Results 1 - 10 of 103

Characterizing the hemodynamic response: Effects of presentation rate, sampling procedure, and the possibility of ordering brain activity based on relative timing

by F. M. Miezin, L. Maccotta, J. M. Ollinger, S. E. Petersen, R. L. Buckner - NEUROIMAGE 11: 735–759 , 2000
"... Rapid-presentation event-related functional MRI (ER-fMRI) allows neuroimaging methods based on hemodynamics to employ behavioral task paradigms typical of cognitive settings. However, the sluggishness of the hemodynamic response and its variance provide constraints on how ER-fMRI can be applied. In ..."
Abstract - Cited by 157 (15 self) - Add to MetaCart
Rapid-presentation event-related functional MRI (ER-fMRI) allows neuroimaging methods based on hemodynamics to employ behavioral task paradigms typical of cognitive settings. However, the sluggishness of the hemodynamic response and its variance provide constraints on how ER-fMRI can be applied. In a series of two studies, estimates of the hemodynamic response in or near the primary visual and motor cortices were compared across various paradigms and sampling procedures to determine the limits of ER-fMRI procedures and, more generally, to describe the behavior of the hemodynamic response. The temporal profile of the hemodynamic response was estimated across overlapping events by solving a set of linear equations within the general linear model. No
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Event-related potential (ERP) studies of memory encoding and retrieval: A selective review

by David Friedman, Ray Johnson - Microscopy Research and Technique , 2000
"... ABSTRACT 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 ..."
Abstract - Cited by 99 (2 self) - Add to MetaCart
ABSTRACT 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 tempo-ral 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. Microsc. Res. Tech. 51:6–28, 2000. © 2000 Wiley-Liss, Inc.

A Temporoparietal and Prefrontal Network for Retrieving the Spatial Context of Lifelike Events

by Neil Burgess, Eleanor A. Maguire, Hugo J. Spiers, John O'Keefe - Neuroimage , 2001
"... steriodorsal medial parietal areas were specifically involved in retrieval of spatial context compared to retrieval of nonspatial context. The posterior activations are consistent with a model of long-term storage of allocentric representations in medial temporal regions with translation to body-cen ..."
Abstract - Cited by 92 (11 self) - Add to MetaCart
steriodorsal medial parietal areas were specifically involved in retrieval of spatial context compared to retrieval of nonspatial context. The posterior activations are consistent with a model of long-term storage of allocentric representations in medial temporal regions with translation to body-centered and head-centered representations computed in right posterior parietal cortex and buffered in the temporoparietal pathway so as to provide an imageable representation in the precuneus. Prefrontal activations are consistent with strategic retrieval processes, including those required to overcome the interference between the highly similar events. 2001 Academic Press INTRODUCTION Memory for the events we experience as we move around our environment is fundamental to normal functioning in daily life. This type of memory is often referred to as "episodic" (Tulving, 1983) and is crucially dependent on the medial temporal lobes (Scoville and Milner, 1957; A
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Similarities and Differences in the Neural Correlates of Episodic Memory Retrieval And Working Memory

by Roberto Cabeza, Florin Dolcos, Reiko Graham, Lars Nyberg - Neuroimage , 2002
"... erations, respectively; and (iii) left posterior/ventral (Broca's area) and bilateral posterior/dorsal areas were more activated during WM than during ER, possibly reflecting phonological and generic WM operations, respectively. Second, hippocampal and parahippocampal regions were activated not ..."
Abstract - Cited by 84 (10 self) - Add to MetaCart
erations, respectively; and (iii) left posterior/ventral (Broca's area) and bilateral posterior/dorsal areas were more activated during WM than during ER, possibly reflecting phonological and generic WM operations, respectively. Second, hippocampal and parahippocampal regions were activated not only for ER but also for WM. This result suggests that indexing operations mediated by the medial temporal lobes apply to both long-term and short-term memory traces. Overall, our results show that direct cross-function comparisons are critical to understand the role of different brain regions in various cognitive functions. 2002 Elsevier Science (USA) INTRODUCTION During the past decade, numerous positron emission tomography (PET) and functional MRI (fMRI) studies have investigated the neural correlates of different cognitive functions (for a review, see Cabeza and Nyberg, 2000). Although most studies have focused on a single function (see however, LaBar et al., 1999; Braver et al., 2001; Ny
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Memory Orientation and Success: Separable Neurocognitive Components Underlying Episodic Recognition

by Ian G. Dobbins, Heather J. Rice, Anthony D. Wagner, Daniel L. Schacter , 2003
"... Episodic recognition can be based on recollection of contextual details, on a sense of recent encounter, or some combination of the two. According to several cognitive models, selectively attending to these distinct aspects of memory may require different retrieval orientations and result in differe ..."
Abstract - Cited by 81 (12 self) - Add to MetaCart
Episodic recognition can be based on recollection of contextual details, on a sense of recent encounter, or some combination of the two. According to several cognitive models, selectively attending to these distinct aspects of memory may require different retrieval orientations and result in different neural responses depending upon whether or not retrieval is successful. Using event-related fMRI, we examined retrieval orientation by having subjects discriminate between two test words in one of two manners. During source recollection, they selected the member of the pair previously associated with a particular encoding task. In contrast, recency judgment required selection of the most recently encountered item of the pair, regardless of how it had been encoded. Furthermore, successful and unsuccessful trials within each retrieval task were contrasted to determine whether retrieval success effects occurred in overlapping or dissimilar neural populations compared to those associated with each retrieval orientation. The results revealed distinct lateral prefrontal and parietal activations that distinguished attempted source recollection from judgments of relative recency; these orientation effects were largely independent of retrieval success. In contrast, medial temporal lobe structures (hippocampus and parahippocampal gyrus) were differentially more active during successful recollection of encoding context, showing similar reduced responses during failed source recollection and judgments of recency. These results indicate that different memory orientations recruit distinct prefrontal and parietal networks and that the recovery of episodic context is associated with the hippocampus and surrounding medial temporal cortices.

Prefrontal contributions to executive control: fMRI evidence for functional distinctions within lateral prefrontal cortex.

by Anthony D Wagner , Anat Maril , Robert A Bjork , Daniel L Schacter - Neuroimage , 2001
"... The prefrontal cortex (PFC) plays a fundamental role in internally guided behavior. Although it is generally accepted that PFC subserves working memory and executive control operations, it remains unclear whether the subregions within lateral PFC support distinct executive control processes. An eve ..."
Abstract - Cited by 75 (4 self) - Add to MetaCart
The prefrontal cortex (PFC) plays a fundamental role in internally guided behavior. Although it is generally accepted that PFC subserves working memory and executive control operations, it remains unclear whether the subregions within lateral PFC support distinct executive control processes. An event-related fMRI study was implemented to test the hypothesis that ventrolateral and dorsolateral PFC are functionally distinct, as well as to assess whether functional specialization exists within ventrolateral PFC. Participants performed two executive control tasks that differed in the types of control processes required. During rote rehearsal, participants covertly rehearsed three words in the order presented, thus requiring phonological access and maintenance. During elaborative rehearsal, participants made semantic comparisons between three words held in working memory, reordering them from least to most desirable. Thus, in addition to maintenance, elaborative rehearsal required goal-relevant coding of items in working memory ("monitoring") and selection from among the items to implement their reordering. Results revealed that left posterior ventrolateral PFC was active during performance of both tasks, whereas right dorsolateral PFC was differentially engaged during elaborative rehearsal. The temporal characteristics of the hemodynamic responses further suggested that dorsolateral activation lagged ventrolateral activation. Finally, differential activation patterns were observed within left ventrolateral PFC, distinguishing between posterior and anterior regions. These data suggest that anatomically separable subregions within lateral PFC may be functionally distinct and are consistent with models that posit a hierarchical relationship between dorsolateral and ventrolateral regions such that the former monitors and selects goal-relevant representations being maintained by the latter.

Renewal of the neurophysiology of language: Functional neuroimaging

by Jean-françois Démonet, Guillaume Thierry, Dominique Cardebat, Physiol Rev, Jean-françois Démonet, Guillaume Thierry, Dominique Cardebat - Physiol. Rev , 2005
"... You might find this additional information useful... This article cites 405 articles, 145 of which you can access free at: ..."
Abstract - Cited by 58 (2 self) - Add to MetaCart
You might find this additional information useful... This article cites 405 articles, 145 of which you can access free at:
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A sensory signature that distinguishes true from false memories.

by Scott D Slotnick , Daniel L Schacter - Nature Neuroscience, , 2004
"... Memory is often accurate, but everyday experience and laboratory research indicate that it is also prone to various kinds of distortions, errors and illusions A fundamental yet poorly understood issue concerns the neural basis of false recognition in relation to true recognition. In an early posit ..."
Abstract - Cited by 54 (14 self) - Add to MetaCart
Memory is often accurate, but everyday experience and laboratory research indicate that it is also prone to various kinds of distortions, errors and illusions A fundamental yet poorly understood issue concerns the neural basis of false recognition in relation to true recognition. In an early positron emission tomography (PET) study 11 , participants heard semantically associated words at study, and on a subsequent test they made old-new recognition decisions to old words (studied items), related words (critical nonstudied lures) and new words. True recognition-related activity was greater than false recognition-related activity in the left temporoparietal region, which may have reflected memory of auditory/phonological information. However, subsequent studies using similar procedures suggest that such true-false differences depend on the format of the recognition test In a more recent fMRI study Based upon the differential activity found during true as compared to false recognition in the previous two studies 11,13 , coupled with findings of greater memory for sensory details during true versus false recognition in behavioral studies 8-10 , we posited that true recognition is associated with greater sensory reactivation than false recognition. Recent studies examining memory retrieval have provided converging evidence for true recognition-related sensory reactivation of the same cortical regions involved in processing stimulus materials during encoding, including reactivation of motor processing regions during memory for motor sequences

Direct comparison of prefrontal cortex regions engaged by working and long-term memory tasks.

by T S raver, D M Barch, W M Kelley, R L Buckner, N J Cohen, F M Miezin - Neuroimage, , 2001
"... ..."
Abstract - Cited by 54 (13 self) - Add to MetaCart
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Confidence in recognition memory for words: Dissociating right prefrontal roles in episodic retrieval

by R. N. A. Henson, M. D. Rugg, T. Shallice, R. J. Dolan - Journal of Cognitive Neuroscience , 2000
"... & We used event-related functional magnetic resonance imaging (efMRI) to investigate brain regions showing differential responses as a function of confidence in an episodic word recognition task. Twelve healthy volunteers indicated whether their old±new judgments were made with high or low confi ..."
Abstract - Cited by 47 (6 self) - Add to MetaCart
& We used event-related functional magnetic resonance imaging (efMRI) to investigate brain regions showing differential responses as a function of confidence in an episodic word recognition task. Twelve healthy volunteers indicated whether their old±new judgments were made with high or low confidence. Hemodynamic responses associated with each judgment were modeled with an ``early' ' and a ``late' ' response function. As predicted by the monitoring hypothesis generated from a previous recognition study
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