The effect of Deprivation and Stimulation on Neuroplasticity

1. The effect of Deprivation and Stimulation on Neuroplasticity By Mr Daniel Hansson

2. Neuroplasticity Neurons can compensate for injury or disease or to adjust their activities in response to new situations or changes in the environment. The brain is most plastic early in life. The brain can rearrange the connections between neurons (dendritic branching) The brain can generate new neurons throughout life (neurogenesis) Learning can increase/decrease neurotransmission between specific neurons (long term potentiation) It is assumed that as your behavior changes, so does the underlying neural circuitry.

3. Questions What are the methodological and ethical strengths and limitations of the following studies on neuroplasticity? What are the general strengths and limitations on research on how the environment affects neuroplasticity? E.g. possible applications, generalisability, methodological problems, other possible factors that may influence or prevent neuroplasticity What conclusion can be drawn from the research? To what extent is the brain affected by environment? How much do we know about these processes?

4. Rosenzweig & Bennett (1972) Aim: To investigate the effect of enrichment or deprivation on the development of neurons in the cerebral cortex in rats Research method: Experiment Procedure: Rats were placed in either a stimulating environment (toys) or a deprived environment (no toys). The rats spent 30 or 60 days in their environment and then they were dissected.

5. Rosenzweig & Bennett (1972) Findings: Post mortem studies of the rats� brains showed that those that had been in a stimulating environment had an increased thickness in the cortex.

6. Kolb (1999) Aim: To investigate if stimulating environments affect the growth of neurons in rats Research method: Experiment Procedure: Rats were placed in enriched environments beginning at weaning or as young adults. Control group were placed in standard cages

7. Kolb (1999) Findings: Both age groups raised in enriched environments showed a large increase of the length of dendrites in cortical neurons.

8. Goldapple (2004) Aim: To investigate how cognitive therapy affects brain changes Research method: Experiment Procedure: PET scans were used to document brain activity before and after 15 to 20 therapies of cognitive therapy over seven weeks in 14 patients. PET scans from a previous study on participants taking antidepressants were used as a control group. Participants were screened to ensure that they had no substance problems or antidepressant treatment one month prior to the study. Some of the participants reported previous negative experiences with drug therapy.

9. Goldapple (2004) Findings: There were significant changes in glucose metabolism in prefrontal-hippocampal pathways. The changes in the brain were the same as with antidepressants.

10. Small & Vorgan (2008) Aim: To investigate the effect of computers on the brain Research method: Quasi experiment Procedure: fMRI scans were used to compare the brains of people who had never used a computer with the brains of people using computers regularly. Both groups first participated in a control condition which involved reading simulated book text. Both groups also conducted an internet search task. All participants were also asked to conduct an internet search each day for five days.

11. Small & Vorgan (2008) Findings: The scan showed a difference in the activity of the dorsolateral prefrontal cortex between experienced and naive computer users. After five days of practice, inexperienced computer users showed the same brain activity as those with experience.

12. Other studies on neuroplasticity Kolb et. al. (2004): Pregnant rat mothers were housed in enriched environments. Their babies had increases in the synaptic spaces of the cortical neurons as adults. Curtis (1977): A case study on a girl (Genie) who was socially isolated (strapped to a potty chair in an isolated room) until the age of 11. She had virtually no language ability. Although tests showed that she was highly intelligent, her language abilities never progressed beyond those of a third grader.

13. Other studies on neuroplasticity Gold et. al. (1999): Rats were injected with a compound called BRDU that labels newly born neurons (BRDU is also a toxic that has the potential of causing mutations, as it enters cells during protein synthesis). Animals were trained on a classical conditioning task that requires the hippocampus. Rats that underwent the training showed a significant increase in the number of new neurons

14. Other studies on neuroplasticity Pascal-Leone (2002): Participants were instructed to learn to practice a five-finger piano exercise for five days, two hours every day. During the session, the participants� motor cortex was investigated by the use of a transcranial-magnetic-stimulation test (TMS). The findings showed that practice altered the structure of the area devoted for the finger movements. For a group of participants who also had been instructed to imagine they were playing five-finger piano tone outside of practice, the area for finger movements in the motor cortex expanded even more. The results suggest that training and imagination can alter brain physiology. University College London (2000): MRI scans on 16 London cab drivers showed that taxi drivers have a larger hippocampus than other people. The hippocampus was larger the more years they had worked as taxi drivers. The hippocampus is thought to be involved in navigation in animals.

15. Other studies on neuroplasticity Van Praag et. al. (1999): If animals are given an opportunity to exercise the number of newly born hippocampal neurons are increased Hull & Vaid (2006): A meta analysis on 1234 bilingual and monolingual participants. Findings showed that participants that had acquired a second language before the age of 6 had more right hemisphere involvement in language tasks.