1,721,016 research outputs found
Episodic encoding is more than the sum of its parts: An fMRI investigation of multifeatural contextual encoding
No full textEpisodic memories are characterized by their contextual richness, yet little is known about how the various features comprising an episode are brought together in memory. Here we employed fMRI and a multidimensional source memory procedure to investigate processes supporting the mnemonic binding of item and contextual information. Volunteers were scanned while encoding items for which the contextual features (color and location) varied independently, allowing activity elicited at the time of study to be segregated according to whether both, one, or neither feature was successfully retrieved on a later memory test. Activity uniquely associated with successful encoding of both features was identified in the intra-parietal sulcus, a region strongly implicated in the support of attentionally mediated perceptual binding. The findings suggest that the encoding of disparate features of an episode into a common memory representation requires that the features be conjoined in a common perceptual representation when the episode is initially experienced
ERP correlates of retrieval orientation: direct versus indirect memory tasks
No full textThe neural correlates of the processes involved in cueing memory retrieval were investigated using ERPs to unstudied (new) items in a yes/no recognition test (direct memory task) and a semantic judgement task (indirect memory task). Subjects encoded either pictures or auditory words and were tested on visual words. We replicated previous findings that ERPs to correct rejections of new items in a yes/no recognition test differ according to the study material, with ERPs to words encoded as pictures being more negative (relative to a average mastoid reference) than words encoded auditorily [Hornberger, M., Morcom, A.M., et al., 2004. Neural correlates of retrieval orientation: effects of study-test similarity. J. Cogn. Neurosci. 16 (7), 1196–1210]. This difference was sustained from approximately 450–1200 ms. An effect of study material on the ERP to new items was found in the indirect memory task but was both earlier onsetting and shorter lived, ca. 250–600 ms. These findings add weight to the concept of ‘retrieval orientation’ [Rugg, M.D., Wilding, E.L., 2000. Retrieval processing and episodic memory. Trends Cogn. Sci. 4 (3) 108–115] – differential processing of retrieval cues according to the form of the sought-for information – by showing that a putative ERP correlate of retrieval orientation is restricted to direct memory tasks
fMRI correlates of retrieval orientation
No full textProcesses related to the cueing of memory retrieval were investigated using fMRI during a yes/no recognition memory test. Participants studied either pictures or auditory words and were subsequently tested with visual words that either corresponded to studied items (old items) or were unstudied (new items). It was expected that neural activity would differ according to the type of information participants are trying to retrieve: a manifestation of the so-called “retrieval orientation” effect. We replicated robust old/new effects in parietal, prefrontal and anterior medial temporal lobe cortices, which did not differ according to the study material. However, we did observe differential activity to test items in temporoparietal cortex and fusiform cortex as a function of the study material. More specifically, attempts to retrieve words encoded auditorily produced greater activity in auditory cortex than attempts to retrieve words encoded as pictures, whereas the converse was found in fusiform cortex. The above pattern was found for both new and old test items. These findings implicate these regions in constraining the search for specific types of encoded information and thus are in accordance with the transfer-appropriate processing framework. Further, we propose that our results can be seen as an extension of the cortical reinstatement hypothesis, in that the same material-specific cortical regions are engaged during both encoding and retrieval, and this increases the likelihood of successful recognition, or rejection, of retrieval cues in a memory test
The inferior parietal lobule and recognition memory : expectancy violation or successful retrieval?
No full textFunctional neuroimaging studies of episodic recognition demonstrate an increased lateral parietal response for studied versus new materials, often termed a retrieval success effect. Using a novel memory analog of attentional cueing, we manipulated the correspondence between anticipated and actual recognition evidence by presenting valid or invalid anticipatory cues (e. g., "likely old") before recognition judgments. Although a superior parietal region demonstrated the retrieval success pattern, a larger inferior parietal lobule (IPL) region tracked the validity of the memory cueing (invalid cueing > valid cueing) and no retrieval success-sensitive lateral parietal region was insensitive to cueing. The invalid cueing response occurred even for correctly identified new items unlikely to trigger substantive episodic retrieval. Within the IPL, although supramarginal and angular gyrus (SMG; AG) regions both demonstrated invalid cueing amplitude elevations, each region differentially coupled with distinct cortical networks when unexpectedly old items were encountered; a connectivity pattern also observed at rest in the same subjects. These findings jointly suggest that the lateral parietal response during recognition does not signify the recovery of episodic content, but is a marker of the violation of memory expectations. A second independent dataset confirmed this interpretation by demonstrating that SMG activation tracked the decision biases of observers, not their accuracy, with increased activation for nondominant recognition judgments. The expectancy violation interpretation of the lateral parietal recognition response is consistent with the literature on visual search and oddball paradigms and suggests that damage to these regions should impair memory-linked orienting behavior and not retrieval per se.Peer reviewe
Confidence in recognition memory for words: Dissociating right prefrontal roles in episodic retrieval
Full text linkWe 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 [Henson, R. N. A., Rugg, M. D., Shallice, T., Josephs, O., & Dolan, R. J. (1999a). Recollection and familiarity in recognition memory: An event-related fMRI study. Journal of Neuroscience, 19, 3962-3972], a right dorsolateral prefrontal region showed a greater response to correct low- versus correct high-confidence judgements. Several regions, including the precuneus, posterior cingulate, and left lateral parietal cortex, showed greater responses to correct old than correct new judgements. The anterior left and right prefrontal regions also showed an old-new difference, but for these regions the difference emerged relatively later in time. These results further support the proposal that different subregions of the prefrontal cortex subserve different functions during episodic retrieval. These functions are discussed in relation to a monitoring process, which operates when familiarity levels are close to response criterion and is associated with nonconfident judgements, and a recollective process, which is associated with the confident recognition of old words
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Separating the brain regions involved in recollection and familiarity in recognition memory
Full text linkThe neural substrates of recognition memory retrieval were examined in a functional magnetic resonance imaging study designed to separate activity related to recollection from that related to continuous variations in familiarity. Across a variety of brain regions, the neural signature of recollection was found to be distinct from familiarity, demonstrating that recollection cannot be attributed to familiarity strength. In the prefrontal cortex, an anterior medial region was related to recollection, but lateral regions, including the anterior and dorsolateral prefrontal cortex, were related to familiarity. Along the lateral parietal cortex, two functionally distinct regions were also observed: a lateral parietal/temporal region related to recollection and a more superior parietal region involved in familiarity. Similarly, in medial parietal regions, the posterior cingulate was related to recollection, whereas the precuneus was related to familiarity. The hippocampus was related to recollection, but also exhibited an inverse relationship to familiarity-driven recognition confidence. The results indicate that recollection and familiarity rely on different networks of brain regions and provide insights into the functional roles of different regions involved in episodic recognition memory
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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