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J E Herron

Publications and source records attributed to J E Herron.

10 recordsLinked to original sources
PubMed2006

Electrophysiological correlates of familiarity in recognition memory and exclusion tasks.

ERPs were acquired in the test phases of three memory experiments, where three classes of word were presented. These were: (i) words encountered in a prior study phase (studied words), (ii) words presented at test for the first time (new words), and (iii) new words repeated after a lag of 7-9 intervening words (repeated test words). In experiments 1 and 2, participants were asked to respond on one key to studied words and on another to new as well as to repeated test words. In experiment 3, a binary response was again required, but in this case repeated test and studied words were assigned to the same key. In each experiment, the principal focus for analysis was on the differences between the ERPs at mid-frontal electrode locations from 300 to 500 ms post-stimulus that were associated with incorrect responses to studied words (misses) and correct responses to new words. It has been proposed that relatively greater positivity for studied than for new words at this locus reflects the greater familiarity of studied than of unstudied words. ERPs elicited by misses were reliably more positive-going than those elicited by correct rejections in experiments 1 and 2 only. These findings support the link between this modulation of the electrical record and familiarity in so far as the designs of the experiments lead to the prediction that the average level of familiarity associated with misses should be higher in the first two experiments than in the third. In combination with findings in other studies, these data support dual-process accounts of recognition memory.

Adult↗
PubMed2006

Brain and behavioral indices of retrieval mode.

In recent event-related potential (ERP) studies of episodic retrieval, ERPs have been acquired in tasks where participants have been cued trial-by-trial to prepare either to make episodic or semantic retrieval judgments. ERPs elicited during this preparatory cue period and separated according to retrieval task have diverged at right frontal scalp electrodes, with a relatively greater positivity associated with preparation for episodic rather than for semantic retrieval. Importantly, this pattern of differences has been observed only on 'stay' trials: those trials where the participant was cued to prepare for the same retrieval task on the previous trial. These findings have provided the basis for the proposal that the ERP modulations index processes that support the adoption or configuration of retrieval mode - a tonic process that can be sustained while recovery of episodic information is required and which facilitates the retrieval process. In these studies, however, the preparatory period on each trial was no more than 2000 ms, raising the possibility that, with more time available, neural correlates of these preparatory processes would not be restricted to stay trials. In this experiment, participants were cued trial-by-trial to complete either an episodic or a semantic retrieval task, and the preparatory period was greater than 4000 ms on the majority of trials. In keeping with previous findings, the ERPs elicited by these two cue types diverged principally on stay trials at right frontal electrode locations, suggesting that time to prepare is not the primary determinant of the onset of task-specific preparatory retrieval processing. In an important addition to previous findings, moreover, the accuracy of episodic memory judgments increased with the number of successive trials of the same task that participants completed, a finding consistent with the view that adopting a retrieval mode successfully can influence the accuracy of episodic memory judgments.

Adolescent↗
PubMed2006

Electrophysiological measures of episodic memory control and memory retrieval.

Event-related potentials (ERPs) index processes that occur before, during and after retrieval of information from episodic memory. In this selective review we provide a loose theoretical framework within which retrieval processes operating at these different stages can be considered. We go on to describe how ERPs have been employed in order to index processes operating at each of these stages. These data have contributed to current understanding of the processes that are engaged around the time of episodic memory retrieval, and also illustrate the potential that ERPs have for understanding in detail how memory retrieval processes changes in populations with memory impairments.

Electroencephalography↗
PubMed2005

Memory retrieval processing: neural indices of processes supporting episodic retrieval.

Event-related potentials (ERPs) were acquired during separate test phases of a verbal recognition memory exclusion task in order to contribute to current understanding of the functional significance of differences between ERPs elicited by new (unstudied) test words, which are assumed to index processes engaged in pursuit of task-relevant information. Participants were asked to endorse old words from one study task (targets), and to reject new test words as well as those from a second study task (non-targets). The study task designated as the target category varied across test phases. The left-parietal ERP old/new effect - the electrophysiological signature of recollection - was reliable for targets and for non-targets in all test phases, consistent with the view that participants recollected information about both of these classes of test word. The contrast between the ERPs evoked by new test words separated according to target designation revealed no reliable differences. These findings contrast with those in a recent study in which the same tasks were used, but in which the accuracy of task judgments was markedly higher (Dzulkifli, M.A., & Wilding, E. L. (2005). Electrophysiological indices of strategic episodic retrieval processing. Neuropsychologia, 43, 1152-1162). In that study, there were reliable differences between the ERPs evoked by the two classes of new words, but reliable left-parietal ERP old/new effects for targets only. In combination, the findings suggest that differences between ERPs evoked by new test words can reflect processes that are important for controlling what kinds of information will and will not be recollected.

Adult↗
PubMed2005

Neural correlates of control processes engaged before and during recovery of information from episodic memory.

Preparing to retrieve episodic information engages content-specific pre-retrieval processes--retrieval orientations--that vary according to the episodic information that is to be retrieved [Rugg, M.D., Wilding, E.L., 2000. Retrieval processing and episodic memory. Trends Cogn. Sci. 4, 108-115]. Retrieval orientations are retrieval sets which can be maintained tonically and which influence the ways in which subsequent stimuli are processed, presumably in order to facilitate recovery of the required episodic information. Indices of processes related to the adoption of a retrieval orientation can therefore be obtained by acquiring measures of neural activity during preparation to retrieve, while processes contingent upon the successful adoption of an orientation can be obtained by measuring the neural activity that is elicited by stimuli to which memory judgments are required. Across three experiments, electrophysiological indices of the former class of process were obtained only when frequent switches between different retrieval tasks were required, confirming that this measure of brain activity reflects processes important for the adoption of a relevant retrieval orientation. Stimulus-specific indices of retrieval orientations were obtained primarily when few switches between retrieval tasks were required, consistent with the view that the engagement of stimulus-specific retrieval processing operations is achieved only when an appropriate retrieval orientation has been adopted fully.

Adolescent↗
PubMed2005

Indexing strategic retrieval of colour information with event-related potentials.

Event-related potentials (ERPs) were acquired during two experiments in order to determine boundary conditions for when recollection of colour information can be controlled strategically. In initial encoding phases, participants saw an equal number of words presented in red or green. In subsequent retrieval phases, all words were shown in white. Participants were asked to endorse old words that had been shown at encoding in one colour (targets), and to reject new test words as well as old words shown in the alternate colour (non-targets). Study and test lists were longer in Experiment 1, and as a result, the accuracy of memory judgments was superior in Experiment 2. The left-parietal ERP old/new effect--the electrophysiological signature of recollection--was reliable for targets in both experiments, and reliable for non-targets in Experiment 1 only. These findings are consistent with the view that participants were able to restrict recollection to targets in Experiment 2, while recollecting information about targets as well as non-targets in Experiment 1. The fact that this selective strategy was implemented in Experiment 2 despite the close correspondence between the kinds of information associated with targets and non-targets indicates that participants were able to exert considerable control over the conditions under which recollection of task-relevant information occurred.

Adult↗
PubMed2005

An electrophysiological investigation of factors facilitating strategic recollection.

Episodic memory is thought to be mediated by executive processes that facilitate the retrieval of task-relevant information at the expense of irrelevant information. The exclusion task [A process dissociation framework: Separating automatic from intentional uses of memory. Journal of Memory and Language, 30, 513-541, 1991] can be used to explore these processes. In this task, studied items from one source ("targets") are endorsed on one response key, whereas new and studied items from another source ("nontargets") are rejected on another key. Herron and Rugg [Strategic influences on recollection in the exclusion task: Electrophysiological evidence. Psychonomic Bulletin and Review, 10, 703-710, 2003] reported that nontargets elicited the ERP correlate of recollection (the "left parietal old/new effect") when target accuracy was low, but not when it was high. Their explanation for this was that participants only focused exclusively on the recollection of target information when the likelihood of target recollection was high, as under these conditions this strategy is one that that will give rise to accurate task performance. The fact, however, that targets were encoded in different tasks in the high- and low-accuracy groups means that the results can also be explained in terms of the encoding operations performed at study rather than in terms of target accuracy. This study was designed to distinguish between these competing accounts. All targets were encoded elaboratively. Target accuracy was reduced in one condition with a 40-min study-test interval. Nontargets elicited no left parietal effect in either condition, suggesting that target-specific strategic retrieval is facilitated by certain classes of encoding operations rather than simply high target accuracy per se.

Adolescent↗
PubMed2004

An electrophysiological dissociation of retrieval mode and retrieval orientation.

The relationship between two classes of retrieval process-retrieval orientation and retrieval mode-was investigated by recording event-related potentials (ERPs) during the period in which participants were preparing to retrieve information from memory. Participants were cued on a trial-by-trial basis to complete either a semantic retrieval task or one of two episodic retrieval tasks (remember spatial location or remember encoding task). ERPs were recorded time-locked to the cues indicating which task to complete. There were commonalities between the ways in which ERPs evoked by the two episodic retrieval cues diverged from those evoked by the semantic cue. These shared differences are a likely correlate of processes related to retrieval mode. Critically, there were also reliable differences between the ERPs evoked by the two episodic cues. This novel finding is consistent with the view that participants adopted task-specific retrieval sets-retrieval orientations-which varied according to the kinds of episodic information that were to be retrieved.

Adolescent↗
PubMed2000

Recurrent detoxification may elevate alcohol craving as measured by the Obsessive Compulsive Drinking scale.

Research has demonstrated a relationship between the number of previous alcohol detoxifications and increased severity of the alcohol withdrawal syndrome (AWS) that is hypothesized to be similar to an electrophysiologic "kindling process." Application of a "kindling" model to AWS suggests that neuroadaptation of the central nervous system to repeated detoxifications may also cause neurobehavioral alterations that may affect "craving." This study examined craving as assessed by the Obsessive Compulsive Drinking Scale (OCDS) in 67 adult outpatients meeting DSM-IV criteria (American Psychiatric Association, 1994) for alcohol dependence and AWS having either < 2 and > or = 2 previous detoxifications. Results of ANCOVA revealed that patients with > or = 2 previous detoxifications had higher scores on a scale that measures obsessive thoughts about alcohol, drinking urges and behaviors, and a composite of these scores after controlling for alcohol dependence severity, depressive symptoms and number of drinks 2 weeks prior to the study. Findings emphasize the need to address craving and other psychological variables with respect to treatment of AWS.

Adult↗