It seems unlikely that there is any basis to this claim.
See this question and the answer and comments posted on psychology.stackexchange.com.
While there are, according to @Fizz, CT devices for larger animals such as horses, CT cannot be used for functional imaging of the brain. The maximum mass that can be put onto the stretcher of the CT device is given as "30 stone or more". 30 stone are about 191kg according to Google conversion. Adult elephants however have a much larger mass from approximately 2.000 to 6.000kg depending on species and sex. If a young elephant was used in any study, this would probably have been mentioned.
There is an MRI table for large animals up to 1.100kg which seems to be in the horse-weight range. Other MRI scanner architectures exist, for example an open upright MRI for humans. Whether larger versions for large animals exist is not known.
In order to determine which region of the brain is active the elephant in addition would have to be awake and see a human, otherwise the brain could not process the picture. It seems difficult to physically constrain an elephant so that his head can be used for PET or fMRI.
While MEG or EEG can also be used to determine the region of brain activity, these methods require the solution of an inverse problem with additional assumptions, which are difficult to make.
(Thanks to @Fizz for the main part of the information contained in this post.)