on it by the use of drug
• When the heroin or cocaine 'high' subsides the brain has less dopamine than it needs for normal functioning causing feelings of dysphoria
• The motivation to self-administer such a drug is overpowering as the person is driven to reduce the feelings of dysphoria and re-experience the euphoria of the drug induced 'high'
• Repeated use of the drug causes the brain to further down-regulate the production of dopamine
• The natural baseline level of dopamine in the brain becomes so low that the user must take ever greater doses of the drug to get a 'high'
• This causes the person to be physically dependant on the drug in order to avoid the experience of withdrawal
• Over time, the person cannot do without the drug-he's addicted
• Withdrawal


  Occurs when drug is no longer active in our system, can be dangerous and cause unpleasant symptoms
• There is a great deal of well-controlled, scientific evidence, often using animals to support conclusions reached on how drugs effect the brain
• Brain scanning techniques have also provided important data on how the brain works whilst using drugs
• The discovery of how drugs influence the brain and synaptic transmission in the dopamine system may enable scientists to develop medications to help addicts give up using drugs
• Scanning techniques are not yet sophisticated enough to show everything that happens in the brain when drugs have been taken, particular the tiny changes in the synapses
• Much of the evidence on the role of synaptic transmission in drug use comes from research with animal and so findings may not be straightforwardly generalised to humans
• There are serious ethical issues raised in such research
• Von den Oever et al. (2008)


  Prefrontal cortex AMPA receptor plasticity is crucial for cue-induced relapse to heroin-seeking