Brain Flashcards
Explain what is meant by the term neurotransmitter. (2)
[2014/01 WBI05/01]
A chemical which is able to travel across the synaptic cleft (1) by diffusion from the pre-synaptic neurone to the post-synaptic neurone (1) which initiates nerve impulses in the post-synaptic neurone (1).
Serotonin is a neurotransmitter found in the human brain. A reduced level of this neurotransmitter has been linked to depression.
A serotonin selective reabsorption inhibitor (SSRI) may be given to patients to reduce depression.
Suggest how this helps to reduce depression. (2)
[2014/01 WBI05/01]
SSRI inhibits the reuptake of serotonin (1) which means that more serotonin (1) can be present in the synaptic cleft (1). This means that a higher frequency of action potentials can be triggered in the post-synaptic neurone (1) which gives the patient a more elevated mood.
An investigation was carried out to study habituation in a group of people.
Each person wore a pair of headphones through which a short sound was played once. This sound made each person blink their eyes.
The degree of contraction of one muscle involved in blinking was recorded. The mean degree of muscle contraction was calculated for the group.
This was repeated with the sound played 5 times, 10 times, 15 times and 20 times. The mean results for the group were recorded.
The results are shown in the graph below.
(i) Suggest an explanation for the change in the mean degree of muscle contraction. (3)
(ii) Describe how this investigation could be extended to obtain valid and reliable data on how the volume of the sound could affect habituation. (4)
[2014/01 WBI05/01]
(i) As the number of times the sound was repeated increases, the mean degree of muscle contraction decreases (1). This is because overexposure to the sound causes the calcium ion channels to be less responsive (1) in the sensory neurone (1). This means that less calcium ions are being diffused into the synaptic knob (1) which means that less vesicles containing neurotransmitters are triggered (1) to fuse with the membrane of the sensory neurone. Hence, as there are less neurotransmitters binding with specific receptor proteins on the post-synaptic membrane, there would be fewer action potentials to the motor neurone (1) and therefore a decrease in muscle contraction.
(ii) The experiment should be repeated with the same sound (1) and time but with different volumes (1). The experiment should also be repeated with people of the same gender and age (1), and the mean muscle contraction should be calculated for every number of times the sound was repeated (1).
The sound made by the siren of a police car needs to be heard. If the same sound is used repeatedly there is a risk that people will become habituated to this sound. The auditory cortex is the part of the brain that responds to the sound made by the police siren.
Explain how fMRI scanning could be used to investigate if habituation occurs when the same sound is used. (5)
[2017/01 WBI05/01]
To investigate habituation, fMRI can be used to show the level of activity in different sections of the brain (1). fMRI measures the levels of oxygen in the brain (1). The more active the section of the brain is, the more oxygenated (1) the area of the brain becomes which shows up in the scan are brighter/whiter (1). To see if habituation occurs, the brain activity, especially in the temporal lobe, would decrease (1) as the frequency of stimulus increases which causes the area of the temporal lobe on the brain scan to appear less bright/white overtime.
Habituation will take place if calcium ion channels in the (1)
A postsynaptic membrane become less responsive B postsynaptic membrane become more responsive C presynaptic membrane become less responsive D presynaptic membrane become more responsive
[2017/01 WBI05/01]
C (presynaptic membrane become less responsive) (1)
