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Anterior Hippocampus (anterior + hippocampus)
Selected AbstractsDifferential 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] Decreased basal fMRI functional connectivity in epileptogenic networks and contralateral compensatory mechanismsHUMAN BRAIN MAPPING, Issue 5 2009Gaelle Bettus Abstract A better understanding of interstructure relationship sustaining drug-resistant epileptogenic networks is crucial for surgical perspective and to better understand the consequences of epileptic processes on cognitive functions. We used resting-state fMRI to study basal functional connectivity within temporal lobes in medial temporal lobe epilepsy (MTLE) during interictal period. Two hundred consecutive single-shot GE-EPI acquisitions were acquired in 37 right-handed subjects (26 controls, eight patients presenting with left and three patients with right MTLE). For each hemisphere, normalized correlation coefficients were computed between pairs of time-course signals extracted from five regions involved in MTLE epileptogenic networks (Brodmann area 38, amygdala, entorhinal cortex (EC), anterior hippocampus (AntHip), and posterior hippocampus (PostHip)). In controls, an asymmetry was present with a global higher connectivity in the left temporal lobe. Relative to controls, the left MTLE group showed disruption of the left EC-AntHip link, and a trend of decreased connectivity of the left AntHip-PostHip link. In contrast, a trend of increased connectivity of the right AntHip-PostHip link was observed and was positively correlated to memory performance. At the individual level, seven out of the eight left MTLE patients showed decreased or disrupted functional connectivity. In this group, four patients with left TLE showed increased basal functional connectivity restricted to the right temporal lobe spared by seizures onset. A reverse pattern was observed at the individual level for patients with right TLE. This is the first demonstration of decreased basal functional connectivity within epileptogenic networks with concomitant contralateral increased connectivity possibly reflecting compensatory mechanisms. Hum Brain Mapp 2009. © 2008 Wiley-Liss, Inc. [source] Neural correlates of verbal episodic memory in patients with MCI and Alzheimer's disease,,a VBM studyINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 11 2008Dirk T. Leube Abstract Objective The hippocampus is a key area for episodic memory processes. Hippocampal atrophy is a hallmark feature of Alzheimer's disease (AD). We used a new and automatized morphometric technique to better characterize brain atrophy in subjects with different levels of cognitive deficit. Methods In this study 21 participants with Mild Cognitive Impairment (MCI), 12 patients with early AD and 29 elderly control subjects were subjected to high resolution MRI and a neuropsychological test battery. Brain volume across participants, measured by voxel-based morphometry (VBM), was correlated with verbal memory capacity, measured with a verbal memory test (VLMT). Results Atrophy in the anterior hippocampus, the ento- and perirhinal cortex as well as the parahippocampal gyrus, middle temporal gyrus and anterior cingulate cortex correlated closely with episodic memory performance. Conclusions These brain areas are known to subserve episodic encoding of verbal material. The data contribute to a better understanding of atrophic brain processes in subjects at risk for AD. A combination of neuropsychological testing and voxel-based morphometry may serve as a diagnostic tool in the future. Copyright © 2008 John Wiley & Sons, Ltd. [source] Comparison of the Effects of Hypothermia at 33°C or 35°C after Cardiac Arrest in RatsACADEMIC EMERGENCY MEDICINE, Issue 4 2007Eric S. Logue BS Abstract Objectives: Hypothermia of 32°C,34°C induced after resuscitation from cardiac arrest improves neurologic recovery, but the optimal depth of cooling is unknown. Using a rat model, the authors tested the hypothesis that cooling to 35°C between hours 1 and 24 after resuscitation would improve neurologic outcome as much as cooling to 33°C. Methods: Halothane-anesthetized rats (n= 38) underwent 8 minutes of asphyxial cardiac arrest and resuscitation. Cranial temperature was maintained at 37°C before, during, and after arrest. Between one and 24 hours after resuscitation, cranial temperature was maintained at 33°C, 35°C, or 37°C using computer-controlled cooling fans and heating lamps. Neurologic scores were measured daily, and rats were killed at 14 days for histologic analysis. Neurons per high-powered field were counted in the CA1 region of the anterior hippocampus using neuronal nuclear antigen staining. Results: After 14 days, 12 of 12 rats (100%) cooled to 33°C, 11 of 12 rats (92%) cooled to 35°C, and ten of 14 rats (71%) cooled to 37°C survived, with hazard of death greater in the rats cooled to 37°C than in the combined hypothermia groups. Neurologic scores were worse in the rats cooled to 37°C than in the hypothermia groups on days 1, 2, and 3. Numbers of surviving neurons were similar between the groups cooled to 33°C and 35°C and were higher than in the group cooled to 37°C. Conclusions: These data illustrate that hypothermia of 35°C or 33°C over the first day of recovery improves neurologic scores and neuronal survival after cardiac arrest in rats. The benefit of induced hypothermia of 35°C appears to be similar to the benefit of 33°C. [source] | |||||||||||||