Histomorphological analysis of the urogenital diaphragm in elderly women: a cadaver study

The objective of this study was to describe the histomorphological structure of the urogenital diaphragm in elderly women using a modern morphometric procedure. Biopsies were taken from the posterior margin of the urogenital diaphragm of 22 female cadavers (mean age, 87 years) using a 60-mm punch. Hematoxylin/eosin and Goldner sections were analyzed with the Cavalieri estimator. The mean thickness of the urogenital diaphragm was 5.5 mm. The main component was connective tissue. All biopsies contained smooth muscle. Eighteen biopsies contained more smooth muscle than striated muscle. In six of 22 biopsies, no striated muscle was found. The ratio of striated to smooth muscle to connective tissue was 1:2.3:13.3. Muscle fibers were dispersed in all parts of the urogenital diaphragm. The urogenital diaphragm of elderly women mainly consists of connective tissue. Smooth muscle was also found but to a lesser extent. The frequently used English term "perineal membrane" for the urogenital diaphragm is justified and well describes our findings in elderly women

Eyeblink conditioning in the infant rat: an animal model of learning in developmental neurotoxicology.

Classical conditioning of the eyeblink reflex is a relatively simple procedure for studying associative learning that was first developed for use with human subjects more than half a century ago. The use of this procedure in laboratory animals by psychologists and neuroscientists over the past 30 years has produced a powerful animal model for studying the behavioral and biological mechanisms of learning. As a result, eyeblink conditioning is beginning to be pursued as a very promising model for predicting and understanding human learning and memory disorders. Among the many advantages of this procedure are (a) the fact that it can be carried out in the same manner in both humans and laboratory animals; (b) the many ways in which it permits one to characterize changes in learning at the behavioral level; (c) the readiness with which hypotheses regarding the neurological basis of behavioral disorders can be formulated and tested; (d) the fact that it can be used in the same way across the life-span; and (e) its ability to distinguish, from normative groups, populations suffering from neurological conditions associated with impaired learning and memory, including those produced by exposure to neurotoxicants. In this article, we argue that these properties of eyeblink conditioning make it an excellent model system for studying early impairments of learning and memory in developmental neurotoxicology. We also review progress that has been made in our laboratory in developing a rodent model of infant eyeblink conditioning for this purpose

Linking canonical microcircuits and neuronal activity: Dynamic causal modelling of laminar recordings

Neural models describe brain activity at different scales, ranging from single cells to whole brain networks. Here, we attempt to reconcile models operating at the microscopic (compartmental) and mesoscopic (neural mass) scales to analyse data from microelectrode recordings of intralaminar neural activity. Although these two classes of models operate at different scales, it is relatively straightforward to create neural mass models of ensemble activity that are equipped with priors obtained after fitting data generated by detailed microscopic models. This provides generative (forward) models of measured neuronal responses that retain construct validity in relation to compartmental models. We illustrate our approach using cross spectral responses obtained from V1 during a visual perception paradigm that involved optogenetic manipulation of the basal forebrain. We find that the resulting neural mass model can distinguish between activity in distinct cortical layers – both with and without optogenetic activation – and that cholinergic input appears to enhance (disinhibit) superficial layer activity relative to deep layers. This is particularly interesting from the perspective of predictive coding, where neuromodulators are thought to boost prediction errors that ascend the cortical hierarchy

A morphologically distinct granule cell type in the dentate gyrus of the red fox correlates with adult hippocampal neurogenesis

Wild red foxes, proverbially cunning carnivores, are investigated for adult hippocampal neurogenesis and morphological characteristics of the dentate gyrus. Adult red foxes harbor almost 15-times more young, doublecortin-positive neurons in their dentate gyrus than domesticated dogs. The number of doublecortin-positive cells corresponds to 4.4% of the total granule cell number, whereas dividing cells amount to only 0.06%. Compared to laboratory mice, proliferating (Ki67-positive) and dying cells are rare, but the percentage of new neurons is quite similar. The number of proliferating cells, young cells of neuronal lineage and dying cells are correlated. Resident granule cells can be divided into two types with strikingly different morphologies, staining patterns and distinct septotemporal distributions. Small sized granule cells with a nuclear diameter of 7.3 μm account for ~83% of all granule cells. The remaining granule cells are significantly larger with a nuclear diameter of 9.4 μm diameter and stain heavily for NeuN. Septally and mid-septotemporally, densely packed small cells dominate. Here, only few large granule cells are scattered throughout the layer. Temporally, granule cells become more loosely packed and most of the cells are of the large type. High rates of neurogenesis are observed in foxes with high numbers of large granule cells, whereas the number of small granule cells does not correlate with any of the neurogenesis-related cell counts. Staining for parvalbumin, glutamate receptor 2/3, GAP-43 and dynorphin show an anatomical context that is a composite of features common also to other mammalian species. In summary, we report a morphologically distinct granule cell type which correlates with adult 3 hippocampal neurogenesis in the fox. Furthermore, the maturation phase of the young neurons may be prolonged as in other long-living species such as primates

The hippocampal region of rats and mice after a single intraperitoneal dose of clioquinol: loss of synaptic zinc, cell death and c-Fos induction

Clioquinol (CQ) is able to chelate synaptic zinc, which can modulate excitatory and inhibitory neurotransmission. In humans, CQ was associated with cases of transient global amnesia (TGA) and with the neurodegenerative syndrome subacute myelo-optico-neuropathy (SMON). We examined the CQ induced loss of synaptic zinc, cell death and c-Fos induction in rats and mice. In rats, we found a strong reduction of histochemically reactive synaptic zinc no later than four hours after the injection of the lowest dose of CQ (50 mg/kg) and, for all doses used, a return to control levels after 48 hours. There was no evidence of cell death for any dose and up to one week after CQ injections. Only a slight induction of c-Fos was seen in the hippocampus for the higher doses used (100-200 mg/kg). In mice injected with 100 mg/kg, CQ also resulted in a fast loss of synaptic zinc. c-Fos was induced after 4 hours in cell populations of the hippocampal region and other parts of the telencephalon, and substantially increased after 24 hours. One day after the injection we found a pattern of cell loss (hilus, parts of CA3, CA1 and layer III of the medial entorhinal cortex) reminiscent of that seen in models of temporal lobe epilepsy. In conjunction with published data on the behavioral effects of zinc chelation and the modulatory effects of zinc in excitatory neurotransmission, our results indicate that the loss of synaptic zinc may have been involved in TGA and the neuropathology associated with SMON