SL - The brain and behaviour - neuroplasticity Flashcards
Neuroplasticity
The brain’s ability to change as a result of experience.
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.
Draganski (2004)
aim ->
To investigate whether “the structure of an adult human brain alters in response to environmental demands.”
Method ->
24 volunteer participants were split into two groups: ‘jugglers’ and ‘non-jugglers’ (no ppts had prior juggling experience). All had their brains scanned (MRI) at the start of the study.
Jugglers had three months to learn a simple juggling pattern. They were rescanned when they could sustain the pattern for at least 60 seconds (they had become “skilled” jugglers); non-jugglers’ brains were also scanned at this point.
Jugglers were asked to stop practising their juggling for the next three months and then all ppts’ brains were scanned a third and final time.
Results ->
Scan one: no significant differences between the two groups.
Scan two: jugglers “demonstrated a significant … expansion in grey matter” in three areas. The amount of change was closely related to the ppts’ juggling performance: better jugglers showed more change in brain structure.
Scan three: the expansion decreased (but didn’t disappear) after three months without juggling.
No change in grey matter was recorded for the non-jugglers.
Conclusion ->
The brain can change structurally in response to learning a new skill. Learning to juggle is more about perception and spatial anticipation of moving objects than about motor skills (because of where the greatest changes were detected). Changes in brain structure can be transient (temporary) unless something is practised.
Can also show that neural networking and pruning exist.
Evaluation ->
✔ Supports/supported by Maguire (2001) who also found that the brain changes in response to experiences in life (greater need for spatial memory for taxi drivers seemingly caused their posterior hippocampi to grow in size)
✔ High validity -> matched pairs design -> groups not compared against other groups that are fundamentally different: ppts were essentially compared against themselves so a direct cause-and-effect relationship can be seen more confidently.
❌ Very low generalisability -> the study used only 24 participants with their ages ranging generally between 20-24 years old. There were only 3 male participants in the study. Because of this, we cannot confidently apply these results to the general world.
❌
Rosenzweig, Bennet, and Diamond (1972)
Aim ->
To see if experience produces any observable change in the brain.
Method ->
Rats were assigned to one of three conditions (each triplet from each litter was assigned to a different condition): Impoverished cage (alone), Normal cage (three rats together), and the Enriched cage (up to twelve rats together in a larger cage with regularly changed toys to keep the rats stimulated). After a particular period of time, the rats were ‘sacrificed’ and their brains were examined for various different features. The rats from different conditions were investigated in a random order by independent technicians to remove the possibility of bias in the analysis.
Results ->
The enriched rats’ cerebral cortex was significantly heavier and thicker than in normal and impoverished rats. Neurons in the enriched rats’ cerebral cortices were bigger. Greater acetylcholinesterase activity was found in the enriched rats’ brain tissue (this enzyme breaks down the neurotransmitter acetylcholine (ACh)).
Conclusion ->
The thickening of the cerebral cortex points to greater brain activity in the enriched rats. With lots of new connections being formed between neurons, with the encoding of additional environmental information, neurons became larger to accommodate and consolidate the new connections. The extra enzyme activity implies additional ACh neurotransmission taking place in the enriched rats’ cerebral cortices.
Evaluation ->
✔ High validity -> high control due to lab experiment. The rats from different conditions were investigated in a random order by independent technicians to remove the possibility of bias in the analysis.
✔ Different aspects of the rats’ brains were measured to form a consistent and detailed understanding of the processes involved. 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.
❌ Huge ethical issues -> This experiment had been repeated for ten years and the rats were killed at the end of the experiments. Considering many rats were isolated, the treatment of these rats raises ethical concerns.
Neural networks
Collection of neurons that have formed connections between themselves. Networks represent memories and skills. More these neurons are rehearsed/practised, stronger connections. Developing neural networks leads to growth of these neurons.
Shown in Draganski (2004) and Maguire (2001)
Neural pruning
Neuron groups that are not used frequently are slowly dismantled in the brain as they are not necessary and keeping them causes a waste of resources. The less that neuron groups are used, the weaker the connections, the smaller the neurons.
Shown in Draganski (2004)
