Implicit memory for novel conceptual associations in amnesia

Verfaellie, Mieke; Martin, Elizabeth G.; Page, Katie; Parks, Elizabeth J.; Keane, Margaret M.

doi:10.3758/cabn.6.2.91

Cited by 19 publications

(15 citation statements)

References 44 publications

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“…Perhaps the most striking evidence, however, comes from amnesic patients, who show marked impairment on tests of explicit memory but normal or near-normal performance on implicit memory tasks (e.g., Cohen & Squire, 1980; Graf & Schacter, 1985; Milner, Corkin, & Teuber, 1968). Of relevance to the present study, previous research has found that amnesic patients are often capable of forming novel semantic or conceptual associations as measured by implicit memory tasks, despite having no explicit knowledge of these associations (Goshen-Gottstein, Moscovitch, & Melo, 2000; Moscovitch, 1986; Verfaellie, Martin, Page & Keane, 2006; Gabrieli, Keane, Zarella, & Poldrack, 1997). These findings indicate that new semantic information may be encoded into implicit memory in the absence of explicit awareness, at least under some circumstances.…”

Section: Introductionmentioning

confidence: 79%

Implicit and Explicit Mechanisms of Word Learning in a Narrative Context: An Event-related Potential Study

Batterink

Neville²

2011

Journal of Cognitive Neuroscience

111

113

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The vast majority of word meanings are learned simply by extracting them from context, rather than by rote memorization or explicit instruction. Although this skill is remarkable, little is known about the brain mechanisms involved. In the present study, ERPs were recorded as participants read stories in which pseudowords were presented multiple times, embedded in consistent, meaningful contexts (referred to as meaning condition, M+) or inconsistent, meaningless contexts (M−). Word learning was then assessed implicitly using a lexical decision task and explicitly through recall and recognition tasks. Overall, during story reading, M− words elicited a larger N400 than M+ words, suggesting that participants were better able to semantically integrate M+ words than M− words throughout the story. In addition, M+ words whose meanings were subsequently correctly recognized and recalled elicited a more positive ERP in a later time-window compared to M+ words whose meanings were incorrectly remembered, consistent with the idea that the late positive component (LPC) is an index of encoding processes. In the lexical decision task, no behavioral or electrophysiological evidence for implicit priming was found for M+ words. In contrast, during the explicit recognition task, M+ words showed a robust N400 effect. The N400 effect was dependent upon recognition performance, such that only correctly recognized M+ words elicited an N400. This pattern of results provides evidence that the explicit representations of word meanings can develop rapidly, while implicit representations may require more extensive exposure or more time to emerge.

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Section: Introductionmentioning

confidence: 79%

Implicit and Explicit Mechanisms of Word Learning in a Narrative Context: An Event-related Potential Study

Batterink

Neville²

2011

Journal of Cognitive Neuroscience

111

113

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“…Yet, it is not the only instance of impaired implicit memory following MTL damage. Impairments have been observed in priming for new verbal associations (e.g., Paller & Mayes, 1994; Shimamura & Squire, 1999; Verfaellie et al, 2006) and in an implicit measure of relational memory for scenes derived from eye movements in patients with hippocampal amnesia (Ryan et al, 2000). However, complicating matters, a subsequent contextual-cueing study showed that patients with damage to the hippocampus but not surrounding cortical regions of the MTL exhibited near-normal contextual cueing (Manns & Squire, 2001).…”

Section: Introductionmentioning

confidence: 99%

Neural correlates of contextual cueing are modulated by explicit learning

et al. 2011

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Contextual cueing refers to the facilitated ability to locate a particular visual element in a scene due to prior exposure to the same scene. This facilitation is thought to reflect implicit learning, as it typically occurs without the observer’s knowledge that scenes repeat. Unlike most other implicit learning effects, contextual cueing can be impaired following damage to the medial temporal lobe. Here we investigated neural correlates of contextual cueing and explicit scene memory in two participant groups. Only one group was explicitly instructed about scene repetition. Participants viewed a sequence of complex scenes that depicted a landscape with five abstract geometric objects. Superimposed on each object was a letter T or L rotated left or right by 90°. Participants responded according to the target letter (T) orientation. Responses were highly accurate for all scenes. Response speeds were faster for repeated versus novel scenes. The magnitude of this contextual cueing did not differ between the two groups. Also, in both groups repeated scenes yielded reduced hemodynamic activation compared with novel scenes in several regions involved in visual perception and attention, and reductions in some of these areas were correlated with response-time facilitation. In the group given instructions about scene repetition, recognition memory for scenes was superior and was accompanied by medial temporal and more anterior activation. Thus, strategic factors can promote explicit memorization of visual scene information, which appears to engage additional neural processing beyond what is required for implicit learning of object configurations and target locations in a scene.

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“…The findings on associative priming in amnesic patients are conflicting. Some studies have shown that amnesic patients are impaired in both associative priming and explicit memory, indicating that the MTL is involved in associative priming (e.g., Graf and Schacter 1985;Mayes and Gooding 1989;Shimamura and Squire 1989;Chun and Phelps 1999;Yang et al 2003;Verfaellie et al 2006). Other studies have shown that amnesic patients are impaired in explicit memory tasks but show normal performance in associative priming and item priming tasks, suggesting that the MTL does not appear to be essential for associative implicit memory (e.g., Moscovitch et al 1986;Musen and Squire 1993;Gabrieli et al 1997;Goshen-Gottstein et al 2000;Verfaellie et al 2006).…”

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confidence: 99%

“…By this, their performance was clearly different from normal controls. It should be noted that when conceptual tasks require subjects to judge the configuration of the presented pairs (e.g., a related judgment task) (Verfaellie et al 2006), amnesic patients manifest longer latencies for old rather than for recombined pairs, as normal subjects do. Also, when tasks require subjects to unitize the items into a whole, associative memory is preserved in amnesia (Mayes et al 2004).…”

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confidence: 99%

“…The posterior PHG seems to play a role in the retrieval of contextual information (Diana et al 2007;Eichenbaum et al 2007). Studies with amnesic patients suggested that MTL subregions other than the hippocampus are more related to implicit contextual task (Chun and Phelps 1999;Manns and Squire 2001;Verfaellie et al 2006). For example, Chun and Phelps (1999) report that a group of amnesic patients had deficits in an implicit contextual learning task.…”

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confidence: 99%

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Decreased parahippocampal activity in associative priming: Evidence from an event-related fMRI study

Yang¹,

Meckingler²,

Xu³

et al. 2008

Learn. Mem.

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In recent years, there has been intense debate on the neural basis of associative priming, particularly on the role of the medial temporal lobe (MTL) in retrieving associative information without awareness. In this study, event-related fMRI was used while healthy subjects performed a perceptual identification task on briefly presented unrelated word pairs and an associative recognition memory task. Contamination of priming by explicit memory was successfully controlled, as associative priming and explicit memory were dissociated on the behavioral level. The fMRI results showed a functional dissociation within the MTL with respect to associative priming effects. The right parahippocampal cortex, but not the hippocampus, showed decreased activation for old vs. new pairs and old vs. recombined pairs (associative priming). The bilateral hippocampus and the right parahippocampal cortex were involved in explicit associative memory. These data provide evidence that subregions of the MTL participate in associative priming even when explicit involvement was controlled. Thus, different regions within the MTL play distinct roles in explicit and implicit associative memory.

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Implicit memory for novel conceptual associations in amnesia

Cited by 19 publications

References 44 publications

Implicit and Explicit Mechanisms of Word Learning in a Narrative Context: An Event-related Potential Study

Implicit and Explicit Mechanisms of Word Learning in a Narrative Context: An Event-related Potential Study

Neural correlates of contextual cueing are modulated by explicit learning

Decreased parahippocampal activity in associative priming: Evidence from an event-related fMRI study

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