Neural and cognitive mechanisms underlying adaptation: Brain mechanisms that change the priority of future information based on their behavioral relevance

The ability of the human brain to change the priority of which information is being processed is a key property that underlies day-to-day functioning. We constantly shift our attention to those stimuli or events that are behaviorally important. This thesis is focused on understanding the biological neural mechanisms by which the brain accomplishes this feat and what the long term consequences are. In the studies described in this dissertation we asked participants to do computer-run cognitive tasks during which we recorded high-temporal resolution electroencephalography (EEG) measures of their electrical brain activity. We used rewards to change the behavioral relevance of certain events, and investigated how the brain was able to facilitate the processing of those events. Besides improved behavioral performance for rewarded stimuli or events, as measured by fast and accurate responses, EEG results indicated that the brain was able to boost the neural activity in less than a second following a reward in those neural populations involved in the processing of those potentially rewarding stimuli or events. These mechanisms were very similar to those involved in the control of attention, suggesting that attention is guided by reward. Moreover, these prioritization processes do not only work on a moment-to-moment basis but can also occur on a much longer timescale, by changing the priority of stimuli by integrating multiple encounters of rewards. Accordingly, as a consequence, the evaluation and use of rewards enables the brain to continually facilitate optimization of specialized neural pathways in the processing and responses to incoming information.