Environmental enrichment (EE) is the study of organisms reared in complex, varied environments and the subsequent influences on behavior. Studies have shown many mechanisms for how EE elicits changes in behavior, mental and physical processes, and neurophysiology. EE has been shown to work as a preventive, protective or restorative treatment for many conditions and maladies. Drug use and abuse solicit changes in the reward pathways of the brain which are a natural incentive system to food and sex. These reward pathways, linked with dopaminergic neurons, are all affected by EE through the regulation of dopamine transporters and receptors, as well as through direct changes in the amount of synapses, neurons and glial cells in structures inherent in reward pathways. To expand on our knowledge of EE and reward systems, the effect of EE on a naturalistic reward such as palatable food was assessed. It was predicted that EE would cause subjects to ingest less palatable food because the same reward system that, under enriched conditions, causes rats to ingest less drugs would drive them to ingest less highly-palatable food as well. Rat subjects were reared in enriched and non-enriched environments, after which subjects' intake of highly-palatable and low-palatability food types was measured. No significant trend was found between environment and food preference in rat subjects.
[...] Since palatable food reward is rated via the dopaminergic system and enrichment affects this dopaminergic system, it was predicted that enrichment would have a similar effect on the intake of palatable foods as it does to the intake of cocaine or amphetamine. Similar to how enriched rats self-administer less cocaine and amphetamine than their IC cohorts, the EC rats in this study were predicted to "self-administer" less highly palatable food than IC rats. It was also hypothesized that EC rats would consume a lower percentage of HP food compared to low palatability food. [...]
[...] The field of environmental enrichment is a fascinating area of science with many opportunities for further discovery. Acknowledgements I would like to thank Dr. Thomas Borowski of Pitzer College for his mentoring and assistance throughout this project during the planning, execution and analysis of this experiment. I would also like to thank Dr. Newton Copp of the Joint Science Department for reviewing this manuscript and for providing helpful criticism throughout the writing process of this report. Special thanks also to Dr. [...]
[...] If the food consumption data were converted from percent consumed to a measure of grams eaten/gram bodyweight method discussed later in this report) then perhaps the results for both EC and IC environments would become similar because then effects on the results of the EC subjects' higher bodyweights would be eliminated. One possible way this experiment could be improved for the future would be to monitor the bodyweight of the subjects during the testing period. If each animal were weighed each day during this period, useful data could be obtained on food consumed per gram bodyweight. [...]
[...] Though technically no significance was found between Environment = p = 0.056 it must be noted that this data approached the predetermined level of significance = 0.05 A high variability in the consumption of LP food was observed, with some EC subjects consuming solely LP food and at least 2 IC subjects frequently consuming none at all and instead focusing their attention entirely on the HP food source. The ANOVA revealed no significant interaction between Day x Environment data (F[6,102] = p = 0.221 The maximum value of LP food consumed (Day EC) was much lower than the maximum value of HP food consumed by both EC and IC groups (see Figure 3). [...]
[...] Tin bowl Clothes hanger Sunglasses frame Computer mouse Frisbee Ankle brace Comb Glass bottle Exercise wheel Elastic band Shoe brush Mouse pad Ankle brace Plastic package Candy tin Tennis ball Lab striker Earphone case Rock Wood block Quartz rock Beaker Pink pong ball Spoon Pen tube Candy tin Fork Magnetic dart Gardening glove Poker chip Domino Corkscrew Domino Button Plastic bowl Plastic bottle Poker chip Pen Coffee mug Tea strainer Twenty-four hours following the last day of enrichment both EC and IC groups were exposed to a 5-day food deprivation schedule. [...]
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