Hormonal chemistry plays a direct role in reinforcement learning, particularly i
ID: 88107 • Letter: H
Question
Hormonal chemistry plays a direct role in reinforcement learning, particularly in those cases in which a reward is unexpected. The pathway for reward learning is well documented: when an individual receives a reward that is unexpected, the event is encoded in the form of a release of dopamine targeting the ventral striatum and the prefrontal cortex. It is through the resultant activity that the individual becomes better at predicting future rewards. The pathway for fear-based learning is less clear, however. Recent studies have pointed to a decay in the response of the amygdala to sequential fear-inducing stimuli as well as an increase in serotonin activity following such events as a potential explanation for prediction error conditioning in fear learning.
Researchers wishing to investigate this pathway tested two groups in a Pavlovian learning task. Prior to testing, one of the two groups followed a protein deficient diet in order to cause tryptophan deprivation (TRP-), resulting in reduced serotonin activity. Researchers applied capsaicin to the forearms of members of both groups to induce increased sensitivity to temperature. Participants were presented with a stimulus consisting of a triangle shown on either the left or right side of a display; reaction times for determining on which side the triangle was shown were recorded. Eight seconds following the display of the visual stimulus, participants were sometimes subjected to a brief temperature increase to the capsaicin-treated area and sometimes were not. Skin conductance readings were taken four seconds after the presentation of the visual stimulus as a measure of autonomic fear response, and fMRI data was acquired.
Researchers discovered no significant difference in reaction times between the two groups. fMRI data showed increased activity in the orbitofrontal cortex and the amygdala for the control group. The TRP group demonstrated no such increase. Skin conductance results are shown in Figure 1.
https://imagebin.ca/v/2qFYwq4KRq6z
Which of the following can be concluded on the basis of the researchers’ study?
A. Tryptophan deprivation may be responsible for a disruption in the ability to learn from prediction errors in anticipation of a reward.
B. Suppression of serotonin pathways is correlated with a decrease in extinction of fear response to inconsistent stimuli.
C. Tryptophan deprivation negatively affects the ability of an individual to develop a fear response to a novel aversive stimulus.
D. Serotonin is largely responsible for the regulation of the physical and emotional aspects of the fear response to aversive stimuli.
Explanation / Answer
Ans B. According to above citation TRP deprivation proceeds with lower serotonin levels. So low TRP = low serotonin.from the graph you see low TRP = high skin conductance, which means low TRP = high fear response. You also see that the skin conductance does not decrease, suggesting that the fear response is not going extinct. So low TRP = disrupt extinction. As question need to know about inconsistent stimuli,Off course it is, because they only get heat shocked some of the time. Since Low TRP = low Serotonin, answer and study both used inconsistent stimuli, it can be propose that Low Serotonin = disrupt extinction.
So It is B. First of all, we are changing TRP levels. Although that affects serotonin, serotonin is not what we are directly changing.
It’s Not A. Because TRP deprivation is related to this study, study not explain in brief about rewards. It was about fear responses to inconsistent averse stimuli.
It’s Not C. TRP deprivation simultaneously with higher skin conductance, which was being used to measure fear response in this study. hence, low TRP is correlated with higher fear.which means it could be easier to develop a fear response to a novel stimulus with TRP deprivation.
It’s Not D. Because, though it may be true, doesn't really seem to be specific to this particular study.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.