The Prefrontal Cortex

The Role of the Prefrontal Cortex in Retrieval

Prefrontal cortex aids in retrieval by making contributions to strategic and executive aspects of memory. Prefrontal regions aid in the organization, selection, monitoring, and evaluation of processing that occurs at retrieval, similar to their role in encoding.

Deficits in retrieval in patients with prefrontal damage are more severe during free recall compared to recognition (e.g., Gershberg & Shimamura, 1995; Wheeler et al., 1995; MacPherson et al., 2016). In free recall, there are minimal cues at test time to aid memory performance and a strategic search through memory must be performed. For example, if trying to answer the question “What was the name of that actor who starred in the movie La La Land?” one might need to do a strategic search through memory thinking about what this actor looks like or what other films you might have seen him in to access his name.

In contrast, in tests of recognition memory, a search through memory is not required as the possibilities are already provided (“Did Justin Timberlake, Ryan Gosling, Zac Efron, or Matt Damon Star in La La Land?”). Also suggesting that the prefrontal cortex is involved in organizing and monitoring memory retrieval, patients with damage to this area tend to confabulate, generating narratives that include false memories (e.g., Moscovitch, 1995).

In some cases, they show an overreliance on familiarity to make their decisions, instead of correctly monitoring whether a specific item was indeed seen. This problem is reflected in an increased proportion of false positives in recognition memory tasks (saying “yes” that an item was viewed when in fact it was not) (Schacter et al., 1996; Curran et al., 1997).

Evidence from neuroimaging indicates that regions of prefrontal cortex are reliably activated during memory retrieval. As we discussed with regards to encoding, these effects are lateralized. For example, left posterior PFC is activated by verbal tasks, including word generation, word classification, and word memorization, while right PFC is activated for nonverbal tasks such as face recognition (McDermott et al., 1999; Wagner et al., 1998).

At least some studies suggest that activity in posterior regions of the prefrontal cortex is more related to retrieval attempt than to retrieval success (Buckner et al., 1998; Konishi et al., 2000). That is, the amount of activation observed in this region is related to the effort required when retrieval is being attempted, and is independent of whether the item is successfully remembered. Such findings fit with the idea that prefrontal regions are involved in guiding the executive processes used to retrieve memories—the harder it is to retrieve information, the more effortful the search.

In addition to strategically aiding in memory recall, prefrontal regions may also play a role in suppressing the retrieval of memories. It may by effectively inhibiting or down-regulating the hippocampus so as to preclude memory retrieval (Depue et al., 2007; Depue, 2012).

Researchers and clinicians alike are intrigued by such findings because they may hold the key to helping people overcome flashbacks and other intrusive memories associated with the experiencing of traumatic events. This role of the prefrontal cortex in suppressing memory retrieval appears to be part of a more general prefrontal mechanism that is involved in inhibitory control (Depue et al., 2015).