Discuss+two+effects+of+the+environment+on+physiological+processes+(for+example,+effects+of+jet+lag+on+bodily+rhythms,+effects+of+deprivation+on+neuroplasticity,+effects+of+environmental+stressors+on+reproductive+mechanisms.

People used to think that the brain was influenced by genetics only, and was therefore fixed. Now, the concept of **neuroplasticity** is widely accepted. This refers to the brain's ability to **rearrange the connections between its neurons**, changing it structurally as well as functionally as a **result of the environment**. Two studies that support the idea that the brain is ever-changing are Maguire's study on spatial navigation and its effect on the hippocampus, and Rosenzweig and Bennett's study on deprivation versus enrichment and its effect on rat brains.



__**Maguire et al. (2000)**__
 * Aim:** To investigate whether or not the hippocampus plays a role in human spatial memory
 * Method:**
 * London taxi drivers with a range of age and experience were the participants because their work requires the extensive use of spatial navigational skills
 * Matched pairs design: participants were age and gender matched with a control group
 * Two different types of MRI scanning were used to assess how the brains of the taxi drivers differed from the control group
 * Quasi experiment
 * Results:**
 * VBM showed significantly more grey matter in both left and right hippocampi of the taxi drivers compared to the control group, but this was restricted to the posterior region.
 * For the control group, the pixel counting revealed a larger anterior right hippocampus than the left and larger body of the hippocampus on the right than the left than in taxi drivers, but the posterior hippocampus was larger in taxi drivers than in controls.
 * Evaluation:**
 * No researcher bias
 * No demand characteristics
 * No ethical implications
 * Only observed males
 * Only observed 16 matched pairs
 * Nature vs. Nurture debate: did the driving influence the change in the hippocampus, or did their larger than average hippocampus lead them to become taxi drivers?
 * Use a longitudinal study to determine which one it is
 * Positive correlation between time spent taxi-driving and the volume of the right posterior hippocampus.
 * Quantitative data received
 * Allowed us to understand that the hippocampus is one of the parts of the brain that stores memory, which helps us understand how to rehabilitate patients with brain damage


 * __Rosenzweig and Bennett (1972)__**
 * Aim:** To measure the effect of either enrichment or deprivation on the development of neurons in the celebral cortex of rats.
 * Method:**
 * Researchers placed rats into two environments
 * One environment was an enriched, stimulating environment with interesting toys for the rats to play with
 * The other was a deprived environment with no toys
 * Rats spent 30-60 days in their respective environments
 * They were sacrificed; researchers then dissected and measured the cortex of the rats.
 * Results:**
 * Rats that were in the stimulating environment had a thicker celebral cortex and heavier frontal lobes than the rats in the depriving environment.
 * Evaluation:**


 * The rats were sacrificed, ethical implications.
 * I t is very difficult to decide on what an ‘enriched’ environment is
 * Animals aren’t able to communicate with us so we cannot possibly know for sure the effect of the environments
 * The subjects of the study were rats. This means that the results of the experiment cannot be generalized to humans as this would be assuming that rat brains are the same to human brains.
 * Results between the two contrasting environments are operationalized in a way that they are in the form of quantitative data, so it is easy to compare.
 * The study was a lab experiment, and so all the variables of the study could be controlled, including the life of the rat’s life, like food and water. This allows for a direct cause and effect relationship to be established as the total control means that there are minimal, if any, confounding variables.

Both of these experiments support the idea that the brain is not fixed, but is actually changing from environmental stimuli. Rosenzweig and Bennett's experiment can be applied to our lives: the results of their study suggest that we //**need**// to play with human babies in order for their celebral cortexes to develop properly.