Fetch Allen Human Brain Atlas microarray expression data from all donors and all genes (author: @saratheriver)

Parameters:csvfile (None or string, optional) – Path to downloaded csvfile. For more threshold and parcellation options, download csvfile from here: https://github.com/saratheriver/enigma-extra/tree/master/ahba If None (default), fetches microarray expression data from the internet (aparc and stable r > 0.2).
Returns:genes – Table of gene co-expression data, shape = (82, 15633)
Return type:pandas.DataFrame