paper 1 bio ERQ Flashcards
Cases 90s Study
AIM (genes & brain)
- investigate correlation between low MAOA lvls, (breaks down neurotransmitters) & impulsive aggression
PARTICIPANTS/IV
- transgenic mice (experimental group) genetically modified to produce less MAOA
- control mice
METHOD
- Transgenic mice removed gene producing MAOA enzyme to cause excess lvls of serotonin, dopamine, & investigate impact on aggression
- After the rats reached maturity stimulated intruder tests were conducted to measure rats responses
RESULTS
- Transgenic mice quicker 2 attack (impulsive) & adopted threatening position
- more offensive aggressive behaviour e.g. biting
- Autopsies showed elevated serotonin levels
IMPLICATIONS
- MAOA-deficient mice more aggressive, & impulsive due 2 excess serotonin
- MAOA, enzyemes, and neurotransmitters are determined by genes which influence behaviour
Rogers & Kesner 2000s Study
AIM (neurotransmitters)
- to determine the role of acetylcholine in the formation and retrieval of spatial memory
PARTICIPANTS/IV
- 30 rats
METHOD
- All rats acclimated to a maze and its objective to find food in the opposing corner of the maze, but before the maze was able to be transferred to long-term memory
Then rats were randomly allocated into 3 groups:
- 1) injected with scopolamine—a drug which blocks the reception of acetylcholine by post-synaptic neurons, and thus preventing acetylcholine, a neurotransmitter expected to help form memories, from functioning, as acetylcholine cannot travel from one neuron to another. As there is a significant number of acetylcholine receptors in the hippocampus which is known for memory storage.
- 2) inject drug physostigmine which blocks an enzyme: cholinesterase which naturally breaks down acetylcholine from receptor proteins on the post-synaptic neurons to return the neurons to their resting potential when no nerve impulse is being sent, thus more acetylcholine than typical.
- 3) injection with a placebo saline solution. These injections were made into the hippocampus.
- After being injected the rats were measured to see how long it would take them to find food they had previously located over 2 days.
formation of spatial memory was assessed by averaging the number of errors the rats made on the 1st 5 trials of the maze on day 1 compared to the last 5 trials of day 1
the retrieval of spatial memory was assessed by comparing the average number of errors made on the last 5 trials of day 1 to the 1st 5 trials of day 2
RESULTS
- The scopolamine group took longer to learn the maze, and made more errors—higher average number of mistakes on the last 5 trials on day 1 thus deficit in memory formation
- The scopolamine did not appear to affect the retrieval of memories that had already been created
- The increased acetylcholine group had increased spatial memory formation with less errors compared to made in the last 5 trials on the 1st day compared to the 1st 5 trials on the 1st day
- However, the increased acetylcholine group showed a deficit in memory retrieval on the 5 trials of the 2nd day compared to the 1st 5 trials of the 1st day
IMPLICATIONS
- This suggests acetylcholine plays an important role in the formation of spatial memories, as the low acetylcholine rats were confused and lost although they were had learned the maze previously.
- However, excess acetylcholine, as demonstrated by the high acetylcholine group, may hinder spatial memory retrieval
Meaney 80s Study
AIM (hormones, brain
- to determine the effect of glucocorticoids (stress hormones) on memory
STUDY
- true experiment
PARTICIPANTS
- Condition 1 rats: experimental group, not handled normally, neglected, removed from mother
- Condition 2 rats: control group, handled normally, staying in care of mother
METHOD
- After the rats reached maturation, they were individually placed in a container with milky water and had to escape by finding a platform
- This experiment was repeated multiple times to see whether the rats would use their memory to reach the platform more effectively
The route the rats took across trials was tracked
RESULTS
- The neglected rats secreted more glucocorticoids in response to the stressful maze than the control rats
The neglected rats also took more ineffective routes to the platform at old age
- At later ages the neglected rats had elevated basic glucocorticoid levels at rest than normal rats, since the neglected rats were exposed to a long period of stress which caused the cortisol or glucocorticoid levels had to increase to remain high, which then became the neglected rats’ baseline
- Accelerated hippocampal neuron loss and thus spatial memory deficits in the neglected rats due to the higher glucocorticoid whereas, this effect was almost absent in the control rats
IMPLICATIONS
- The higher level glucocorticoids from prolonged stress leads to hippocampal neuron loss which causes reduced spatial memory abilities
animal ethical considerations
- animal welfare (care of animals in captivity)
- reduction of number of animals used
- refinement using less invasive research techniques
- replacement of animal research with alternatives
- undue stress and harm
- cost-benefit analysis of whether animal research is valuable
