Dr. Mullis is most likely a psychologist testing for dyscalculia or another math learning disability rather than simply needing extra support in math. A psychologist can also give input as to the possibility of other learning differences, such as ADHD or dyslexia.
A mirror neuron is a neuron that fires both when an animal acts and when the animal observes the same action performed by another. it “mirrors” the behavior of the other.