Neurotransmission Flashcards
Define neurotransmission + Neurotransmitters
Neurotranmission
- The process of transferring information from one neuron to another at a synapse. 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.
Neurotransmitters
- Chemical messenger
- Are stored in the neurons terminal buttons.
- After crossing the synapse neurotransmitter fits into receptor sites on the postsynaptic cell like a key in a lock. Some undergo the process of re-uptake where they are reabsorbed, to be reused.
What is the neurotransmission and behviour involved in Caspi et al (2003) and Yu et al (2011)?
[Name/Location/Function/Behaviour]
Serotonin also known as 5HT
(5HTT -> serotonin transporter gene) = A gene that allows drugs to enter cells
Location: The start of the serotonin pathways in the brain stem, especially the area called a Raphe Nuclei. It is manufactured in the brain and intestines. Found widely across body, believes that it plays a role in influencing a large variety of body and psychological functions.
Function/Behaviour: It stabilizes our mood, hunger, sleep, and arousal. An undersupply can link to the depression.
Aim of Yu
To gain insight into the neurophysiological mechanisms involved in Zen meditation.
Method of Yu
Lab Experiment. 15 novice volunteers took part.
They first completed POMS mood questionnaire (pre-test), then engaged in meditation. During the 20 minute meditation session of FA on Tanden breathing, they measured haemodynamic changes in the prefrontal cortex, (an attention-related brain region), using spectroscopy. After the meditation they completed the mood questionnaire again (post test)
Findings of Yu
The levels of oxygenated hemoglobin in the anterior PFC was significantly increased during FA on Tanden breathing.
By comparing the pre- and post- mood questionnaire results showed a significant reduction in feelings of negative mood.
EEG revealed increased alpha band activity and decreased theta band activity during and after FA on Tanden breathing.
EEG changes were correlated with a significant increase in blood serotonin (5-HT) levels.
Conclusion of Yu
- Suggests that activation of the anterior PFC and 5-HT system are responsible for the improvement of negative mood and EEG signal changes observed during FA on Tanden breathing.
- Positive correlation (5HT goes up, mood also up because higher serotinin levels are thought to block negative mood).
Aim of Caspi
To investigate whether a functional change in the 5HTT gene is linked to a higher or lower risk of depression in an individual.
Method of Caspi
The researchers used an opportunity sample from the cohort of participants who are part in the Dunedin longitudinal research study. In total there were 847 participants of 26 y/o. They were split into three groups depending on the length of the alleles on their 5HTT transporter gene.
Group 1: Two short alleles
Group 2: One short one long allele
Group 3: Two long alleles
Data was gathered on:
- stressful life events occurring after the 21th- before 26th birthday
- past year depression was assessed using the diagnostic interview schedule.
- Correlation was tested between stressful life events and depression, between length of the alleles and depression, and an interaction betwen percieved stress and the length of the alleles.
Findings of Caspi
Participants with two short alleles reported more symptoms of depression in response to stressful life events.
Moreover child maltreatment was predictive of depression and adulthood only in adults with either one or two short alleles.
Conclusion of Caspi
There is a relationship between short alleles and depression and incidences of stress and subsequent depression.
Long alleles seem to protect against suffering depression as a result of stress (give resilience) which identifies individual differences.
What is antagonist?
Introduce neurotransmitters first.
An antagonist is any substance that fits into a receptor site on the post-synaptic neuron, inhibiting the neuron. This means that the neuron will not fire and therefore a behaviour will not happen.
What is an example of an antagonist
- Acetylcholine is a neurotransmitter that plays a role in the formation of memories.
- It is not possible for researchers to directly observe the role of neurotransmitters, so one of the ways that they attempt to understand the role of different neurotransmitters is by giving animals or human participants an antagonist. They want to see what happens when acetylcholine receptors are blocked and the neurons are “not allowed” to fire.
What studies to use for antagonist/angonist?
Antonova - antagonist
Aim of Antonova
To see if scopolamine affected the hippocampal activity in the creation of spatial memory
Method of Antonova
- PPTS randomly allocated to one of the two conditions
- Either injected with scopolamine (An exogenous antagonist for acetylcholine) or a placebo 70-90 min before the experimental task
- PPTS put into an fMRI where they were scanned while playing the “arena task” (video game)
- Researchers observed how well ppts were able to create spatial memories
- The goal for the ppts was to navigate around the arena and reach a pole and later they reached it the screen would go black for 30 seconds
- During the black screen the ppts were asked to rehearse how to get to the pole in the arena
- When the new arena appeared they had to use their spatial memory to determine how to get back to the pole
- 6 trials were done per participant
After 3-4 weeks, ppts would return and redo the test receiving the opposite condition
