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December 4, 2011

Dopamine: Dictating Dangerous Decisions


Decisions shape lives. Every day in the news, we are berated with stories of people who‚??s lives were changed due to decisions they made, both good and bad. It seems plausible that the most rewarding outcomes are often accompanied by a risk of adverse consequences. So what is it that dictates how humans evaluate risk and reward? How do people decide if something is ‚??worth the risk‚??. Why are some people seemingly better at making decisions than others? A study published on November 30th 2011 in the Journal of Neuroscience provides some insight into how different dopamine receptor subtypes are involved in evaluating risk behavior and making decisions.
The experimenters investigated the role which dopaminergic subunits may play in helping people to evaluate scenarios and make beneficial decision. For example, they found that by systematically activating D2-like receptors in rats, risk taking behavior was substantially diminished. Unlike D2 receptors, activating D1-like receptors had no significant effect on risk taking behavior in the rats. Additionally, lower levels of D2 mRNA in the dorsal striatum were associated with increases in risk taking behavior among the rats being tested.
The experiment provided the rats with a choice between a small reward with minimal risk as opposed to a large reward with greater risk. The greater risk for the large reward was presented in the form of electric shocks to the rats feet. Rat‚??s who received the shock also received three times as much sucrose as the rats who settled for a third as much sucrose with no shock. Motivational tests were used to attempt to ensure that the rats desired the higher dosage of sucrose more than the lower dose. D1 and D2 probes were used to analyze mRNA expression in the rats.
This type of experimental procedure can be problematic because there is a high degree of variability in the preferences of rats in relation to risk and reward. Although certain correlations drawn by the experimenters may be considered questionable for this reason, the experiment does attempt to relate the experimental results to risk=-taking behavior. Unlike previous works which found rat performance to be stable, this experiment found that rat performance could change in nature ranging from strongly risk averse to strongly risk taking. The procedure was complicated and based on many experimental procedures which were not well explained. For example, what baselines did the experimenters use in their motivational tests and how were these type of arbitrary statistical markers determined? Throughout this paper, there were manipulations which were apparently done systematically, yet without more information on what ‚??systematically‚?? means in specific scenarios, it is difficult to draw conclusions regarding the legitimacy of the procedures, and thus their actual relevance to risk taking.
Regardless of these concerns, this experiment does attempt to further investigate how the dopamine signaling pathway is involved in risk taking. Understanding the implications of these pathways may provide explanations as to how decision making processes can be altered in the cases of psychological disorders. These types of disorders are often classified by abnormalities in decision making and risk taking behavior, and consequently, individuals who suffer from them often have a very hard time making the decisions or performing the behaviors necessary to succeed in their endeavors. Furthermore, if more is determined about these pathways, it may also be possible to investigate why drugs cause people to make bad decisions from a scientific perspective. For now, when conflicted with a tough choice, each person still must use their personal preferences and insights to determine what decision to make. Perhaps, further research can help to discover exactly how dopamine receptors can be manipulated in order to assist struggling individuals in their decisions.
Posted by      Aaron R. at 5:15 PM MST

Comments:

  Aaron R.  says:
Simon, Nicholas W., Karienne S. Montgomery, Blanca S. Beas, Marci R. Mitchell, Candi L. LaSarge, Ian A. Mendez, Christina Banuelos, Colin M. Vokes, Aaron B. Taylor, Rebecca P. Haberman, Jennifer L. Bizon, and Barry Setlow. "Dopaminergic Modulation of Risky Decision-Makin." Journal of Neuroscience 31.48 (2011): 17460-7470. Web. 4 Dec. 2011. .
Posted on Sun, 4 Dec 2011 5:26 PM MST by Aaron R.

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