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Animal Models
A concept that refers to using animal research to test a certain cause-effect hypothesis about a certain human behavior. It is a specific model with four major types of experimental manipulation.
Experimental Manipulation
Genetic manipulation (animals are bred in a certain way)
Invasive manipulations with the nervous system (parts of brain are stimulated, lesioned or removed
Invasive manipulations with other body parts (stimulated by substances or damaged)
Behavioral and environmental manipulations (i.e. shocking a rat depending on performance in a maze)
Benefits of animal research over humans
Simplicity, comparative approach, lifespan approach, ethics
Simplicity
Benefits of Animal Research Over Humans
The brains and behavior of nonhuman subjects are simpler than those of human subjects. Hence, the study of nonhuman species is more likely to reveal fundamental brain-behavior interactions. Example “knockout technique” in which genes are inactivated, removed, or artificially introduced. Can establish causal relationships in ways often not possible in humans. For example, the MAOA gene was “knocked out” of rats to help prove the impact of the gene (Critical thinking for McDermott study).
Comparative Approach
Benefits of Animal Research Over Humans
The study of biological processes by comparing different species. For example, comparing the behavior of species that do not have a cerebral cortex with the behavior of species that do can provide valuable clues about cortical functioning.
Lifespan Approach
Benefits of Animal Research Over Humans
This means that research can more easily assess how an organism develops due to modifications across a whole life. This is particularly advantageous in lab mice as they often only live for 2-3 years.
Ethics
Benefits of Animal Research Over Humans
It is possible to conduct research on laboratory animals that, for ethical reasons, is not possible with human subjects. This is not to say that the study of nonhumans is not governed by a strict code of ethics; it is. However, there are fewer ethical constraints on the study of laboratory species than on the study of humans.
Cost-benefit analysis
Benefits of Animal Research Over Humans
If we learn valuable insights into human behavior through the use of animals in research, and this knowledge has practical applications, then the animals’ suffering is justified.
Refinement
Ethical consideration: If animal research is undertaken it should be as focused and specific as possible. Psychological and physical harm should be avoided when and where possible but if it is deemed necessary then specific justification should be given by the researcher.
Replacement
Ethical consideration: Before undertaking animal research, all other possible avenues must be explored. In recent years, great advances have been made in the area of computer simulations based on previous data. These offer a more humane alternative to animal research.
Reduction
Ethical consideration: The number of animals used in the research should be reduced as much as possible. This is to ensure that suffering is endured by the minimum number of animals possible.
Rosenzweig et al (1972) - Development of neurons vs. environmental factors
!! NEUROPLASTICITY STUDY !!
A - To investigate whether environmental factors such as a rich or an impoverished environment would affect the development of neurons in the cerebral cortex.
P - 3 male rats from a common litter were randomly allocated to one of 3 environments. Rats were assigned to one of three possible conditions. All conditions had adequate food and water.
The control condition - a standard laboratory colony cage that contained several rats. The impoverished condition - a slight smaller cage isolated in a room in which the rat was placed alone. The enriched environment - 6 to 8 rats in a larger cage furnished with a variety of objects with which they could play.
The individual cages lacked the toys and the maze which were in the enriched environment. All groups had free and adequate access to food and water. The rats typically spent 30 to 60 days in their environments before they were killed in order for the researchers to study changes in the brain's anatomy.
R - The cerebral cortex of the enriched rats was significantly heavier and thicker than the impoverished rats.
The enriched environment rats also produced larger neurons than the impoverished rats and the synapses of the enriched rats’ brains were 50% larger than those of the impoverished rats.
C - The implications of the study are that the human brain should also be affected by environmental factors such as intellectual and social stimulation.
Rogers and Kesner (2003) - The role of acetylcholine on memory
A - To determine the role of acetylcholine in the formation of spatial memories
P - 30 rats got familiar with a Hebb Williams maze by placing food in one corner.
Two conditions: Experimental - injected with scopolamine, intended to block the receptor sites of acetylcholine, thus, inhibiting response. Control - placebo saline solution. Encoding memory was assessed by the average number of errors in the first five trials of Day #1 vs the last five trials of Day #1. Retrieval of memory was assessed by the average number of errors in the last five trials of Day #1 vs the first five trials of Day #2.
R - The findings were that the scopolamine group took longer and made more mistakes in the learning of the maze - that is, there was a higher average number of mistakes made on the last five trials on Day 1.
However, it did not appear to have an effect on retrieval of memories that had already been created.
C - It appears that acetylcholine may play an important role in the consolidation of spatial memories.
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