In this type of research, the relationship between variables is studied, but there is no manipulation of an independent variable:

Frequencies of lower than 200 Hz are encoded

a. by rapid movements of the cilia. b. by movement of the basilar membrane closest to the tectorial membrane. c. anatomically. d. temporally. e. locally.

Sleep is partially regulated by melatonin from the:

a. Thalamus b. Hypothalamus c. Limbic system d. Pineal gland