Dissociation of Dorsal Hippocampal Regional Activation Under the Influence of Stress in Freely Behaving Rats

Stress has deleterious effects on brain, body, and behavior in humans and animals alike. The present work investigated how 30-min acute photic stress exposure impacts on spatial information processing in the main sub-regions of the dorsal hippocampal formation [CA1, CA3, and dentate gyrus (DG)], a brain structure prominently implicated in memory and spatial representation. Recordings were performed from spatially tuned hippocampal and DG cells in rats while animals foraged in a square arena for food. The stress procedure induced a decrease in firing frequencies in CA1 and CA3 place cells while sparing locational characteristics. In contrast to the CA1–CA3 network, acute stress failed to induce major changes in the DG neuronal population. These data demonstrate a clear dissociation of the effects of stress on the main hippocampal sub-regions. Our findings further support the notion of decreased hippocampal excitability arising from behavioral stress in areas CA1 and CA3, but not in DG

Evidence for Spatially-Responsive Neurons in the Rostral Thalamus

Damage involving the anterior thalamic and adjacent rostral thalamic nuclei may result in a severe anterograde amnesia, similar to the amnesia resulting from damage to the hippocampal formation. Little is known, however, about the information represented in these nuclei. To redress this deficit, we recorded units in three rostral thalamic nuclei in freely-moving rats (the parataenial nucleus, the anteromedial nucleus and nucleus reuniens). We found units in these nuclei possessing previously unsuspected spatial properties. The various cell types show clear similarities to place cells, head direction cells, and perimeter/border cells described in hippocampal and parahippocampal regions. Based on their connectivity, it had been predicted that the anterior thalamic nuclei process information with high spatial and temporal resolution while the midline nuclei have more diffuse roles in attention and arousal. Our current findings strongly support the first prediction but directly challenge or substantially moderate the second prediction. The rostral thalamic spatial cells described here may reflect direct hippocampal/parahippocampal inputs, a striking finding of itself, given the relative lack of place cells in other sites receiving direct hippocampal formation inputs. Alternatively, they may provide elemental thalamic spatial inputs to assist hippocampal spatial computations. Finally, they could represent a parallel spatial system in the brain

A systematic review on intra-abdominal pressure in severely burned patients

Objective: Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are complications that may occur in severely burned patients. Evidenced based medicine for these patients is in its early development. The aim of this study was to provide an overview of literature regarding IAH and ACS in severely burned patients. Methods: A systematic search was performed in Cochrane Central Register of Controlled Trials, PubMed, Embase, Web of Science and CINAHL on October 1, 2012. These databases were searched on 'burn', 'intra-abdominal hypertension', 'abdominal compartment syndrome', synonyms and abbreviations. Studies reporting original data on mortality, abdominal decompression or abdominal pressure related complications were included. Results: Fifty publications met the criteria, reporting 1616 patients. The prevalence of ACS and IAH in severely burned patients is 4.1-16.6% and 64.7-74.5%, respectively. The mean mortality rate for ACS in burn patients is 74.8%. The use of plasma and hypertonic lactated resuscitation may prevent IAH or ACS. Despite colloids decrease resuscitation volume needs, no benefit in preventing IAH was proven. Escharotomy, peritoneal catheter drainage, and decompression laparotomy are effective intra-abdominal pressure (IAP) diminishing treatments in burn patients. Markers for IAP-related organ damage might be superior to IAP measurement itself. Conclusion: ACS and IAH are frequently seen devastating complications in already severely injured burn patients. Prevention is challenging but can be achieved by improving fluid resuscitation strategies. Surgical decompression measures are effective and often unavoidable. Timing is essential since decompression should prevent progression to ACS rather than limit its effects. Prognosis of ACS remains poor, but options for care improvement are available in literature. (C) 2013 Elsevier Ltd and ISBI. All rights reserved