Churchland, P. S. & Sejnowski, T. J. (1988). Perspectives on cognitive neuroscience. Science, 242, 741–745. An early, classic paper (before the advent of fMRI) that sets out the agenda for the field.
Coltheart, M. (2004). Brain imaging, connectionism and cognitive neuropsychology. Cognitive Neuropsychology, 21, 21–26. A critique of the cognitive neuroscience approach; in particular, whether brain imaging can inform cognitive theory.
Henson, R. (2005). What can functional neuroimaging tell the experimental psychologist? Quarterly Journal of Experimental Psychology, 58A, 193–233. An excellent summary of the role of functional imaging in psychology and a rebuttal of common criticisms.