Tomorrow, it will be 2013! And while it may seem that the world around us has not changed, calendars and clocks remind us that it’s time to kick old habits, set goals, and make resolutions. As 2012 fades into memory, we optimistically look forward to the blank slate that 2013 can offer.
I am one of millions of people who sincerely sets out to make endless positive changes in the New Year. For the first few months, I maintain a strict athletic routine and avoid my favorite meals (sweets) along with late-nights involving alcohol. But, oh how the mind can be weak! Like muscles after a workout, my will power quickly gives way to old habits. Apparently, this also happens to 88% of people who embark on the journey to positive change. So, why do we fail to keep resolutions?
Researchers from Princeton University help to address this question by pointing to the prefrontal cortex (PFC) and the midbrain dopamine system as essential players in encoding, updating, and maintaining goals. The results by D’Ardenne et al., published in this month’s edition of PNAS, dissect how we are able to focus on the pursuit of a goal, while also updating our goal in an ever-changing world. It’s a truly amazing feature of the brain. For example, it enables us to stop working on a paper for class to have a discussion with a classmate, or ignoring other conversations and distractions around us as we write.
The PFC, which is located just behind your forehead, is essential for maintaining and updating goals. It supports working memory by retaining contextual information that is necessary to perform a goal-oriented task. In this study, two psychological experiments were performed using functional Magnetic Resonance Imaging (fMRI). The participants were positioned in the fMRI, handed a controller with two buttons, and asked to watch a white screen. During the experiment, participants were asked to view the screen and remember if an “A” or a “B” was displayed. After a delay time, where the screen was blank, an “X” appeared on the screen and the subject had to hit button #1 or #2 after seeing the letter “A” or “B”, respectively. In other trials, the participants were asked to hit button #1 irrespective of what cue was on the screen.
The fMRI recorded the participants’ brain activity during each trial and compared the regions of the brain that were active during the first and second set of experiments. The first experiment showed the brain activity during the working memory task, where the participant had to remember the cue-button association (i.e. remember “A” and hit button #1), while the second experiment showed the brain activity when the participant was asked to ignore the cue altogether (i.e. hit button #1 regardless of “A” or “B”). The researches then compared the differences in brain activity between the two experiment types to see which regions were most important for contextual working memory (“Remember ‘A’ and hit button #1”). The results of these experiments highlighted the dorsolateral prefrontal cortex (DLPFC) as a necessary area involved in contextualizing information during these tasks.
To prove that the DLPFC was required for working memory context updating during a goal-oriented task, researchers disrupted the function of the DLPFC by using transcranial magnetic stimulation (TMS). This non-invasive technique allows researchers to inhibit the activity of specific brain regions. When a TMS pulse was applied to the DLPFC during the experiments, participants showed significantly impaired performance! This suggests that the DLPFC is essential for updating context information in goal-oriented tasks, like goals or New Year’s resolutions.
Even more exciting was the link found between the DLPFC and the brain’s reward system. Using high-resolution fMRI, the research team found that the substantia nigra (SN) and the ventral tegmental area (VTA) were activated at the same time as the DLPFC when context updating was required! These observations suggest that the activity of the brain’s reward system is coordinated with the DLPFC and may even allow the DLPFC to update the goal depending on the current context.
So, what does this mean for our New Year’s resolutions? Because of the link to the dopamine system, we may update our goals to things that are more pleasing. For example, we may choose to go to a late-night party instead of the gym, or we may choose to eat a slice of cheesecake instead of a salad. Perhaps we all need some TMS in our reward pathways so our DLPFC can’t update our goals and our New Year’s resolutions don’t get derailed! We, at Knowing Neurons, wish you success at keeping your resolutions in 2013!10.1073/pnas.1116727109 Images by Juan Velasquez and Kate Jones and adapted from Napadow V., Kettner N., Liu J., Li M., Kwong K.K., Vangel M., Makris N., Audette J. & Hui K.K.S. (2007). Hypothalamus and amygdala response to acupuncture stimuli in carpal tunnel syndrome, PAIN, 130 (3) 254-266. DOI: 10.1016/j.pain.2006.12.003
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