The dendrite physically holds the neuron in place. * 1 point True False The speed with which an action potential moves down the axon is determined by the axon's size and the thickness of its myelin sheath. * 1 point True False The longer and thicker the axon the more rapid the impulse. * 1 point True False The abilities to regulate or suppress pain and to experience pleasure are influenced by endorphins. * 1 point True False The fMRI scan also has the potential to treat some psychological disorders. * 0 points True False The limbic system contains three primary components: the thalamus, hypothalamus, and hippocampus. * 1 point True False