The chemical composition of some drugs, such as opioids, mirrors that of naturally occurring substances, such as opiates.

Abnormality in this area of the brain has been associated with autism.

a.) frontal lobes b.) brain stem c.) cerebellum d.) corpus callosum

In part, the contemporary version of color vision says that

a. there are four types of color cones in the retina, rather than three. b. ganglion cells combine outputs of cone types in an opponent-process manner. c. color cones are equally responsive to all wavelengths of light. d. people who are color-blind possess an inhibitory system, but lack an excitatory system.