On the search for the neurophysiological manifestation of recollective experience (original) (raw)
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Event related brain potentials and illusory memories: the effects of differential encoding
Brain research. Cognitive brain research, 2001
This study investigates event related potentials (ERP) elicited by true and false recognition using words from different semantic categories. In Experiment 1, ERPs for true and false recognition were more positive than for correctly rejected NEW words starting around 300 ms after test word presentation (old/new ERP effects). ERP waveforms for true and false recognition revealed equal early (300-500 ms) fronto-medial old/new ERP effects, reflecting similar familiarity processes, but smaller parietal old/new ERP effects (500-700 ms) for false relative to true recognition, suggesting less active recollection. Interestingly, a subsequent performance based group comparison showed equivalent old/new ERP effects for true and false recognition for participants with high rates of false recognition. In contrast, false recognition failed to elicit an old/new ERP effect in a group with low false recognition rates. To examine whether this between group difference was driven by the differential u...
Psychophysiology, 1998
Episodic memory encoding and distinctiveness detection were examined using event-related potentials~ERP! in a single-trial word list learning paradigm with free recall following distraction. To manipulate distinctiveness, encoding of high-and very low-frequency words was contrasted. Amplitudes of the N400 and late positive component~LPC! were larger for low-than for high-frequency words, and ERPs were more positive for subsequently recalled than not recalled words. This subsequent memory effect was dissociated from the correlates of distinctiveness by polarity for the N400 and by time course for the LPC and dissociable into two effects. The data suggest that the first subsequent memory effect, which occurred for both word categories, is more directly related to episodic memory formation, whereas the second effect, which occurred for high-frequency words only, is related to processes influencing episodic encoding success indirectly.
The control of memory retrieval: Insights from event-related potentials
Cognitive Brain Research, 2005
Effective performance on episodic retrieval tasks requires the ability to flexibly adapt to changing retrieval demands (Fretrieval orientations_; [M.D. Rugg, E.L. Wilding, Retrieval processing and episodic memory, Trends Cogn. Sci. 4 (2000) 108-115]). We used eventrelated potentials (ERP) to examine whether maintaining a specific retrieval orientation and changing flexibly between different retrieval demands are mediated by the same brain systems or whether dissociable aspects of cognitive control are involved. Sixteen participants performed two recognition memory tasks. One required mere old/new decisions for words (general task), whereas the other task required the additional retrieval of each word's study font typeface (specific task). Furthermore, the participants either were asked to perform the same task continuously or to switch between the two tasks after every second test word. ERPs elicited by correctly rejected new (unstudied) words were analyzed. This enabled us to examine the ERP correlates of having adapted and maintained a task instruction as required during continuous blocks and of flexibly changing between retrieval demands during alternating blocks. The ERP analysis revealed more positivegoing ERP slow waves for alternating blocks than for continuous blocks over bilateral frontal recording sites. This effect started around 250 ms after the test word and extended for several hundred milliseconds. As it was present for trials requiring a switch to the other task or to stay on the same task between 500 and 750 ms and no differences between the latter two trial types were obtained, it can be assumed that it is more related to general coordination requirements in alternating blocks, rather than to the actual control required to switch the retrieval task set. In addition, contrasting ERPs for the two task types revealed more positive-going ERP slow waves in the specific task than in the general task in the continuous blocks at lateral frontal recording sites between 250 and 700 ms. Together, these findings suggest that there are electrophysiologically dissociable aspects of cognitive control, namely for adapting and maintaining a retrieval orientation and for flexibly changing between varying retrieval demands.
Frontiers in Human Neuroscience, 2015
Understanding the electrophysiological correlates of recognition memory processes has been a focus of research in recent years. This study investigated the effects of retention interval on recognition memory by comparing memory for objects encoded four weeks (remote) or 5 min (recent) before testing. In Experiment 1, event related potentials (ERPs) were acquired while participants performed a yes-no recognition memory task involving remote, recent and novel objects. Relative to correctly rejected new items, remote and recent hits showed an attenuated frontal negativity from 300-500 ms post-stimulus. This effect, also known as the FN400, has been previously associated with familiarity memory. Recent and remote recognition ERPs did not differ from each other at this time-window. By contrast, recent but not remote recognition showed increased parietal positivity from around 500 ms post-stimulus. This late parietal effect (LPE), which is considered a correlate of recollection-related processes, also discriminated between recent and remote memories. A second, behavioral experiment confirmed that remote memories unlike recent memories were based almost exclusively on familiarity. These findings support the idea that the FN400 and LPE are indices of familiarity and recollection memory, respectively and show that remote and recent memories are functionally and anatomically distinct.
Event-related potential (ERP) studies of memory encoding and retrieval: A selective review
Microscopy Research and Technique, 2000
As event-related brain potential (ERP) researchers have increased the number of recording sites, they have gained further insights into the electrical activity in the neural networks underlying explicit memory. A review of the results of such ERP mapping studies suggests that there is good correspondence between ERP results and those from brain imaging studies that map hemodynamic changes. This concordance is important because the combination of the high temporal resolution of ERPs with the high spatial resolution of hemodynamic imaging methods will provide a greatly increased understanding of the spatio-temporal dynamics of the brain networks that encode and retrieve explicit memories.
Event-related potentials and recognition memory within the'levels of processing'framework
NeuroReport, 1993
According to dual-process models, recognition memory is supported by distinct retrieval processes known as familiarity and recollection. Important evidence supporting the dual-process framework has come from studies using event-related brain potentials (ERPs). These studies have identified two topographically distinct ERP correlates of recognition memory -the 'parietal' and 'mid-frontal' old/new effects -that are dissociated by variables that selectively modulate recollection and familiarity, respectively. We evaluate the extent to which ERP data support dual-process models in light of the proposal that recollection is a continuous rather than a discrete memory process. We also examine the claim that the putative ERP index of familiarity is a reflection of implicit rather than explicit memory. We conclude that ERP findings continue to offer strong support for the dual-process perspective.
Probability effects on event-related potential correlates of recognition memory
Cognitive Brain Research, 2003
A common finding in event-related potential (ERP) studies of recognition memory is that recognised items elicit greater positivity at parietal electrode sites than new items (the 'left parietal old / new effect'). Parietal positivity (the P300 or P3b) is also elicited in detection tasks with no memory demands by items of low probability of occurrence and high 'target value'. It has been argued that correctly recognised items are typically associated with lower probability and higher target value than new items, raising the question of the extent to which the old / new effect receives a contribution from, or interacts with, P300 activity. The present study explored this issue by comparing ERPs associated with correctly classified old and new items across three different ratios of old to new items: 25:75, 50:50 and 75:25. The left parietal old / new effect was not influenced by this manipulation in the latency range in which it is conventionally measured. Probability did influence the parietal ERPs to correctly recognised items post-800 ms; the scalp distribution of this probability effect was however qualitatively distinct from that of the preceding old / new effect. The left parietal old / new effect appears to be a relatively pure reflection of episodic retrieval, uncontaminated by the non-mnemonic factors of probability and target value.
Experimental Brain Research, 1998
The probability that words would be recollected during tests of recognition memory was varied by manipulating depth of processing at study. Experiment 1 employed scalp-recorded event-related potentials (ERPs), and identified as a correlate of recollection a late (onset c. 500 ms), strongly left-lateralized positive-going modulation of the ERP waveform. The findings from experiment 2, which employed positron emission tomography (PET), indicated that recollection was associated with activation of the left hippocampal formation together with an extensive region of left temporal and frontal cortex. The findings support current ideas about the role of the hippocampal formation in episodic memory retrieval, and provide complementary information about the time course and localization of the cortical correlates of the recollection of recently experienced words.