Anterior Thalamic Inputs Are Required for Subiculum Spatial Coding, with Associated Consequences for Hippocampal Spatial Memory.

Just as hippocampal lesions are principally responsible for "temporal lobe" amnesia, lesions affecting the anterior thalamic nuclei seem principally responsible for a similar loss of memory, "diencephalic" amnesia. Compared with the former, the causes of diencephalic amnesia have remained elusive. A potential clue comes from how the two sites are interconnected, as within the hippocampal formation, only the subiculum has direct, reciprocal connections with the anterior thalamic nuclei. We found that both permanent and reversible anterior thalamic nuclei lesions in male rats cause a cessation of subicular spatial signaling, reduce spatial memory performance to chance, but leave hippocampal CA1 place cells largely unaffected. We suggest that a core element of diencephalic amnesia stems from the information loss in hippocampal output regions following anterior thalamic pathology.SIGNIFICANCE STATEMENT At present, we know little about interactions between temporal lobe and diencephalic memory systems. Here, we focused on the subiculum, as the sole hippocampal formation region directly interconnected with the anterior thalamic nuclei. We combined reversible and permanent lesions of the anterior thalamic nuclei, electrophysiological recordings of the subiculum, and behavioral analyses. Our results were striking and clear: following permanent thalamic lesions, the diverse spatial signals normally found in the subiculum (including place cells, grid cells, and head-direction cells) all disappeared. Anterior thalamic lesions had no discernible impact on hippocampal CA1 place fields. Thus, spatial firing activity within the subiculum requires anterior thalamic function, as does successful spatial memory performance. Our findings provide a key missing part of the much bigger puzzle concerning why anterior thalamic damage is so catastrophic for spatial memory in rodents and episodic memory in humans.

Place cells in the claustrum remap under NMDA receptor control.

Place cells are cells that exhibit location-dependent responses; they have mostly been studied in the hippocampus. Place cells have also been reported in the rat claustrum, an underexplored paracortical region with extensive corto-cortical connectivity. It has been hypothesised that claustral neuronal responses are anchored to cortical visual inputs. We show rat claustral place cells remap when visual inputs are eliminated from the environment, and that this remapping is NMDA-receptor-dependent. Eliminating visual input decreases claustral delta-band oscillatory activity, increases theta-band oscillatory activity, and increases simultaneously recorded visual cortical activity. We conclude that, like the hippocampus, claustral place field remapping might be mediated by NMDA receptor activity, and is modulated by visual cortical inputs.

NeuroChaT: A toolbox to analyse the dynamics of neuronal encoding in freely-behaving rodents in vivo.

There is a dearth of freely-available, standardised open source analysis tools available for the analysis of neuronal signals recorded in vivo in the freely-behaving animal. In response, we have developed a freely-available, open-source toolbox, NeuroChaT ( Neuron Characterisation Toolbox), specifically addressing this lacuna. Although we have particularly emphasised single unit analyses for spatial coding, NeuroChaT also characterises rhythmic properties of units and their dynamics associated with local field potential signals. NeuroChaT was developed using Python and facilitates a complete pipeline from automation of analysis to producing and managing publication-quality figures. Additionally, we have adopted a platform-independent format (Hierarchical Data Format version 5) for storing recorded and analysed data. By providing an easy-to-use software package, we aim to simplify the adoption of standardised analyses for behavioural neurophysiology and facilitate open data sharing and collaboration between laboratories.

Subcutaneous fat necrosis as the presenting feature of a pancreatic carcinoma: the challenge of differentiating endocrine and acinar pancreatic neoplasms.

The association between pancreatic panniculitis and pancreatic disease is well described, but differentiation among the neoplastic causes of the syndrome remains difficult due to substantial overlap in histological and immunohistochemical features. We report a case of subcutaneous fat necrosis as the presenting feature in a 61-year-old man with metastatic carcinoma of pancreatic origin. Previous pathological evaluation of the patient's liver biopsy led to an initial diagnosis of adenocarcinoma of unknown primary site. One month later, the patient presented with pancreatic panniculitis, prompting further investigation. Immunohistochemistry was consistent with neuroendocrine differentiation, but the patient rapidly decompensated and died before the evaluation was complete, leaving the definitive diagnosis in question. In our review of the published reports of tumor types associated with pancreatic panniculitis, we found that immunohistochemical staining and electron microscopy can and should be used in conjunction with clinical correlation to accurately differentiate neuroendocrine tumors from carcinomas with acinar cell features. Accurate diagnosis of these tumors is necessary to determine prognosis and define appropriate therapy.

Blunt trauma patients with prehospital pulseless electrical activity (PEA): poor ending assured.

BACKGROUND: The paucity of information on the outcome of patients experiencing prehospital pulseless electrical activity (PEA) after blunt injury led to the present study. METHODS: A retrospective review was performed of all blunt trauma victims with prehospital PEA from 1997 to 2001 in an urban county trauma system. RESULTS: One hundred ten patients, 78 men and 32 women, met study criteria. Seventy-nine patients had PEA at the scene, and 31 experienced PEA en route to a trauma center. All patients were transported in advanced life support ambulances. Cardiopulmonary resuscitation was initiated when PEA was detected. Vital signs were regained en route or at the trauma center by 25 patients (23%). The incidence of pupillary reactivity at the scene was higher in patients who regained vital signs (48% vs. 16%). Only one patient, who has significant residual neurologic impairment, survived. The mean Injury Severity Score of this population was 45.1. CONCLUSION: If these grim results are corroborated by other investigators, consideration should be given to allowing paramedics to declare blunt trauma victims with PEA dead at the scene.