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Full-Text Articles in Medicine and Health Sciences

The Relationship Between The Field-Shifting Phenomenon And Representational Coherence Of Place Cells In Ca1 And Ca3 In A Cue-Altered Environment, Inah Lee, James J Knierim Nov 2007

The Relationship Between The Field-Shifting Phenomenon And Representational Coherence Of Place Cells In Ca1 And Ca3 In A Cue-Altered Environment, Inah Lee, James J Knierim

Journal Articles

Subfields of the hippocampus display differential dynamics in processing a spatial environment, especially when changes are introduced to the environment. Specifically, when familiar cues in the environment are spatially rearranged, place cells in the CA3 subfield tend to rotate with a particular set of cues (e.g., proximal cues), maintaining a coherent spatial representation. Place cells in CA1, in contrast, display discordant behaviors (e.g., rotating with different sets of cues or remapping) in the same condition. In addition, on average, CA3 place cells shift their firing locations (measured by the center of mass, or COM) backward over time when the animal …


Neuropathological Findings Processed By Artificial Neural Networks (Anns) Can Perfectly Distinguish Alzheimer's Patients From Controls In The Nun Study, Enzo Grossi, Massimo P. Buscema, David Snowdon, Piero Antuono Jun 2007

Neuropathological Findings Processed By Artificial Neural Networks (Anns) Can Perfectly Distinguish Alzheimer's Patients From Controls In The Nun Study, Enzo Grossi, Massimo P. Buscema, David Snowdon, Piero Antuono

Sanders-Brown Center on Aging Faculty Publications

BACKGROUND: Many reports have described that there are fewer differences in AD brain neuropathologic lesions between AD patients and control subjects aged 80 years and older, as compared with the considerable differences between younger persons with AD and controls. In fact some investigators have suggested that since neurofibrillary tangles (NFT) can be identified in the brains of non-demented elderly subjects they should be considered as a consequence of the aging process. At present, there are no universally accepted neuropathological criteria which can mathematically differentiate AD from healthy brain in the oldest old. The aim of this study is to discover …


Formation Of Native Prions From Minimal Components In Vitro, Nathan R. Deleault, Brent T. Harris, Judy R. Rees, Surachai Supattapone Jun 2007

Formation Of Native Prions From Minimal Components In Vitro, Nathan R. Deleault, Brent T. Harris, Judy R. Rees, Surachai Supattapone

Dartmouth Scholarship

The conformational change of a host protein, PrPC, into a disease-associated isoform, PrPSc, appears to play a critical role in the pathogenesis of prion diseases such as Creutzfeldt–Jakob disease and scrapie. However, the fundamental mechanism by which infectious prions are produced in neurons remains unknown. To investigate the mechanism of prion formation biochemically, we conducted a series of experiments using the protein misfolding cyclic amplification (PMCA) technique with a preparation containing only native PrPC and copurified lipid molecules. These experiments showed that successful PMCA propagation of PrPScmolecules in a purified system requires accessory polyanion molecules. In addition, we found that …


Traumatic Brain Injury Stimulates Hippocampal Catechol-O-Methyl Transferase Expression In Microglia, John B Redell, Pramod K Dash Feb 2007

Traumatic Brain Injury Stimulates Hippocampal Catechol-O-Methyl Transferase Expression In Microglia, John B Redell, Pramod K Dash

Journal Articles

Outcome following traumatic brain injury (TBI) is in large part determined by the combined action of multiple processes. In order to better understand the response of the central nervous system to injury, we utilized an antibody array to simultaneously screen 507 proteins for altered expression in the injured hippocampus, a structure critical for memory formation. Array analysis indicated 41 candidate proteins have altered expression levels 24h after TBI. Of particular interest was catechol-O-methyl transferase (COMT), an enzyme involved in metabolizing catecholamines released following neuronal activity. Altered catecholamine signaling has been observed after brain injury, and may contribute to the cognitive …


Contrasting Roles Of Neural Firing Rate And Local Field Potentials In Human Memory, A. Ekstrom, Indre Viskontas, M. Kahana, J. Jacobs, K. Upchurch, S. Bookheimer, I. Fried Jan 2007

Contrasting Roles Of Neural Firing Rate And Local Field Potentials In Human Memory, A. Ekstrom, Indre Viskontas, M. Kahana, J. Jacobs, K. Upchurch, S. Bookheimer, I. Fried

Psychology

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 …