Cognitive effort has been implicated in numerous theories regarding normal and aberrant
behavior and the physiological response to engagement with demanding tasks. Yet, despite …

When rats come to a decision point, they sometimes pause and look back and forth as if
deliberating over the choice; at other times, they proceed as if they have already made their …

Why does performing certain tasks cause the aversive experience of mental effort and
concomitant deterioration in task performance? One explanation posits a physical resource …

The mesostriatal dopamine system is prominently implicated in model-free reinforcement
learning, with fMRI BOLD signals in ventral striatum notably covarying with model-free …

Experiences affect mood, which in turn affects subsequent experiences. Recent studies
suggest two specific principles. First, mood depends on how recent reward outcomes differ …

Reward contains separable psychological components of learning, incentive motivation and
pleasure. Most computational models have focused only on the learning component of …

We review the current state of knowledge on the computational and neural mechanisms of
reinforcement-learning with a particular focus on fronto-striatal circuits. We divide the …

Intense research interest over the past decade has yielded diverse and often discrepant
theories about the function of anterior cingulate cortex (ACC). In particular, a dichotomy has …

The significantly expanded and updated new edition of a widely used text on reinforcement
learning, one of the most active research areas in artificial intelligence. Reinforcement …

Serotonin's function in the brain is unclear. One challenge in testing the numerous
hypotheses about serotonin's function has been observing the activity of identified …