There is an optimal emotional state for learning which is affected and moderated by the fear and pleasure centers in the brain.  We call this state optimal Relaxed Alertness.  In Making Connections (Caine and Caine, 1994) it was defined as consisting of low threat and high challenge.  

The state exists in  a learner who feels competent and confident, and is interested or intrinsically motivated.  Relaxed Alertness is also a state that is present in  classrooms and learning environments in which emotional and social competence is the goal.

Such  an environment allows all students ongoing opportunities to  experience competence and confidence accompanied by motivation linked to personal goals and interests.