Off-Line Processing: Reciprocal Interactions between Declarative and Procedural Memories

Abstract

The acquisition of declarative (i.e., facts) and procedural (i.e., skills) memories may be supported by independent systems. This same organization may exist, after memory acquisition, when memories are processed off-line during consolidation. Alternatively, memory consolidation may be supported by interactive systems. This latter interactive organization predicts interference between declarative and procedural memories. Here, we show that procedural consolidation, expressed as an off-line motor skill improvement, can be blocked by declarative learning over wake, but not over a night of sleep. The extent of the blockade on procedural consolidation was correlated to participants' declarative word recall. Similarly, in another experiment, the reciprocal relationship was found: declarative consolidation was blocked by procedural learning over wake, but not over a night of sleep. The decrease in declarative recall was correlated to participants' procedural learning. These results challenge the concept of fixed independent memory systems; instead, they suggest a dynamic relationship, modulated by when consolidation takes place, allowing at times for a reciprocal interaction between memory systems.

Offline consolidation in implicit sequence learning

“…For example, Brown and Robertson (2007) have argued that offline consolidation of a procedural memory trace can be blocked by declarative learning, particularly across intervals involving wakefulness (i.e. rather than sleep).…”

“…As the opposite situation can also be found, with offline processing of a declarative memory being blocked by an episode of procedural learning, Brown and Robertson have suggested a dynamic declarativeprocedural relation (i.e. equivalent to the explicit-implicit distinction), in which the balance is modulated by when the consolidation takes place, and which allows for reciprocal interaction between the two memory systems (Brown & Robertson, 2007;Cohen & Robertson, 2011).…”

“…For example, it has been demonstrated that the performance of some procedures can be significantly improved after a "silent" or offline interval subsequent to training. During this interval, there is no further practice, or even mention, of the procedure, and learning remains largely tacit or implicit (Brown & Robertson, 2007;Hallgato, Gyori-Dani, Pekar, Janacsek, & Nemeth, 2013;Krakauer & Shadmehr, 2006;Németh et al, 2010). Consolidation is also sometimes referred to as resistance to interference and forgetting (Ghilardi, Moisello, Silvestri, Ghez, & Krakauer, 2009;Goedert & Willingham, 2002; Stephan, Meier, Orosz, Cattapan-Ludewig, & KaelinLang, 2009).…”

Sleep in children improves memory performance on declarative but not procedural tasks

“…Competitive interference from hippocampus-dependent memory systems might have been furthered by the fixed task order used in our study, with the word-pair associate task always following the finger tapping task. However, in a recent study in adults (Brown and Robertson 2007), an interpolated declarative task blocked offline improvements across wake intervals only but not across nocturnal sleep. Thus, task order is not likely a factor that can fully account for the lacking overnight gain of skill in our children.…”

Cross-modal transfer of statistical information benefits from sleep

“…Over time, due to the need for the hippocampus to reuse its limited storage capacity (McClelland et al 1995), these connections are weakened and replaced by cortico-cortical connections, although the memories may not become entirely independent of the hippocampus (Nadel and Moscovitch 1997;Moscovitch and Nadel 1998). In order that external input (Robertson 2009) and internal interactions between different memory systems (Poldrack et al 2001;Brown and Robertson 2007) should not interfere with this process, it has been proposed that it takes place during sleep (Born et al 2006;Walker 2009). Our findings support and extend this, suggesting that this is the case not only for declarative tasks but also procedural tasks in which a transfer from the MTL to the striatum takes place over time (Reiss et al 2005;Rieckmann et al 2010).…”