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Human Memory (human + memory)
Selected AbstractsContrasting roles of neural firing rate and local field potentials in human memoryHIPPOCAMPUS, Issue 8 2007Arne Ekstrom Abstract Recording the activity of neurons is a mainstay of animal memory research, while human recordings are generally limited to the activity of large ensembles of cells. The relationship between ensemble activity and neural firing rate during declarative memory processes, however, remains unclear. We recorded neurons and local field potentials (LFPs) simultaneously from the same sites in the human hippocampus and entorhinal cortex (ERC) in patients with implanted intracranial electrodes during a virtual taxi-driver task that also included a memory retrieval component. Neurons increased their firing rate in response to specific passengers or landmarks both during navigation and retrieval. Although we did not find item specificity in the broadband LFP, both ,- and ,-band LFPs increased power to specific items on a small but significant percent of channels. These responses, however, did not correlate with item-specific neural responses. To contrast item-specific responses with process-specific responses during memory, we compared neural and LFP responses during encoding (navigation) and retrieval (associative and item-specific recognition). A subset of neurons also altered firing rates nonspecifically while subjects viewed items during encoding. Interestingly, LFPs in the hippocampus and ERC increased in power nonspecifically while subjects viewed items during retrieval, more often during associative than item-recognition. Furthermore, we found no correlation between neural firing rate and broadband, ,-band, and ,-band LFPs during process-specific responses. Our findings suggest that neuronal firing and ensemble activity can be dissociated during encoding, item-maintenance, and retrieval in the human hippocampal area, likely relating to functional properties unique to this region. © 2007 Wiley-Liss, Inc. [source] Neuropsychological correlates of hippocampal and rhinal cortex volumes in patients with mesial temporal sclerosisHIPPOCAMPUS, Issue 8 2003Catherine E. O'Brien Abstract Considerable progress has been made toward understanding the function of the primate rhinal cortex, comprising the entorhinal (ErC) and perirhinal (PrC) cortices. However, translating animal models to human memory has been limited by the technological problems associated with characterizing neural structures in vivo. Functional correlates of hippocampal and rhinal cortex volume changes were examined in a sample of 61 temporal lobe epilepsy patients with mesial temporal sclerosis (MTS; 33 left, 28 right). Patients were administered the Wechsler Adult Intelligence Scale (revised or third edition), the Wechsler Memory Scale (revised or third edition), and a spatial maze task. Neuropsychological data, together with rhinal cortex and hippocampal volumes, collected in our earlier study (O'Brien CE, Bowden SC, Whelan G, Cook MJ, unpublished observations), were analyzed using multiple regression. The only significant predictor of verbal memory function was the difference score between the volume of left hippocampus and the left PrC. Spatial maze scores were predicted by the bilateral sum of ErC volume. The difference score between the left hippocampus and left PrC volumes was the most powerful predictor of verbal episodic memory. Right hippocampal volume was not a significant predictor of nonverbal episodic memory. Verbal and nonverbal semantic memory were not significantly predicted by any combination of rhinal cortex structures. This quantitative study suggests a lateralized or material-specific memory function for the left hippocampus and left PrC, in contrast to the bilateral role of the ErC. The left hippocampus and left PrC appear to act on verbal memory function through an opposing relationship. Finally, differentiation between hippocampal and subhippocampal components in terms of episodic and semantic memory, respectively, could not be supported by the current data. © 2003 Wiley-Liss, Inc. [source] Differential contributions of the parahippocampal place area and the anterior hippocampus to human memory for scenesHIPPOCAMPUS, Issue 6 2002Stefan Köhler Abstract Past neuroimaging research has identified a parahippocampal place area (PPA) in the posterior medial temporal lobe (MTL), which responds preferentially to visual scenes and plays a role in episodic memory for this class of stimuli. In the present positron emission tomography study, we examined to what extent the functional characteristics of the PPA resemble those of other, more anterior MTL regions across various learning and recognition-memory tasks. We also determined whether the involvement of the PPA in recognition of previously studied scenes is specific to a particular type of scene information. We found that, like the PPA, anterior hippocampal regions showed a novelty response (higher activation for novel than repeated scenes) and a stimulus-related response (higher activation for scenes than objects) during learning, indicating that MTL structures other than the PPA contribute to the encoding of novel stimulus relationships in scenes. However, these anterior hippocampal regions showed no involvement during recognition of either spatial or nonspatial information contained in scenes. The PPA, by contrast, was consistently involved in recognition of all types of scene details, presumably through interactions with co-activated parietal and occipitotemporal cortices. We suggest that MTL contributions from the PPA are sufficient to support recognition of scenes when the task can be based on a perceptually based familiarity process. Hippocampus 2002;12:718,723. © 2002 Wiley-Liss, Inc. [source] Face as an index: Knowing who is who using a PDAINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 1 2003Jie Yang Abstract In this article, we present a PDA-based system for extending human memory or/and information retrieval using a human face as the lookup index. The system can help a user to remember names of people whom he/she has met before and find useful information, such as names and research interests, about people whom he/she is interested in talking to. The system uses a captured face image as the lookup index to retrieve information from some available resource such as departmental directory, web sites, personal homepages, etc. We describe the development of a PDA-based face recognition system and introduce algorithms for image preprocessing to enhance the quality of the image by sharpening focus and normalizing both lighting condition and head rotation. We use a unified LDA/PCA algorithm for face recognition. We address design issues of the interface to assist in visualization and comprehension of retrieved information. We present user study and experiment results to demonstrate the feasibility of the proposed system. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13: 33,41, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10046 [source] Towards memory supporting personal information management toolsJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 7 2007David Elsweiler In this article, the authors discuss reretrieving personal information objects and relate the task to recovering from lapse(s) in memory. They propose that memory lapses impede users from successfully refinding the information they need. Their hypothesis is that by learning more about memory lapses in noncomputing contexts and about how people cope and recover from these lapses, we can better inform the design of personal information management (PIM) tools and improve the user's ability to reaccess and reuse objects. They describe a diary study that investigates the everyday memory problems of 25 people from a wide range of backgrounds. Based on the findings, they present a series of principles that they hypothesize will improve the design of PIM tools. This hypothesis is validated by an evaluation of a tool for managing personal photographs, which was designed with respect to the authors' findings. The evaluation suggests that users' performance when refinding objects can be improved by building personal information management tools to support characteristics of human memory. [source] The Sources and Fortunes of Piranesi's Archaeological IllustrationsART HISTORY, Issue 4 2002Susan M. Dixon Susan M. Dixon earned her doctorate from Cornell University in 1991 with a dissertation on the archaeological publications of Giovanni Battista Piranesi. She studies the history of pre,scientific archaeology, from Pirro Ligorio to Piranesi, with a particular focus on illustration as a means to convey historical knowledge. She has published on this subject in a variety of venues, and is beginning a book,length manuscript on the subject. In 1995,96, she was awarded a J. Paul Getty post,doctoral fellowship to study the Accademia degli Arcadi, a society founded in 1690 primarily to restore good taste in literature, and its successes and failures in bringing about the reform of Italian society and architecture. She has written a book entitled The Bosco Parrasio: Performance and Perfectibility in the Garden of the Arcadians, which focuses on their garden meeting place as a breeding ground for a utopian society. Dr Dixon teaches art history at the University of Tulsa in Oklahoma. Giovanni Battista Piranesi (1720,1778) developed a way of representing the archaeological past by using the multi,informational image, an engraved illustration which appears to be a composite of various drawings, on various surfaces, and employing various modes of representation, scale and detail. The cartographic tradition, particularly maps from sixteenth,century Europe, offer a precedent for this type of illustration. Piranesi found theoretical underpinnings for it in contemporary discussions about the workings of the human memory, which was identified as a viable tool for those pursuing historical knowledge. His illustrations make visible the processes of memory on an assemblage of archaeological information, and they were a means to historical reconstruction. Archaeologists of the generation after Piranesi did not use the multi,informational image as the science of archaeology underwent a sea change at the end of the century. However, some compilers of travel literature, in particular Jean,Laurent,Pierre HoÃ,el, author and illustrator of Voyage pittoresque des isles de Sicile, de Malte, et de Lipari, found the format suitable to their purposes. Like Piranesi's, Hoüel's multi,informational images reveal the hand of the artist on the information he had diligently collected and ordered; Hoüel's picturesque illustrations of the southern Italian islands' people and places are self,consciously subjective. The format also makes apparent what was so appealing to many a voyager ,the apparent survival of the past in the culture of the present. [source] Memory with emotional content, brain amygdala and Alzheimer's diseaseACTA NEUROLOGICA SCANDINAVICA, Issue 2 2009R. R. Schultz Objectives,,, A highly adaptive aspect of human memory is the enhancement of explicit, consciously accessible memory by emotional stimuli. We studied the performance of Alzheimer's disease (AD) patients and elderly controls using a memory battery with emotional content, and we correlated these results with the amygdala and hippocampus volume. Methods,,, Twenty controls and 20 early AD patients were subjected to the International Affective Picture System (IAPS) and to magnetic resonance imaging-based volumetric measurements of the medial temporal lobe structures. Results,,, The results show that excluding control group subjects with 5 or more years of schooling, both groups showed improvement with pleasant or unpleasant figures for the IAPS in an immediate free recall test. Likewise, in a delayed free recall test, both the controls and the AD group showed improvement for pleasant pictures, when education factor was not controlled. The AD group showed improvement in the immediate and delayed free recall test proportional to the medial temporal lobe structures, with no significant clinical correlation between affective valence and amygdala volume. Conclusion,,, AD patients can correctly identify emotions, at least at this early stage, but this does not improve their memory performance. [source] Decision Structure and the Problem of Scale in DeliberationCOMMUNICATION THEORY, Issue 2 2006Raymond J. Pingree Deliberation has been limited to small groups because coherence seems to require full reception, meaning that all participants receive all messages sent. Assuming that full reception actually leads to coherence ignores fundamental limits of human memory and group processes. Full reception is also not the only route to coherence because the forms of coherence desired in deliberation are decision specific and because all deliberations at least implicitly contain a structure of subdecisions. Coherent deliberation is plausible at large scales, without full reception, via a theoretical model called decision-structured deliberation. This model allows coherent contributions by participants who are unaware of large parts of the discussion and may reduce negative effects of limits of memory and group processes on the quality of deliberation. [source] | |||||||||||||