Graded potentials decrease in size as they spread; the term for this is:

Results from neuroimaging studies suggest that

a. a single "thinking center" mediates thought. b. thought occurs in widely distributed areas of the brain. c. a single brain region mediates thought. d. the cerebellum is loosely divided into subsections which deal with different kinds of thought. e. most types of mental processing occur throughout the brainstem.

Given the inconsistent evidence about levels of neurotransmitters in people with mood disorders, researchers have begun to focus research efforts on

a) whether specific levels of serotonin or dopamine are important. b) understanding the types of people who have no disturbances in their absolute levels of neurotransmitters. c) finding a new neurotransmitter. d) the sensitivity of postsynaptic receptors.