The Role of the Ventral Tegmental Area in the Extinction of Probabilistic Rewards

Persistent Link:
http://hdl.handle.net/10150/188389
Title:
The Role of the Ventral Tegmental Area in the Extinction of Probabilistic Rewards
Author:
Song, Minryung
Issue Date:
2011
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Because most of the events in the world are probabilistic and changing, the extinction of probabilistic events that no longer occur is important for survival. Here, we investigated the effect of reward probability on the rate of extinction using behavioral and pharmacological experiments in rats and temporal difference model simulations. Our experimental results suggested that ambiguity during extinction and the value of probabilistic reward are the two major causes that resulted in the inverted U-shaped relationship between the rate of extinction and reward probability. Using pharmacological activation and inactivation of midbrain dopamine neurons, we reasoned that ambiguity may not be signaled by dopamine neurons. By adding an ambiguity signal into an existing temporal difference model, we reproduced the inverted U-shape for the first time and supported our conclusion. Our study provides insights into the extinction of probabilistic rewards and gives a useful computational model for further investigation.
Type:
text; Electronic Thesis
Degree Name:
M.S.
Degree Level:
masters
Degree Program:
Graduate College; Neuroscience
Degree Grantor:
University of Arizona
Committee Chair:
Fallous, Jean-Marc

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleThe Role of the Ventral Tegmental Area in the Extinction of Probabilistic Rewardsen_US
dc.creatorSong, Minryungen_US
dc.contributor.authorSong, Minryungen_US
dc.date.issued2011-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractBecause most of the events in the world are probabilistic and changing, the extinction of probabilistic events that no longer occur is important for survival. Here, we investigated the effect of reward probability on the rate of extinction using behavioral and pharmacological experiments in rats and temporal difference model simulations. Our experimental results suggested that ambiguity during extinction and the value of probabilistic reward are the two major causes that resulted in the inverted U-shaped relationship between the rate of extinction and reward probability. Using pharmacological activation and inactivation of midbrain dopamine neurons, we reasoned that ambiguity may not be signaled by dopamine neurons. By adding an ambiguity signal into an existing temporal difference model, we reproduced the inverted U-shape for the first time and supported our conclusion. Our study provides insights into the extinction of probabilistic rewards and gives a useful computational model for further investigation.en_US
dc.typetexten_US
dc.typeElectronic Thesisen_US
thesis.degree.nameM.S.en_US
thesis.degree.levelmastersen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineNeuroscienceen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairFallous, Jean-Marcen_US
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