BLO #7: What are two effects of the environment on physiological processes?

How the environment affects the brain Pre-1960s the brain was believed to solely a product of genetics and therefore it was unchangeable Studies in the 1960s demonstrated that the brains of rats could change in response to the environment Later studies confirmed the same ability of the human brain to change in response to its environment

“Environment” refers to: Learning Socializing with others Technology

“ Physiological changes” refers to: Brain plasticity which means the brain’s ability to rearrange the connections between neurons the brain’s structure can change as a result of experience or learning

How does plasticity occur? High levels of stimulation and learning can lead to an increase in the density of neural connections This happens because every time we learn something new the dendrites of the neurons grow in number and connect with other neurons.

This is called dendritic branching.

Lifecycle of Neural Connections At birth we have about 2500 neural connections By age 2-3 we have built around 15,000 connections As we get older these connections decrease, but the ones that are well-used become stronger

Enriched/Deprived Environment Rat Study (Rosenzweig and Bennett, 1972) AIM: to see if rat brains would change in response to their environment METHOD: Researchers placed rats into one of two environments for 30-60 days The first was a rich, stimulating environment filled with interesting toys to play with The second was characterized by no toys

RESULTS: The rats from the enriched environment had an increased thickness in the cortex The frontal lobe (responsible for thinking, planning, and decision-making) was also heavier in this group of rats

Follow-up studies have shown that the cortical thickness increases even further when the rats are placed with other rats

London taxi driver Study (Maguire et al. 2000) AIM: to identify whether London cab drivers had structural differences in their Hippocampi as a result of their learning the job.

Method Researchers used MRI scans to compare the hippocampi of fully licensed male cab drivers to average males who did not drive cabs.

Findings The more experienced drivers had more volume in their hippocampi which was explained as being a result of more neural connections built up in that part of the brain needed for spatial memory.