What are the neural substrates of retrieval induced forgetting? Retrieval-induced effects
It is well known that practicing retrieval of remembered items increases the probability of correctly recalling that item in future tests: the testing effect. Retrieval-induced forgetting (RIFo) and retrieval-induced facilitation (RIFa) are less known, but related phenomena with, in my view, large theoretical and practical implications for cognitive memory research and educational theory.
In RIFo, learned items associated with a remembered item subjected to retrieval practice appear to suffer from increased forgetting in future tests (Anderson, Bjork and Bjork, 1994). Some papers report that the inverse also appears to occur: in RIFa, the probability of recalling associated remembered items also increases (Chan, 2009). RIFo appears to be a reasonably robust phenomenon with many replications, while RIFa is not as well established an effect.
The cognitive neuroscience of RIF
Where the classical view might have attributed the effect to relative strengthening of associations and decay, modern theories revolve around variations on an automatic inhibition process associated with recall attempts (Anderson, Bjork and Bjork, 2000). This might suggest that the PFC and frontal cortex more generally should be doing most of the legwork here, but is that empirically the case?
What are the known neural substrates of RIFo (and RIFa) effects?
References

Anderson, M. C., Bjork, E. L., &amp; Bjork, R. A. (2000). Retrieval-induced forgetting: Evidence for a recall-specific mechanism. Psychonomic Bulletin &amp; Review, 7(3), 522-530.
Anderson, M. C., Bjork, R. A., &amp; Bjork, E. L. (1994). Remembering can cause forgetting: retrieval dynamics in long-term memory. Journal of Experimental Psychology: Learning, Memory, and Cognition, 20(5), 1063.
Chan, J. C. (2009). When does retrieval induce forgetting and when does it induce facilitation? Implications for retrieval inhibition, testing effect, and text processing. Journal of Memory and Language, 61(2), 153-170.
The neural substrates most involved in retrieval-induced forgetting (RIF) appear to be the anterior cingulate cortex (ACC), the dorsolateral pre-frontal cortex (DLPFC) and the ventrolateral pre-frontal cortex (VLPFC) (Bäuml, Pastötter and Hanslmayr, 2010). I will not pretend to one-up their concise summation of the evidence.


  The results are consistent with the view that the ACC detects interference from unpracticed material and the DLPFC and VLPFC resolve the conflict by strengthening the practiced memories and inhibiting the unpracticed memories.


Evidence for ACC-DLPFC-VLPFC involvement in RIF

Bäuml, Pastötter and Hanslmayr draw on a number of fMRI and EEG studies in order to support their narrative. Generally speaking, a study of electrophysiological correlates of RIF found that frontal activity was predictive of RIF effects (Johansson et al, 2007); this broadly concurs with my original intuition that the frontal regions are of primary importance in RIF.

More specifically, Wimber et al. (2009) reported fMRI evidence for ACC and DLPFC involvement during RIF, while fMRI evidence for VLPFC involvement was reported in Kuhl et al. (2007). These are only highlights of the main supports; a more complete basis is presented in the Bäuml, Pastötter and Hanslmayr (2010) paper.

References


Bäuml, K. H., Pastötter, B., &amp; Hanslmayr, S. (2010). Binding and inhibition in episodic memory—Cognitive, emotional, and neural processes. Neuroscience &amp; Biobehavioral Reviews, 34(7), 1047-1054.
Johansson, M., Aslan, A., Bäuml, K. H., Gäbel, A., &amp; Mecklinger, A. (2007). When remembering causes forgetting: Electrophysiological correlates of retrieval-induced forgetting. Cerebral Cortex, 17(6), 1335-1341.
Kuhl, B. A., Dudukovic, N. M., Kahn, I., &amp; Wagner, A. D. (2007). Decreased demands on cognitive control reveal the neural processing benefits of forgetting. Nature neuroscience, 10(7), 908-914.
Wimber, M., Rutschmann, R. M., Greenlee, M. W., &amp; Bäuml, K. H. (2009). Retrieval from episodic memory: Neural mechanisms of interference resolution. Journal of Cognitive Neuroscience, 21(3), 538-549.