Sunday, 25 March 2012

Decreasing Impulsivity


Each of us has experienced impulsivity at some point in our lives. For some of us however, impulsivity can manifest itself in negative ways, commonly seen as addictive behaviours such as smoking, sex, drugs etc. Luckily however, Pena-Oliver and his team of research scientists discovered just at the end of last year a link between a protein (known as alpha-synuclein) that each of us synthesise from the scna gene within our brain, and impulsive behaviour in animals. Pena-Oliver and his team theorise that if we can find a way to effectively decrease the prevalence of alpha-synuclein within our brains, then society could see a massive decrease in addictive-behaviours such as smoking etc.

Unfortunately however, both Pena-Oliver et al and other researchers have noticed that there is currently a clear link between decreased levels of alpha-synuclein in the human brain, and development of Parkinson’s disease. Ironically, it was this link that allowed Pena-Oliver and his team to discover that decreased levels of alpha-synuclein correlated with decreased impulsivity as they noted that PD suffers displayed lower impulsivity. To test their theory, Pena-Oliver and his team bred two strands of mice: a wild type strand that had no alteration to their scna gene, and an ‘H’ strand, which had their scna gene deleted prior to development. Pena-Oliver and his team then devised 5 types of experiments to test the degree of impulsivity within each of the strands of mice. As the figures below indicate, Pena-Oliver and his team certainly discovered direct variation between levels of alpha-synuclein within the brain and degrees of impulsivity.


As the above diagram illustrates, as the amount of alpha-synuclein increased within the brain, the percentage of mice which acted impulsively increased. But simply saying that high levels of alpha-synuclein in the brain increased impulsivity did not seem to satisfy Pena-Oliver and his team. Upon gathering these findings, Pena-Oliver et al theorised that alpha-synuclein has a direct effect on the hippocampus, an area of the brain heavily involved with the decision making process. Whilst they were unsure of the specific role alpha-synuclein played in the hippocampus, they hypothesised that alpha-synuclein somehow interferes with the hippocampus’ ability plan courses of action within an environment, and that when alpha-synuclein is absent from the brain, the ability of the animal to plan a course of action becomes far greater. This therefore allowed the ‘H’ mice to plan appropriately and make an informed decision, unlike the wild type mice, which were unable to make an informed decision and simply acted out of impulse.
 
So if the deletion of the scna gene in mice decreased impulsiveness, does that mean the same can be done with humans? Not necessarily. Whilst it is certainly possible that impulsivity may be reduced in humans should alpha-synuclein within our hippocampus’ be removed, Pena-Oliver and his team stress that it appears the alpha-synuclein protein plays an important role in humans in inhibiting the onset of Parkinson’s disease and that if the scna gene is deleted within the human brain, the incidence rate of Parkinson’s disease could increase dramatically. Should this obstacle be overcome however, then society may see a drastic decrease in addictive behaviours within the human population.

If you would like to read more on the topic of scna deletion, please follow this link: http://onlinelibrary.wiley.com/doi/10.1111/j.1601-183X.2011.00758.x/full
If you would like to read more on the role the hippocampus plays in decision making, please follow this link: http://www.sciencedaily.com/releases/2010/03/100311123620.htm
 
Reference List:
Pena-Oliver, Y, Buchman, V, Dalley, J, Robbins, T, Schumann, G, Ripley, T, King, S, Stephens, D 2011, Deletion of alpha-synuclein decreases impulsivity in mice, Genes, Brain and Behaviour Volume no. 11, The International Behavioural and Neural Genetics Society, viewed 11 March 2012, http://onlinelibrary.wiley.com/doi/10.1111/j.1601-183X.2011.00758.x/full
Science Daily 2010, New Insight into Brain’s Decision-Making Process, viewed 18 March 2012, http://www.sciencedaily.com/releases/2010/03/100311123620.htm

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