Synaptic transmission

• Process of synaptic transmission

  • An electrical impulse is triggered due to the change in charge in the neuron (action potential)
  • When the electrical signal reaches the terminal button, it changes into a chemical message
  • The chemical message is a neurotransmitter which is released from vesicles
  • The neurotransmitter travels across the synapse to the next neuron
  • The neurotransmitter binds with the receptors on the next neuron to pass the message on
  • Neurotransmitter is then either reabsorbed or is destroyed by enzymes in the synapse, returning the neuron to a resting state
• What are neurotransmitters?

  • Chemical messengers that act between the neurons in the brain
  • Allows the brain to process thoughts and memory
• Where are neurotransmitters released?

  • Into the synaptic gap and are taken up by the receptors on dendrites of another neuron, to send a message or they can inhibit a message.
  • They remain in the synaptic cleft where they are either reabsorbed by the pre-synaptic neuron or destroyed by enzymes
• Function of dopamine

  • Gives you feelings of pleasure, satisfaction and motivation
  • Controls memory, mood, sleep, learning, concentration and movement
• Function of seretonin


  • Regulates your mood
  • Feeling pain, sleep, hunger and regulation of body temperature
• Function of GABA

  • Is an inhibitory neurotransmitter
  • Reduces the activity of any neutron that it binds to
• Strength of neurotransmitters (supporting evidence)

  • There is evidence that serotonin is linked to changes in behaviour. Dee Highley studied rhesus monkeys in the wild and found that those who were killed or injured in reckless leaping or fights with older, larger monkeys were more likely to have low serotonin levels (serotonin inhibits aggression). This supports the view that neurotransmitters like serotonin affect behaviour such as aggression.
• Strength of neurotransmitters (supporting evidence)

  • There is evidence dopamine changes behaviour. Brisch (2014), Irregularities in the dopamine system can also be found in the amygdala, pre-frontal cortex and that the hippocampus is overactive in schizophrenia patients. This supports role of dopamine in disorders such as schizophrenia.
• Weakness of neurotransmitters

  • There is evidence that dopamine doesnt change behaviour. Depatie found that giving people drugs that increase their production of dopamine doesn't create the symptoms of schizophrenia as would be expected if excess dopamine caused it. This suggests neurochemicals such as dopamine may not be the only explanation of the causes of schizophrenia
• Weakness of neurotransmitters

  • Brain scans are used to research the effect of neurochemicals such as GABA on behaviour and these are conducted in artificial environments using artificial tasks that may change neurotransmission due to stress. This means neurotransmitters like GABA may not have such significant impact on human behaviour in the real world
• Balanced conclusion of neurotransmitters

  This can be considered useful because it can be used to help develop treatments for people with conditions such as depression and schizophrenia, e.g selective serotonin. However this can be considered less useful because it can be used as an excuse for behaviour such as aggression and therefore used as defence in court which may lead to violent offences.