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Scientists have identified the specific neural circuitry that triggers anxiety in individuals when confronted with critical decisions. Our brains can actually gauge how critical a decision is and trigger anxiety in us accordingly!
Do you freak out when you have to decide if you want to order pizza or a tub of fried chicken for dinner? No? But you definitely get anxious when you have to decide between schools for your kid or figure out which job offer to accept — the one that will keep you tied to your desk and pay you a hefty paycheck or the one that promises a lot of adventure for peanuts. There is a reason why we get anxious when we have to make certain decisions, and why we decide on other matters without batting an eyelid. The reason is inside the brain.
A mystery solved leads to a discovery
It was pure chance that led scientists to stumble upon the fact that the human brain processes decision-making activities of varying degrees of criticality in different regions. They had started out trying to find out the exact role of striosomes.
Striosomes are bunches of cells scattered throughout the striatum. The striatum is responsible for coordinating our movements and processing emotions. Scientists believed that the striosomes had a hand in the development of certain disorders in humans. But they couldn’t be certain till they had pinpointed the role of these cells.
They also had a hunch that the striosomes play a role in processing emotions because some regions of the prefrontal cortex extend into the striatum. The role of the prefrontal cortex in evaluating stimuli and triggering appropriate emotional responses is well-documented, as evident from the following two studies.
According to one of the studies, different regions of the medial prefrontal cortex (mPFC) contribute equally to facilitate the normal processing of emotions. The dorsal-caudal region of the mPFC is activated in response to negative stimuli while the ventral-rostral portion is responsible for regulating emotional responses.
According to the findings of another study, the ventromedial prefrontal cortex region is involved in the ability of a person to normally differentiate between right and wrong. The study suggests that in cases of certain moral dilemmas, these judgments are influenced by emotions. The study was carried out on persons with damage to the ventromedial prefrontal cortex regions of their brains. It was found that these people displayed abnormal judgment patterns that were devoid of emotional considerations when confronted with situations that presented moral dilemmas.
Based on the above findings and those from other studies, scientists were now curious to know if and how striosomes influence emotions. In an experiment on laboratory mice, the animals were made to choose between two options. In one scenario, the rats could choose a strong-smelling and intensely-flavored chocolate but, in turn, they would be subjected to bright light that they don’t like. In the other scenario, the light was not so bright, but the chocolate was also weak. Clearly, this approach-avoidance scenario was stressful for the animals and they experienced anxiety.
The rats were also made to go through other tests that were not so stressful, so they were less anxious at these times.
In the chocolate-light experiment, it was found that the cortex-striosomes circuit was activated when the rats had to make the decision. But this circuit remained inert in the other less-stressful tests.
When the scientists disrupted the flow of signals between the cortex and the striosomes in the chocolate-light experiment, the rats chose the high-risk, high-reward (strong chocolate-bright light) option 20 percent more than when the flow of input was not interfered with. When the striosomes were forcefully activated by bombarding them with sensory inputs, the rats chose the high-risk, high-reward option less often.
Neuroeconomic studies to find out how humans make decisions had hinted that anxiety and decision-making share neural networks that involve brain regions like the striatum, the ventromedial PFC, the dorsolateral PFC, and the amygdala. This overlap of the brain systems indicates that negative emotions like fear and anxiety determine how an individual calculates value before making a choice. At that time, the scientists were unsure how the circuit worked. Now they know!
The framing effect
Another study points out to the role of the “framing effect” during decision-making activities and how it triggers anxieties.
Individuals also tend to make decisions based on the outcomes they perceive—in terms of gains and losses. That is, how the outcomes are framed — positively or negatively — can greatly influence their decisions in stressful situations. The normal human reaction is to choose positively-framed options and avoid the negative ones. In this study, it was found that the subjects did the opposite (chose the negatively-framed options and avoided the positive ones) when the dorsomedial and dorsolateral PFC regions of their brains along with the anterior cingulate cortex were activated.
Implications of the recent findings
The latest findings that clearly establish how certain decision-making situations can trigger anxiety in individuals have widespread implications. A keen understanding of the neural connections and the associated relationships can help scientists find more effective ways to manage the symptoms of psychiatric disorders like schizophrenia and borderline personality disorder where the decision-making capability of the patient is severely impaired.
The above findings also suggest a possibility that scientists can consider looking into – the relationship between people suffering from anxiety disorders and their tendency to avert risks.
Additionally, these findings should interest psychiatrists and counselors in devising therapies for their patients suffering from anxiety disorders. People suffering from severe anxiety tend to avoid situations that they perceive to be threatening and make decisions accordingly. Such behavioral traits and coping mechanisms can negatively impact on the quality of their lives. The identification of the neural circuitry that governs anxiety response in the face of decision-making and how it works can provide clues to medicine-makers when they try to come up with drug therapies.
Etkin, A., Egner, T., & Kalisch, R. (2011). Emotional processing in anterior cingulate and medial prefrontal cortex Trends in Cognitive Sciences, 15 (2), 85-93 DOI: 10.1016/j.tics.2010.11.004
Friedman, A., Homma, D., Gibb, L., Amemori, K., Rubin, S., Hood, A., Riad, M., & Graybiel, A. (2015). A Corticostriatal Path Targeting Striosomes Controls Decision-Making under Conflict Cell, 161 (6), 1320-1333 DOI: 10.1016/j.cell.2015.04.049
Hartley, C., & Phelps, E. (2012). Anxiety and Decision-Making Biological Psychiatry, 72 (2), 113-118 DOI: 10.1016/j.biopsych.2011.12.027
Jepma, M., & Lopez-Sola, M. (2014). Anxiety and Framing Effects on Decision Making: Insights from Neuroimaging Journal of Neuroscience, 34 (10), 3455-3456 DOI: 10.1523/JNEUROSCI.5352-13.2014
Koenigs, M., Young, L., Adolphs, R., Tranel, D., Cushman, F., Hauser, M., & Damasio, A. (2007). Damage to the prefrontal cortex increases utilitarian moral judgements Nature, 446 (7138), 908-911 DOI: 10.1038/nature05631
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