[Regularities of interaction between neural analyzers (a review of the literature)].
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Emotions↗
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Analyzing neural responses to natural signals: maximally informative dimensions.
We propose a method that allows for a rigorous statistical analysis of neural responses to natural stimuli that are nongaussian and exhibit strong correlations. We have in mind a model in which neurons are selective for a small number of stimulus dimensions out of a high-dimensional stimulus space, but within this subspace the responses can be arbitrarily nonlinear. Existing analysis methods are based on correlation functions between stimuli and responses, but these methods are guaranteed to work only in the case of gaussian stimulus ensembles. As an alternative to correlation functions, we maximize the mutual information between the neural responses and projections of the stimulus onto low-dimensional subspaces. The procedure can be done iteratively by increasing the dimensionality of this subspace. Those dimensions that allow the recovery of all of the information between spikes and the full unprojected stimuli describe the relevant subspace. If the dimensionality of the relevant subspace indeed is small, it becomes feasible to map the neuron's input-output function even under fully natural stimulus conditions. These ideas are illustrated in simulations on model visual and auditory neurons responding to natural scenes and sounds, respectively.
Acoustic Stimulation↗
A validity study of the Neural Efficiency Analyzer in relation to selected measures of intelligence.
This study attempted to determine the validity of the Ertl Neural Efficiency Analyzer as a measure of intellectual ability by using NEA-Alpha and Neural Efficiency scores to predict collage grade point average (GPA) both alone and in combination with paper-and-pencil measures of intelligence for 22 male and 64 female college students. Results indicate that NEA-Alpha scores can predict GPA with moderate sucess and also that NEA-Alpha scores account for variability in grade point average not associated with paper-and-pencil tests.
Adult↗
Optimization of the kernel functions in a probabilistic neural network analyzing the local pattern distribution.
This article proposes a procedure for the automatic determination of the elements of the covariance matrix of the gaussian kernel function of probabilistic neural networks. Two matrices, a rotation matrix and a matrix of variances, can be calculated by analyzing the local environment of each training pattern. The combination of them will form the covariance matrix of each training pattern. This automation has two advantages: First, it will free the neural network designer from indicating the complete covariance matrix, and second, it will result in a network with better generalization ability than the original model. A variation of the famous two-spiral problem and real-world examples from the UCI Machine Learning Repository will show a classification rate not only better than the original probabilistic neural network but also that this model can outperform other well-known classification techniques.
Neural Networks, Computer↗
Neural efficiency analyzer scores of reading disabled, normally reading and academically superior children.
Usefulness, under field-testing conditions, of one version of a Neural Efficiency Analygated. The equipment was said to measure efficiency of information processing as reflected in time between alternate EEG falling zero-crossing points. Special emphasis was placed on the difference score, a measure of right-left hemisphere "efficiency" differences. Contrary to earlier reports, no significant differences were found between such scores of groups of reading disabled, normally reading, and academically superior children. Possible reasons for the negative findings are explored.
Achievement↗
Pulmonary function changes in asthmatics associated with low-level SO2 and NO2 air pollution, weather, and medicine intake. An 8-month prospective study analyzed by neural networks.
This paper presents the response in subjects with asthma to gaseous air-pollution levels, weather, and medicine intake as identified by principal-component analysis and neural network techniques. Pulmonary function measured by respiratory peak-flow rate in nonallergic asthmatics was associated with ambient, low-level, air-pollution concentrations of sulfur dioxide and nitrogen dioxide, temperature, relative humidity, and medicine intake. Results from 27 nonallergic asthmatics aged 18-60 years with well-characterized bronchial asthma and regular medical treatment were analyzed from two cities. During an 8-month period, each subject kept a diary table, which included symptoms, lung function (evening peak flow), medicine intake, and tobacco smoking. High intake of medicine and high ambient temperatures corresponded to decreased peak flow. The changes in temperature did not occur in situations with low medicine intake. During frost periods, peak-flow values decreased independently of medicine intake and levels of SO2. During other times, increased levels of SO2 and NO2 increased temperature, and increased intake of medicine, and low relative humidity corresponded to decreased peak flow. Increased levels of SO2 and NO2 corresponded synergistically to decreased peak flow at levels above 40 micrograms/m3.
Adolescent↗
Changes in protein expression during neural development analyzed by two-dimensional gel electrophoresis.
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Animals↗
THE ROLE OF A DIGITAL COMPUTER AS A BIOLOGICAL INSTRUMENT.
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Animals↗
The inversion of sensory processing by feedback pathways: a model of visual cognitive functions.
The mammalian visual system has a hierarchic structure with extensive reciprocal connections. A model is proposed in which the feedback pathways serve to modify afferent sensory stimuli in ways that enhance and complete sensory input patterns, suppress irrelevant features, and generate quasi-sensory patterns when afferent stimulation is weak or absent. Such inversion of sensory coding and feature extraction can be achieved by optimization processes in which scalar responses derived from high-level neural analyzers are used as cost functions to modify the filter properties of more peripheral sensory relays. An optimization algorithm, Alopex, which is used in the model, is readily implemented with known neural circuitry. The functioning of the system is investigated by computer simulations.
Algorithms↗
Information-geometric measure for neural spikes.
This study introduces information-geometric measures to analyze neural firing patterns by taking not only the second-order but also higher-order interactions among neurons into account. Information geometry provides useful tools and concepts for this purpose, including the orthogonality of coordinate parameters and the Pythagoras relation in the Kullback-Leibler divergence. Based on this orthogonality, we show a novel method for analyzing spike firing patterns by decomposing the interactions of neurons of various orders. As a result, purely pairwise, triple-wise, and higher-order interactions are singled out. We also demonstrate the benefits of our proposal by using several examples.
Action Potentials↗
Isolation of an early neural maker gene abundantly expressed in the nervous system of the ascidian, Halocynthia roretzi.
Ascidian tadpole larvae possess a primitive nervous system, which is a prospective prototype of the chordate nervous system. It is composed of relatively few cells but sufficient for complex larval behavior. Here we report on HrETR-1, a gene zygotically expressed in a large proportion of the developing neural cells of the ascidian, Halocynthia roretzi. HrETR-1 is an early neural marker which can be used for analyzing neural differentiation. HrETR-1 expression intensified in most neural cells of genes isolated to date, in both central and peripheral nervous systems including palps as early as the 110-cell stage. Using this gene as a probe, we characterized neural cells in the nervous system as well as confirming their origins. Also, we recognized three types of peripheral epidermal neurons which presumably correlate to the larval neurons previously reported for another ascidian. Among these, five bilateral neurons located in the anterior region of the trunk appeared to be derived from a8.26 blastomeres.
Amino Acid Sequence↗
Differentiation of rat neural tissue in a serum-free embryo culture model followed by in vivo transplantation.
AIM: To analyze neural tissue differentiation in a unique, chemically-defined in vitro culture model of gastrulating rat embryo proper by use of transmission electron microscopy (TEM), proliferating cell nuclear antigen (PCNA) expression, and in vivo transplantation after a 2-week culture in serum-free or serum-supplemented media. Influence of protein-free medium unfavorable for differentiation of neural tissue in vitro was compared with favorable serum-free media enriched with transferrin or albumin. Differentiation of mesodermal derivatives in transplants was also investigated. METHODS: We cultivated 9.5-day-old Fischer rat embryos on the gas-liquid interface in the protein-free Eagle's Minimum Essential Medium (MEM), in MEM with either iron-saturated holotransferrin (50 microg/mL) or iron-free apotransferrin (50 microg/mL), and in medium saturated with either bovine serum albumin (BSA) (4 mg/mL or 400 microg/mL) or rat serum (50%). After the two-week culture period, light microscopy, TEM, and immunohistochemical method for detection of PCNA were done. Some explants were transplanted under the kidney capsule of adult male rats to be cultured in vivo for additional two weeks. Chi-square test or Fisher exact test were used to compare the proportion of tissues developed. RESULTS: Proportion of differentiated neural tissue was similar in explants cultivated in apotransferrin- and holotransferrin-supplemented media (13/33 and 9/20, respectively), but higher than in explants cultivated in protein-free medium (1/13). Neurons and glia cells produced a neuropil structure. Myelinization occurred only in serum-supplemented medium. PCNA expression was detected in a small number of neural tissue cells, even in serum-free cultivated embryos. Differentiation of brain-like tissue, cerebrospinal, and vegetative ganglionic cells occurred in all groups of transplants. However, in the transplants derived from protein-free medium, the proportion of neural tissue, cartilage, bone, skeletal and smooth muscle was significantly lower than in transferrin-supplemented media (p<0.01). Albumin seemed to promote differentiation of all tissues except vegetative ganglionic cells. CONCLUSION: Nerve tissue differentiated to a rather high degree in a two-week in vitro postimplantation embryo culture. Transferrin or albumin, as the only proteins used for serum-free precultivation, significantly improved subsequent differentiation of nerve tissue and mesodermal derivatives in transplants in vivo.
Animals↗
Lin(-)CD34(-) bone marrow cells from adult mice can differentiate into neural-like cells.
Numerous studies have shown that some populations of bone marrow cells (BMCs) have the capacity to differentiate into neural cells, which is useful for repairing brain lesions. In this paper, we analyze neural differentiation features of lineage-negative/CD34-negative (Lin(-)CD34(-)) cells in the bone marrow of adult mice. The population of Lin(-)CD34(-) in BMCs was isolated by magnetic bead sorting and fluorescence-activated cell sorter (FACS) using specific lineage (CD4, CD8a, CD11b, CD45R, Gr-1 and TER-119) antibodies and CD34 antibody. First, we cultured Lin(-)CD34(-) BMCs in the presence of RNIF: vitamin A derivative retinoic acid (RA) and neural-inducing factors (platelet-derived growth factor BB (PDGF-BB), epidermal growth factor (EGF) and fibroblast growth factor-basic (FGF-b)). Analyses of RT-PCR and immunocytochemistry indicated that RNIF-treated Lin(-)CD34(-) BMCs expressed neural phenotypes as well as neurogenic transcription factors. When we implanted the Lin(-)CD34(-) BMCs isolated from enhanced green fluorescent protein (eGFP) transgenic mice into the subventricular zone (SVZ) of postnatal mice, eGFP-positive cells survived 3 weeks after the injection in the various brain regions, some of which expressed the neural phenotypes. Our data suggest that certain subsets in the CD34(-) populations of adult bone marrow could have the capacity to differentiate into neural cells in a suitable environment.
Animals↗
Fear-potentiated startle: a neural and pharmacological analysis.
The fear-potentiated startle paradigm has proven to be a useful system with which to analyze neural systems involved in fear and anxiety. This test measures conditioned fear by an increase in the amplitude of a simple reflex (the acoustic startle reflex) in the presence of a cue previously paired with a shock. Fear-potentiated startle is sensitive to a variety of drugs such as diazepam, morphine, and buspirone that reduce anxiety in people and can be measured reliably in humans when the eyeblink component of startle is elicited at a time when they are anticipating a shock. Electrical stimulation techniques suggest that a visual conditioned stimulus ultimately alters acoustic startle at a specific point along the acoustic startle pathway. The lateral, basolateral and central amygdaloid nuclei and the caudal branch of the ventral amygdalofugal pathway projecting to the brainstem are necessary for potentiated startle to occur. The central nucleus of the amygdala projects directly to one of the brainstem nuclei critical for startle and electrical stimulation of this nucleus increases startle amplitude. Chemical or electrolytic lesions of either the central nucleus or the lateral and basolateral nuclei of the amygdala block the expression of fear-potentiated startle. The perirhinal cortex, which projects directly to the lateral and basolateral amygdaloid nuclei, plays a critical role in the expression of fear-potentiated startle using either visual or auditory conditioned stimuli. These latter amygdaloid nuclei may actually be the site of plasticity for fear conditioning, because local infusion of the NMDA antagonist AP5 into these nuclei blocks the acquisition of fear-potentiated startle. On the other hand, the expression of fear-potentiated startle is blocked by local infusion of the non-NMDA ionotropic antagonist CNQX or the G-protein inactivating toxin, pertussis toxin, but not by AP5. Finally, we have begun to investigate brain systems that might be involved in the inhibition of fear. Local infusion of AP5 into the amygdala was found to block the acquisition of experimental extinction, a prototypical method for reducing fear. We have also established a reliable procedure for producing both external and conditioned inhibition of fear-potentiated startle and hope to eventually understand the neural systems involved in these phenomena.
Animals↗
Promoter analysis in ES cell-derived neural cells.
Neural cells derived from ES cells in cell culture (ESNCs) have many of the properties of normal neural cells and provide a model of "neurogenesis-in-a-dish." Here we show that ESNCs provide a powerful system for analyzing neural gene transcription. ES cells are transfected with bacterial artificial chromosomes (BACs) containing Olig2, a gene with a key role in neural fate choice. One BAC is modified by recombineering to insert a reporter gene and a gene for selecting stably transfected clones. Another BAC contains a deletion of a suspected Olig2 promoter. Stable transgenic clones of ES cells are isolated, differentiated in culture, and the expression of transgenes is assayed. Differentiated cells dramatically up-regulate transgene expression and a deletion analysis reveals a basal promoter for Olig2. The combination of ESNCs and BAC recombineering will have broad application for analyzing gene transcription in the nervous system and will be applicable to human ES cells. The general approach should also be applicable to the many other cell lineages that can now be derived from mouse and human ES cells in culture.
Animals↗
Transforming growth factor beta-SMAD2 signaling regulates aortic arch innervation and development.
Aortic arch interruptions in humans and animal models are mainly caused by aberrant development of the fourth pharyngeal arch artery. Little is known about the maturation of this vessel during normal and abnormal development, which is the subject of this study. Tgfbeta2 knockout mice that present with fourth artery defects have been associated with defective neural crest cell migration. In this study, we concentrated on pharyngeal arch artery development during developmental days 12.5 to 18.5, focusing on neural crest cell migration using a Wnt1-Cre by R26R neural crest cell reporter mouse. Fourth arch artery maturation was studied with antibodies directed against smooth muscle alpha-actin and neural NCAM-1 and RMO-270. For diminished transforming growth factor beta (TGF-beta) signaling, SMAD2 and fibronectin have been analyzed. Neural crest migration and differentiation into smooth muscle cells is unaltered in mutants, regardless of the cardiovascular defect found; however, innervation of the fourth arch artery is affected. Absent staining for nuclear SMAD2, NCAM-1, and RMO-270 in the fourth artery in mutant coincides with severe defects of this segment. Likewise, fibronectin expression is diminished in these cases. From these data we conclude the following: (1) neural crest cell migration is not a common denominator in cardiovascular defects of Tgfbeta2-/- mice; (2) fourth arch artery maturation is a complex process involving innervation; and (3) TGF-beta2 depletion diminishes SMAD2-signaling in the fourth arch artery and coincides with reduced vascular NCAM-1 expression and neural innervation of this artery. We hypothesize that disturbed maturation of the fourth pharyngeal arch artery, and especially abrogated vascular innervation, will result in fourth arch interruptions.
Abnormalities, Multiple↗
[Airway occlusion pressure during sleep in normal subjects].
Sleep has been shown to be associated with a variety of changes in ventilatory mechanics. Recently, airway occlusion pressure (P0.1) has come to be widely used as an index of the neural output of the respiratory center, and is considered to be independent of lung mechanics. The purpose of this study was to analyze neural output of the respiratory center during sleep, utilizing an airway occlusion pressure procedure. Nine normal male subjects, 19 to 32 yrs of age, were used. Each subject was fitted with a face mask, and the area between the mask and the face was sealed with medical silicone rubber. They breathed through the mask, which was attached to a "J" valve that separated the inspiratory from the expiratory line. A radio-controlled camera shutter was joined to the "J" valve on the inspiratory line. The volume of dead space of this system was about 150 ml. Inspiratory pressure developing in the oral cavity was measured using a pressure transducer and a photocorder. Flow rate, tidal volume (VT) and inspiratory time (TI) were measured using a hot wire flow meter. Airway occlusion pressure (P0.1) was measured 0.1 second after the onset of the inspiratory effort by occluding the shutter on the inspiratory line during expiration. The onset of inspiration and expiration was detected by changes in airway pressure. Great care was taken to make the subjects as comfortable as possible during the procedure. Continuous recordings were made on a polygraph recorder of EEG, EOG, EMG and cardiorespiratory variables. Sleep stages were determined using the standard criteria.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
A method for spike sorting and detection based on wavelet packets and Shannon's mutual information.
Studying the dynamics of neural activity via electrical recording, relies on the ability to detect and sort neural spikes recorded from a number of neurons by the same electrode. We suggest the wavelet packets decomposition (WPD) as a tool to analyze neural spikes and extract their main features. The unique quality of the wavelet packets-adaptive coverage of both time and frequency domains using a set of localized packets, facilitate the task. The best basis algorithm utilizing the Shannon's information cost function and local discriminant basis (LDB) using mutual information are employed to select a few packets that are sufficient for both detection and sorting of spikes. The efficiency of the method is demonstrated on data recorded from in vitro 2D neural networks, placed on electrodes that read data from as many as five neurons. Comparison between our method and the widely used principal components method and a sorting technique based on the ordinary wavelet transform (WT) shows that our method is more efficient both in separating spikes from noise and in resolving overlapping spikes.
Action Potentials↗