Gloria says she has an old EEG machine, which she says can be used to determine if the hippocampus is functioning properly. EEGs only measure electrical activity at the cortical surface and can't be used to determine the source of the activity. The hippocampus is a deep brain structure, so a surface EEG would be useless by itself in determining its functionality.
Audrey has a smartphone, with no physical buttons. As she is blind, there is no way she can dial Nathan's number.