The problem with the fMRI

The functional Magnetic Resonance Image or fMRI has become a powerful
tool for researchers of the mind.

Here's a study I don't really understand yet.
What we can do and what we cannot do with fMRI
Nikos K. Logothetis
http://www.kyb.tuebingen.mpg.de/publications/attachments/NikosNatureJune2008_[0].pdf

Here's a snip.
"
I hope to point out that the
ultimate limitations of fMRI are mainly due to the very fact that it
reflects mass action, and much less to limitations imposed by the
existing hardware or the acquisition methods. Functional MRI is
an excellent tool for formulating intelligent, data-based hypotheses,
but only in certain special cases can it be really useful for unambiguously
selecting one of them, or for explaining the detailed neural
mechanisms underlying the studied cognitive capacities. In the vast
majority of cases, it is the combination of fMRI with other techniques
and the parallel use of animal models that will be the most effective
strategy for understanding brain function.
"