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SAQ marking: Neurotransmission

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  • SAQ marking: Neurotransmission

Below you will find four sample SAQs for the question: Explain one effect of one neurotransmitter on human behaviour with reference to one study.

For each of the samples, refer to the rubric to award marks 1 - 9. After each sample, there is a predicted grade as well as feedback on the strengths and limitations of the sample.

SAQ rubric

SAQ Sample 1

Neurotransmission is the process in which neurotransmitters are released from the axon terminal of one neuron to bind with the dendrites on another neuron. One neurotransmitter that is linked to memory is acetylcholine. There are many acetylcholine receptor sites in the hippocampus.  It is believed that acetylcholine plays a role in the formation of memories. In Maguire’s (2000) study on neurotransmission, they had rats go through a maze in order to reach a prize. Two groups were created; one group was injected with scopolamine, which inhibits acetylcholine receptor sites on neurons.  The other group was injected with a placebo saline solution to rule out the possibility that the injection caused a difference in performance. Maguire found that the mice that were injected with scopolamine took longer and made more mistakes than those injected with the placebo, which shows that acetylcholine may have a role in the consolidation of spatial memories. This is just one effect of neurotransmission on behavior. This can be applied to humans due to the biological similarities of our brains to rats, although this study has not been replicated in humans to confirm this.

177 words

The fact that the researcher is misidentified does not have an effect on the score of this response. There is a very brief description of neurotransmission, but this needs to be more developed. A neurotransmitter is identified and linked to a study and an effect.  The study is clearly described. The link at the end of the study is not sufficient to answer the question about the effect on human behaviour. This means that the research is not used effectively to answer the question.  4 marks.

SAQ Sample 2

Neurotransmission was studied in Rogers and Kesner’s study. The aim of the study was to determine the role of acetylcholine which affects our hippocampus and our memory.

Rogers and Kesner used rats in their experiment.  They had them go through a simple maze where there was food for them in the corner of the maze. After they found the food, the rats were injected with acetylcholine, which strengthens the memory and makes the memory clearer and vivid.  Some of the rats were injected with a placebo to make sure that the fact of getting injected didn’t have an effect on the results. After the injection, the rats were placed at the start of the maze and were supposed to find the food in the same place as before.

The results were that the rats that were injected with acetylcholine had a significantly better memory of finding the food and made fewer mistakes in the maze and the rats who were injected with the placebo.

This study shows that neurotransmission in the hippocampus has an effect on how well we are able to remember certain things and patterns. 

187 words

This is a weak response.  First, there is no link to human behaviour.  Secondly, there is no explanation of neurotransmission. Finally, there are significant errors in the study - eg. that the rats were injected with the neurotransmitter. 2 marks

SAQ Sample 3

Neurotransmission is the process where neurons communicate with other neurons.  This is done when the presynaptic neuron releases chemicals called neurotransmitters to cross the gap between two neurons called the synapse. These neurotransmitters then bind to specific receptor sites on the postsynaptic neuron creating an electrical signal called the action potential. If these receptor sites are blocked by another chemical the postsynaptic neuron will not be able to create an action potential, inhibiting the process of neurotransmission. This is a common way of studying effects of neurotransmission, blocking the receptor sites of a specific neurotransmitter and then noting behavioural changes.

In some patients with memory problems, we see a lower rate of activity in the hippocampus. This could be because of a lack of a neurotransmitter called acetylcholine.  As it is not possible to directly observe the activity of neurotransmission in the brain, and it would be unethical to manipulate levels of acetylcholine in a patient, animal research is used with the hope of better understanding human behaviour.

Rogers and Kesner carried out a study on the effects of acetylcholine on spatial memory. To do this they tested rats ability to learn a maze. Firstly, the rats were acclimated to the maze, so that distress caused by a new environment would not be a confounding variable and influence the ability to create memories. Then, the rats were allocated to one of two conditions. In one group, they were injected with scopolamine, a chemical known to block acetylcholine receptor sites. In the second group, they were injected with a placebo, a saline solution with no active ingredient in order to control for an adrenaline increase from the stress of an injection. The researchers then had the rats run the maze again. The researchers found that the group injected with scopolamine performed significantly worse on the maze, taking longer to learn it and making more mistakes. This allowed the researchers to conclude that acetylcholine plays a role in the consolidation of spatial memory in the hippocampus. These findings were later supported in tests on humans such as Antonova's virtual reality study where she also tested the impact of inhibiting acetylcholine receptor sites on spatial memory in people and found results that appeared to support Rogers and Kesner’s conclusions.

376 words

Neurotransmission is clearly explained.  Although animal research is used, it is clearly justified and there is a clear link to human behaviour.  The study is clearly described and relevant.  The effect of acetylcholine is clearly explained.  9 marks.

SAQ Sample 4

Neurotransmission is the process in which neurons send and receive electrical impulses. An electrical impulse travels along the axon of a neuron until it releases neurotransmitters into the synaptic gap between two neurons. This is where the neurotransmitters are potentially received by receptors from the opposing neuron; otherwise, they are either decomposed by enzymes or taken back into the previous neuron.

In Antonova’s study, male participants were asked to take part in a double-blind study, meaning that the participant and the researcher were not aware of which group they were a part of. The participants were randomly allocated to either the scopolamine group or the placebo saline solution group. The participants were then placed into an fMRI in order to read their brain activity. They were told it to play a few rounds of a virtual reality game with a joystick in order to become familiar with the controls. The game consisted of the participants being dropped in the middle of an arena and told to find a special landmark. Each round of the game started them at a different location within the arena. After a few rounds, the researchers recorded their brain activity in the next few rounds.

The participants were asked to come back after 3 to 4 weeks where they repeated the procedure.  The study found that the participants injected with scopolamine had less brain activity in the area used for spatial recognition compared to the placebo participants. This shows that the scopolamine actually blocked the receptors on the neuron for acetylcholine and prevented neurotransmission from taking place, thus impairing the participants’ ability to create spatial memories.

111 words

The response definitely demonstrates some understanding relevant to the question, but it lacks precision.  The explanation of neurotransmission is a bit limited and imprecise. The study is appropriate and there is a general sense of understanding, but the results are not really clearly explained.  5 marks.