Evaluate research on the role of neurotransmission in human behaviour

Definition and process

Neurotransmitters

Researches

Structure of answer

Evaluation of researches

Evaluation of theory/concept

Fisher et al. (2005)

Caspi et al (2003)

How neurotransmission works?


  • An electrical impulse travels down the axon (body) of the neuron.
  • When it reaches an axonal terminal a neurotransmitter is released that then crosses the synaptic gap to the next neuron.
  • After crossing the synapse, the neurotransmitter fits into receptor sites on the post- synaptic cell, like a key in lock
  • After a neurotransmitter has signaled an electrical impulse in the postsynaptic cell, some types are ‘cleaned up’ by transporter molecules released by the presynaptic neuron.
  • This process is known as reuptake, and they are reabsorbed, re-entering the presynaptic cell to be reused.
  • Not all neurotransmitters are cleared from the synaptic gap via reuptake
  • In some cases, neurotransmitters are broken down. Breaking down of neurotransmitters is known as degradation

Start answer with definition of neurotransmission and explaining the process- hence, introducing neurotransmitters.
One-two lines about the main neurotransmitters in focus for the answer and their general effect.
Mention of the researches used

Types of Neurotransmitters

Evaluating the concept of neurotransmission affecting behaviour by weighing the construct validity of the theory, reflexivity, reliability and validity of the studies previously evaluated.
Given that neurotransmission is a biological concept and not just a proposed theory- strong evidence exists for the same, even in the realm of natural sciences. Since reflexivity of most studies is strong, and there is high triangulation for impacts of neurotransmitters like serotonin, construct validity is likely to be high.

The body’s natural chemical messengers which transmit information from one neuron to another - more than a 100 have been identified

Excitatory neurotransmitters

Allow the impulse to cross the synapse

Produces stimulating effects on the brain

Neurotransmitters that compel a neuron to activate

Inhibitory neurotransmitters

Prevent and stop the impulse from crossing the synapse

Turn off a neuron or reduces its likelihood of firing

They serve to inhibit or prevent the postsynaptic receiving neuron from firing

Produces calming effects on the brain

NEUROTRANSMISSION


  • All neurons carry information by means of electrical impulses


  • Neurons send chemicals called neurotransmitters across a gap between neurons, called the synapse, to pick up the receptors of another neuron.


  • This activity is called neurotransmission


An experiment aiming to investigate the impact of allele length of the 5HTT (serotonin transporter) gene on percieved stressed levels and depression in participants. Study showed ltwo long alleles being positively correlated with lower levels of percieved stress and depression. Hence, show the impact of the neurotransmittor serotonin on human behaviour.

Neurotransmitter in the researches picked

Caspi et al (2003)

DOPAMINE

SEROTONIN

Serotonin is the key hormone that stabilizes our mood, feelings of well-being, and happiness. This hormone impacts your entire body. It enables brain cells and other nervous system cells to communicate with each other. Serotonin also helps with sleeping, eating, and digestion

Dopamine: A neurotransmitter associated with movement, attention and learning and the brain's pleasure and reward system.


This suggests that dopamine produces a 'rush' of excitement and pleasure associated with the loved one, particularly at the start of relationships

High number of participants (837)- high ecological validity, strong research design to test percieved stress levels of the previous year and stressful events between 21st and 26th birthday. High epistemological reflexivity as direct correlation between allele length and depression is not inferred but is well connected with low percieved stress. Although migh be subject to acquiscense bias- tendency to respond positively or sensitivity bias (participants may not be conmfortable with sharing personal life details), was overall a strong research contributing to the construct validity of the concept of neurotransmission.

CRITICAL ANALYSIS


The results indicate the possibility of brain circuits dedicated to attraction are the same circuits associated with addiction. Dopamine increases with anticipation of reward (not just getting a reward). We anticipate reward, so our brains are wired to drive us towards attaining those rewards. This is evolutionary explanations of human behaviour; if we don't have sex our genes won't be passed on

Fisher et el. (2005)

Strengths:
This is a highly controlled clinical method of obtaining data and Fisher and her colleagues checked objectivity at every stage of the procedure.
Identification of the reward centres of the brain support the idea that human beings may have an evolved brain system which ensures that they become 'hooked' on an individual, which increases the possibility of them reproducing.
The standardised procedure means that the study is replicable, which increases its reliability.


Limitations
The small sample size of 17 participants means that the results are not very meaningful and may not be robust in terms of statistical analysis.
The sample comprised relatively young students from the same university, which also limits generalisability.
Additionally, it is overly reductionist to use brain scans to determine how romantic love is experienced: there may be a range of other factors involved, such as similarity, same upbringing, shared ideals, cultural influences.
So little is really known about the brain that there may be other explanations for the activation of the reward centres during the fMRI scan - perhaps the participants were simply excited to be in a brain scanner for the first time and this stimulated the dopamine-rich areas.
Scanning participants' brains is clearly an artificial task, which means that the results are low in ecological validity. Use of fMRI scans is also an expensive way to collect data, which is possibly why the sample is so small.