Intact Neural Tissue Research Articles

Incoherent color holography lattice light-sheet for subcellular imaging of dynamic structures

The purpose of the article is to explore the need and advantages of using the incoherent color holography lattice light-sheet (ICHLLS) to provide multiwavelength quantitative monitoring of 3D cellular dynamics in live tissue to further understand complex functions of cells and cellular compartments. We have explored the use of incoherent color holography lattice light-sheet to investigate colocalization of fluorescent markers in live cells in intact tissue. Neuronal structures provide an attractive target for incoherent color holography lattice light-sheet. The cells show a complex architecture in 3D space in which signaling both between cells and within subcellular structures requires colocalization of proteins and lipids to function. During activity and over long periods it is important in understanding these signaling functions in Parkinson’s, Alzheimer’s and motoneuron diseases within live cells in intact tissue. As a proof of concept this article recalls the key aspects in lattice light-sheet imaging and provides a description of the incoherent detection system configuration to actively control dual diffractive lenses phase-shifting at multiple excitation wavelengths sequentially, and per each z-galvo scanning level, with extended field-of-view. The incoherent color holography lattice light-sheet system will allow simultaneous recording of multidimensional object waves that contain intensity in 3D space, phase, and wavelength information. We measure colocalization of fluorescence indicators introduced into live cells in intact neural tissue.

Interhemispheric Transcingulate Sulcus Approach to Deep-Seated Medial Frontal and Parietal Lesions-Fiber Dissection Study With Illustrative Cases.

Surgery for lesions located in the medial frontal and parietal lobes can be quite challenging for neurosurgeons because of morbidities that may arise from damage to critical midline structures or intact neural tissue that need to be crossed to reach the lesion. In our anatomic studies, the cingulate sulcus was observed as an alternative access route for lesions located in medial frontal and parietal lobes. To explain the microsurgical anatomy of the medial hemisphere and cingulate sulcus and to demonstrate the interhemispheric transcingulate sulcus approach (ITCSA) with 3 clinical cases. Five formalin-fixed brain specimens, which were frozen at -18 °C for at least 2 weeks and then thawed under tap water, were gradually dissected from medial to lateral. Diffusion fiber tracking performed using DSI Studio software in data was provided by the Human Connectome Project. Clinical data of 3 patients who underwent ITCSA were reviewed. Cingulate sulcus is an effortlessly identifiable continuous sulcus on the medial surface of the brain. Our anatomic dissection study revealed that the lesions located in the deep medial frontal and parietal lobes can be reached through the cingulate sulcus with minor injury only to the cingulum and callosal fibers. Three patients were treated with ITCSA without any neurological morbidity. Deep-seated lesions in the medial frontal lobe and parietal lobe medial to the corona radiata can be approached by using microsurgical techniques based on anatomic information. ITCSA offers an alternative route to these lesions besides the known lateral transcortical/transsulcal and interhemispheric transcingulate gyrus approaches.

Investigating the network consequences of focal brain lesions through comparisons of real and simulated lesions

Given the increased interest in the functional human connectome, a number of computer simulation studies have sought to develop a better quantitative understanding of the effects of focal lesions on the brain’s functional network organization. However, there has been little work evaluating the predictions of this simulation work vis a vis real lesioned connectomes. One of the few relevant studies reported findings from real chronic focal lesions that only partially confirmed simulation predictions. We hypothesize that these discrepancies arose because although the effects of focal lesions likely consist of two components: short-term node subtraction and long-term network re-organization, previous simulation studies have primarily modeled only the short-term consequences of the subtraction of lesioned nodes and their connections. To evaluate this hypothesis, we compared network properties (modularity, participation coefficient, within-module degree) between real functional connectomes obtained from chronic stroke participants and “pseudo-lesioned” functional connectomes generated by subtracting the same sets of lesioned nodes/connections from healthy control connectomes. We found that, as we hypothesized, the network properties of real-lesioned connectomes in chronic stroke differed from those of the pseudo-lesioned connectomes which instantiated only the short-term consequences of node subtraction. Reflecting the long-term consequences of focal lesions, we found re-organization of the neurotopography of global and local hubs in the real but not the pseudo-lesioned connectomes. We conclude that the long-term network re-organization that occurs in response to focal lesions involves changes in functional connectivity within the remaining intact neural tissue that go well beyond the short-term consequences of node subtraction.

Native System and Cultured Cell Electrophysiology for Investigating Anesthetic Mechanisms.

Anesthetic agents interact with a variety of ion channels and membrane-bound receptors, often at agent-specific binding sites of a single protein. These molecular-level interactions are ultimately responsible for producing the clinically anesthetized state. Between these two scales of effect, anesthetic agents can be studied in terms of how they impact the physiology of neuronal circuits, individual neurons, and cells expressing individual receptor types. The acutely dissected hippocampal slice is one of the most extensively studied and characterized preparations of intact neural tissue and serves as a highly useful experimental model system to test hypotheses of anesthetic mechanisms. Specific agent-receptor interactions and their effect on excitable membranes can further be defined with molecular precision in cell-based expression systems. We highlight several approaches in these respective systems that we have used and that also have been used by many investigators worldwide. We emphasize economy and quality control, to allow an experimenter to carry out these types of studies in a rigorous and efficient manner.

Combinatorial therapy with two pro-coagulants and one osmotic agent reduces the extent of the lesion in the acute phase of spinal cord injury in the rat

BackgroundSpinal cord injury (SCI) is a complex disease that leads to a motor, sensitive, and vegetative impairment. So far, single therapies are ineffective for treating SCI in humans and a multifactorial therapeutic approach may be required. The aim of this work was to assess the effect of a triple therapy (TT) associating two pro-coagulant therapies (tranexamic acid and fibrinogen) with an anti-edema therapy (hypertonic saline solution), on the extent of the lesion 24 h post-injury.MethodsThe design of this study is a randomized controlled study. The setting of this study is an experimental study.Male Wistar rats were assigned to receive saline solution for the control group or one of the treatment, or a combination of two treatments or the three treatments (triple therapy group (TT)). Animals were anesthetized and received a weight-drop SCI induced at the level of the 12th thoracic vertebra (Th12). They were treated by single therapies, double therapies, or TT started 5 min after the SCI.ResultsThe extent of the lesion was assessed 24 h after injury by spectrophotometry (quantification of parenchymal hemorrhage and blood-spinal cord barrier disruption) and by histology (quantification of spared neuronal tissue).As compared with the control group, the TT significantly reduced parenchymal hemorrhage (p < 0.05) and improved the total amount of intact neural tissue, measured 24 h later (p = 0.003).ConclusionsCombinatorial therapy associating two pro-coagulants (tranexamic acid and fibrinogen) with an anti-edema therapy (hypertonic saline solution) reduces the extent of the lesion in the acute phase of spinal cord injury in the rat.

Advances in research on combining the opotogenetics with bionic olfaction sensor

There are plenty of amazing wonders existing in nature, and the crisis-crossing connections between them are performing their best duties. For example, biological olfactory system is an ingenious biosensor, since the olfactory sensory neurons in peripheral nervous respond to the external stimuli, then the signals are transmitted to the olfactory bulb to be integrated and processed, the axonal connection is precisely organized signals from about 1000 different types of odorant receptors, then sorted out in 1800 glomeruli in the mouse olfactory bulb, after delivered to the most advanced central nervous system, the information can be distinguished eventually. Cortical regions underlying vision, audition, and somatosens- ation receive sensory information from the thalamus and also make corticothalamic feedback projections that influence thalamic sensory processing. This process is responding with particularly high sentivity, specificity and rapidity. The ability to detect odorants is crucial for survival as it informs an organism with its environment: food, approaching predators, mates nearby, etc. During recently year, researchers have employed optogenetics technology to explore deeper in the mechanism of olfactory system. Microbial proteins that can be rapidly activated by light have been adapted for research in neuroscience, including ChR2 and NpHR, which permit millisecond-precision optical control of genetically defined cell types in intact neural tissue. This technology allows the use of light to alter neural processing at the level of single spikes and synaptic events, yielding a widely applicable tool for neuroscientists and biomedical engineers. An important question in the study of the olfactory system is the role of spatial factors in olfactory processing, but traditional methods have been relatively unsuccessful in elucidating their theories, odor stimulation evokes complex spatiotemporal activity in the olfactory bulb, suggesting that both the identity of activated neurons and the timing of their activity convey information about odors, the emergency of optogenetics technology can solve this problem efficiently. Biological olfactory systems can recognize and discriminate thousands of distinct odors with very high sensitivity and specificity, with the progress of research on olfactory mechanisms and the advancements of olfaction, many types of biomimetic olfactory-based biosensors have been developed by the combination of olfactory functional components with various secondary sensors. The bioinspired olfaction sensor is an innovative chemical sensing bionic system with far-reaching significance, it contains various biological components as the sensitive elements including olfactory receptors, olfactory cells and olfactory tissues, which has great applicable prospects in many fields for detecting specific odorants with high sensitivity, also by chronically coupling multiple microelectrodes to olfactory bulb of behaving rats, we extract an array of mitral/tufted cells which could generate odor-specific temporal patterns of neural discharge. They have great potential commercial prospects and promising applications in such fields as biomedicine, environmental monitoring, pharmaceutical screening and the quality control of food and water. This review interpreted the transferring mechanism of biological olfactory system and the applications of optogenetics in researches concerning the foundamental research of olfactory system. In addition, a combination of the work of our laboratory with other domestic and international researchers were presented here to predict the future scenario and the promising applications in disease diagnosis, environmental monitoring, military and food quality control.

Do focal brain lesions have distant effects on intact neural tissue?

Event Abstract Back to Event Do focal brain lesions have distant effects on intact neural tissue? Yuan Tao1* and Brenda Rapp1 1 Johns Hopkins University, Cognitive Science Department, United States Introduction. The remote effects of focal brain lesions (“diaschisis”) have long been of interest for clinical reasons and for understanding neural connectivity and modularity. Recent computer simulation work in connectomics predicts that lesions affecting highly connected brain areas within the frontal and parietal lobes and midline structures should have effects on the functioning of distant, intact cortical areas in both hemispheres (Honey & Sporns, 2008). However, these predictions have not been evaluated with neuroimaging data from individuals with brain lesions. In this study, we examined individuals with acquired dysgraphia as a result of left hemisphere stroke. Their lesions affected left frontal, parietal or superior temporal areas that have been predicted should produce diaschisis. Using fMRI, we evaluated activation patterns during two tasks: spelling and face processing. These tasks were selected because the brain-lesioned individuals had spelling deficits but normal performance in face processing. Furthermore, both tasks involve key brain regions in ventral occipito-temporal cortices that were preserved in the brain-lesioned participants. This allowed to us to examine whether or not focal brain lesions necessarily produce disruption in neural activation in distant, intact neural substrates. Methods and Results. The dysgraphic participants (n=18) had a mean age of 63, and had suffered a single left hemisphere stroke, at least one year before the investigation. The neurotypical participants (n=30) ranged in age from 30 to 69. All participants carried out spelling and face processing tasks during fMRI scanning. In the spelling task, on each trial participants were asked to judge if a visually presented letter was in the spelling of a heard word. In the face processing task, participants viewed blocks of faces, object, scenes, and scrambled images. Group-level GLM analyses for spelling indicated that the dysgraphic group failed to show the activation in left mid-fusiform gyrus exhibited by the control group (Fig.1). In contrast, the dysgraphic group exhibited similar face processing activation patterns as control participants in bilateral occipital and fusiform areas. Comparable results were observed when individual participant activation patterns were evaluated. Discussion. Our findings suggest that non-local, distant disruption of BOLD response is not a necessary consequence of focal brain lesions, supporting the notion of a significant degree of modular neural organization. Furthermore, the results suggest that distant disruption may be “context dependent”, in that it is modulated by the functional relationships between lesioned and intact substrates. However, firm conclusions will require more detailed analysis of neural responsivity in distant, intact areas, including measures of functional and structure network connectivity. Acknowledgements The research reported here was part of a larger, multi-site NIH-funded P50 project examining the neurobiology of language recovery in people with aphasia (DC 012283). We thank all of the research participants, and Jennifer Shea and Donna Gotsch for data collection. References Honey, C. & Sporns, O. (2008). Dynamical consequences of lesions in cortical networks. Human Brain Mapping, 29, 802-809. Keywords: dysgraphia, lesion, face processing, VWFA, diaschisis Conference: Academy of Aphasia 55th Annual Meeting , Baltimore, United States, 5 Nov - 7 Nov, 2017. Presentation Type: poster presentation Topic: General Submission Citation: Tao Y and Rapp B (2019). Do focal brain lesions have distant effects on intact neural tissue?. Conference Abstract: Academy of Aphasia 55th Annual Meeting . doi: 10.3389/conf.fnhum.2017.223.00016 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 04 May 2017; Published Online: 25 Jan 2019. * Correspondence: Dr. Yuan Tao, Johns Hopkins University, Cognitive Science Department, Baltimore, MD, 21210, United States, yuan.tao@jhu.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Yuan Tao Brenda Rapp Google Yuan Tao Brenda Rapp Google Scholar Yuan Tao Brenda Rapp PubMed Yuan Tao Brenda Rapp Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Arterial spin labelling shows functional depression of non-lesion tissue in chronic Wernicke's aphasia

Behavioural impairment post-stroke is a consequence of structural damage and altered functional network dynamics. Hypoperfusion of intact neural tissue is frequently observed in acute stroke, indicating reduced functional capacity of regions outside the lesion. However, cerebral blood flow (CBF) is rarely investigated in chronic stroke. This study investigated CBF in individuals with chronic Wernicke's aphasia (WA) and examined the relationship between lesion, CBF and neuropsychological impairment.Arterial spin labelling CBF imaging and structural MRIs were collected in 12 individuals with chronic WA and 13 age-matched control participants. Joint independent component analysis (jICA) investigated the relationship between structural lesion and hypoperfusion. Partial correlations explored the relationship between lesion, hypoperfusion and language measures.Joint ICA revealed significant differences between the control and WA groups reflecting a large area of structural lesion in the left posterior hemisphere and an associated area of hypoperfusion extending into grey matter surrounding the lesion. Small regions of remote cortical hypoperfusion were observed, ipsilateral and contralateral to the lesion. Significant correlations were observed between the neuropsychological measures (naming, repetition, reading and semantic association) and the jICA component of interest in the WA group. Additional ROI analyses found a relationship between perfusion surrounding the core lesion and the same neuropsychological measures.This study found that core language impairments in chronic WA are associated with a combination of structural lesion and abnormal perfusion in non-lesioned tissue. This indicates that post-stroke impairments are due to a wider disruption of neural function than observable on structural T1w MRI.

Methods to identify and analyze gene products involved in neuronal intracellular transport using Drosophila.

Proper neuronal function critically depends on efficient intracellular transport and disruption of transport leads to neurodegeneration. Molecular pathways that support or regulate neuronal transport are not fully understood. A greater understanding of these pathways will help reveal the pathological mechanisms underlying disease. Drosophila melanogaster is the premier model system for performing large-scale genetic functional screens. Here we describe methods to carry out primary and secondary genetic screens in Drosophila aimed at identifying novel gene products and pathways that impact neuronal intracellular transport. These screens are performed using whole animal or live cell imaging of intact neural tissue to ensure integrity of neurons and their cellular environment. The primary screen is used to identify gross defects in neuronal function indicative of a disruption in microtubule-based transport. The secondary screens, conducted in both motoneurons and dendritic arborization neurons, will confirm the function of candidate gene products in intracellular transport. Together, the methodologies described here will support labs interested in identifying and characterizing gene products that alter intracellular transport in Drosophila.

The fibrotic scar in neurological disorders.

Tissue fibrosis, or scar formation, is a common response to damage in most organs of the body. The central nervous system (CNS) is special in that fibrogenic cells are restricted to vascular and meningeal niches. However, disruption of the blood-brain barrier and inflammation can unleash stromal cells and trigger scar formation. Astroglia segregate from the inflammatory lesion core, and the so-called "glial scar" composed of hypertrophic astrocytes seals off the intact neural tissue from damage. In the lesion core, a second type of "fibrotic scar" develops, which is sensitive to inflammatory mediators. Genetic fate mapping studies suggest that pericytes and perivascular fibroblasts are activated, but other precursor cells may also be involved in generating a transient fibrous extracellular matrix in the CNS. The stromal cells sense inflammation and attract immune cells, which in turn drive myofibroblast transdifferentiation. We believe that the fibrotic scar represents a major barrier to CNS regeneration. Targeting of fibrosis may therefore prove to be a valuable therapeutic strategy for neurological disorders such as stroke, spinal cord injury and multiple sclerosis.

Neuroscience Findings on Coordination of Reaching to Grasp an Object

Background. Knowledge of how damage to brain regions and pathways affects central nervous system control of coordination of reach-to-grasp (RTG) following stroke may not be sufficiently used in existing treatment interventions or in research that assesses their effectiveness. Objective. To review current knowledge of motor control of coordination of RTG and discuss the extent to which this information is being used in research evaluating treatment interventions. Method. This review (1) summarizes the current knowledge of motor control of RTG coordination in healthy individuals, including speculative models and structures of the brain identified as being involved; (2) summarizes evidence of RTG coordination deficits in people with stroke; (3) evaluates current interventions directed at retraining coordination of RTG, including a review of the extent to which these interventions are based on putative neurobiological mechanisms and reports on their effectiveness; and (4) recommends directions for research on treatment interventions for coordination of RTG. Results. Functional task-specific therapy, electrical stimulation, and robot or computerized training were identified as treatments targeted at improving coordination of RTG. However, none of the studies reporting the effect of these interventions related results to individual brain regions affected, and neurobiological mechanisms underlying improved performance were only minimally discussed. Conclusions. Research on treatment interventions for coordination of RTG needs to combine measures of interruption to brain networks and how remaining intact neural tissue and networks respond to therapy with measures of spatiotemporal motor control and upper-limb function to gain a fuller understanding of treatment effects and their mechanisms.

Cut-loading: A Useful Tool for Examining the Extent of Gap Junction Tracer Coupling Between Retinal Neurons

In addition to chemical synaptic transmission, neurons that are connected by gap junctions can also communicate rapidly via electrical synaptic transmission. Increasing evidence indicates that gap junctions not only permit electrical current flow and synchronous activity between interconnected or coupled cells, but that the strength or effectiveness of electrical communication between coupled cells can be modulated to a great extent1,2. In addition, the large internal diameter (~1.2 nm) of many gap junction channels permits not only electric current flow, but also the diffusion of intracellular signaling molecules and small metabolites between interconnected cells, so that gap junctions may also mediate metabolic and chemical communication. The strength of gap junctional communication between neurons and its modulation by neurotransmitters and other factors can be studied by simultaneously electrically recording from coupled cells and by determining the extent of diffusion of tracer molecules, which are gap junction permeable, but not membrane permeable, following iontophoretic injection into single cells. However, these procedures can be extremely difficult to perform on neurons with small somata in intact neural tissue.Numerous studies on electrical synapses and the modulation of electrical communication have been conducted in the vertebrate retina, since each of the five retinal neuron types is electrically connected by gap junctions3,4. Increasing evidence has shown that the circadian (24-hour) clock in the retina and changes in light stimulation regulate gap junction coupling3-8. For example, recent work has demonstrated that the retinal circadian clock decreases gap junction coupling between rod and cone photoreceptor cells during the day by increasing dopamine D2 receptor activation, and dramatically increases rod-cone coupling at night by reducing D2 receptor activation7,8. However, not only are these studies extremely difficult to perform on neurons with small somata in intact neural retinal tissue, but it can be difficult to adequately control the illumination conditions during the electrophysiological study of single retinal neurons to avoid light-induced changes in gap junction conductance.Here, we present a straightforward method of determining the extent of gap junction tracer coupling between retinal neurons under different illumination conditions and at different times of the day and night. This cut-loading technique is a modification of scrape loading9-12, which is based on dye loading and diffusion through open gap junction channels. Scrape loading works well in cultured cells, but not in thick slices such as intact retinas. The cut-loading technique has been used to study photoreceptor coupling in intact fish and mammalian retinas7, 8,13, and can be used to study coupling between other retinal neurons, as described here.

Cut-loading: A Useful Tool for Examining the Extent of Gap Junction Tracer Coupling Between Retinal Neurons

In addition to chemical synaptic transmission, neurons that are connected by gap junctions can also communicate rapidly via electrical synaptic transmission. Increasing evidence indicates that gap junctions not only permit electrical current flow and synchronous activity between interconnected or coupled cells, but that the strength or effectiveness of electrical communication between coupled cells can be modulated to a great extent1,2. In addition, the large internal diameter (~1.2 nm) of many gap junction channels permits not only electric current flow, but also the diffusion of intracellular signaling molecules and small metabolites between interconnected cells, so that gap junctions may also mediate metabolic and chemical communication. The strength of gap junctional communication between neurons and its modulation by neurotransmitters and other factors can be studied by simultaneously electrically recording from coupled cells and by determining the extent of diffusion of tracer molecules, which are gap junction permeable, but not membrane permeable, following iontophoretic injection into single cells. However, these procedures can be extremely difficult to perform on neurons with small somata in intact neural tissue. Numerous studies on electrical synapses and the modulation of electrical communication have been conducted in the vertebrate retina, since each of the five retinal neuron types is electrically connected by gap junctions3,4. Increasing evidence has shown that the circadian (24-hour) clock in the retina and changes in light stimulation regulate gap junction coupling3-8. For example, recent work has demonstrated that the retinal circadian clock decreases gap junction coupling between rod and cone photoreceptor cells during the day by increasing dopamine D2 receptor activation, and dramatically increases rod-cone coupling at night by reducing D2 receptor activation7,8. However, not only are these studies extremely difficult to perform on neurons with small somata in intact neural retinal tissue, but it can be difficult to adequately control the illumination conditions during the electrophysiological study of single retinal neurons to avoid light-induced changes in gap junction conductance. Here, we present a straightforward method of determining the extent of gap junction tracer coupling between retinal neurons under different illumination conditions and at different times of the day and night. This cut-loading technique is a modification of scrape loading9-12, which is based on dye loading and diffusion through open gap junction channels. Scrape loading works well in cultured cells, but not in thick slices such as intact retinas. The cut-loading technique has been used to study photoreceptor coupling in intact fish and mammalian retinas7, 8,13, and can be used to study coupling between other retinal neurons, as described here.

Erythropoietin Augments Survival of Glioma Cells After Radiation and Temozolomide

Despite beneficial effects of irradiation/chemotherapy on survival of glioblastoma (GBM) patients, collateral damage to intact neural tissue leads to "radiochemobrain" and reduced quality of life in survivors. For prophylactic neuroprotection, erythropoietin (EPO) is a promising candidate, provided that concerns regarding potential tumor promoting effects are alleviated. Human GBM-derived cell lines U87, G44, G112, and the gliosarcoma-derived line G28 were treated with EPO, with and without combinations of irradiation or temozolomide (TMZ). Responsiveness of glioma cells to EPO was measured by cell migration from spheroids, cell proliferation, and clonogenic survival. Implantation of U87 cells into brains of nude mice, followed 5 days later by EPO treatment (5,000 U/kg intraperitoneal every other day for 2 weeks) should reveal effects of EPO on tumor growth in vivo. Reverse transcriptase-polymerase chain reaction was performed for EPOR, HIF-1alpha, and epidermal growth factor receptor (EGFR)vIII in cell lines and 22 human GBM specimens. EPO did not modulate basal glioma cell migration and stimulated proliferation in only one of four cell lines. Importantly, EPO did not enhance tumor growth in mouse brains. Preincubation of glioma cells with EPO for 3 h, followed by irradiation and TMZ for another 24 h, resulted in protection against chemoradiation-induced cytotoxicity in three cell lines. Conversely, EPO induced a dose-dependent decrease in survival of G28 gliosarcoma cells. In GBM specimens, expression of HIF-1alpha correlated positively with expression of EPOR and EGFRvIII. EPOR and EGFRvIII expression did not correlate. EPO is unlikely to appreciably influence basal glioma growth. However, concomitant use of EPO with irradiation/chemotherapy in GBM patients is not advisable.

Principles of Two-Photon Excitation Microscopy and Its Applications to Neuroscience

The brain is complex and dynamic. The spatial scales of interest to the neurobiologist range from individual synapses (approximately 1 microm) to neural circuits (centimeters); the timescales range from the flickering of channels (less than a millisecond) to long-term memory (years). Remarkably, fluorescence microscopy has the potential to revolutionize research on all of these spatial and temporal scales. Two-photon excitation (2PE) laser scanning microscopy allows high-resolution and high-sensitivity fluorescence microscopy in intact neural tissue, which is hostile to traditional forms of microscopy. Over the last 10 years, applications of 2PE, including microscopy and photostimulation, have contributed to our understanding of a broad array of neurobiological phenomena, including the dynamics of single channels in individual synapses and the functional organization of cortical maps. Here we review the principles of 2PE microscopy, highlight recent applications, discuss its limitations, and point to areas for future research and development.

Proerectile pharmacological prophylaxis following nerve-sparing radical prostatectomy (NSRP).

The importance of an early pharmacological prophylaxis for erectile function following nerve-sparing radical prostatectomy has been recently stressed by several authors. In spite of that, patient's compliance to erectile rehabilitation protocols seems to be low. The present review is an attempt to define the expected benefits of the currently proposed rehabilitative protocols in terms of cost-efficiency and quality of life. The conclusion is that current scientific evidence in support of an early postoperative use of erectile aids is based mainly on indirect proof of a cavernosal damage that may follow the temporary postoperative 'erectile silence'. Intracavernosal injections or a vacuum device may represent the best first-line treatment option for the first few months from the procedure as their mechanism of action does not require intact neural tissue for erection. Thereafter oral phosphodiesterase 5 inhibitor therapy may be a reasonable choice for those patients who can achieve at least a partial erection. A phosphodiesterase 5 inhibitor may not be effective when spontaneous erections are absent. It is possible, since the rehabilitation of sexual function aims to prevent cavernosal tissue damage by providing oxygenation to the erectile tissue, the choice of a potentially ineffective treatment may jeopardize the results of a reasonable nerve-sparing procedure.

Retain or sacrifice the posterior cruciate ligament in total knee arthroplasty? A histopathological study of the cruciate ligament in osteoarthritic and rheumatoid disease

Background—The decision whether to retain or resect the posterior cruciate ligament in total knee arthroplasty is at present determined clinically by preoperative radiological variables focusing upon the amount of joint...

Computerized biofeedback training aids in spinal injury rehabilitation

Motor learning by trial error—the result of biofeedback training that uses essentially the same method people employ unconsciously in learning to ride a bicycle—may be a key to more mobility for many persons with spinal cord injury, according to a report made at the National Spinal Cord Injury Association convention in Boston. Bernard S. Brucker, PhD, assistant professor of orthopedics rehabilitation director of the BBiofeedback Laboratory at Jackson Memorial Rehabilitation Center, University of Miami (Fla) School of Medicine, told the assembled group of physicians other medical scientists, physical therapists, nurses, patients in wheelchairs that computerized biofeedback techniques offer the best means yet for training spinally injured persons—with some intact neural tissue—to activate useful motion in their limbs. Patients are taught to take the focus off the limb, Brucker explains, and put it on neurosignal combinations. Almost all rehabilitation centers use biofeedback techniques to some extent. However,