We argue in this paper that so-called new wave reductionism fails to capture the nature of the interlevel relations between psychology and neuroscience. Bickle (1995, Psychoneural reduction of the genuinely cognitive: some accomplished facts, Philosophical Psychology, 8, 265-285; 1998, Psychoneural reduction: the new wave, Cambridge, MA: MIT Press) has claimed that a (bottom-up) reduction of the psychological concepts of learning and memory to the concepts of neuroscience has in fact already been accomplished. An investigation of current research on the phenomenon of long-term potentiation reveals that this claim overstates the facts. Both the psychological and the neural concepts involved have not yet stabilized and face further correction under the influence of both bottom-up and top-down selection pressures. In addition, psychological concepts often refer to functions, and functions are indispensable and irreducible. Function ascriptions pick out objective patterns involving historical factors and distal goals. This view of functions implies that psychological facts cannot be simply read off from the neurophysiological facts. Although psychological theorizing is constrained by neurophysiology (and vice versa), psychology remains distinct at least to some degree.