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An Investigation of Striatal Activity During Delayed and Effort-based Learning

出版	Rutgers University, 2012
URL	http://books.google.com.hk/books?id=SoFNAQAACAAJ&hl=&source=gbs_api

註釋Motivation influences human learning and outcome valuation. Depending on the context, one can interpret an outcome in a positive way or not pay attention to the action outcome at all. The striatum is one of the primary structures involved in outcome valuation and learning and of action-outcome contingencies. Striatal activity has been shown to be context-dependent and to reflect individuals' subjective preferences. This dissertation examined striatal activity in the context of delayed and effort-based learning, as well as whether people are willing to overcome effort costs in order to benefit an unfamiliar disadvantaged person. Two functional magnetic resonance imaging experiments were conducted examining striatal activity during performance-related feedback under different time frames (Experiment 1) and following different cognitive effort requirements (Experiment 2). Behavioral Experiment 3 looked at whether individuals are willing to exert cognitive effort during learning to reduce inequity between themselves and a disadvantaged individual. Experiment 1 replicated previous findings of ventral striatal activation to immediate feedback presentation. It was also shown that when feedback is presented after a substantial delay of 25 minutes, processing of feedback switches away from the striatum to posterior parts of the basal ganglia. Experiment 2 revealed that activity of the ventral striatum associated with feedback reflects effort expenditure required to obtain it. Experiment 3 showed that unfair social context can motivate individuals to exert cognitive effort during learning. This work shows that striatal response to learning outcomes is differentially influenced by delay and effort requirements and that effort costs can motivate learning.