Using one or more examples, explain the effects of neurotransmission on human behaviour.


  • State what you are doing in the essay
    • This essay will explain the effects of neurotransmission on human behaviour. 
  • Introduce topic
    • One of the most important discoveries that have influenced psychology is the role of neurotransmission in behaviour, thought and emotion.
    • To understand the effect of neurotransmission on human behaviour, the physiology or method of neurotransmission should be understood.
  • Define Neuron 
    • Neurons are nerve cells - one of the building blocks of behaviour.
    • Send electrochemical messages to the brain so that people can respond to stimuli:
      • Either from external stimuli (environment) 
      • From internal changes in the body 
    • This transferral of messages is known as neurotransmission. 
  • Define Neurotransmission 
    • Neurotransmission is the method by which messages are sent through the central nervous 
  • Explain Neurotransmission
    • When an electrical impulse travels down the axon (body of neuron), it releases neurotransmitters which cross the gap between two neurons known as a synapse.
  • Define Neurotransmitters
    • Neurotransmitters are the body’s natural chemical messengers which transmit information from one neuron to another.
    • They are stored in the neurons' terminal buttons.
    • After crossing synapse, neurotransmitters fir into receptor sites on the post synaptic membrane (like a key in a lock).
    • Once the message has been passed on, they are either broken down or reabsorbed by terminal buttons known as reuptake.
  • So what is the significance of neurotransmitters in the BLA? 
    • Neurotransmitters have been shown to have a range of different effects on human behaviour. 
    • Neurotransmission underlies behaviour as varied as mood, memory, sexual arousal and mental illness.
  • State examples of some neurotransmitters 
    • There are various types of neurotransmitters, such as serotonin, dopamine, acetylcholine and noradrenaline that influence behaviour.
    • Several studies have been undertaken to demonstrate the effects of neurotransmission on human behaviour. 
  • Outline and state which neurotransmitters will be explained 
    • Serotonin and acetylcholine will be explained in the following essay.


Neurotransmitter 1: Serotonin 

  • Introduce serotonin 
    • One example of a neurotransmitter is serotonin, which is commonly associated with depression and aggression. 
  • Outline serotonin 
    • Serotonin is a body regulator it controls bodily processes such as sleep, libido and body temperature.
    • It protects us from negative emotions such as anxiety and depression.
    • Serotonin stimulates neurotransmission in the post-synaptic neuron, increasing arousal, emotion and is also implicated in depression.
    • Secreted into the human body by the pineal glands.
    • Low levels of serotonin due to efficient re-uptake in the pre-synaptic neuron leads to low levels of arousal and lack of positive emotion, hence symptoms of depression

Supporting Study 1: Kasamatsu and Hirai (1999)

Introduce Study (Signpost):

  • One example of how the neurotransmitter serotonin can affect behaviour was seen by researchers, Kasamatsu and Hirai, 1999. 

  • To see how sensory deprivation affects the brain 
  • Also to see how the serotonin affects behaviour 


  • Studied a group of Buddhist monks who went on a 72-hour pilgrimage to a holy mountain in Japan. 
  • Monks did not consume water or food; did not speak and were also exposed to cold weather. 
  • Researchers took a blood sample before monks ascended into the mountain and immediately after they reported having hallucinations 


  • After about 48 hours, monks began to have hallucinations, seeing ancient ancestors or feeling their presence by their sides. 
  • They found that serotonin levels had increased in the monks? brainsthus the higher levels of serotonin activated the hypothalamus and frontal cortex resulting in the hallucinations. 


  • Researchers concluded that sensory deprivation triggered the release of serotonin, which altered the way that the monks experienced the world, a behaviour expressed by humans. 

Connection of study to question

    • Thus, this study shows that the neurotransmitter serotonin affects the human behaviour of increased arousal causing hallucinations (as demonstrated by monks after a spike in serotonin), therefore affecting human behaviour in terms of arousal and emotion.

Neurotransmitter 2: Acetylcholine (Ach) 

  • Introduce acetylcholine
    • Another example of a neurotransmitter is acetylcholine (Ach).
  • Outline Ach 
    • Serotonin is associated with the brain - in how it involved in learning and memory.
    • Present in the peripheral nervous system (PNS) and acetylcholine receptors are found widely throughout the body and brain.
    • Effects of Ach in the body include:
      • Effective deliverer of sodium ions stimulates muscle contractions; excites nerves 
    • An increase in Ach causes
      • Decreased heart rate 
      • Increased production of saliva 
      • High doses - convulsions and tremors 
      • Deficient levels - contribute to motor dysfunction 

Supporting Study 2: Martinez & Kesner (1991)

Introduce Study (Signpost):

  • One example of how the acetylcholine can affect behaviour was seen by researchers, Martinez & Kesner, 1991.

  • Aim:
    • To determine role of neurotransmitter acetylcholine on memory, specifically memory formation.

  • Methods: 
    • Rats were trained to go through maze and get to the end where they received food. 
    • After rats were able to do this, he injected:
      • 1st group -scopolamine, which blocks acetylcholine receptor sites. 
      • 2nd group - physostigmine, blocks production of cholinesterase (does 'clean-up' of - acetylcholine from synapse and returns neuron to its 'resting state'). 
      • 3rd group – control (no injections). 

  • Results:

Results showed that:

    • Scopolamine - slower at finding way round maze and made more errors than control/physostigmine group.
    • Physostigmine - ran faster compared to both groups and made fewer wrong turns.

  • Conclusion:
    • Acetylcholine played an important role in creating a memory of the maze.

  • Evaluation
    • Strengths:
      • Design and application 
      • Use of an experimental method with a control group made it possible to establish cause- and-effect relationship between levels of acetylcholine and memory. 
    • Limitations:
      • Questionable to what extent these findings can be generalized to humans. (Possible tapply research on rats to human beings)
      • Assumed that memory processes are the same for all animals.
  • Connection of study to question
    • Thus, this study shows that the neurotransmitter acetylcholine affects the human behaviour of memory causing an increase in memory functions with higher amounts of Ach compared to lower levels of Ach, which decreases memory functioning.


  • Conclude with a few statements about the effect of neurotransmitters on behaviour:
    • Neurotransmission is an effective way to communicate messages through the brain.
    • Thus neurotransmitters such as Serotonin & Acetylcholine affect specific human behaviours such as mood and memory.
    • Overall, it can be seen that neurotransmitters do affect human behaviour in a variety of ways.