Date of Completion

2017

Document Type

Honors College Thesis

Department

Neuroscience

Thesis Type

College of Arts and Science Honors, Honors College

First Advisor

Scott Mackey

Second Advisor

John Green

Third Advisor

Mark Bouton

Keywords

neuroimaging, neuroscience, instrumental learning, psychology, habit-based, goal-directed

Abstract

Addiction has been proposed to result from an overreliance on the habit-based and goal-directed controllers of behavior; however, few data exist to simultaneously support both behavioral and neuoranatomical aspects of this theory in humans. Here, we clarify the locations of the homologous structures controlling behavior in the human brain to those studied in animal models. The study included two parts. 1) The first part established in a behavioral experiment that the devaluation video in the present paradigm was able to influence instrumental behavior. Using a 3-session instrumental learning task to examine behavior, we examined 78 participants, aged 18-35. A significant difference in the change in response rate immediately before and after devaluation was found between the 2 groups viewing worms in devaluation compared to the group not viewing worms. There was a significant difference in change in liking immediately before and after devaluation between the three conditions, as well as in the change in liking, hunger, and response rate between the paired and empty bowl unpaired conditions. There was a significant correlation between snack liking pre-session 3 and response rate in session 3, as well as between pre-extinction snack liking and response rate in the start of extinction.

2) The second part of the study used the same 3-session training paradigm over 3-days, with fMRI on the third day to measure neural activity during this same instrumental learning task. Although the results are preliminary (N=10), these show that the comparable regions of the human brain are involved in goal-directed and habit-based control of behavior, with a perfect negative Spearman correlation of mean vmPFC activity at the end of training and the change in responding from immediately before to immediately after devaluation.

Three of the 10 subjects were addicted smokers, which is insufficient data to determine whether they were less sensitive to reward devaluation and whether they relied more heavily on brain structures associated with habit-based controllers of behavior. However, understanding the relationship between habit-based and goal-directed controllers of behavior and their role in addiction and clarifying the human brain structures responsible for these systems can lead to the development of therapies for addiction.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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