SL - The brain and behaviour - localisation in the brain Flashcards
Sharot (2007)
aim ->
To investigate the effect of emotion on FBMs
Method ->
Ppts were placed in an fMRI scanner and then asked to retrieve autobiographical memories from cue words presented on screen. The memories were either to be from an event from the summer of 2001 or from 9/11 (referred to as ‘September’ memories). Then ppts were asked, of the summer and September memories, to rate them on a number of factors including arousal (strength of emotion), vividness, and confidence. Finally, ppts were asked to write a description of the two memories they had been recalling during the study.
Results ->
The left amygdalae of Downtown ppts showed significantly more activity during 9/11 recollections than when recalling summer memories.
Conclusion ->
The retrieval of memories of shocking public events affects the activation of the amygdala only when there has been personal experience of the event.
Evaluation ->
✔ Triangulation of different data types - rating scales, descriptions, brain imaging, distance from and engagement with the event - increases the credibility of the conclusions.
✔ Supports Brown and Kulik (1977) - worked on the premise that there would be a biologically-distinct pathway for processing flashbulb memories and helped to support and refine an existing theory.
❌ Ethical issues (protection from harm) - Potential distress caused to ppts who had traumatic memories of 9/11 (mitigated by the sampling method and the gaining of informed consent).
❌ correlational study - correlation is not causation
❌ The findings can’t demonstrate the involvement of the amygdala in the formation of flashbulb memories, so this suggestion remains plausible but unproven.
Rogers and Kesner (2003)
aim ->
To investigate the role of acetylcholine (ACh) during the
encoding and retrieval of spatial information.
Method ->
Rats had cannulae surgically placed in their brains to deliver chemicals to specific regions of the hippocampi and were tested for their ability to learn a simple maze. The rats ran the same maze in blocks of five, with two blocks run each day. Encoding was measured by comparing errors made in the first five trials of one day with the errors made in the final five trials of that same day. Retrieval was measured by comparing errors made in the final five trials of one day with the errors made in the first five trials of the next day.
There were three conditions: rats injected with physostigmine (ACh agonist - enhancing the transmission of acetylcholine), scopolamine (ACh antagonist - inhibits the transmission of ACH), and a saline solution (a control condition).
Results -> Scopolamine condition encoded worse but consolidated better. Physostigmine encoded better but retrieved worse. Results were in comparison to the control condition.
Conclusion -> ACh has two clear effects on memory processes: it facilitates the encoding of new information and inhibits the consolidation (long-term storage) of information. The reason for this two-fold function is to enable the efficient processing of information. One particular region of the hippocampi is involved in both the encoding and consolidation processes. These processes interfere with each other, and so for one to happen effectively the other must be inhibited. This is what ACh does.
Evaluation ->
✔ The measurements of encoding and retrieval were well-conceived and enabled a precise identification of the role of ACh in spatial memory.
✔ The use of rats enabled otherwise-unobtainable insights to be gained. Additionally, there has been research that has found rats’ brains are similar to ours so rat brains may be a suitable model for human brains.
❌ Cannot apply to human brains - Rat brains are not human brains so there remain questions over the usefulness of animal models for the understanding of human brains.
❌ Ethical issues ->The rats are likely to have suffered through the procedure for, and effect of, fixing cannulae in their brains. They were also killed at the end.
Maguire (2001)
Aim ->
To see if physical changes “could be detected in the healthy human brain associated with extensive experience of spatial navigation.”
Method ->
All ppts had their brains scanned using MRI (magnetic resonance imaging), with the region of interest being the hippocampi, already known to be involved in spatial and navigational memory. Maguire compared the average brain scan of taxi drivers (TD) with the average brain scan of the controls, to see if there were any differences. Maguire also compared the size of the difference between individual TDs’ brains and the average control with the number of months the drivers had been doing their job.
Results ->
The taxi drivers’ (TDs’) anterior hippocampi on both sides were smaller than the controls, while the TDs’ posterior hippocampi were significantly larger. In addition, as time as a taxi driver increased the size of the right posterior hippocampus increased. As time as a taxi driver increased the size of the anterior hippocampi (bilateral) decreased.
Conclusion ->
The use of spatial memory for navigation is localized to the posterior hippocampus. Since the posterior hippocampi are used in spatial memory, as taxi drivers require more spatial memory, their brain focuses the neurones in the posterior hippocampus from the anterior hippocampus.
Evaluation ->
✔ Control over the type of ppts and controls ensured the greatest chance that the brains scanned were approximately similar.
✔ The use of different analyses allowed for stronger conclusions to be drawn regarding neuroplasticity. For example, the use of MRI scanning allowed for neuroplasticity to be investigated.
❌ Correlational study -> The use of correlational data makes conclusions less secure than an experiment.
❌ Low generalizability -> the small sample (16 taxi drivers, 50 controls) means that it’s not clear how valid these findings are and how much trust we can have in them.
Localization of function in the brain
The view that specific parts of the brain are responsible for specific aspects of behaviour.
MRI
Pictures of the brain, used to look at the structure of the brain. Helps with neuroplasticity (Maguire, Draganski)
fMRI
Video of the brain, used to look at activity within the brain of the brain. Helps with localisation of function (Sharot, Kobiella)
functional magnetic resonance imaging (fMRI) detects blood flow in the brain using radio and waves and magnetic fields to detect blood-oxygen levels from different parts of the brain. This shows the level of activity in a specific part of the brain.
